memcontrol.c 190.6 KB
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/* memcontrol.c - Memory Controller
 *
 * Copyright IBM Corporation, 2007
 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
 *
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 * Copyright 2007 OpenVZ SWsoft Inc
 * Author: Pavel Emelianov <xemul@openvz.org>
 *
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 * Memory thresholds
 * Copyright (C) 2009 Nokia Corporation
 * Author: Kirill A. Shutemov
 *
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 * Kernel Memory Controller
 * Copyright (C) 2012 Parallels Inc. and Google Inc.
 * Authors: Glauber Costa and Suleiman Souhlal
 *
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 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/res_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/smp.h>
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#include <linux/page-flags.h>
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#include <linux/backing-dev.h>
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#include <linux/bit_spinlock.h>
#include <linux/rcupdate.h>
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#include <linux/limits.h>
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/rbtree.h>
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#include <linux/slab.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/spinlock.h>
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#include <linux/eventfd.h>
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#include <linux/poll.h>
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#include <linux/sort.h>
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#include <linux/fs.h>
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#include <linux/seq_file.h>
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#include <linux/vmpressure.h>
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#include <linux/mm_inline.h>
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#include <linux/page_cgroup.h>
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#include <linux/cpu.h>
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#include <linux/oom.h>
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#include <linux/lockdep.h>
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#include <linux/file.h>
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#include "internal.h"
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#include <net/sock.h>
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#include <net/ip.h>
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#include <net/tcp_memcontrol.h>
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#include "slab.h"
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#include <asm/uaccess.h>

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#include <trace/events/vmscan.h>

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struct cgroup_subsys memory_cgrp_subsys __read_mostly;
EXPORT_SYMBOL(memory_cgrp_subsys);
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#define MEM_CGROUP_RECLAIM_RETRIES	5
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static struct mem_cgroup *root_mem_cgroup __read_mostly;
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#ifdef CONFIG_MEMCG_SWAP
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/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
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int do_swap_account __read_mostly;
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/* for remember boot option*/
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#ifdef CONFIG_MEMCG_SWAP_ENABLED
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static int really_do_swap_account __initdata = 1;
#else
static int really_do_swap_account __initdata = 0;
#endif

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#else
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#define do_swap_account		0
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#endif


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static const char * const mem_cgroup_stat_names[] = {
	"cache",
	"rss",
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	"rss_huge",
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	"mapped_file",
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	"writeback",
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	"swap",
};

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enum mem_cgroup_events_index {
	MEM_CGROUP_EVENTS_PGPGIN,	/* # of pages paged in */
	MEM_CGROUP_EVENTS_PGPGOUT,	/* # of pages paged out */
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	MEM_CGROUP_EVENTS_PGFAULT,	/* # of page-faults */
	MEM_CGROUP_EVENTS_PGMAJFAULT,	/* # of major page-faults */
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	MEM_CGROUP_EVENTS_NSTATS,
};
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static const char * const mem_cgroup_events_names[] = {
	"pgpgin",
	"pgpgout",
	"pgfault",
	"pgmajfault",
};

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static const char * const mem_cgroup_lru_names[] = {
	"inactive_anon",
	"active_anon",
	"inactive_file",
	"active_file",
	"unevictable",
};

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/*
 * Per memcg event counter is incremented at every pagein/pageout. With THP,
 * it will be incremated by the number of pages. This counter is used for
 * for trigger some periodic events. This is straightforward and better
 * than using jiffies etc. to handle periodic memcg event.
 */
enum mem_cgroup_events_target {
	MEM_CGROUP_TARGET_THRESH,
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	MEM_CGROUP_TARGET_SOFTLIMIT,
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	MEM_CGROUP_TARGET_NUMAINFO,
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	MEM_CGROUP_NTARGETS,
};
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#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
#define NUMAINFO_EVENTS_TARGET	1024
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struct mem_cgroup_stat_cpu {
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	long count[MEM_CGROUP_STAT_NSTATS];
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	unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
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	unsigned long nr_page_events;
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	unsigned long targets[MEM_CGROUP_NTARGETS];
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};

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struct mem_cgroup_reclaim_iter {
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	/*
	 * last scanned hierarchy member. Valid only if last_dead_count
	 * matches memcg->dead_count of the hierarchy root group.
	 */
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	struct mem_cgroup *last_visited;
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	int last_dead_count;
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	/* scan generation, increased every round-trip */
	unsigned int generation;
};

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/*
 * per-zone information in memory controller.
 */
struct mem_cgroup_per_zone {
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	struct lruvec		lruvec;
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	unsigned long		lru_size[NR_LRU_LISTS];
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	struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];

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	struct rb_node		tree_node;	/* RB tree node */
	unsigned long long	usage_in_excess;/* Set to the value by which */
						/* the soft limit is exceeded*/
	bool			on_tree;
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	struct mem_cgroup	*memcg;		/* Back pointer, we cannot */
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						/* use container_of	   */
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};

struct mem_cgroup_per_node {
	struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
};

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/*
 * Cgroups above their limits are maintained in a RB-Tree, independent of
 * their hierarchy representation
 */

struct mem_cgroup_tree_per_zone {
	struct rb_root rb_root;
	spinlock_t lock;
};

struct mem_cgroup_tree_per_node {
	struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
};

struct mem_cgroup_tree {
	struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
};

static struct mem_cgroup_tree soft_limit_tree __read_mostly;

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struct mem_cgroup_threshold {
	struct eventfd_ctx *eventfd;
	u64 threshold;
};

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/* For threshold */
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struct mem_cgroup_threshold_ary {
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	/* An array index points to threshold just below or equal to usage. */
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	int current_threshold;
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	/* Size of entries[] */
	unsigned int size;
	/* Array of thresholds */
	struct mem_cgroup_threshold entries[0];
};
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struct mem_cgroup_thresholds {
	/* Primary thresholds array */
	struct mem_cgroup_threshold_ary *primary;
	/*
	 * Spare threshold array.
	 * This is needed to make mem_cgroup_unregister_event() "never fail".
	 * It must be able to store at least primary->size - 1 entries.
	 */
	struct mem_cgroup_threshold_ary *spare;
};

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/* for OOM */
struct mem_cgroup_eventfd_list {
	struct list_head list;
	struct eventfd_ctx *eventfd;
};
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/*
 * cgroup_event represents events which userspace want to receive.
 */
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struct mem_cgroup_event {
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	/*
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	 * memcg which the event belongs to.
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	 */
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	struct mem_cgroup *memcg;
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	/*
	 * eventfd to signal userspace about the event.
	 */
	struct eventfd_ctx *eventfd;
	/*
	 * Each of these stored in a list by the cgroup.
	 */
	struct list_head list;
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	/*
	 * register_event() callback will be used to add new userspace
	 * waiter for changes related to this event.  Use eventfd_signal()
	 * on eventfd to send notification to userspace.
	 */
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	int (*register_event)(struct mem_cgroup *memcg,
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			      struct eventfd_ctx *eventfd, const char *args);
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	/*
	 * unregister_event() callback will be called when userspace closes
	 * the eventfd or on cgroup removing.  This callback must be set,
	 * if you want provide notification functionality.
	 */
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	void (*unregister_event)(struct mem_cgroup *memcg,
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				 struct eventfd_ctx *eventfd);
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	/*
	 * All fields below needed to unregister event when
	 * userspace closes eventfd.
	 */
	poll_table pt;
	wait_queue_head_t *wqh;
	wait_queue_t wait;
	struct work_struct remove;
};

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static void mem_cgroup_threshold(struct mem_cgroup *memcg);
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
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/*
 * The memory controller data structure. The memory controller controls both
 * page cache and RSS per cgroup. We would eventually like to provide
 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
 * to help the administrator determine what knobs to tune.
 *
 * TODO: Add a water mark for the memory controller. Reclaim will begin when
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 * we hit the water mark. May be even add a low water mark, such that
 * no reclaim occurs from a cgroup at it's low water mark, this is
 * a feature that will be implemented much later in the future.
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 */
struct mem_cgroup {
	struct cgroup_subsys_state css;
	/*
	 * the counter to account for memory usage
	 */
	struct res_counter res;
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	/* vmpressure notifications */
	struct vmpressure vmpressure;

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	/*
	 * the counter to account for mem+swap usage.
	 */
	struct res_counter memsw;
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	/*
	 * the counter to account for kernel memory usage.
	 */
	struct res_counter kmem;
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	/*
	 * Should the accounting and control be hierarchical, per subtree?
	 */
	bool use_hierarchy;
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	unsigned long kmem_account_flags; /* See KMEM_ACCOUNTED_*, below */
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	bool		oom_lock;
	atomic_t	under_oom;
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	atomic_t	oom_wakeups;
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	int	swappiness;
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	/* OOM-Killer disable */
	int		oom_kill_disable;
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	/* set when res.limit == memsw.limit */
	bool		memsw_is_minimum;

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	/* protect arrays of thresholds */
	struct mutex thresholds_lock;

	/* thresholds for memory usage. RCU-protected */
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	struct mem_cgroup_thresholds thresholds;
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	/* thresholds for mem+swap usage. RCU-protected */
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	struct mem_cgroup_thresholds memsw_thresholds;
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	/* For oom notifier event fd */
	struct list_head oom_notify;
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	/*
	 * Should we move charges of a task when a task is moved into this
	 * mem_cgroup ? And what type of charges should we move ?
	 */
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	unsigned long move_charge_at_immigrate;
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	/*
	 * set > 0 if pages under this cgroup are moving to other cgroup.
	 */
	atomic_t	moving_account;
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	/* taken only while moving_account > 0 */
	spinlock_t	move_lock;
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	/*
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	 * percpu counter.
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	 */
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	struct mem_cgroup_stat_cpu __percpu *stat;
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	/*
	 * used when a cpu is offlined or other synchronizations
	 * See mem_cgroup_read_stat().
	 */
	struct mem_cgroup_stat_cpu nocpu_base;
	spinlock_t pcp_counter_lock;
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	atomic_t	dead_count;
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#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
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	struct cg_proto tcp_mem;
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#endif
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#if defined(CONFIG_MEMCG_KMEM)
	/* analogous to slab_common's slab_caches list. per-memcg */
	struct list_head memcg_slab_caches;
	/* Not a spinlock, we can take a lot of time walking the list */
	struct mutex slab_caches_mutex;
        /* Index in the kmem_cache->memcg_params->memcg_caches array */
	int kmemcg_id;
#endif
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	int last_scanned_node;
#if MAX_NUMNODES > 1
	nodemask_t	scan_nodes;
	atomic_t	numainfo_events;
	atomic_t	numainfo_updating;
#endif
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	/* List of events which userspace want to receive */
	struct list_head event_list;
	spinlock_t event_list_lock;

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	struct mem_cgroup_per_node *nodeinfo[0];
	/* WARNING: nodeinfo must be the last member here */
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};

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/* internal only representation about the status of kmem accounting. */
enum {
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	KMEM_ACCOUNTED_ACTIVE, /* accounted by this cgroup itself */
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	KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */
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};

#ifdef CONFIG_MEMCG_KMEM
static inline void memcg_kmem_set_active(struct mem_cgroup *memcg)
{
	set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}
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static bool memcg_kmem_is_active(struct mem_cgroup *memcg)
{
	return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}

static void memcg_kmem_mark_dead(struct mem_cgroup *memcg)
{
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	/*
	 * Our caller must use css_get() first, because memcg_uncharge_kmem()
	 * will call css_put() if it sees the memcg is dead.
	 */
	smp_wmb();
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	if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags))
		set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags);
}

static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg)
{
	return test_and_clear_bit(KMEM_ACCOUNTED_DEAD,
				  &memcg->kmem_account_flags);
}
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#endif

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/* Stuffs for move charges at task migration. */
/*
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 * Types of charges to be moved. "move_charge_at_immitgrate" and
 * "immigrate_flags" are treated as a left-shifted bitmap of these types.
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 */
enum move_type {
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	MOVE_CHARGE_TYPE_ANON,	/* private anonymous page and swap of it */
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	MOVE_CHARGE_TYPE_FILE,	/* file page(including tmpfs) and swap of it */
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	NR_MOVE_TYPE,
};

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/* "mc" and its members are protected by cgroup_mutex */
static struct move_charge_struct {
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	spinlock_t	  lock; /* for from, to */
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	struct mem_cgroup *from;
	struct mem_cgroup *to;
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	unsigned long immigrate_flags;
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	unsigned long precharge;
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	unsigned long moved_charge;
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	unsigned long moved_swap;
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	struct task_struct *moving_task;	/* a task moving charges */
	wait_queue_head_t waitq;		/* a waitq for other context */
} mc = {
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	.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
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	.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
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static bool move_anon(void)
{
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	return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags);
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}

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static bool move_file(void)
{
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	return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags);
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}

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/*
 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
 * limit reclaim to prevent infinite loops, if they ever occur.
 */
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#define	MEM_CGROUP_MAX_RECLAIM_LOOPS		100
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#define	MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS	2
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enum charge_type {
	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
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	MEM_CGROUP_CHARGE_TYPE_ANON,
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	MEM_CGROUP_CHARGE_TYPE_SWAPOUT,	/* for accounting swapcache */
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	MEM_CGROUP_CHARGE_TYPE_DROP,	/* a page was unused swap cache */
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	NR_CHARGE_TYPE,
};

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/* for encoding cft->private value on file */
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enum res_type {
	_MEM,
	_MEMSWAP,
	_OOM_TYPE,
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	_KMEM,
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};

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#define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
#define MEMFILE_TYPE(val)	((val) >> 16 & 0xffff)
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#define MEMFILE_ATTR(val)	((val) & 0xffff)
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/* Used for OOM nofiier */
#define OOM_CONTROL		(0)
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/*
 * Reclaim flags for mem_cgroup_hierarchical_reclaim
 */
#define MEM_CGROUP_RECLAIM_NOSWAP_BIT	0x0
#define MEM_CGROUP_RECLAIM_NOSWAP	(1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
#define MEM_CGROUP_RECLAIM_SHRINK_BIT	0x1
#define MEM_CGROUP_RECLAIM_SHRINK	(1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)

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/*
 * The memcg_create_mutex will be held whenever a new cgroup is created.
 * As a consequence, any change that needs to protect against new child cgroups
 * appearing has to hold it as well.
 */
static DEFINE_MUTEX(memcg_create_mutex);

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struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
{
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	return s ? container_of(s, struct mem_cgroup, css) : NULL;
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}

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/* Some nice accessors for the vmpressure. */
struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
{
	if (!memcg)
		memcg = root_mem_cgroup;
	return &memcg->vmpressure;
}

struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
{
	return &container_of(vmpr, struct mem_cgroup, vmpressure)->css;
}

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static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
{
	return (memcg == root_mem_cgroup);
}

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/*
 * We restrict the id in the range of [1, 65535], so it can fit into
 * an unsigned short.
 */
#define MEM_CGROUP_ID_MAX	USHRT_MAX

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static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
{
	/*
	 * The ID of the root cgroup is 0, but memcg treat 0 as an
	 * invalid ID, so we return (cgroup_id + 1).
	 */
	return memcg->css.cgroup->id + 1;
}

static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
	struct cgroup_subsys_state *css;

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	css = css_from_id(id - 1, &memory_cgrp_subsys);
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	return mem_cgroup_from_css(css);
}

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/* Writing them here to avoid exposing memcg's inner layout */
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#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
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void sock_update_memcg(struct sock *sk)
{
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	if (mem_cgroup_sockets_enabled) {
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		struct mem_cgroup *memcg;
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		struct cg_proto *cg_proto;
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		BUG_ON(!sk->sk_prot->proto_cgroup);

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		/* Socket cloning can throw us here with sk_cgrp already
		 * filled. It won't however, necessarily happen from
		 * process context. So the test for root memcg given
		 * the current task's memcg won't help us in this case.
		 *
		 * Respecting the original socket's memcg is a better
		 * decision in this case.
		 */
		if (sk->sk_cgrp) {
			BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
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			css_get(&sk->sk_cgrp->memcg->css);
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			return;
		}

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		rcu_read_lock();
		memcg = mem_cgroup_from_task(current);
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		cg_proto = sk->sk_prot->proto_cgroup(memcg);
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		if (!mem_cgroup_is_root(memcg) &&
		    memcg_proto_active(cg_proto) && css_tryget(&memcg->css)) {
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			sk->sk_cgrp = cg_proto;
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		}
		rcu_read_unlock();
	}
}
EXPORT_SYMBOL(sock_update_memcg);

void sock_release_memcg(struct sock *sk)
{
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	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
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		struct mem_cgroup *memcg;
		WARN_ON(!sk->sk_cgrp->memcg);
		memcg = sk->sk_cgrp->memcg;
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		css_put(&sk->sk_cgrp->memcg->css);
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	}
}
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struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
{
	if (!memcg || mem_cgroup_is_root(memcg))
		return NULL;

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	return &memcg->tcp_mem;
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}
EXPORT_SYMBOL(tcp_proto_cgroup);
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static void disarm_sock_keys(struct mem_cgroup *memcg)
{
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	if (!memcg_proto_activated(&memcg->tcp_mem))
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		return;
	static_key_slow_dec(&memcg_socket_limit_enabled);
}
#else
static void disarm_sock_keys(struct mem_cgroup *memcg)
{
}
#endif

613
#ifdef CONFIG_MEMCG_KMEM
614 615
/*
 * This will be the memcg's index in each cache's ->memcg_params->memcg_caches.
L
Li Zefan 已提交
616 617 618 619 620
 * The main reason for not using cgroup id for this:
 *  this works better in sparse environments, where we have a lot of memcgs,
 *  but only a few kmem-limited. Or also, if we have, for instance, 200
 *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
 *  200 entry array for that.
621 622 623 624 625 626
 *
 * The current size of the caches array is stored in
 * memcg_limited_groups_array_size.  It will double each time we have to
 * increase it.
 */
static DEFINE_IDA(kmem_limited_groups);
627 628
int memcg_limited_groups_array_size;

629 630 631 632 633 634
/*
 * MIN_SIZE is different than 1, because we would like to avoid going through
 * the alloc/free process all the time. In a small machine, 4 kmem-limited
 * cgroups is a reasonable guess. In the future, it could be a parameter or
 * tunable, but that is strictly not necessary.
 *
L
Li Zefan 已提交
635
 * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
636 637
 * this constant directly from cgroup, but it is understandable that this is
 * better kept as an internal representation in cgroup.c. In any case, the
L
Li Zefan 已提交
638
 * cgrp_id space is not getting any smaller, and we don't have to necessarily
639 640 641
 * increase ours as well if it increases.
 */
#define MEMCG_CACHES_MIN_SIZE 4
L
Li Zefan 已提交
642
#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX
643

644 645 646 647 648 649
/*
 * A lot of the calls to the cache allocation functions are expected to be
 * inlined by the compiler. Since the calls to memcg_kmem_get_cache are
 * conditional to this static branch, we'll have to allow modules that does
 * kmem_cache_alloc and the such to see this symbol as well
 */
650
struct static_key memcg_kmem_enabled_key;
651
EXPORT_SYMBOL(memcg_kmem_enabled_key);
652 653 654

static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
655
	if (memcg_kmem_is_active(memcg)) {
656
		static_key_slow_dec(&memcg_kmem_enabled_key);
657 658
		ida_simple_remove(&kmem_limited_groups, memcg->kmemcg_id);
	}
659 660 661 662 663
	/*
	 * This check can't live in kmem destruction function,
	 * since the charges will outlive the cgroup
	 */
	WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0);
664 665 666 667 668 669 670 671 672 673 674 675 676
}
#else
static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */

static void disarm_static_keys(struct mem_cgroup *memcg)
{
	disarm_sock_keys(memcg);
	disarm_kmem_keys(memcg);
}

677
static void drain_all_stock_async(struct mem_cgroup *memcg);
678

679
static struct mem_cgroup_per_zone *
680
mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
681
{
682
	VM_BUG_ON((unsigned)nid >= nr_node_ids);
683
	return &memcg->nodeinfo[nid]->zoneinfo[zid];
684 685
}

686
struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
687
{
688
	return &memcg->css;
689 690
}

691
static struct mem_cgroup_per_zone *
692
page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
693
{
694 695
	int nid = page_to_nid(page);
	int zid = page_zonenum(page);
696

697
	return mem_cgroup_zoneinfo(memcg, nid, zid);
698 699
}

700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857
static struct mem_cgroup_tree_per_zone *
soft_limit_tree_node_zone(int nid, int zid)
{
	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}

static struct mem_cgroup_tree_per_zone *
soft_limit_tree_from_page(struct page *page)
{
	int nid = page_to_nid(page);
	int zid = page_zonenum(page);

	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}

static void
__mem_cgroup_insert_exceeded(struct mem_cgroup *memcg,
				struct mem_cgroup_per_zone *mz,
				struct mem_cgroup_tree_per_zone *mctz,
				unsigned long long new_usage_in_excess)
{
	struct rb_node **p = &mctz->rb_root.rb_node;
	struct rb_node *parent = NULL;
	struct mem_cgroup_per_zone *mz_node;

	if (mz->on_tree)
		return;

	mz->usage_in_excess = new_usage_in_excess;
	if (!mz->usage_in_excess)
		return;
	while (*p) {
		parent = *p;
		mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
					tree_node);
		if (mz->usage_in_excess < mz_node->usage_in_excess)
			p = &(*p)->rb_left;
		/*
		 * We can't avoid mem cgroups that are over their soft
		 * limit by the same amount
		 */
		else if (mz->usage_in_excess >= mz_node->usage_in_excess)
			p = &(*p)->rb_right;
	}
	rb_link_node(&mz->tree_node, parent, p);
	rb_insert_color(&mz->tree_node, &mctz->rb_root);
	mz->on_tree = true;
}

static void
__mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
				struct mem_cgroup_per_zone *mz,
				struct mem_cgroup_tree_per_zone *mctz)
{
	if (!mz->on_tree)
		return;
	rb_erase(&mz->tree_node, &mctz->rb_root);
	mz->on_tree = false;
}

static void
mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
				struct mem_cgroup_per_zone *mz,
				struct mem_cgroup_tree_per_zone *mctz)
{
	spin_lock(&mctz->lock);
	__mem_cgroup_remove_exceeded(memcg, mz, mctz);
	spin_unlock(&mctz->lock);
}


static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
{
	unsigned long long excess;
	struct mem_cgroup_per_zone *mz;
	struct mem_cgroup_tree_per_zone *mctz;
	int nid = page_to_nid(page);
	int zid = page_zonenum(page);
	mctz = soft_limit_tree_from_page(page);

	/*
	 * Necessary to update all ancestors when hierarchy is used.
	 * because their event counter is not touched.
	 */
	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
		mz = mem_cgroup_zoneinfo(memcg, nid, zid);
		excess = res_counter_soft_limit_excess(&memcg->res);
		/*
		 * We have to update the tree if mz is on RB-tree or
		 * mem is over its softlimit.
		 */
		if (excess || mz->on_tree) {
			spin_lock(&mctz->lock);
			/* if on-tree, remove it */
			if (mz->on_tree)
				__mem_cgroup_remove_exceeded(memcg, mz, mctz);
			/*
			 * Insert again. mz->usage_in_excess will be updated.
			 * If excess is 0, no tree ops.
			 */
			__mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
			spin_unlock(&mctz->lock);
		}
	}
}

static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
{
	int node, zone;
	struct mem_cgroup_per_zone *mz;
	struct mem_cgroup_tree_per_zone *mctz;

	for_each_node(node) {
		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
			mz = mem_cgroup_zoneinfo(memcg, node, zone);
			mctz = soft_limit_tree_node_zone(node, zone);
			mem_cgroup_remove_exceeded(memcg, mz, mctz);
		}
	}
}

static struct mem_cgroup_per_zone *
__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
	struct rb_node *rightmost = NULL;
	struct mem_cgroup_per_zone *mz;

retry:
	mz = NULL;
	rightmost = rb_last(&mctz->rb_root);
	if (!rightmost)
		goto done;		/* Nothing to reclaim from */

	mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
	/*
	 * Remove the node now but someone else can add it back,
	 * we will to add it back at the end of reclaim to its correct
	 * position in the tree.
	 */
	__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
	if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
		!css_tryget(&mz->memcg->css))
		goto retry;
done:
	return mz;
}

static struct mem_cgroup_per_zone *
mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
	struct mem_cgroup_per_zone *mz;

	spin_lock(&mctz->lock);
	mz = __mem_cgroup_largest_soft_limit_node(mctz);
	spin_unlock(&mctz->lock);
	return mz;
}

858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876
/*
 * Implementation Note: reading percpu statistics for memcg.
 *
 * Both of vmstat[] and percpu_counter has threshold and do periodic
 * synchronization to implement "quick" read. There are trade-off between
 * reading cost and precision of value. Then, we may have a chance to implement
 * a periodic synchronizion of counter in memcg's counter.
 *
 * But this _read() function is used for user interface now. The user accounts
 * memory usage by memory cgroup and he _always_ requires exact value because
 * he accounts memory. Even if we provide quick-and-fuzzy read, we always
 * have to visit all online cpus and make sum. So, for now, unnecessary
 * synchronization is not implemented. (just implemented for cpu hotplug)
 *
 * If there are kernel internal actions which can make use of some not-exact
 * value, and reading all cpu value can be performance bottleneck in some
 * common workload, threashold and synchonization as vmstat[] should be
 * implemented.
 */
877
static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
878
				 enum mem_cgroup_stat_index idx)
879
{
880
	long val = 0;
881 882
	int cpu;

883 884
	get_online_cpus();
	for_each_online_cpu(cpu)
885
		val += per_cpu(memcg->stat->count[idx], cpu);
886
#ifdef CONFIG_HOTPLUG_CPU
887 888 889
	spin_lock(&memcg->pcp_counter_lock);
	val += memcg->nocpu_base.count[idx];
	spin_unlock(&memcg->pcp_counter_lock);
890 891
#endif
	put_online_cpus();
892 893 894
	return val;
}

895
static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
896 897 898
					 bool charge)
{
	int val = (charge) ? 1 : -1;
899
	this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val);
900 901
}

902
static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
903 904 905 906 907
					    enum mem_cgroup_events_index idx)
{
	unsigned long val = 0;
	int cpu;

908
	get_online_cpus();
909
	for_each_online_cpu(cpu)
910
		val += per_cpu(memcg->stat->events[idx], cpu);
911
#ifdef CONFIG_HOTPLUG_CPU
912 913 914
	spin_lock(&memcg->pcp_counter_lock);
	val += memcg->nocpu_base.events[idx];
	spin_unlock(&memcg->pcp_counter_lock);
915
#endif
916
	put_online_cpus();
917 918 919
	return val;
}

920
static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
921
					 struct page *page,
922
					 bool anon, int nr_pages)
923
{
924 925 926 927 928 929
	/*
	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
	 * counted as CACHE even if it's on ANON LRU.
	 */
	if (anon)
		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
930
				nr_pages);
931
	else
932
		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
933
				nr_pages);
934

935 936 937 938
	if (PageTransHuge(page))
		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
				nr_pages);

939 940
	/* pagein of a big page is an event. So, ignore page size */
	if (nr_pages > 0)
941
		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
942
	else {
943
		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
944 945
		nr_pages = -nr_pages; /* for event */
	}
946

947
	__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
948 949
}

950
unsigned long
951
mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
952 953 954 955 956 957 958 959
{
	struct mem_cgroup_per_zone *mz;

	mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
	return mz->lru_size[lru];
}

static unsigned long
960
mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
961
			unsigned int lru_mask)
962 963
{
	struct mem_cgroup_per_zone *mz;
H
Hugh Dickins 已提交
964
	enum lru_list lru;
965 966
	unsigned long ret = 0;

967
	mz = mem_cgroup_zoneinfo(memcg, nid, zid);
968

H
Hugh Dickins 已提交
969 970 971
	for_each_lru(lru) {
		if (BIT(lru) & lru_mask)
			ret += mz->lru_size[lru];
972 973 974 975 976
	}
	return ret;
}

static unsigned long
977
mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
978 979
			int nid, unsigned int lru_mask)
{
980 981 982
	u64 total = 0;
	int zid;

983
	for (zid = 0; zid < MAX_NR_ZONES; zid++)
984 985
		total += mem_cgroup_zone_nr_lru_pages(memcg,
						nid, zid, lru_mask);
986

987 988
	return total;
}
989

990
static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
991
			unsigned int lru_mask)
992
{
993
	int nid;
994 995
	u64 total = 0;

996
	for_each_node_state(nid, N_MEMORY)
997
		total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
998
	return total;
999 1000
}

1001 1002
static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
				       enum mem_cgroup_events_target target)
1003 1004 1005
{
	unsigned long val, next;

1006
	val = __this_cpu_read(memcg->stat->nr_page_events);
1007
	next = __this_cpu_read(memcg->stat->targets[target]);
1008
	/* from time_after() in jiffies.h */
1009 1010 1011 1012 1013
	if ((long)next - (long)val < 0) {
		switch (target) {
		case MEM_CGROUP_TARGET_THRESH:
			next = val + THRESHOLDS_EVENTS_TARGET;
			break;
1014 1015 1016
		case MEM_CGROUP_TARGET_SOFTLIMIT:
			next = val + SOFTLIMIT_EVENTS_TARGET;
			break;
1017 1018 1019 1020 1021 1022 1023 1024
		case MEM_CGROUP_TARGET_NUMAINFO:
			next = val + NUMAINFO_EVENTS_TARGET;
			break;
		default:
			break;
		}
		__this_cpu_write(memcg->stat->targets[target], next);
		return true;
1025
	}
1026
	return false;
1027 1028 1029 1030 1031 1032
}

/*
 * Check events in order.
 *
 */
1033
static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
1034
{
1035
	preempt_disable();
1036
	/* threshold event is triggered in finer grain than soft limit */
1037 1038
	if (unlikely(mem_cgroup_event_ratelimit(memcg,
						MEM_CGROUP_TARGET_THRESH))) {
1039
		bool do_softlimit;
1040
		bool do_numainfo __maybe_unused;
1041

1042 1043
		do_softlimit = mem_cgroup_event_ratelimit(memcg,
						MEM_CGROUP_TARGET_SOFTLIMIT);
1044 1045 1046 1047 1048 1049
#if MAX_NUMNODES > 1
		do_numainfo = mem_cgroup_event_ratelimit(memcg,
						MEM_CGROUP_TARGET_NUMAINFO);
#endif
		preempt_enable();

1050
		mem_cgroup_threshold(memcg);
1051 1052
		if (unlikely(do_softlimit))
			mem_cgroup_update_tree(memcg, page);
1053
#if MAX_NUMNODES > 1
1054
		if (unlikely(do_numainfo))
1055
			atomic_inc(&memcg->numainfo_events);
1056
#endif
1057 1058
	} else
		preempt_enable();
1059 1060
}

1061
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
1062
{
1063 1064 1065 1066 1067 1068 1069 1070
	/*
	 * mm_update_next_owner() may clear mm->owner to NULL
	 * if it races with swapoff, page migration, etc.
	 * So this can be called with p == NULL.
	 */
	if (unlikely(!p))
		return NULL;

1071
	return mem_cgroup_from_css(task_css(p, memory_cgrp_id));
1072 1073
}

1074
static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
1075
{
1076
	struct mem_cgroup *memcg = NULL;
1077

1078 1079
	rcu_read_lock();
	do {
1080 1081
		memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
		if (unlikely(!memcg))
1082
			memcg = root_mem_cgroup;
1083
	} while (!css_tryget(&memcg->css));
1084
	rcu_read_unlock();
1085
	return memcg;
1086 1087
}

1088 1089 1090 1091 1092 1093 1094
/*
 * Returns a next (in a pre-order walk) alive memcg (with elevated css
 * ref. count) or NULL if the whole root's subtree has been visited.
 *
 * helper function to be used by mem_cgroup_iter
 */
static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root,
1095
		struct mem_cgroup *last_visited)
1096
{
1097
	struct cgroup_subsys_state *prev_css, *next_css;
1098

1099
	prev_css = last_visited ? &last_visited->css : NULL;
1100
skip_node:
1101
	next_css = css_next_descendant_pre(prev_css, &root->css);
1102 1103 1104 1105 1106 1107 1108

	/*
	 * Even if we found a group we have to make sure it is
	 * alive. css && !memcg means that the groups should be
	 * skipped and we should continue the tree walk.
	 * last_visited css is safe to use because it is
	 * protected by css_get and the tree walk is rcu safe.
1109 1110 1111 1112 1113 1114 1115 1116
	 *
	 * We do not take a reference on the root of the tree walk
	 * because we might race with the root removal when it would
	 * be the only node in the iterated hierarchy and mem_cgroup_iter
	 * would end up in an endless loop because it expects that at
	 * least one valid node will be returned. Root cannot disappear
	 * because caller of the iterator should hold it already so
	 * skipping css reference should be safe.
1117
	 */
1118
	if (next_css) {
1119 1120
		if ((next_css == &root->css) ||
		    ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)))
1121
			return mem_cgroup_from_css(next_css);
1122 1123 1124

		prev_css = next_css;
		goto skip_node;
1125 1126 1127 1128 1129
	}

	return NULL;
}

1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157
static void mem_cgroup_iter_invalidate(struct mem_cgroup *root)
{
	/*
	 * When a group in the hierarchy below root is destroyed, the
	 * hierarchy iterator can no longer be trusted since it might
	 * have pointed to the destroyed group.  Invalidate it.
	 */
	atomic_inc(&root->dead_count);
}

static struct mem_cgroup *
mem_cgroup_iter_load(struct mem_cgroup_reclaim_iter *iter,
		     struct mem_cgroup *root,
		     int *sequence)
{
	struct mem_cgroup *position = NULL;
	/*
	 * A cgroup destruction happens in two stages: offlining and
	 * release.  They are separated by a RCU grace period.
	 *
	 * If the iterator is valid, we may still race with an
	 * offlining.  The RCU lock ensures the object won't be
	 * released, tryget will fail if we lost the race.
	 */
	*sequence = atomic_read(&root->dead_count);
	if (iter->last_dead_count == *sequence) {
		smp_rmb();
		position = iter->last_visited;
1158 1159 1160 1161 1162 1163 1164 1165 1166

		/*
		 * We cannot take a reference to root because we might race
		 * with root removal and returning NULL would end up in
		 * an endless loop on the iterator user level when root
		 * would be returned all the time.
		 */
		if (position && position != root &&
				!css_tryget(&position->css))
1167 1168 1169 1170 1171 1172 1173 1174
			position = NULL;
	}
	return position;
}

static void mem_cgroup_iter_update(struct mem_cgroup_reclaim_iter *iter,
				   struct mem_cgroup *last_visited,
				   struct mem_cgroup *new_position,
1175
				   struct mem_cgroup *root,
1176 1177
				   int sequence)
{
1178 1179
	/* root reference counting symmetric to mem_cgroup_iter_load */
	if (last_visited && last_visited != root)
1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191
		css_put(&last_visited->css);
	/*
	 * We store the sequence count from the time @last_visited was
	 * loaded successfully instead of rereading it here so that we
	 * don't lose destruction events in between.  We could have
	 * raced with the destruction of @new_position after all.
	 */
	iter->last_visited = new_position;
	smp_wmb();
	iter->last_dead_count = sequence;
}

1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208
/**
 * mem_cgroup_iter - iterate over memory cgroup hierarchy
 * @root: hierarchy root
 * @prev: previously returned memcg, NULL on first invocation
 * @reclaim: cookie for shared reclaim walks, NULL for full walks
 *
 * Returns references to children of the hierarchy below @root, or
 * @root itself, or %NULL after a full round-trip.
 *
 * Caller must pass the return value in @prev on subsequent
 * invocations for reference counting, or use mem_cgroup_iter_break()
 * to cancel a hierarchy walk before the round-trip is complete.
 *
 * Reclaimers can specify a zone and a priority level in @reclaim to
 * divide up the memcgs in the hierarchy among all concurrent
 * reclaimers operating on the same zone and priority.
 */
1209
struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
1210
				   struct mem_cgroup *prev,
1211
				   struct mem_cgroup_reclaim_cookie *reclaim)
K
KAMEZAWA Hiroyuki 已提交
1212
{
1213
	struct mem_cgroup *memcg = NULL;
1214
	struct mem_cgroup *last_visited = NULL;
1215

1216 1217
	if (mem_cgroup_disabled())
		return NULL;
1218

1219 1220
	if (!root)
		root = root_mem_cgroup;
K
KAMEZAWA Hiroyuki 已提交
1221

1222
	if (prev && !reclaim)
1223
		last_visited = prev;
K
KAMEZAWA Hiroyuki 已提交
1224

1225 1226
	if (!root->use_hierarchy && root != root_mem_cgroup) {
		if (prev)
1227
			goto out_css_put;
1228
		return root;
1229
	}
K
KAMEZAWA Hiroyuki 已提交
1230

1231
	rcu_read_lock();
1232
	while (!memcg) {
1233
		struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
1234
		int uninitialized_var(seq);
1235

1236 1237 1238 1239 1240 1241 1242
		if (reclaim) {
			int nid = zone_to_nid(reclaim->zone);
			int zid = zone_idx(reclaim->zone);
			struct mem_cgroup_per_zone *mz;

			mz = mem_cgroup_zoneinfo(root, nid, zid);
			iter = &mz->reclaim_iter[reclaim->priority];
1243
			if (prev && reclaim->generation != iter->generation) {
M
Michal Hocko 已提交
1244
				iter->last_visited = NULL;
1245 1246
				goto out_unlock;
			}
M
Michal Hocko 已提交
1247

1248
			last_visited = mem_cgroup_iter_load(iter, root, &seq);
1249
		}
K
KAMEZAWA Hiroyuki 已提交
1250

1251
		memcg = __mem_cgroup_iter_next(root, last_visited);
K
KAMEZAWA Hiroyuki 已提交
1252

1253
		if (reclaim) {
1254 1255
			mem_cgroup_iter_update(iter, last_visited, memcg, root,
					seq);
1256

M
Michal Hocko 已提交
1257
			if (!memcg)
1258 1259 1260 1261
				iter->generation++;
			else if (!prev && memcg)
				reclaim->generation = iter->generation;
		}
1262

1263
		if (prev && !memcg)
1264
			goto out_unlock;
1265
	}
1266 1267
out_unlock:
	rcu_read_unlock();
1268 1269 1270 1271
out_css_put:
	if (prev && prev != root)
		css_put(&prev->css);

1272
	return memcg;
K
KAMEZAWA Hiroyuki 已提交
1273
}
K
KAMEZAWA Hiroyuki 已提交
1274

1275 1276 1277 1278 1279 1280 1281
/**
 * mem_cgroup_iter_break - abort a hierarchy walk prematurely
 * @root: hierarchy root
 * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
 */
void mem_cgroup_iter_break(struct mem_cgroup *root,
			   struct mem_cgroup *prev)
1282 1283 1284 1285 1286 1287
{
	if (!root)
		root = root_mem_cgroup;
	if (prev && prev != root)
		css_put(&prev->css);
}
K
KAMEZAWA Hiroyuki 已提交
1288

1289 1290 1291 1292 1293 1294
/*
 * Iteration constructs for visiting all cgroups (under a tree).  If
 * loops are exited prematurely (break), mem_cgroup_iter_break() must
 * be used for reference counting.
 */
#define for_each_mem_cgroup_tree(iter, root)		\
1295
	for (iter = mem_cgroup_iter(root, NULL, NULL);	\
1296
	     iter != NULL;				\
1297
	     iter = mem_cgroup_iter(root, iter, NULL))
1298

1299
#define for_each_mem_cgroup(iter)			\
1300
	for (iter = mem_cgroup_iter(NULL, NULL, NULL);	\
1301
	     iter != NULL;				\
1302
	     iter = mem_cgroup_iter(NULL, iter, NULL))
K
KAMEZAWA Hiroyuki 已提交
1303

1304
void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
1305
{
1306
	struct mem_cgroup *memcg;
1307 1308

	rcu_read_lock();
1309 1310
	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
	if (unlikely(!memcg))
1311 1312 1313 1314
		goto out;

	switch (idx) {
	case PGFAULT:
1315 1316 1317 1318
		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
		break;
	case PGMAJFAULT:
		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
1319 1320 1321 1322 1323 1324 1325
		break;
	default:
		BUG();
	}
out:
	rcu_read_unlock();
}
1326
EXPORT_SYMBOL(__mem_cgroup_count_vm_event);
1327

1328 1329 1330
/**
 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
 * @zone: zone of the wanted lruvec
1331
 * @memcg: memcg of the wanted lruvec
1332 1333 1334 1335 1336 1337 1338 1339 1340
 *
 * Returns the lru list vector holding pages for the given @zone and
 * @mem.  This can be the global zone lruvec, if the memory controller
 * is disabled.
 */
struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
				      struct mem_cgroup *memcg)
{
	struct mem_cgroup_per_zone *mz;
1341
	struct lruvec *lruvec;
1342

1343 1344 1345 1346
	if (mem_cgroup_disabled()) {
		lruvec = &zone->lruvec;
		goto out;
	}
1347 1348

	mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
1349 1350 1351 1352 1353 1354 1355 1356 1357 1358
	lruvec = &mz->lruvec;
out:
	/*
	 * Since a node can be onlined after the mem_cgroup was created,
	 * we have to be prepared to initialize lruvec->zone here;
	 * and if offlined then reonlined, we need to reinitialize it.
	 */
	if (unlikely(lruvec->zone != zone))
		lruvec->zone = zone;
	return lruvec;
1359 1360
}

K
KAMEZAWA Hiroyuki 已提交
1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373
/*
 * Following LRU functions are allowed to be used without PCG_LOCK.
 * Operations are called by routine of global LRU independently from memcg.
 * What we have to take care of here is validness of pc->mem_cgroup.
 *
 * Changes to pc->mem_cgroup happens when
 * 1. charge
 * 2. moving account
 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
 * It is added to LRU before charge.
 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
 * When moving account, the page is not on LRU. It's isolated.
 */
1374

1375
/**
1376
 * mem_cgroup_page_lruvec - return lruvec for adding an lru page
1377
 * @page: the page
1378
 * @zone: zone of the page
1379
 */
1380
struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
K
KAMEZAWA Hiroyuki 已提交
1381 1382
{
	struct mem_cgroup_per_zone *mz;
1383 1384
	struct mem_cgroup *memcg;
	struct page_cgroup *pc;
1385
	struct lruvec *lruvec;
1386

1387 1388 1389 1390
	if (mem_cgroup_disabled()) {
		lruvec = &zone->lruvec;
		goto out;
	}
1391

K
KAMEZAWA Hiroyuki 已提交
1392
	pc = lookup_page_cgroup(page);
1393
	memcg = pc->mem_cgroup;
1394 1395

	/*
1396
	 * Surreptitiously switch any uncharged offlist page to root:
1397 1398 1399 1400 1401 1402 1403
	 * an uncharged page off lru does nothing to secure
	 * its former mem_cgroup from sudden removal.
	 *
	 * Our caller holds lru_lock, and PageCgroupUsed is updated
	 * under page_cgroup lock: between them, they make all uses
	 * of pc->mem_cgroup safe.
	 */
1404
	if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
1405 1406
		pc->mem_cgroup = memcg = root_mem_cgroup;

1407
	mz = page_cgroup_zoneinfo(memcg, page);
1408 1409 1410 1411 1412 1413 1414 1415 1416 1417
	lruvec = &mz->lruvec;
out:
	/*
	 * Since a node can be onlined after the mem_cgroup was created,
	 * we have to be prepared to initialize lruvec->zone here;
	 * and if offlined then reonlined, we need to reinitialize it.
	 */
	if (unlikely(lruvec->zone != zone))
		lruvec->zone = zone;
	return lruvec;
K
KAMEZAWA Hiroyuki 已提交
1418
}
1419

1420
/**
1421 1422 1423 1424
 * mem_cgroup_update_lru_size - account for adding or removing an lru page
 * @lruvec: mem_cgroup per zone lru vector
 * @lru: index of lru list the page is sitting on
 * @nr_pages: positive when adding or negative when removing
1425
 *
1426 1427
 * This function must be called when a page is added to or removed from an
 * lru list.
1428
 */
1429 1430
void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
				int nr_pages)
1431 1432
{
	struct mem_cgroup_per_zone *mz;
1433
	unsigned long *lru_size;
1434 1435 1436 1437

	if (mem_cgroup_disabled())
		return;

1438 1439 1440 1441
	mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
	lru_size = mz->lru_size + lru;
	*lru_size += nr_pages;
	VM_BUG_ON((long)(*lru_size) < 0);
K
KAMEZAWA Hiroyuki 已提交
1442
}
1443

1444
/*
1445
 * Checks whether given mem is same or in the root_mem_cgroup's
1446 1447
 * hierarchy subtree
 */
1448 1449
bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
				  struct mem_cgroup *memcg)
1450
{
1451 1452
	if (root_memcg == memcg)
		return true;
1453
	if (!root_memcg->use_hierarchy || !memcg)
1454
		return false;
1455
	return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
1456 1457 1458 1459 1460 1461 1462
}

static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
				       struct mem_cgroup *memcg)
{
	bool ret;

1463
	rcu_read_lock();
1464
	ret = __mem_cgroup_same_or_subtree(root_memcg, memcg);
1465 1466
	rcu_read_unlock();
	return ret;
1467 1468
}

1469 1470
bool task_in_mem_cgroup(struct task_struct *task,
			const struct mem_cgroup *memcg)
1471
{
1472
	struct mem_cgroup *curr = NULL;
1473
	struct task_struct *p;
1474
	bool ret;
1475

1476
	p = find_lock_task_mm(task);
1477
	if (p) {
1478
		curr = get_mem_cgroup_from_mm(p->mm);
1479 1480 1481 1482 1483 1484 1485
		task_unlock(p);
	} else {
		/*
		 * All threads may have already detached their mm's, but the oom
		 * killer still needs to detect if they have already been oom
		 * killed to prevent needlessly killing additional tasks.
		 */
1486
		rcu_read_lock();
1487 1488 1489
		curr = mem_cgroup_from_task(task);
		if (curr)
			css_get(&curr->css);
1490
		rcu_read_unlock();
1491
	}
1492
	/*
1493
	 * We should check use_hierarchy of "memcg" not "curr". Because checking
1494
	 * use_hierarchy of "curr" here make this function true if hierarchy is
1495 1496
	 * enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
	 * hierarchy(even if use_hierarchy is disabled in "memcg").
1497
	 */
1498
	ret = mem_cgroup_same_or_subtree(memcg, curr);
1499
	css_put(&curr->css);
1500 1501 1502
	return ret;
}

1503
int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
1504
{
1505
	unsigned long inactive_ratio;
1506
	unsigned long inactive;
1507
	unsigned long active;
1508
	unsigned long gb;
1509

1510 1511
	inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
	active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
1512

1513 1514 1515 1516 1517 1518
	gb = (inactive + active) >> (30 - PAGE_SHIFT);
	if (gb)
		inactive_ratio = int_sqrt(10 * gb);
	else
		inactive_ratio = 1;

1519
	return inactive * inactive_ratio < active;
1520 1521
}

1522 1523 1524
#define mem_cgroup_from_res_counter(counter, member)	\
	container_of(counter, struct mem_cgroup, member)

1525
/**
1526
 * mem_cgroup_margin - calculate chargeable space of a memory cgroup
W
Wanpeng Li 已提交
1527
 * @memcg: the memory cgroup
1528
 *
1529
 * Returns the maximum amount of memory @mem can be charged with, in
1530
 * pages.
1531
 */
1532
static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
1533
{
1534 1535
	unsigned long long margin;

1536
	margin = res_counter_margin(&memcg->res);
1537
	if (do_swap_account)
1538
		margin = min(margin, res_counter_margin(&memcg->memsw));
1539
	return margin >> PAGE_SHIFT;
1540 1541
}

1542
int mem_cgroup_swappiness(struct mem_cgroup *memcg)
K
KOSAKI Motohiro 已提交
1543 1544
{
	/* root ? */
T
Tejun Heo 已提交
1545
	if (!css_parent(&memcg->css))
K
KOSAKI Motohiro 已提交
1546 1547
		return vm_swappiness;

1548
	return memcg->swappiness;
K
KOSAKI Motohiro 已提交
1549 1550
}

1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564
/*
 * memcg->moving_account is used for checking possibility that some thread is
 * calling move_account(). When a thread on CPU-A starts moving pages under
 * a memcg, other threads should check memcg->moving_account under
 * rcu_read_lock(), like this:
 *
 *         CPU-A                                    CPU-B
 *                                              rcu_read_lock()
 *         memcg->moving_account+1              if (memcg->mocing_account)
 *                                                   take heavy locks.
 *         synchronize_rcu()                    update something.
 *                                              rcu_read_unlock()
 *         start move here.
 */
1565 1566 1567 1568

/* for quick checking without looking up memcg */
atomic_t memcg_moving __read_mostly;

1569
static void mem_cgroup_start_move(struct mem_cgroup *memcg)
1570
{
1571
	atomic_inc(&memcg_moving);
1572
	atomic_inc(&memcg->moving_account);
1573 1574 1575
	synchronize_rcu();
}

1576
static void mem_cgroup_end_move(struct mem_cgroup *memcg)
1577
{
1578 1579 1580 1581
	/*
	 * Now, mem_cgroup_clear_mc() may call this function with NULL.
	 * We check NULL in callee rather than caller.
	 */
1582 1583
	if (memcg) {
		atomic_dec(&memcg_moving);
1584
		atomic_dec(&memcg->moving_account);
1585
	}
1586
}
1587

1588 1589 1590
/*
 * 2 routines for checking "mem" is under move_account() or not.
 *
1591 1592
 * mem_cgroup_stolen() -  checking whether a cgroup is mc.from or not. This
 *			  is used for avoiding races in accounting.  If true,
1593 1594 1595 1596 1597 1598 1599
 *			  pc->mem_cgroup may be overwritten.
 *
 * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
 *			  under hierarchy of moving cgroups. This is for
 *			  waiting at hith-memory prressure caused by "move".
 */

1600
static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
1601 1602
{
	VM_BUG_ON(!rcu_read_lock_held());
1603
	return atomic_read(&memcg->moving_account) > 0;
1604
}
1605

1606
static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
1607
{
1608 1609
	struct mem_cgroup *from;
	struct mem_cgroup *to;
1610
	bool ret = false;
1611 1612 1613 1614 1615 1616 1617 1618 1619
	/*
	 * Unlike task_move routines, we access mc.to, mc.from not under
	 * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
	 */
	spin_lock(&mc.lock);
	from = mc.from;
	to = mc.to;
	if (!from)
		goto unlock;
1620

1621 1622
	ret = mem_cgroup_same_or_subtree(memcg, from)
		|| mem_cgroup_same_or_subtree(memcg, to);
1623 1624
unlock:
	spin_unlock(&mc.lock);
1625 1626 1627
	return ret;
}

1628
static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
1629 1630
{
	if (mc.moving_task && current != mc.moving_task) {
1631
		if (mem_cgroup_under_move(memcg)) {
1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643
			DEFINE_WAIT(wait);
			prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
			/* moving charge context might have finished. */
			if (mc.moving_task)
				schedule();
			finish_wait(&mc.waitq, &wait);
			return true;
		}
	}
	return false;
}

1644 1645 1646 1647
/*
 * Take this lock when
 * - a code tries to modify page's memcg while it's USED.
 * - a code tries to modify page state accounting in a memcg.
1648
 * see mem_cgroup_stolen(), too.
1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
 */
static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
				  unsigned long *flags)
{
	spin_lock_irqsave(&memcg->move_lock, *flags);
}

static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
				unsigned long *flags)
{
	spin_unlock_irqrestore(&memcg->move_lock, *flags);
}

1662
#define K(x) ((x) << (PAGE_SHIFT-10))
1663
/**
1664
 * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
1665 1666 1667 1668 1669 1670 1671 1672
 * @memcg: The memory cgroup that went over limit
 * @p: Task that is going to be killed
 *
 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
 * enabled
 */
void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
{
T
Tejun Heo 已提交
1673
	/* oom_info_lock ensures that parallel ooms do not interleave */
1674
	static DEFINE_MUTEX(oom_info_lock);
1675 1676
	struct mem_cgroup *iter;
	unsigned int i;
1677

1678
	if (!p)
1679 1680
		return;

1681
	mutex_lock(&oom_info_lock);
1682 1683
	rcu_read_lock();

T
Tejun Heo 已提交
1684 1685 1686 1687 1688
	pr_info("Task in ");
	pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
	pr_info(" killed as a result of limit of ");
	pr_cont_cgroup_path(memcg->css.cgroup);
	pr_info("\n");
1689 1690 1691

	rcu_read_unlock();

1692
	pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n",
1693 1694 1695
		res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
		res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
		res_counter_read_u64(&memcg->res, RES_FAILCNT));
1696
	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n",
1697 1698 1699
		res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
		res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
		res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1700
	pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n",
1701 1702 1703
		res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
		res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
		res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
1704 1705

	for_each_mem_cgroup_tree(iter, memcg) {
T
Tejun Heo 已提交
1706 1707
		pr_info("Memory cgroup stats for ");
		pr_cont_cgroup_path(iter->css.cgroup);
1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722
		pr_cont(":");

		for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
			if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
				continue;
			pr_cont(" %s:%ldKB", mem_cgroup_stat_names[i],
				K(mem_cgroup_read_stat(iter, i)));
		}

		for (i = 0; i < NR_LRU_LISTS; i++)
			pr_cont(" %s:%luKB", mem_cgroup_lru_names[i],
				K(mem_cgroup_nr_lru_pages(iter, BIT(i))));

		pr_cont("\n");
	}
1723
	mutex_unlock(&oom_info_lock);
1724 1725
}

1726 1727 1728 1729
/*
 * This function returns the number of memcg under hierarchy tree. Returns
 * 1(self count) if no children.
 */
1730
static int mem_cgroup_count_children(struct mem_cgroup *memcg)
1731 1732
{
	int num = 0;
K
KAMEZAWA Hiroyuki 已提交
1733 1734
	struct mem_cgroup *iter;

1735
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
1736
		num++;
1737 1738 1739
	return num;
}

D
David Rientjes 已提交
1740 1741 1742
/*
 * Return the memory (and swap, if configured) limit for a memcg.
 */
1743
static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
D
David Rientjes 已提交
1744 1745 1746
{
	u64 limit;

1747 1748
	limit = res_counter_read_u64(&memcg->res, RES_LIMIT);

D
David Rientjes 已提交
1749
	/*
1750
	 * Do not consider swap space if we cannot swap due to swappiness
D
David Rientjes 已提交
1751
	 */
1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765
	if (mem_cgroup_swappiness(memcg)) {
		u64 memsw;

		limit += total_swap_pages << PAGE_SHIFT;
		memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);

		/*
		 * If memsw is finite and limits the amount of swap space
		 * available to this memcg, return that limit.
		 */
		limit = min(limit, memsw);
	}

	return limit;
D
David Rientjes 已提交
1766 1767
}

1768 1769
static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
				     int order)
1770 1771 1772 1773 1774 1775 1776
{
	struct mem_cgroup *iter;
	unsigned long chosen_points = 0;
	unsigned long totalpages;
	unsigned int points = 0;
	struct task_struct *chosen = NULL;

1777
	/*
1778 1779 1780
	 * If current has a pending SIGKILL or is exiting, then automatically
	 * select it.  The goal is to allow it to allocate so that it may
	 * quickly exit and free its memory.
1781
	 */
1782
	if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
1783 1784 1785 1786 1787
		set_thread_flag(TIF_MEMDIE);
		return;
	}

	check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
1788 1789
	totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
	for_each_mem_cgroup_tree(iter, memcg) {
1790
		struct css_task_iter it;
1791 1792
		struct task_struct *task;

1793 1794
		css_task_iter_start(&iter->css, &it);
		while ((task = css_task_iter_next(&it))) {
1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806
			switch (oom_scan_process_thread(task, totalpages, NULL,
							false)) {
			case OOM_SCAN_SELECT:
				if (chosen)
					put_task_struct(chosen);
				chosen = task;
				chosen_points = ULONG_MAX;
				get_task_struct(chosen);
				/* fall through */
			case OOM_SCAN_CONTINUE:
				continue;
			case OOM_SCAN_ABORT:
1807
				css_task_iter_end(&it);
1808 1809 1810 1811 1812 1813 1814 1815
				mem_cgroup_iter_break(memcg, iter);
				if (chosen)
					put_task_struct(chosen);
				return;
			case OOM_SCAN_OK:
				break;
			};
			points = oom_badness(task, memcg, NULL, totalpages);
1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827
			if (!points || points < chosen_points)
				continue;
			/* Prefer thread group leaders for display purposes */
			if (points == chosen_points &&
			    thread_group_leader(chosen))
				continue;

			if (chosen)
				put_task_struct(chosen);
			chosen = task;
			chosen_points = points;
			get_task_struct(chosen);
1828
		}
1829
		css_task_iter_end(&it);
1830 1831 1832 1833 1834 1835 1836 1837 1838
	}

	if (!chosen)
		return;
	points = chosen_points * 1000 / totalpages;
	oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg,
			 NULL, "Memory cgroup out of memory");
}

1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874
static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
					gfp_t gfp_mask,
					unsigned long flags)
{
	unsigned long total = 0;
	bool noswap = false;
	int loop;

	if (flags & MEM_CGROUP_RECLAIM_NOSWAP)
		noswap = true;
	if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum)
		noswap = true;

	for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) {
		if (loop)
			drain_all_stock_async(memcg);
		total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap);
		/*
		 * Allow limit shrinkers, which are triggered directly
		 * by userspace, to catch signals and stop reclaim
		 * after minimal progress, regardless of the margin.
		 */
		if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK))
			break;
		if (mem_cgroup_margin(memcg))
			break;
		/*
		 * If nothing was reclaimed after two attempts, there
		 * may be no reclaimable pages in this hierarchy.
		 */
		if (loop && !total)
			break;
	}
	return total;
}

1875 1876
/**
 * test_mem_cgroup_node_reclaimable
W
Wanpeng Li 已提交
1877
 * @memcg: the target memcg
1878 1879 1880 1881 1882 1883 1884
 * @nid: the node ID to be checked.
 * @noswap : specify true here if the user wants flle only information.
 *
 * This function returns whether the specified memcg contains any
 * reclaimable pages on a node. Returns true if there are any reclaimable
 * pages in the node.
 */
1885
static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
1886 1887
		int nid, bool noswap)
{
1888
	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
1889 1890 1891
		return true;
	if (noswap || !total_swap_pages)
		return false;
1892
	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
1893 1894 1895 1896
		return true;
	return false;

}
1897
#if MAX_NUMNODES > 1
1898 1899 1900 1901 1902 1903 1904

/*
 * Always updating the nodemask is not very good - even if we have an empty
 * list or the wrong list here, we can start from some node and traverse all
 * nodes based on the zonelist. So update the list loosely once per 10 secs.
 *
 */
1905
static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
1906 1907
{
	int nid;
1908 1909 1910 1911
	/*
	 * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
	 * pagein/pageout changes since the last update.
	 */
1912
	if (!atomic_read(&memcg->numainfo_events))
1913
		return;
1914
	if (atomic_inc_return(&memcg->numainfo_updating) > 1)
1915 1916 1917
		return;

	/* make a nodemask where this memcg uses memory from */
1918
	memcg->scan_nodes = node_states[N_MEMORY];
1919

1920
	for_each_node_mask(nid, node_states[N_MEMORY]) {
1921

1922 1923
		if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
			node_clear(nid, memcg->scan_nodes);
1924
	}
1925

1926 1927
	atomic_set(&memcg->numainfo_events, 0);
	atomic_set(&memcg->numainfo_updating, 0);
1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941
}

/*
 * Selecting a node where we start reclaim from. Because what we need is just
 * reducing usage counter, start from anywhere is O,K. Considering
 * memory reclaim from current node, there are pros. and cons.
 *
 * Freeing memory from current node means freeing memory from a node which
 * we'll use or we've used. So, it may make LRU bad. And if several threads
 * hit limits, it will see a contention on a node. But freeing from remote
 * node means more costs for memory reclaim because of memory latency.
 *
 * Now, we use round-robin. Better algorithm is welcomed.
 */
1942
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1943 1944 1945
{
	int node;

1946 1947
	mem_cgroup_may_update_nodemask(memcg);
	node = memcg->last_scanned_node;
1948

1949
	node = next_node(node, memcg->scan_nodes);
1950
	if (node == MAX_NUMNODES)
1951
		node = first_node(memcg->scan_nodes);
1952 1953 1954 1955 1956 1957 1958 1959 1960
	/*
	 * We call this when we hit limit, not when pages are added to LRU.
	 * No LRU may hold pages because all pages are UNEVICTABLE or
	 * memcg is too small and all pages are not on LRU. In that case,
	 * we use curret node.
	 */
	if (unlikely(node == MAX_NUMNODES))
		node = numa_node_id();

1961
	memcg->last_scanned_node = node;
1962 1963 1964
	return node;
}

1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
/*
 * Check all nodes whether it contains reclaimable pages or not.
 * For quick scan, we make use of scan_nodes. This will allow us to skip
 * unused nodes. But scan_nodes is lazily updated and may not cotain
 * enough new information. We need to do double check.
 */
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
	int nid;

	/*
	 * quick check...making use of scan_node.
	 * We can skip unused nodes.
	 */
	if (!nodes_empty(memcg->scan_nodes)) {
		for (nid = first_node(memcg->scan_nodes);
		     nid < MAX_NUMNODES;
		     nid = next_node(nid, memcg->scan_nodes)) {

			if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
				return true;
		}
	}
	/*
	 * Check rest of nodes.
	 */
	for_each_node_state(nid, N_MEMORY) {
		if (node_isset(nid, memcg->scan_nodes))
			continue;
		if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
			return true;
	}
	return false;
}

2000
#else
2001
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
2002 2003 2004
{
	return 0;
}
2005

2006 2007 2008 2009
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
	return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
}
2010 2011
#endif

2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059
static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
				   struct zone *zone,
				   gfp_t gfp_mask,
				   unsigned long *total_scanned)
{
	struct mem_cgroup *victim = NULL;
	int total = 0;
	int loop = 0;
	unsigned long excess;
	unsigned long nr_scanned;
	struct mem_cgroup_reclaim_cookie reclaim = {
		.zone = zone,
		.priority = 0,
	};

	excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;

	while (1) {
		victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
		if (!victim) {
			loop++;
			if (loop >= 2) {
				/*
				 * If we have not been able to reclaim
				 * anything, it might because there are
				 * no reclaimable pages under this hierarchy
				 */
				if (!total)
					break;
				/*
				 * We want to do more targeted reclaim.
				 * excess >> 2 is not to excessive so as to
				 * reclaim too much, nor too less that we keep
				 * coming back to reclaim from this cgroup
				 */
				if (total >= (excess >> 2) ||
					(loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
					break;
			}
			continue;
		}
		if (!mem_cgroup_reclaimable(victim, false))
			continue;
		total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
						     zone, &nr_scanned);
		*total_scanned += nr_scanned;
		if (!res_counter_soft_limit_excess(&root_memcg->res))
			break;
2060
	}
2061 2062
	mem_cgroup_iter_break(root_memcg, victim);
	return total;
2063 2064
}

2065 2066 2067 2068 2069 2070
#ifdef CONFIG_LOCKDEP
static struct lockdep_map memcg_oom_lock_dep_map = {
	.name = "memcg_oom_lock",
};
#endif

2071 2072
static DEFINE_SPINLOCK(memcg_oom_lock);

K
KAMEZAWA Hiroyuki 已提交
2073 2074 2075 2076
/*
 * Check OOM-Killer is already running under our hierarchy.
 * If someone is running, return false.
 */
2077
static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
2078
{
2079
	struct mem_cgroup *iter, *failed = NULL;
2080

2081 2082
	spin_lock(&memcg_oom_lock);

2083
	for_each_mem_cgroup_tree(iter, memcg) {
2084
		if (iter->oom_lock) {
2085 2086 2087 2088 2089
			/*
			 * this subtree of our hierarchy is already locked
			 * so we cannot give a lock.
			 */
			failed = iter;
2090 2091
			mem_cgroup_iter_break(memcg, iter);
			break;
2092 2093
		} else
			iter->oom_lock = true;
K
KAMEZAWA Hiroyuki 已提交
2094
	}
K
KAMEZAWA Hiroyuki 已提交
2095

2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106
	if (failed) {
		/*
		 * OK, we failed to lock the whole subtree so we have
		 * to clean up what we set up to the failing subtree
		 */
		for_each_mem_cgroup_tree(iter, memcg) {
			if (iter == failed) {
				mem_cgroup_iter_break(memcg, iter);
				break;
			}
			iter->oom_lock = false;
2107
		}
2108 2109
	} else
		mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
2110 2111 2112 2113

	spin_unlock(&memcg_oom_lock);

	return !failed;
2114
}
2115

2116
static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
2117
{
K
KAMEZAWA Hiroyuki 已提交
2118 2119
	struct mem_cgroup *iter;

2120
	spin_lock(&memcg_oom_lock);
2121
	mutex_release(&memcg_oom_lock_dep_map, 1, _RET_IP_);
2122
	for_each_mem_cgroup_tree(iter, memcg)
2123
		iter->oom_lock = false;
2124
	spin_unlock(&memcg_oom_lock);
2125 2126
}

2127
static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
2128 2129 2130
{
	struct mem_cgroup *iter;

2131
	for_each_mem_cgroup_tree(iter, memcg)
2132 2133 2134
		atomic_inc(&iter->under_oom);
}

2135
static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
2136 2137 2138
{
	struct mem_cgroup *iter;

K
KAMEZAWA Hiroyuki 已提交
2139 2140 2141 2142 2143
	/*
	 * When a new child is created while the hierarchy is under oom,
	 * mem_cgroup_oom_lock() may not be called. We have to use
	 * atomic_add_unless() here.
	 */
2144
	for_each_mem_cgroup_tree(iter, memcg)
2145
		atomic_add_unless(&iter->under_oom, -1, 0);
2146 2147
}

K
KAMEZAWA Hiroyuki 已提交
2148 2149
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);

K
KAMEZAWA Hiroyuki 已提交
2150
struct oom_wait_info {
2151
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
2152 2153 2154 2155 2156 2157
	wait_queue_t	wait;
};

static int memcg_oom_wake_function(wait_queue_t *wait,
	unsigned mode, int sync, void *arg)
{
2158 2159
	struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
	struct mem_cgroup *oom_wait_memcg;
K
KAMEZAWA Hiroyuki 已提交
2160 2161 2162
	struct oom_wait_info *oom_wait_info;

	oom_wait_info = container_of(wait, struct oom_wait_info, wait);
2163
	oom_wait_memcg = oom_wait_info->memcg;
K
KAMEZAWA Hiroyuki 已提交
2164 2165

	/*
2166
	 * Both of oom_wait_info->memcg and wake_memcg are stable under us.
K
KAMEZAWA Hiroyuki 已提交
2167 2168
	 * Then we can use css_is_ancestor without taking care of RCU.
	 */
2169 2170
	if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg)
		&& !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg))
K
KAMEZAWA Hiroyuki 已提交
2171 2172 2173 2174
		return 0;
	return autoremove_wake_function(wait, mode, sync, arg);
}

2175
static void memcg_wakeup_oom(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
2176
{
2177
	atomic_inc(&memcg->oom_wakeups);
2178 2179
	/* for filtering, pass "memcg" as argument. */
	__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
K
KAMEZAWA Hiroyuki 已提交
2180 2181
}

2182
static void memcg_oom_recover(struct mem_cgroup *memcg)
2183
{
2184 2185
	if (memcg && atomic_read(&memcg->under_oom))
		memcg_wakeup_oom(memcg);
2186 2187
}

2188
static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
2189
{
2190 2191
	if (!current->memcg_oom.may_oom)
		return;
K
KAMEZAWA Hiroyuki 已提交
2192
	/*
2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204
	 * We are in the middle of the charge context here, so we
	 * don't want to block when potentially sitting on a callstack
	 * that holds all kinds of filesystem and mm locks.
	 *
	 * Also, the caller may handle a failed allocation gracefully
	 * (like optional page cache readahead) and so an OOM killer
	 * invocation might not even be necessary.
	 *
	 * That's why we don't do anything here except remember the
	 * OOM context and then deal with it at the end of the page
	 * fault when the stack is unwound, the locks are released,
	 * and when we know whether the fault was overall successful.
K
KAMEZAWA Hiroyuki 已提交
2205
	 */
2206 2207 2208 2209
	css_get(&memcg->css);
	current->memcg_oom.memcg = memcg;
	current->memcg_oom.gfp_mask = mask;
	current->memcg_oom.order = order;
2210 2211 2212 2213
}

/**
 * mem_cgroup_oom_synchronize - complete memcg OOM handling
2214
 * @handle: actually kill/wait or just clean up the OOM state
2215
 *
2216 2217
 * This has to be called at the end of a page fault if the memcg OOM
 * handler was enabled.
2218
 *
2219
 * Memcg supports userspace OOM handling where failed allocations must
2220 2221 2222 2223
 * sleep on a waitqueue until the userspace task resolves the
 * situation.  Sleeping directly in the charge context with all kinds
 * of locks held is not a good idea, instead we remember an OOM state
 * in the task and mem_cgroup_oom_synchronize() has to be called at
2224
 * the end of the page fault to complete the OOM handling.
2225 2226
 *
 * Returns %true if an ongoing memcg OOM situation was detected and
2227
 * completed, %false otherwise.
2228
 */
2229
bool mem_cgroup_oom_synchronize(bool handle)
2230
{
2231
	struct mem_cgroup *memcg = current->memcg_oom.memcg;
2232
	struct oom_wait_info owait;
2233
	bool locked;
2234 2235 2236

	/* OOM is global, do not handle */
	if (!memcg)
2237
		return false;
2238

2239 2240
	if (!handle)
		goto cleanup;
2241 2242 2243 2244 2245 2246

	owait.memcg = memcg;
	owait.wait.flags = 0;
	owait.wait.func = memcg_oom_wake_function;
	owait.wait.private = current;
	INIT_LIST_HEAD(&owait.wait.task_list);
K
KAMEZAWA Hiroyuki 已提交
2247

2248
	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261
	mem_cgroup_mark_under_oom(memcg);

	locked = mem_cgroup_oom_trylock(memcg);

	if (locked)
		mem_cgroup_oom_notify(memcg);

	if (locked && !memcg->oom_kill_disable) {
		mem_cgroup_unmark_under_oom(memcg);
		finish_wait(&memcg_oom_waitq, &owait.wait);
		mem_cgroup_out_of_memory(memcg, current->memcg_oom.gfp_mask,
					 current->memcg_oom.order);
	} else {
2262
		schedule();
2263 2264 2265 2266 2267
		mem_cgroup_unmark_under_oom(memcg);
		finish_wait(&memcg_oom_waitq, &owait.wait);
	}

	if (locked) {
2268 2269 2270 2271 2272 2273 2274 2275
		mem_cgroup_oom_unlock(memcg);
		/*
		 * There is no guarantee that an OOM-lock contender
		 * sees the wakeups triggered by the OOM kill
		 * uncharges.  Wake any sleepers explicitely.
		 */
		memcg_oom_recover(memcg);
	}
2276 2277
cleanup:
	current->memcg_oom.memcg = NULL;
2278
	css_put(&memcg->css);
K
KAMEZAWA Hiroyuki 已提交
2279
	return true;
2280 2281
}

2282 2283 2284
/*
 * Currently used to update mapped file statistics, but the routine can be
 * generalized to update other statistics as well.
2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301
 *
 * Notes: Race condition
 *
 * We usually use page_cgroup_lock() for accessing page_cgroup member but
 * it tends to be costly. But considering some conditions, we doesn't need
 * to do so _always_.
 *
 * Considering "charge", lock_page_cgroup() is not required because all
 * file-stat operations happen after a page is attached to radix-tree. There
 * are no race with "charge".
 *
 * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
 * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
 * if there are race with "uncharge". Statistics itself is properly handled
 * by flags.
 *
 * Considering "move", this is an only case we see a race. To make the race
2302 2303
 * small, we check mm->moving_account and detect there are possibility of race
 * If there is, we take a lock.
2304
 */
2305

2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318
void __mem_cgroup_begin_update_page_stat(struct page *page,
				bool *locked, unsigned long *flags)
{
	struct mem_cgroup *memcg;
	struct page_cgroup *pc;

	pc = lookup_page_cgroup(page);
again:
	memcg = pc->mem_cgroup;
	if (unlikely(!memcg || !PageCgroupUsed(pc)))
		return;
	/*
	 * If this memory cgroup is not under account moving, we don't
2319
	 * need to take move_lock_mem_cgroup(). Because we already hold
2320
	 * rcu_read_lock(), any calls to move_account will be delayed until
2321
	 * rcu_read_unlock() if mem_cgroup_stolen() == true.
2322
	 */
2323
	if (!mem_cgroup_stolen(memcg))
2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340
		return;

	move_lock_mem_cgroup(memcg, flags);
	if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
		move_unlock_mem_cgroup(memcg, flags);
		goto again;
	}
	*locked = true;
}

void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
{
	struct page_cgroup *pc = lookup_page_cgroup(page);

	/*
	 * It's guaranteed that pc->mem_cgroup never changes while
	 * lock is held because a routine modifies pc->mem_cgroup
2341
	 * should take move_lock_mem_cgroup().
2342 2343 2344 2345
	 */
	move_unlock_mem_cgroup(pc->mem_cgroup, flags);
}

2346
void mem_cgroup_update_page_stat(struct page *page,
S
Sha Zhengju 已提交
2347
				 enum mem_cgroup_stat_index idx, int val)
2348
{
2349
	struct mem_cgroup *memcg;
2350
	struct page_cgroup *pc = lookup_page_cgroup(page);
2351
	unsigned long uninitialized_var(flags);
2352

2353
	if (mem_cgroup_disabled())
2354
		return;
2355

2356
	VM_BUG_ON(!rcu_read_lock_held());
2357 2358
	memcg = pc->mem_cgroup;
	if (unlikely(!memcg || !PageCgroupUsed(pc)))
2359
		return;
2360

2361
	this_cpu_add(memcg->stat->count[idx], val);
2362
}
2363

2364 2365 2366 2367
/*
 * size of first charge trial. "32" comes from vmscan.c's magic value.
 * TODO: maybe necessary to use big numbers in big irons.
 */
2368
#define CHARGE_BATCH	32U
2369 2370
struct memcg_stock_pcp {
	struct mem_cgroup *cached; /* this never be root cgroup */
2371
	unsigned int nr_pages;
2372
	struct work_struct work;
2373
	unsigned long flags;
2374
#define FLUSHING_CACHED_CHARGE	0
2375 2376
};
static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
2377
static DEFINE_MUTEX(percpu_charge_mutex);
2378

2379 2380 2381 2382 2383 2384 2385 2386 2387 2388
/**
 * consume_stock: Try to consume stocked charge on this cpu.
 * @memcg: memcg to consume from.
 * @nr_pages: how many pages to charge.
 *
 * The charges will only happen if @memcg matches the current cpu's memcg
 * stock, and at least @nr_pages are available in that stock.  Failure to
 * service an allocation will refill the stock.
 *
 * returns true if successful, false otherwise.
2389
 */
2390
static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2391 2392 2393 2394
{
	struct memcg_stock_pcp *stock;
	bool ret = true;

2395 2396 2397
	if (nr_pages > CHARGE_BATCH)
		return false;

2398
	stock = &get_cpu_var(memcg_stock);
2399 2400
	if (memcg == stock->cached && stock->nr_pages >= nr_pages)
		stock->nr_pages -= nr_pages;
2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413
	else /* need to call res_counter_charge */
		ret = false;
	put_cpu_var(memcg_stock);
	return ret;
}

/*
 * Returns stocks cached in percpu to res_counter and reset cached information.
 */
static void drain_stock(struct memcg_stock_pcp *stock)
{
	struct mem_cgroup *old = stock->cached;

2414 2415 2416 2417
	if (stock->nr_pages) {
		unsigned long bytes = stock->nr_pages * PAGE_SIZE;

		res_counter_uncharge(&old->res, bytes);
2418
		if (do_swap_account)
2419 2420
			res_counter_uncharge(&old->memsw, bytes);
		stock->nr_pages = 0;
2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432
	}
	stock->cached = NULL;
}

/*
 * This must be called under preempt disabled or must be called by
 * a thread which is pinned to local cpu.
 */
static void drain_local_stock(struct work_struct *dummy)
{
	struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
	drain_stock(stock);
2433
	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
2434 2435
}

2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446
static void __init memcg_stock_init(void)
{
	int cpu;

	for_each_possible_cpu(cpu) {
		struct memcg_stock_pcp *stock =
					&per_cpu(memcg_stock, cpu);
		INIT_WORK(&stock->work, drain_local_stock);
	}
}

2447 2448
/*
 * Cache charges(val) which is from res_counter, to local per_cpu area.
2449
 * This will be consumed by consume_stock() function, later.
2450
 */
2451
static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2452 2453 2454
{
	struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);

2455
	if (stock->cached != memcg) { /* reset if necessary */
2456
		drain_stock(stock);
2457
		stock->cached = memcg;
2458
	}
2459
	stock->nr_pages += nr_pages;
2460 2461 2462 2463
	put_cpu_var(memcg_stock);
}

/*
2464
 * Drains all per-CPU charge caches for given root_memcg resp. subtree
2465 2466
 * of the hierarchy under it. sync flag says whether we should block
 * until the work is done.
2467
 */
2468
static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
2469
{
2470
	int cpu, curcpu;
2471

2472 2473
	/* Notify other cpus that system-wide "drain" is running */
	get_online_cpus();
2474
	curcpu = get_cpu();
2475 2476
	for_each_online_cpu(cpu) {
		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2477
		struct mem_cgroup *memcg;
2478

2479 2480
		memcg = stock->cached;
		if (!memcg || !stock->nr_pages)
2481
			continue;
2482
		if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
2483
			continue;
2484 2485 2486 2487 2488 2489
		if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
			if (cpu == curcpu)
				drain_local_stock(&stock->work);
			else
				schedule_work_on(cpu, &stock->work);
		}
2490
	}
2491
	put_cpu();
2492 2493 2494 2495 2496 2497

	if (!sync)
		goto out;

	for_each_online_cpu(cpu) {
		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2498
		if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
2499 2500 2501
			flush_work(&stock->work);
	}
out:
A
Andrew Morton 已提交
2502
	put_online_cpus();
2503 2504 2505 2506 2507 2508 2509 2510
}

/*
 * Tries to drain stocked charges in other cpus. This function is asynchronous
 * and just put a work per cpu for draining localy on each cpu. Caller can
 * expects some charges will be back to res_counter later but cannot wait for
 * it.
 */
2511
static void drain_all_stock_async(struct mem_cgroup *root_memcg)
2512
{
2513 2514 2515 2516 2517
	/*
	 * If someone calls draining, avoid adding more kworker runs.
	 */
	if (!mutex_trylock(&percpu_charge_mutex))
		return;
2518
	drain_all_stock(root_memcg, false);
2519
	mutex_unlock(&percpu_charge_mutex);
2520 2521 2522
}

/* This is a synchronous drain interface. */
2523
static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
2524 2525
{
	/* called when force_empty is called */
2526
	mutex_lock(&percpu_charge_mutex);
2527
	drain_all_stock(root_memcg, true);
2528
	mutex_unlock(&percpu_charge_mutex);
2529 2530
}

2531 2532 2533 2534
/*
 * This function drains percpu counter value from DEAD cpu and
 * move it to local cpu. Note that this function can be preempted.
 */
2535
static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
2536 2537 2538
{
	int i;

2539
	spin_lock(&memcg->pcp_counter_lock);
2540
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
2541
		long x = per_cpu(memcg->stat->count[i], cpu);
2542

2543 2544
		per_cpu(memcg->stat->count[i], cpu) = 0;
		memcg->nocpu_base.count[i] += x;
2545
	}
2546
	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
2547
		unsigned long x = per_cpu(memcg->stat->events[i], cpu);
2548

2549 2550
		per_cpu(memcg->stat->events[i], cpu) = 0;
		memcg->nocpu_base.events[i] += x;
2551
	}
2552
	spin_unlock(&memcg->pcp_counter_lock);
2553 2554
}

2555
static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
2556 2557 2558 2559 2560
					unsigned long action,
					void *hcpu)
{
	int cpu = (unsigned long)hcpu;
	struct memcg_stock_pcp *stock;
2561
	struct mem_cgroup *iter;
2562

2563
	if (action == CPU_ONLINE)
2564 2565
		return NOTIFY_OK;

2566
	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
2567
		return NOTIFY_OK;
2568

2569
	for_each_mem_cgroup(iter)
2570 2571
		mem_cgroup_drain_pcp_counter(iter, cpu);

2572 2573 2574 2575 2576
	stock = &per_cpu(memcg_stock, cpu);
	drain_stock(stock);
	return NOTIFY_OK;
}

2577

2578
/* See mem_cgroup_try_charge() for details */
2579 2580 2581 2582 2583 2584 2585
enum {
	CHARGE_OK,		/* success */
	CHARGE_RETRY,		/* need to retry but retry is not bad */
	CHARGE_NOMEM,		/* we can't do more. return -ENOMEM */
	CHARGE_WOULDBLOCK,	/* GFP_WAIT wasn't set and no enough res. */
};

2586
static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
2587
				unsigned int nr_pages, unsigned int min_pages,
2588
				bool invoke_oom)
2589
{
2590
	unsigned long csize = nr_pages * PAGE_SIZE;
2591 2592 2593 2594 2595
	struct mem_cgroup *mem_over_limit;
	struct res_counter *fail_res;
	unsigned long flags = 0;
	int ret;

2596
	ret = res_counter_charge(&memcg->res, csize, &fail_res);
2597 2598 2599 2600

	if (likely(!ret)) {
		if (!do_swap_account)
			return CHARGE_OK;
2601
		ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
2602 2603 2604
		if (likely(!ret))
			return CHARGE_OK;

2605
		res_counter_uncharge(&memcg->res, csize);
2606 2607 2608 2609
		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
	} else
		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
2610 2611 2612 2613
	/*
	 * Never reclaim on behalf of optional batching, retry with a
	 * single page instead.
	 */
2614
	if (nr_pages > min_pages)
2615 2616 2617 2618 2619
		return CHARGE_RETRY;

	if (!(gfp_mask & __GFP_WAIT))
		return CHARGE_WOULDBLOCK;

2620 2621 2622
	if (gfp_mask & __GFP_NORETRY)
		return CHARGE_NOMEM;

2623
	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
2624
	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
2625
		return CHARGE_RETRY;
2626
	/*
2627 2628 2629 2630 2631 2632 2633
	 * Even though the limit is exceeded at this point, reclaim
	 * may have been able to free some pages.  Retry the charge
	 * before killing the task.
	 *
	 * Only for regular pages, though: huge pages are rather
	 * unlikely to succeed so close to the limit, and we fall back
	 * to regular pages anyway in case of failure.
2634
	 */
2635
	if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret)
2636 2637 2638 2639 2640 2641 2642 2643 2644
		return CHARGE_RETRY;

	/*
	 * At task move, charge accounts can be doubly counted. So, it's
	 * better to wait until the end of task_move if something is going on.
	 */
	if (mem_cgroup_wait_acct_move(mem_over_limit))
		return CHARGE_RETRY;

2645 2646
	if (invoke_oom)
		mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize));
2647

2648
	return CHARGE_NOMEM;
2649 2650
}

2651 2652 2653 2654 2655
/**
 * mem_cgroup_try_charge - try charging a memcg
 * @memcg: memcg to charge
 * @nr_pages: number of pages to charge
 * @oom: trigger OOM if reclaim fails
2656
 *
2657 2658
 * Returns 0 if @memcg was charged successfully, -EINTR if the charge
 * was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed.
2659
 */
2660 2661 2662 2663
static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
				 gfp_t gfp_mask,
				 unsigned int nr_pages,
				 bool oom)
2664
{
2665
	unsigned int batch = max(CHARGE_BATCH, nr_pages);
2666 2667
	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
	int ret;
2668

2669 2670
	if (mem_cgroup_is_root(memcg))
		goto done;
K
KAMEZAWA Hiroyuki 已提交
2671
	/*
2672 2673 2674 2675
	 * Unlike in global OOM situations, memcg is not in a physical
	 * memory shortage.  Allow dying and OOM-killed tasks to
	 * bypass the last charges so that they can exit quickly and
	 * free their memory.
K
KAMEZAWA Hiroyuki 已提交
2676
	 */
2677 2678
	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
		     fatal_signal_pending(current)))
K
KAMEZAWA Hiroyuki 已提交
2679
		goto bypass;
2680

2681
	if (unlikely(task_in_memcg_oom(current)))
2682
		goto nomem;
2683

2684 2685
	if (gfp_mask & __GFP_NOFAIL)
		oom = false;
K
KAMEZAWA Hiroyuki 已提交
2686
again:
2687 2688
	if (consume_stock(memcg, nr_pages))
		goto done;
2689

2690
	do {
2691
		bool invoke_oom = oom && !nr_oom_retries;
2692

2693
		/* If killed, bypass charge */
2694
		if (fatal_signal_pending(current))
2695
			goto bypass;
2696

2697 2698
		ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
					   nr_pages, invoke_oom);
2699 2700 2701 2702
		switch (ret) {
		case CHARGE_OK:
			break;
		case CHARGE_RETRY: /* not in OOM situation but retry */
2703
			batch = nr_pages;
K
KAMEZAWA Hiroyuki 已提交
2704
			goto again;
2705 2706 2707
		case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
			goto nomem;
		case CHARGE_NOMEM: /* OOM routine works */
2708
			if (!oom || invoke_oom)
K
KAMEZAWA Hiroyuki 已提交
2709
				goto nomem;
2710 2711
			nr_oom_retries--;
			break;
2712
		}
2713 2714
	} while (ret != CHARGE_OK);

2715
	if (batch > nr_pages)
2716
		refill_stock(memcg, batch - nr_pages);
2717
done:
2718 2719
	return 0;
nomem:
2720
	if (!(gfp_mask & __GFP_NOFAIL))
2721
		return -ENOMEM;
K
KAMEZAWA Hiroyuki 已提交
2722
bypass:
2723
	return -EINTR;
2724
}
2725

2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754
/**
 * mem_cgroup_try_charge_mm - try charging a mm
 * @mm: mm_struct to charge
 * @nr_pages: number of pages to charge
 * @oom: trigger OOM if reclaim fails
 *
 * Returns the charged mem_cgroup associated with the given mm_struct or
 * NULL the charge failed.
 */
static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
				 gfp_t gfp_mask,
				 unsigned int nr_pages,
				 bool oom)

{
	struct mem_cgroup *memcg;
	int ret;

	memcg = get_mem_cgroup_from_mm(mm);
	ret = mem_cgroup_try_charge(memcg, gfp_mask, nr_pages, oom);
	css_put(&memcg->css);
	if (ret == -EINTR)
		memcg = root_mem_cgroup;
	else if (ret)
		memcg = NULL;

	return memcg;
}

2755 2756 2757 2758 2759
/*
 * Somemtimes we have to undo a charge we got by try_charge().
 * This function is for that and do uncharge, put css's refcnt.
 * gotten by try_charge().
 */
2760
static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
2761
				       unsigned int nr_pages)
2762
{
2763
	if (!mem_cgroup_is_root(memcg)) {
2764 2765
		unsigned long bytes = nr_pages * PAGE_SIZE;

2766
		res_counter_uncharge(&memcg->res, bytes);
2767
		if (do_swap_account)
2768
			res_counter_uncharge(&memcg->memsw, bytes);
2769
	}
2770 2771
}

2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789
/*
 * Cancel chrages in this cgroup....doesn't propagate to parent cgroup.
 * This is useful when moving usage to parent cgroup.
 */
static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
					unsigned int nr_pages)
{
	unsigned long bytes = nr_pages * PAGE_SIZE;

	if (mem_cgroup_is_root(memcg))
		return;

	res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
	if (do_swap_account)
		res_counter_uncharge_until(&memcg->memsw,
						memcg->memsw.parent, bytes);
}

2790 2791
/*
 * A helper function to get mem_cgroup from ID. must be called under
T
Tejun Heo 已提交
2792 2793 2794
 * rcu_read_lock().  The caller is responsible for calling css_tryget if
 * the mem_cgroup is used for charging. (dropping refcnt from swap can be
 * called against removed memcg.)
2795 2796 2797 2798 2799 2800
 */
static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
{
	/* ID 0 is unused ID */
	if (!id)
		return NULL;
L
Li Zefan 已提交
2801
	return mem_cgroup_from_id(id);
2802 2803
}

2804
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2805
{
2806
	struct mem_cgroup *memcg = NULL;
2807
	struct page_cgroup *pc;
2808
	unsigned short id;
2809 2810
	swp_entry_t ent;

2811
	VM_BUG_ON_PAGE(!PageLocked(page), page);
2812 2813

	pc = lookup_page_cgroup(page);
2814
	lock_page_cgroup(pc);
2815
	if (PageCgroupUsed(pc)) {
2816 2817 2818
		memcg = pc->mem_cgroup;
		if (memcg && !css_tryget(&memcg->css))
			memcg = NULL;
2819
	} else if (PageSwapCache(page)) {
2820
		ent.val = page_private(page);
2821
		id = lookup_swap_cgroup_id(ent);
2822
		rcu_read_lock();
2823 2824 2825
		memcg = mem_cgroup_lookup(id);
		if (memcg && !css_tryget(&memcg->css))
			memcg = NULL;
2826
		rcu_read_unlock();
2827
	}
2828
	unlock_page_cgroup(pc);
2829
	return memcg;
2830 2831
}

2832
static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
2833
				       struct page *page,
2834
				       unsigned int nr_pages,
2835 2836
				       enum charge_type ctype,
				       bool lrucare)
2837
{
2838
	struct page_cgroup *pc = lookup_page_cgroup(page);
2839
	struct zone *uninitialized_var(zone);
2840
	struct lruvec *lruvec;
2841
	bool was_on_lru = false;
2842
	bool anon;
2843

2844
	lock_page_cgroup(pc);
2845
	VM_BUG_ON_PAGE(PageCgroupUsed(pc), page);
2846 2847 2848 2849
	/*
	 * we don't need page_cgroup_lock about tail pages, becase they are not
	 * accessed by any other context at this point.
	 */
2850 2851 2852 2853 2854 2855 2856 2857 2858

	/*
	 * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
	 * may already be on some other mem_cgroup's LRU.  Take care of it.
	 */
	if (lrucare) {
		zone = page_zone(page);
		spin_lock_irq(&zone->lru_lock);
		if (PageLRU(page)) {
2859
			lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2860
			ClearPageLRU(page);
2861
			del_page_from_lru_list(page, lruvec, page_lru(page));
2862 2863 2864 2865
			was_on_lru = true;
		}
	}

2866
	pc->mem_cgroup = memcg;
2867 2868 2869 2870 2871 2872
	/*
	 * We access a page_cgroup asynchronously without lock_page_cgroup().
	 * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
	 * is accessed after testing USED bit. To make pc->mem_cgroup visible
	 * before USED bit, we need memory barrier here.
	 * See mem_cgroup_add_lru_list(), etc.
A
Andrew Morton 已提交
2873
	 */
K
KAMEZAWA Hiroyuki 已提交
2874
	smp_wmb();
2875
	SetPageCgroupUsed(pc);
2876

2877 2878
	if (lrucare) {
		if (was_on_lru) {
2879
			lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2880
			VM_BUG_ON_PAGE(PageLRU(page), page);
2881
			SetPageLRU(page);
2882
			add_page_to_lru_list(page, lruvec, page_lru(page));
2883 2884 2885 2886
		}
		spin_unlock_irq(&zone->lru_lock);
	}

2887
	if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON)
2888 2889 2890 2891
		anon = true;
	else
		anon = false;

2892
	mem_cgroup_charge_statistics(memcg, page, anon, nr_pages);
2893
	unlock_page_cgroup(pc);
2894

2895
	/*
2896 2897 2898
	 * "charge_statistics" updated event counter. Then, check it.
	 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
	 * if they exceeds softlimit.
2899
	 */
2900
	memcg_check_events(memcg, page);
2901
}
2902

2903 2904
static DEFINE_MUTEX(set_limit_mutex);

2905
#ifdef CONFIG_MEMCG_KMEM
2906 2907
static DEFINE_MUTEX(activate_kmem_mutex);

2908 2909 2910
static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
{
	return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
2911
		memcg_kmem_is_active(memcg);
2912 2913
}

G
Glauber Costa 已提交
2914 2915 2916 2917 2918 2919 2920 2921 2922 2923
/*
 * This is a bit cumbersome, but it is rarely used and avoids a backpointer
 * in the memcg_cache_params struct.
 */
static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p)
{
	struct kmem_cache *cachep;

	VM_BUG_ON(p->is_root_cache);
	cachep = p->root_cache;
2924
	return cache_from_memcg_idx(cachep, memcg_cache_id(p->memcg));
G
Glauber Costa 已提交
2925 2926
}

2927
#ifdef CONFIG_SLABINFO
2928
static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v)
2929
{
2930
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946
	struct memcg_cache_params *params;

	if (!memcg_can_account_kmem(memcg))
		return -EIO;

	print_slabinfo_header(m);

	mutex_lock(&memcg->slab_caches_mutex);
	list_for_each_entry(params, &memcg->memcg_slab_caches, list)
		cache_show(memcg_params_to_cache(params), m);
	mutex_unlock(&memcg->slab_caches_mutex);

	return 0;
}
#endif

2947 2948 2949 2950 2951 2952 2953 2954 2955
static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
{
	struct res_counter *fail_res;
	int ret = 0;

	ret = res_counter_charge(&memcg->kmem, size, &fail_res);
	if (ret)
		return ret;

2956 2957
	ret = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT,
				    oom_gfp_allowed(gfp));
2958 2959
	if (ret == -EINTR)  {
		/*
2960
		 * mem_cgroup_try_charge() chosed to bypass to root due to
2961 2962 2963 2964 2965 2966 2967 2968 2969
		 * OOM kill or fatal signal.  Since our only options are to
		 * either fail the allocation or charge it to this cgroup, do
		 * it as a temporary condition. But we can't fail. From a
		 * kmem/slab perspective, the cache has already been selected,
		 * by mem_cgroup_kmem_get_cache(), so it is too late to change
		 * our minds.
		 *
		 * This condition will only trigger if the task entered
		 * memcg_charge_kmem in a sane state, but was OOM-killed during
2970
		 * mem_cgroup_try_charge() above. Tasks that were already
2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989
		 * dying when the allocation triggers should have been already
		 * directed to the root cgroup in memcontrol.h
		 */
		res_counter_charge_nofail(&memcg->res, size, &fail_res);
		if (do_swap_account)
			res_counter_charge_nofail(&memcg->memsw, size,
						  &fail_res);
		ret = 0;
	} else if (ret)
		res_counter_uncharge(&memcg->kmem, size);

	return ret;
}

static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
{
	res_counter_uncharge(&memcg->res, size);
	if (do_swap_account)
		res_counter_uncharge(&memcg->memsw, size);
2990 2991 2992 2993 2994

	/* Not down to 0 */
	if (res_counter_uncharge(&memcg->kmem, size))
		return;

2995 2996 2997 2998 2999 3000 3001 3002
	/*
	 * Releases a reference taken in kmem_cgroup_css_offline in case
	 * this last uncharge is racing with the offlining code or it is
	 * outliving the memcg existence.
	 *
	 * The memory barrier imposed by test&clear is paired with the
	 * explicit one in memcg_kmem_mark_dead().
	 */
3003
	if (memcg_kmem_test_and_clear_dead(memcg))
3004
		css_put(&memcg->css);
3005 3006
}

3007 3008 3009 3010 3011 3012 3013 3014 3015 3016
/*
 * helper for acessing a memcg's index. It will be used as an index in the
 * child cache array in kmem_cache, and also to derive its name. This function
 * will return -1 when this is not a kmem-limited memcg.
 */
int memcg_cache_id(struct mem_cgroup *memcg)
{
	return memcg ? memcg->kmemcg_id : -1;
}

3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042
static size_t memcg_caches_array_size(int num_groups)
{
	ssize_t size;
	if (num_groups <= 0)
		return 0;

	size = 2 * num_groups;
	if (size < MEMCG_CACHES_MIN_SIZE)
		size = MEMCG_CACHES_MIN_SIZE;
	else if (size > MEMCG_CACHES_MAX_SIZE)
		size = MEMCG_CACHES_MAX_SIZE;

	return size;
}

/*
 * We should update the current array size iff all caches updates succeed. This
 * can only be done from the slab side. The slab mutex needs to be held when
 * calling this.
 */
void memcg_update_array_size(int num)
{
	if (num > memcg_limited_groups_array_size)
		memcg_limited_groups_array_size = memcg_caches_array_size(num);
}

3043 3044
static void kmem_cache_destroy_work_func(struct work_struct *w);

3045 3046 3047 3048
int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
{
	struct memcg_cache_params *cur_params = s->memcg_params;

3049
	VM_BUG_ON(!is_root_cache(s));
3050 3051 3052

	if (num_groups > memcg_limited_groups_array_size) {
		int i;
3053
		struct memcg_cache_params *new_params;
3054 3055 3056
		ssize_t size = memcg_caches_array_size(num_groups);

		size *= sizeof(void *);
3057
		size += offsetof(struct memcg_cache_params, memcg_caches);
3058

3059 3060
		new_params = kzalloc(size, GFP_KERNEL);
		if (!new_params)
3061 3062
			return -ENOMEM;

3063
		new_params->is_root_cache = true;
3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076

		/*
		 * There is the chance it will be bigger than
		 * memcg_limited_groups_array_size, if we failed an allocation
		 * in a cache, in which case all caches updated before it, will
		 * have a bigger array.
		 *
		 * But if that is the case, the data after
		 * memcg_limited_groups_array_size is certainly unused
		 */
		for (i = 0; i < memcg_limited_groups_array_size; i++) {
			if (!cur_params->memcg_caches[i])
				continue;
3077
			new_params->memcg_caches[i] =
3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089
						cur_params->memcg_caches[i];
		}

		/*
		 * Ideally, we would wait until all caches succeed, and only
		 * then free the old one. But this is not worth the extra
		 * pointer per-cache we'd have to have for this.
		 *
		 * It is not a big deal if some caches are left with a size
		 * bigger than the others. And all updates will reset this
		 * anyway.
		 */
3090 3091 3092
		rcu_assign_pointer(s->memcg_params, new_params);
		if (cur_params)
			kfree_rcu(cur_params, rcu_head);
3093 3094 3095 3096
	}
	return 0;
}

3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119
char *memcg_create_cache_name(struct mem_cgroup *memcg,
			      struct kmem_cache *root_cache)
{
	static char *buf = NULL;

	/*
	 * We need a mutex here to protect the shared buffer. Since this is
	 * expected to be called only on cache creation, we can employ the
	 * slab_mutex for that purpose.
	 */
	lockdep_assert_held(&slab_mutex);

	if (!buf) {
		buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
		if (!buf)
			return NULL;
	}

	cgroup_name(memcg->css.cgroup, buf, NAME_MAX + 1);
	return kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
			 memcg_cache_id(memcg), buf);
}

3120 3121
int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
			     struct kmem_cache *root_cache)
3122
{
3123
	size_t size;
3124 3125 3126 3127

	if (!memcg_kmem_enabled())
		return 0;

3128 3129
	if (!memcg) {
		size = offsetof(struct memcg_cache_params, memcg_caches);
3130
		size += memcg_limited_groups_array_size * sizeof(void *);
3131 3132
	} else
		size = sizeof(struct memcg_cache_params);
3133

3134 3135 3136 3137
	s->memcg_params = kzalloc(size, GFP_KERNEL);
	if (!s->memcg_params)
		return -ENOMEM;

G
Glauber Costa 已提交
3138
	if (memcg) {
3139
		s->memcg_params->memcg = memcg;
G
Glauber Costa 已提交
3140
		s->memcg_params->root_cache = root_cache;
3141 3142
		INIT_WORK(&s->memcg_params->destroy,
				kmem_cache_destroy_work_func);
3143
		css_get(&memcg->css);
3144 3145 3146
	} else
		s->memcg_params->is_root_cache = true;

3147 3148 3149
	return 0;
}

3150 3151
void memcg_free_cache_params(struct kmem_cache *s)
{
3152 3153 3154 3155
	if (!s->memcg_params)
		return;
	if (!s->memcg_params->is_root_cache)
		css_put(&s->memcg_params->memcg->css);
3156 3157 3158
	kfree(s->memcg_params);
}

3159
void memcg_register_cache(struct kmem_cache *s)
3160
{
3161 3162 3163 3164
	struct kmem_cache *root;
	struct mem_cgroup *memcg;
	int id;

3165 3166 3167
	if (is_root_cache(s))
		return;

3168 3169 3170 3171 3172 3173
	/*
	 * Holding the slab_mutex assures nobody will touch the memcg_caches
	 * array while we are modifying it.
	 */
	lockdep_assert_held(&slab_mutex);

3174 3175 3176 3177
	root = s->memcg_params->root_cache;
	memcg = s->memcg_params->memcg;
	id = memcg_cache_id(memcg);

3178
	/*
3179 3180 3181
	 * Since readers won't lock (see cache_from_memcg_idx()), we need a
	 * barrier here to ensure nobody will see the kmem_cache partially
	 * initialized.
3182
	 */
3183 3184
	smp_wmb();

3185 3186 3187 3188 3189
	/*
	 * Initialize the pointer to this cache in its parent's memcg_params
	 * before adding it to the memcg_slab_caches list, otherwise we can
	 * fail to convert memcg_params_to_cache() while traversing the list.
	 */
3190
	VM_BUG_ON(root->memcg_params->memcg_caches[id]);
3191
	root->memcg_params->memcg_caches[id] = s;
3192 3193 3194 3195

	mutex_lock(&memcg->slab_caches_mutex);
	list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
	mutex_unlock(&memcg->slab_caches_mutex);
3196
}
3197

3198 3199 3200 3201 3202 3203 3204 3205
void memcg_unregister_cache(struct kmem_cache *s)
{
	struct kmem_cache *root;
	struct mem_cgroup *memcg;
	int id;

	if (is_root_cache(s))
		return;
3206

3207 3208 3209 3210 3211 3212
	/*
	 * Holding the slab_mutex assures nobody will touch the memcg_caches
	 * array while we are modifying it.
	 */
	lockdep_assert_held(&slab_mutex);

3213
	root = s->memcg_params->root_cache;
3214 3215
	memcg = s->memcg_params->memcg;
	id = memcg_cache_id(memcg);
3216 3217 3218 3219 3220

	mutex_lock(&memcg->slab_caches_mutex);
	list_del(&s->memcg_params->list);
	mutex_unlock(&memcg->slab_caches_mutex);

3221 3222 3223 3224 3225
	/*
	 * Clear the pointer to this cache in its parent's memcg_params only
	 * after removing it from the memcg_slab_caches list, otherwise we can
	 * fail to convert memcg_params_to_cache() while traversing the list.
	 */
3226
	VM_BUG_ON(root->memcg_params->memcg_caches[id] != s);
3227
	root->memcg_params->memcg_caches[id] = NULL;
3228 3229
}

3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260
/*
 * During the creation a new cache, we need to disable our accounting mechanism
 * altogether. This is true even if we are not creating, but rather just
 * enqueing new caches to be created.
 *
 * This is because that process will trigger allocations; some visible, like
 * explicit kmallocs to auxiliary data structures, name strings and internal
 * cache structures; some well concealed, like INIT_WORK() that can allocate
 * objects during debug.
 *
 * If any allocation happens during memcg_kmem_get_cache, we will recurse back
 * to it. This may not be a bounded recursion: since the first cache creation
 * failed to complete (waiting on the allocation), we'll just try to create the
 * cache again, failing at the same point.
 *
 * memcg_kmem_get_cache is prepared to abort after seeing a positive count of
 * memcg_kmem_skip_account. So we enclose anything that might allocate memory
 * inside the following two functions.
 */
static inline void memcg_stop_kmem_account(void)
{
	VM_BUG_ON(!current->mm);
	current->memcg_kmem_skip_account++;
}

static inline void memcg_resume_kmem_account(void)
{
	VM_BUG_ON(!current->mm);
	current->memcg_kmem_skip_account--;
}

G
Glauber Costa 已提交
3261 3262 3263 3264 3265 3266 3267 3268 3269
static void kmem_cache_destroy_work_func(struct work_struct *w)
{
	struct kmem_cache *cachep;
	struct memcg_cache_params *p;

	p = container_of(w, struct memcg_cache_params, destroy);

	cachep = memcg_params_to_cache(p);

G
Glauber Costa 已提交
3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285
	/*
	 * If we get down to 0 after shrink, we could delete right away.
	 * However, memcg_release_pages() already puts us back in the workqueue
	 * in that case. If we proceed deleting, we'll get a dangling
	 * reference, and removing the object from the workqueue in that case
	 * is unnecessary complication. We are not a fast path.
	 *
	 * Note that this case is fundamentally different from racing with
	 * shrink_slab(): if memcg_cgroup_destroy_cache() is called in
	 * kmem_cache_shrink, not only we would be reinserting a dead cache
	 * into the queue, but doing so from inside the worker racing to
	 * destroy it.
	 *
	 * So if we aren't down to zero, we'll just schedule a worker and try
	 * again
	 */
3286
	if (atomic_read(&cachep->memcg_params->nr_pages) != 0)
G
Glauber Costa 已提交
3287
		kmem_cache_shrink(cachep);
3288
	else
G
Glauber Costa 已提交
3289 3290 3291 3292 3293 3294 3295 3296
		kmem_cache_destroy(cachep);
}

void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
{
	if (!cachep->memcg_params->dead)
		return;

G
Glauber Costa 已提交
3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316
	/*
	 * There are many ways in which we can get here.
	 *
	 * We can get to a memory-pressure situation while the delayed work is
	 * still pending to run. The vmscan shrinkers can then release all
	 * cache memory and get us to destruction. If this is the case, we'll
	 * be executed twice, which is a bug (the second time will execute over
	 * bogus data). In this case, cancelling the work should be fine.
	 *
	 * But we can also get here from the worker itself, if
	 * kmem_cache_shrink is enough to shake all the remaining objects and
	 * get the page count to 0. In this case, we'll deadlock if we try to
	 * cancel the work (the worker runs with an internal lock held, which
	 * is the same lock we would hold for cancel_work_sync().)
	 *
	 * Since we can't possibly know who got us here, just refrain from
	 * running if there is already work pending
	 */
	if (work_pending(&cachep->memcg_params->destroy))
		return;
G
Glauber Costa 已提交
3317 3318 3319 3320 3321 3322 3323
	/*
	 * We have to defer the actual destroying to a workqueue, because
	 * we might currently be in a context that cannot sleep.
	 */
	schedule_work(&cachep->memcg_params->destroy);
}

3324
int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
3325 3326
{
	struct kmem_cache *c;
3327
	int i, failed = 0;
3328 3329 3330 3331 3332 3333 3334 3335

	/*
	 * If the cache is being destroyed, we trust that there is no one else
	 * requesting objects from it. Even if there are, the sanity checks in
	 * kmem_cache_destroy should caught this ill-case.
	 *
	 * Still, we don't want anyone else freeing memcg_caches under our
	 * noses, which can happen if a new memcg comes to life. As usual,
3336 3337
	 * we'll take the activate_kmem_mutex to protect ourselves against
	 * this.
3338
	 */
3339
	mutex_lock(&activate_kmem_mutex);
3340 3341
	for_each_memcg_cache_index(i) {
		c = cache_from_memcg_idx(s, i);
3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358
		if (!c)
			continue;

		/*
		 * We will now manually delete the caches, so to avoid races
		 * we need to cancel all pending destruction workers and
		 * proceed with destruction ourselves.
		 *
		 * kmem_cache_destroy() will call kmem_cache_shrink internally,
		 * and that could spawn the workers again: it is likely that
		 * the cache still have active pages until this very moment.
		 * This would lead us back to mem_cgroup_destroy_cache.
		 *
		 * But that will not execute at all if the "dead" flag is not
		 * set, so flip it down to guarantee we are in control.
		 */
		c->memcg_params->dead = false;
G
Glauber Costa 已提交
3359
		cancel_work_sync(&c->memcg_params->destroy);
3360
		kmem_cache_destroy(c);
3361 3362 3363

		if (cache_from_memcg_idx(s, i))
			failed++;
3364
	}
3365
	mutex_unlock(&activate_kmem_mutex);
3366
	return failed;
3367 3368
}

G
Glauber Costa 已提交
3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385
static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
	struct kmem_cache *cachep;
	struct memcg_cache_params *params;

	if (!memcg_kmem_is_active(memcg))
		return;

	mutex_lock(&memcg->slab_caches_mutex);
	list_for_each_entry(params, &memcg->memcg_slab_caches, list) {
		cachep = memcg_params_to_cache(params);
		cachep->memcg_params->dead = true;
		schedule_work(&cachep->memcg_params->destroy);
	}
	mutex_unlock(&memcg->slab_caches_mutex);
}

3386 3387 3388 3389 3390 3391
struct create_work {
	struct mem_cgroup *memcg;
	struct kmem_cache *cachep;
	struct work_struct work;
};

3392 3393
static void memcg_create_cache_work_func(struct work_struct *w)
{
3394 3395 3396
	struct create_work *cw = container_of(w, struct create_work, work);
	struct mem_cgroup *memcg = cw->memcg;
	struct kmem_cache *cachep = cw->cachep;
3397

3398
	kmem_cache_create_memcg(memcg, cachep);
3399
	css_put(&memcg->css);
3400 3401 3402 3403 3404 3405
	kfree(cw);
}

/*
 * Enqueue the creation of a per-memcg kmem_cache.
 */
3406 3407
static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
					 struct kmem_cache *cachep)
3408 3409 3410 3411
{
	struct create_work *cw;

	cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
3412 3413
	if (cw == NULL) {
		css_put(&memcg->css);
3414 3415 3416 3417 3418 3419 3420 3421 3422 3423
		return;
	}

	cw->memcg = memcg;
	cw->cachep = cachep;

	INIT_WORK(&cw->work, memcg_create_cache_work_func);
	schedule_work(&cw->work);
}

3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441
static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
				       struct kmem_cache *cachep)
{
	/*
	 * We need to stop accounting when we kmalloc, because if the
	 * corresponding kmalloc cache is not yet created, the first allocation
	 * in __memcg_create_cache_enqueue will recurse.
	 *
	 * However, it is better to enclose the whole function. Depending on
	 * the debugging options enabled, INIT_WORK(), for instance, can
	 * trigger an allocation. This too, will make us recurse. Because at
	 * this point we can't allow ourselves back into memcg_kmem_get_cache,
	 * the safest choice is to do it like this, wrapping the whole function.
	 */
	memcg_stop_kmem_account();
	__memcg_create_cache_enqueue(memcg, cachep);
	memcg_resume_kmem_account();
}
3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458
/*
 * Return the kmem_cache we're supposed to use for a slab allocation.
 * We try to use the current memcg's version of the cache.
 *
 * If the cache does not exist yet, if we are the first user of it,
 * we either create it immediately, if possible, or create it asynchronously
 * in a workqueue.
 * In the latter case, we will let the current allocation go through with
 * the original cache.
 *
 * Can't be called in interrupt context or from kernel threads.
 * This function needs to be called with rcu_read_lock() held.
 */
struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
					  gfp_t gfp)
{
	struct mem_cgroup *memcg;
3459
	struct kmem_cache *memcg_cachep;
3460 3461 3462 3463

	VM_BUG_ON(!cachep->memcg_params);
	VM_BUG_ON(!cachep->memcg_params->is_root_cache);

3464 3465 3466
	if (!current->mm || current->memcg_kmem_skip_account)
		return cachep;

3467 3468 3469 3470
	rcu_read_lock();
	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));

	if (!memcg_can_account_kmem(memcg))
3471
		goto out;
3472

3473 3474 3475
	memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));
	if (likely(memcg_cachep)) {
		cachep = memcg_cachep;
3476
		goto out;
3477 3478
	}

3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505
	/* The corresponding put will be done in the workqueue. */
	if (!css_tryget(&memcg->css))
		goto out;
	rcu_read_unlock();

	/*
	 * If we are in a safe context (can wait, and not in interrupt
	 * context), we could be be predictable and return right away.
	 * This would guarantee that the allocation being performed
	 * already belongs in the new cache.
	 *
	 * However, there are some clashes that can arrive from locking.
	 * For instance, because we acquire the slab_mutex while doing
	 * kmem_cache_dup, this means no further allocation could happen
	 * with the slab_mutex held.
	 *
	 * Also, because cache creation issue get_online_cpus(), this
	 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
	 * that ends up reversed during cpu hotplug. (cpuset allocates
	 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
	 * better to defer everything.
	 */
	memcg_create_cache_enqueue(memcg, cachep);
	return cachep;
out:
	rcu_read_unlock();
	return cachep;
3506 3507 3508
}
EXPORT_SYMBOL(__memcg_kmem_get_cache);

3509 3510 3511 3512 3513 3514 3515 3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529
/*
 * We need to verify if the allocation against current->mm->owner's memcg is
 * possible for the given order. But the page is not allocated yet, so we'll
 * need a further commit step to do the final arrangements.
 *
 * It is possible for the task to switch cgroups in this mean time, so at
 * commit time, we can't rely on task conversion any longer.  We'll then use
 * the handle argument to return to the caller which cgroup we should commit
 * against. We could also return the memcg directly and avoid the pointer
 * passing, but a boolean return value gives better semantics considering
 * the compiled-out case as well.
 *
 * Returning true means the allocation is possible.
 */
bool
__memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
{
	struct mem_cgroup *memcg;
	int ret;

	*_memcg = NULL;
3530 3531 3532 3533 3534 3535 3536 3537 3538 3539 3540 3541 3542 3543 3544

	/*
	 * Disabling accounting is only relevant for some specific memcg
	 * internal allocations. Therefore we would initially not have such
	 * check here, since direct calls to the page allocator that are marked
	 * with GFP_KMEMCG only happen outside memcg core. We are mostly
	 * concerned with cache allocations, and by having this test at
	 * memcg_kmem_get_cache, we are already able to relay the allocation to
	 * the root cache and bypass the memcg cache altogether.
	 *
	 * There is one exception, though: the SLUB allocator does not create
	 * large order caches, but rather service large kmallocs directly from
	 * the page allocator. Therefore, the following sequence when backed by
	 * the SLUB allocator:
	 *
A
Andrew Morton 已提交
3545 3546 3547
	 *	memcg_stop_kmem_account();
	 *	kmalloc(<large_number>)
	 *	memcg_resume_kmem_account();
3548 3549 3550 3551 3552 3553 3554 3555 3556 3557
	 *
	 * would effectively ignore the fact that we should skip accounting,
	 * since it will drive us directly to this function without passing
	 * through the cache selector memcg_kmem_get_cache. Such large
	 * allocations are extremely rare but can happen, for instance, for the
	 * cache arrays. We bring this test here.
	 */
	if (!current->mm || current->memcg_kmem_skip_account)
		return true;

3558
	memcg = get_mem_cgroup_from_mm(current->mm);
3559 3560 3561 3562 3563 3564 3565 3566 3567 3568 3569 3570 3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581 3582 3583 3584 3585 3586 3587 3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620

	if (!memcg_can_account_kmem(memcg)) {
		css_put(&memcg->css);
		return true;
	}

	ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order);
	if (!ret)
		*_memcg = memcg;

	css_put(&memcg->css);
	return (ret == 0);
}

void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg,
			      int order)
{
	struct page_cgroup *pc;

	VM_BUG_ON(mem_cgroup_is_root(memcg));

	/* The page allocation failed. Revert */
	if (!page) {
		memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
		return;
	}

	pc = lookup_page_cgroup(page);
	lock_page_cgroup(pc);
	pc->mem_cgroup = memcg;
	SetPageCgroupUsed(pc);
	unlock_page_cgroup(pc);
}

void __memcg_kmem_uncharge_pages(struct page *page, int order)
{
	struct mem_cgroup *memcg = NULL;
	struct page_cgroup *pc;


	pc = lookup_page_cgroup(page);
	/*
	 * Fast unlocked return. Theoretically might have changed, have to
	 * check again after locking.
	 */
	if (!PageCgroupUsed(pc))
		return;

	lock_page_cgroup(pc);
	if (PageCgroupUsed(pc)) {
		memcg = pc->mem_cgroup;
		ClearPageCgroupUsed(pc);
	}
	unlock_page_cgroup(pc);

	/*
	 * We trust that only if there is a memcg associated with the page, it
	 * is a valid allocation
	 */
	if (!memcg)
		return;

3621
	VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
3622 3623
	memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
}
G
Glauber Costa 已提交
3624 3625 3626 3627
#else
static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
}
3628 3629
#endif /* CONFIG_MEMCG_KMEM */

3630 3631
#ifdef CONFIG_TRANSPARENT_HUGEPAGE

3632
#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
3633 3634
/*
 * Because tail pages are not marked as "used", set it. We're under
3635 3636 3637
 * zone->lru_lock, 'splitting on pmd' and compound_lock.
 * charge/uncharge will be never happen and move_account() is done under
 * compound_lock(), so we don't have to take care of races.
3638
 */
3639
void mem_cgroup_split_huge_fixup(struct page *head)
3640 3641
{
	struct page_cgroup *head_pc = lookup_page_cgroup(head);
3642
	struct page_cgroup *pc;
3643
	struct mem_cgroup *memcg;
3644
	int i;
3645

3646 3647
	if (mem_cgroup_disabled())
		return;
3648 3649

	memcg = head_pc->mem_cgroup;
3650 3651
	for (i = 1; i < HPAGE_PMD_NR; i++) {
		pc = head_pc + i;
3652
		pc->mem_cgroup = memcg;
3653 3654 3655
		smp_wmb();/* see __commit_charge() */
		pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
	}
3656 3657
	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
		       HPAGE_PMD_NR);
3658
}
3659
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3660

3661
/**
3662
 * mem_cgroup_move_account - move account of the page
3663
 * @page: the page
3664
 * @nr_pages: number of regular pages (>1 for huge pages)
3665 3666 3667 3668 3669
 * @pc:	page_cgroup of the page.
 * @from: mem_cgroup which the page is moved from.
 * @to:	mem_cgroup which the page is moved to. @from != @to.
 *
 * The caller must confirm following.
K
KAMEZAWA Hiroyuki 已提交
3670
 * - page is not on LRU (isolate_page() is useful.)
3671
 * - compound_lock is held when nr_pages > 1
3672
 *
3673 3674
 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
 * from old cgroup.
3675
 */
3676 3677 3678 3679
static int mem_cgroup_move_account(struct page *page,
				   unsigned int nr_pages,
				   struct page_cgroup *pc,
				   struct mem_cgroup *from,
3680
				   struct mem_cgroup *to)
3681
{
3682 3683
	unsigned long flags;
	int ret;
3684
	bool anon = PageAnon(page);
3685

3686
	VM_BUG_ON(from == to);
3687
	VM_BUG_ON_PAGE(PageLRU(page), page);
3688 3689 3690 3691 3692 3693 3694
	/*
	 * The page is isolated from LRU. So, collapse function
	 * will not handle this page. But page splitting can happen.
	 * Do this check under compound_page_lock(). The caller should
	 * hold it.
	 */
	ret = -EBUSY;
3695
	if (nr_pages > 1 && !PageTransHuge(page))
3696 3697 3698 3699 3700 3701 3702 3703
		goto out;

	lock_page_cgroup(pc);

	ret = -EINVAL;
	if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
		goto unlock;

3704
	move_lock_mem_cgroup(from, &flags);
3705

3706 3707 3708 3709 3710 3711
	if (!anon && page_mapped(page)) {
		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
			       nr_pages);
		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
			       nr_pages);
	}
3712

3713 3714 3715 3716 3717 3718
	if (PageWriteback(page)) {
		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],
			       nr_pages);
		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],
			       nr_pages);
	}
3719

3720
	mem_cgroup_charge_statistics(from, page, anon, -nr_pages);
3721

3722
	/* caller should have done css_get */
K
KAMEZAWA Hiroyuki 已提交
3723
	pc->mem_cgroup = to;
3724
	mem_cgroup_charge_statistics(to, page, anon, nr_pages);
3725
	move_unlock_mem_cgroup(from, &flags);
3726 3727
	ret = 0;
unlock:
3728
	unlock_page_cgroup(pc);
3729 3730 3731
	/*
	 * check events
	 */
3732 3733
	memcg_check_events(to, page);
	memcg_check_events(from, page);
3734
out:
3735 3736 3737
	return ret;
}

3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757
/**
 * mem_cgroup_move_parent - moves page to the parent group
 * @page: the page to move
 * @pc: page_cgroup of the page
 * @child: page's cgroup
 *
 * move charges to its parent or the root cgroup if the group has no
 * parent (aka use_hierarchy==0).
 * Although this might fail (get_page_unless_zero, isolate_lru_page or
 * mem_cgroup_move_account fails) the failure is always temporary and
 * it signals a race with a page removal/uncharge or migration. In the
 * first case the page is on the way out and it will vanish from the LRU
 * on the next attempt and the call should be retried later.
 * Isolation from the LRU fails only if page has been isolated from
 * the LRU since we looked at it and that usually means either global
 * reclaim or migration going on. The page will either get back to the
 * LRU or vanish.
 * Finaly mem_cgroup_move_account fails only if the page got uncharged
 * (!PageCgroupUsed) or moved to a different group. The page will
 * disappear in the next attempt.
3758
 */
3759 3760
static int mem_cgroup_move_parent(struct page *page,
				  struct page_cgroup *pc,
3761
				  struct mem_cgroup *child)
3762 3763
{
	struct mem_cgroup *parent;
3764
	unsigned int nr_pages;
3765
	unsigned long uninitialized_var(flags);
3766 3767
	int ret;

3768
	VM_BUG_ON(mem_cgroup_is_root(child));
3769

3770 3771 3772 3773 3774
	ret = -EBUSY;
	if (!get_page_unless_zero(page))
		goto out;
	if (isolate_lru_page(page))
		goto put;
3775

3776
	nr_pages = hpage_nr_pages(page);
K
KAMEZAWA Hiroyuki 已提交
3777

3778 3779 3780 3781 3782 3783
	parent = parent_mem_cgroup(child);
	/*
	 * If no parent, move charges to root cgroup.
	 */
	if (!parent)
		parent = root_mem_cgroup;
3784

3785
	if (nr_pages > 1) {
3786
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3787
		flags = compound_lock_irqsave(page);
3788
	}
3789

3790
	ret = mem_cgroup_move_account(page, nr_pages,
3791
				pc, child, parent);
3792 3793
	if (!ret)
		__mem_cgroup_cancel_local_charge(child, nr_pages);
3794

3795
	if (nr_pages > 1)
3796
		compound_unlock_irqrestore(page, flags);
K
KAMEZAWA Hiroyuki 已提交
3797
	putback_lru_page(page);
3798
put:
3799
	put_page(page);
3800
out:
3801 3802 3803
	return ret;
}

3804
int mem_cgroup_charge_anon(struct page *page,
3805
			      struct mm_struct *mm, gfp_t gfp_mask)
3806
{
3807
	unsigned int nr_pages = 1;
3808
	struct mem_cgroup *memcg;
3809
	bool oom = true;
A
Andrea Arcangeli 已提交
3810

3811 3812 3813 3814 3815 3816 3817
	if (mem_cgroup_disabled())
		return 0;

	VM_BUG_ON_PAGE(page_mapped(page), page);
	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
	VM_BUG_ON(!mm);

A
Andrea Arcangeli 已提交
3818
	if (PageTransHuge(page)) {
3819
		nr_pages <<= compound_order(page);
3820
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3821 3822 3823 3824 3825
		/*
		 * Never OOM-kill a process for a huge page.  The
		 * fault handler will fall back to regular pages.
		 */
		oom = false;
A
Andrea Arcangeli 已提交
3826
	}
3827

3828 3829 3830
	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);
	if (!memcg)
		return -ENOMEM;
3831 3832
	__mem_cgroup_commit_charge(memcg, page, nr_pages,
				   MEM_CGROUP_CHARGE_TYPE_ANON, false);
3833 3834 3835
	return 0;
}

3836 3837 3838
/*
 * While swap-in, try_charge -> commit or cancel, the page is locked.
 * And when try_charge() successfully returns, one refcnt to memcg without
3839
 * struct page_cgroup is acquired. This refcnt will be consumed by
3840 3841
 * "commit()" or removed by "cancel()"
 */
3842 3843 3844 3845
static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
					  struct page *page,
					  gfp_t mask,
					  struct mem_cgroup **memcgp)
3846
{
3847
	struct mem_cgroup *memcg = NULL;
3848
	struct page_cgroup *pc;
3849
	int ret;
3850

3851 3852 3853 3854 3855 3856 3857 3858 3859
	pc = lookup_page_cgroup(page);
	/*
	 * Every swap fault against a single page tries to charge the
	 * page, bail as early as possible.  shmem_unuse() encounters
	 * already charged pages, too.  The USED bit is protected by
	 * the page lock, which serializes swap cache removal, which
	 * in turn serializes uncharging.
	 */
	if (PageCgroupUsed(pc))
3860 3861 3862
		goto out;
	if (do_swap_account)
		memcg = try_get_mem_cgroup_from_page(page);
3863
	if (!memcg)
3864 3865
		memcg = get_mem_cgroup_from_mm(mm);
	ret = mem_cgroup_try_charge(memcg, mask, 1, true);
3866
	css_put(&memcg->css);
3867
	if (ret == -EINTR)
3868 3869 3870 3871 3872 3873
		memcg = root_mem_cgroup;
	else if (ret)
		return ret;
out:
	*memcgp = memcg;
	return 0;
3874 3875
}

3876 3877 3878
int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
				 gfp_t gfp_mask, struct mem_cgroup **memcgp)
{
3879 3880
	if (mem_cgroup_disabled()) {
		*memcgp = NULL;
3881
		return 0;
3882
	}
3883 3884 3885 3886 3887 3888 3889
	/*
	 * A racing thread's fault, or swapoff, may have already
	 * updated the pte, and even removed page from swap cache: in
	 * those cases unuse_pte()'s pte_same() test will fail; but
	 * there's also a KSM case which does need to charge the page.
	 */
	if (!PageSwapCache(page)) {
3890
		struct mem_cgroup *memcg;
3891

3892 3893 3894 3895 3896
		memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
		if (!memcg)
			return -ENOMEM;
		*memcgp = memcg;
		return 0;
3897
	}
3898 3899 3900
	return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
}

3901 3902 3903 3904 3905 3906 3907 3908 3909
void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
{
	if (mem_cgroup_disabled())
		return;
	if (!memcg)
		return;
	__mem_cgroup_cancel_charge(memcg, 1);
}

D
Daisuke Nishimura 已提交
3910
static void
3911
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
D
Daisuke Nishimura 已提交
3912
					enum charge_type ctype)
3913
{
3914
	if (mem_cgroup_disabled())
3915
		return;
3916
	if (!memcg)
3917
		return;
3918

3919
	__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
3920 3921 3922
	/*
	 * Now swap is on-memory. This means this page may be
	 * counted both as mem and swap....double count.
3923 3924 3925
	 * Fix it by uncharging from memsw. Basically, this SwapCache is stable
	 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
	 * may call delete_from_swap_cache() before reach here.
3926
	 */
3927
	if (do_swap_account && PageSwapCache(page)) {
3928
		swp_entry_t ent = {.val = page_private(page)};
3929
		mem_cgroup_uncharge_swap(ent);
3930
	}
3931 3932
}

3933 3934
void mem_cgroup_commit_charge_swapin(struct page *page,
				     struct mem_cgroup *memcg)
D
Daisuke Nishimura 已提交
3935
{
3936
	__mem_cgroup_commit_charge_swapin(page, memcg,
3937
					  MEM_CGROUP_CHARGE_TYPE_ANON);
D
Daisuke Nishimura 已提交
3938 3939
}

3940
int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
3941
				gfp_t gfp_mask)
3942
{
3943
	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
3944
	struct mem_cgroup *memcg;
3945 3946
	int ret;

3947
	if (mem_cgroup_disabled())
3948 3949 3950 3951
		return 0;
	if (PageCompound(page))
		return 0;

3952
	if (PageSwapCache(page)) { /* shmem */
3953 3954
		ret = __mem_cgroup_try_charge_swapin(mm, page,
						     gfp_mask, &memcg);
3955 3956 3957 3958
		if (ret)
			return ret;
		__mem_cgroup_commit_charge_swapin(page, memcg, type);
		return 0;
3959
	}
3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973

	/*
	 * Page cache insertions can happen without an actual mm
	 * context, e.g. during disk probing on boot.
	 */
	if (unlikely(!mm))
		memcg = root_mem_cgroup;
	else {
		memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
		if (!memcg)
			return -ENOMEM;
	}
	__mem_cgroup_commit_charge(memcg, page, 1, type, false);
	return 0;
3974 3975
}

3976
static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
3977 3978
				   unsigned int nr_pages,
				   const enum charge_type ctype)
3979 3980 3981
{
	struct memcg_batch_info *batch = NULL;
	bool uncharge_memsw = true;
3982

3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993
	/* If swapout, usage of swap doesn't decrease */
	if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
		uncharge_memsw = false;

	batch = &current->memcg_batch;
	/*
	 * In usual, we do css_get() when we remember memcg pointer.
	 * But in this case, we keep res->usage until end of a series of
	 * uncharges. Then, it's ok to ignore memcg's refcnt.
	 */
	if (!batch->memcg)
3994
		batch->memcg = memcg;
3995 3996
	/*
	 * do_batch > 0 when unmapping pages or inode invalidate/truncate.
L
Lucas De Marchi 已提交
3997
	 * In those cases, all pages freed continuously can be expected to be in
3998 3999 4000 4001 4002 4003 4004 4005
	 * the same cgroup and we have chance to coalesce uncharges.
	 * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
	 * because we want to do uncharge as soon as possible.
	 */

	if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
		goto direct_uncharge;

4006
	if (nr_pages > 1)
A
Andrea Arcangeli 已提交
4007 4008
		goto direct_uncharge;

4009 4010 4011 4012 4013
	/*
	 * In typical case, batch->memcg == mem. This means we can
	 * merge a series of uncharges to an uncharge of res_counter.
	 * If not, we uncharge res_counter ony by one.
	 */
4014
	if (batch->memcg != memcg)
4015 4016
		goto direct_uncharge;
	/* remember freed charge and uncharge it later */
4017
	batch->nr_pages++;
4018
	if (uncharge_memsw)
4019
		batch->memsw_nr_pages++;
4020 4021
	return;
direct_uncharge:
4022
	res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
4023
	if (uncharge_memsw)
4024 4025 4026
		res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
	if (unlikely(batch->memcg != memcg))
		memcg_oom_recover(memcg);
4027
}
4028

4029
/*
4030
 * uncharge if !page_mapped(page)
4031
 */
4032
static struct mem_cgroup *
4033 4034
__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
			     bool end_migration)
4035
{
4036
	struct mem_cgroup *memcg = NULL;
4037 4038
	unsigned int nr_pages = 1;
	struct page_cgroup *pc;
4039
	bool anon;
4040

4041
	if (mem_cgroup_disabled())
4042
		return NULL;
4043

A
Andrea Arcangeli 已提交
4044
	if (PageTransHuge(page)) {
4045
		nr_pages <<= compound_order(page);
4046
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
A
Andrea Arcangeli 已提交
4047
	}
4048
	/*
4049
	 * Check if our page_cgroup is valid
4050
	 */
4051
	pc = lookup_page_cgroup(page);
4052
	if (unlikely(!PageCgroupUsed(pc)))
4053
		return NULL;
4054

4055
	lock_page_cgroup(pc);
K
KAMEZAWA Hiroyuki 已提交
4056

4057
	memcg = pc->mem_cgroup;
4058

K
KAMEZAWA Hiroyuki 已提交
4059 4060 4061
	if (!PageCgroupUsed(pc))
		goto unlock_out;

4062 4063
	anon = PageAnon(page);

K
KAMEZAWA Hiroyuki 已提交
4064
	switch (ctype) {
4065
	case MEM_CGROUP_CHARGE_TYPE_ANON:
4066 4067 4068 4069 4070
		/*
		 * Generally PageAnon tells if it's the anon statistics to be
		 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
		 * used before page reached the stage of being marked PageAnon.
		 */
4071 4072
		anon = true;
		/* fallthrough */
K
KAMEZAWA Hiroyuki 已提交
4073
	case MEM_CGROUP_CHARGE_TYPE_DROP:
4074
		/* See mem_cgroup_prepare_migration() */
4075 4076 4077 4078 4079 4080 4081 4082 4083 4084
		if (page_mapped(page))
			goto unlock_out;
		/*
		 * Pages under migration may not be uncharged.  But
		 * end_migration() /must/ be the one uncharging the
		 * unused post-migration page and so it has to call
		 * here with the migration bit still set.  See the
		 * res_counter handling below.
		 */
		if (!end_migration && PageCgroupMigration(pc))
K
KAMEZAWA Hiroyuki 已提交
4085 4086 4087 4088 4089 4090 4091 4092 4093 4094 4095
			goto unlock_out;
		break;
	case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
		if (!PageAnon(page)) {	/* Shared memory */
			if (page->mapping && !page_is_file_cache(page))
				goto unlock_out;
		} else if (page_mapped(page)) /* Anon */
				goto unlock_out;
		break;
	default:
		break;
4096
	}
K
KAMEZAWA Hiroyuki 已提交
4097

4098
	mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages);
K
KAMEZAWA Hiroyuki 已提交
4099

4100
	ClearPageCgroupUsed(pc);
4101 4102 4103 4104 4105 4106
	/*
	 * pc->mem_cgroup is not cleared here. It will be accessed when it's
	 * freed from LRU. This is safe because uncharged page is expected not
	 * to be reused (freed soon). Exception is SwapCache, it's handled by
	 * special functions.
	 */
4107

4108
	unlock_page_cgroup(pc);
K
KAMEZAWA Hiroyuki 已提交
4109
	/*
4110
	 * even after unlock, we have memcg->res.usage here and this memcg
L
Li Zefan 已提交
4111
	 * will never be freed, so it's safe to call css_get().
K
KAMEZAWA Hiroyuki 已提交
4112
	 */
4113
	memcg_check_events(memcg, page);
K
KAMEZAWA Hiroyuki 已提交
4114
	if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
4115
		mem_cgroup_swap_statistics(memcg, true);
L
Li Zefan 已提交
4116
		css_get(&memcg->css);
K
KAMEZAWA Hiroyuki 已提交
4117
	}
4118 4119 4120 4121 4122 4123
	/*
	 * Migration does not charge the res_counter for the
	 * replacement page, so leave it alone when phasing out the
	 * page that is unused after the migration.
	 */
	if (!end_migration && !mem_cgroup_is_root(memcg))
4124
		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
4125

4126
	return memcg;
K
KAMEZAWA Hiroyuki 已提交
4127 4128 4129

unlock_out:
	unlock_page_cgroup(pc);
4130
	return NULL;
4131 4132
}

4133 4134
void mem_cgroup_uncharge_page(struct page *page)
{
4135 4136 4137
	/* early check. */
	if (page_mapped(page))
		return;
4138
	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
4139 4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150
	/*
	 * If the page is in swap cache, uncharge should be deferred
	 * to the swap path, which also properly accounts swap usage
	 * and handles memcg lifetime.
	 *
	 * Note that this check is not stable and reclaim may add the
	 * page to swap cache at any time after this.  However, if the
	 * page is not in swap cache by the time page->mapcount hits
	 * 0, there won't be any page table references to the swap
	 * slot, and reclaim will free it and not actually write the
	 * page to disk.
	 */
4151 4152
	if (PageSwapCache(page))
		return;
4153
	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
4154 4155 4156 4157
}

void mem_cgroup_uncharge_cache_page(struct page *page)
{
4158 4159
	VM_BUG_ON_PAGE(page_mapped(page), page);
	VM_BUG_ON_PAGE(page->mapping, page);
4160
	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
4161 4162
}

4163 4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176
/*
 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
 * In that cases, pages are freed continuously and we can expect pages
 * are in the same memcg. All these calls itself limits the number of
 * pages freed at once, then uncharge_start/end() is called properly.
 * This may be called prural(2) times in a context,
 */

void mem_cgroup_uncharge_start(void)
{
	current->memcg_batch.do_batch++;
	/* We can do nest. */
	if (current->memcg_batch.do_batch == 1) {
		current->memcg_batch.memcg = NULL;
4177 4178
		current->memcg_batch.nr_pages = 0;
		current->memcg_batch.memsw_nr_pages = 0;
4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198
	}
}

void mem_cgroup_uncharge_end(void)
{
	struct memcg_batch_info *batch = &current->memcg_batch;

	if (!batch->do_batch)
		return;

	batch->do_batch--;
	if (batch->do_batch) /* If stacked, do nothing. */
		return;

	if (!batch->memcg)
		return;
	/*
	 * This "batch->memcg" is valid without any css_get/put etc...
	 * bacause we hide charges behind us.
	 */
4199 4200 4201 4202 4203 4204
	if (batch->nr_pages)
		res_counter_uncharge(&batch->memcg->res,
				     batch->nr_pages * PAGE_SIZE);
	if (batch->memsw_nr_pages)
		res_counter_uncharge(&batch->memcg->memsw,
				     batch->memsw_nr_pages * PAGE_SIZE);
4205
	memcg_oom_recover(batch->memcg);
4206 4207 4208 4209
	/* forget this pointer (for sanity check) */
	batch->memcg = NULL;
}

4210
#ifdef CONFIG_SWAP
4211
/*
4212
 * called after __delete_from_swap_cache() and drop "page" account.
4213 4214
 * memcg information is recorded to swap_cgroup of "ent"
 */
K
KAMEZAWA Hiroyuki 已提交
4215 4216
void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
4217 4218
{
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
4219 4220 4221 4222 4223
	int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;

	if (!swapout) /* this was a swap cache but the swap is unused ! */
		ctype = MEM_CGROUP_CHARGE_TYPE_DROP;

4224
	memcg = __mem_cgroup_uncharge_common(page, ctype, false);
4225

K
KAMEZAWA Hiroyuki 已提交
4226 4227
	/*
	 * record memcg information,  if swapout && memcg != NULL,
L
Li Zefan 已提交
4228
	 * css_get() was called in uncharge().
K
KAMEZAWA Hiroyuki 已提交
4229 4230
	 */
	if (do_swap_account && swapout && memcg)
L
Li Zefan 已提交
4231
		swap_cgroup_record(ent, mem_cgroup_id(memcg));
4232
}
4233
#endif
4234

A
Andrew Morton 已提交
4235
#ifdef CONFIG_MEMCG_SWAP
4236 4237 4238 4239 4240
/*
 * called from swap_entry_free(). remove record in swap_cgroup and
 * uncharge "memsw" account.
 */
void mem_cgroup_uncharge_swap(swp_entry_t ent)
K
KAMEZAWA Hiroyuki 已提交
4241
{
4242
	struct mem_cgroup *memcg;
4243
	unsigned short id;
4244 4245 4246 4247

	if (!do_swap_account)
		return;

4248 4249 4250
	id = swap_cgroup_record(ent, 0);
	rcu_read_lock();
	memcg = mem_cgroup_lookup(id);
4251
	if (memcg) {
4252 4253 4254 4255
		/*
		 * We uncharge this because swap is freed.
		 * This memcg can be obsolete one. We avoid calling css_tryget
		 */
4256
		if (!mem_cgroup_is_root(memcg))
4257
			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
4258
		mem_cgroup_swap_statistics(memcg, false);
L
Li Zefan 已提交
4259
		css_put(&memcg->css);
4260
	}
4261
	rcu_read_unlock();
K
KAMEZAWA Hiroyuki 已提交
4262
}
4263 4264 4265 4266 4267 4268 4269 4270 4271 4272 4273 4274 4275 4276 4277 4278

/**
 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
 * @entry: swap entry to be moved
 * @from:  mem_cgroup which the entry is moved from
 * @to:  mem_cgroup which the entry is moved to
 *
 * It succeeds only when the swap_cgroup's record for this entry is the same
 * as the mem_cgroup's id of @from.
 *
 * Returns 0 on success, -EINVAL on failure.
 *
 * The caller must have charged to @to, IOW, called res_counter_charge() about
 * both res and memsw, and called css_get().
 */
static int mem_cgroup_move_swap_account(swp_entry_t entry,
4279
				struct mem_cgroup *from, struct mem_cgroup *to)
4280 4281 4282
{
	unsigned short old_id, new_id;

L
Li Zefan 已提交
4283 4284
	old_id = mem_cgroup_id(from);
	new_id = mem_cgroup_id(to);
4285 4286 4287

	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
		mem_cgroup_swap_statistics(from, false);
4288
		mem_cgroup_swap_statistics(to, true);
4289
		/*
4290 4291 4292
		 * This function is only called from task migration context now.
		 * It postpones res_counter and refcount handling till the end
		 * of task migration(mem_cgroup_clear_mc()) for performance
L
Li Zefan 已提交
4293 4294 4295 4296 4297 4298
		 * improvement. But we cannot postpone css_get(to)  because if
		 * the process that has been moved to @to does swap-in, the
		 * refcount of @to might be decreased to 0.
		 *
		 * We are in attach() phase, so the cgroup is guaranteed to be
		 * alive, so we can just call css_get().
4299
		 */
L
Li Zefan 已提交
4300
		css_get(&to->css);
4301 4302 4303 4304 4305 4306
		return 0;
	}
	return -EINVAL;
}
#else
static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
4307
				struct mem_cgroup *from, struct mem_cgroup *to)
4308 4309 4310
{
	return -EINVAL;
}
4311
#endif
K
KAMEZAWA Hiroyuki 已提交
4312

4313
/*
4314 4315
 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
 * page belongs to.
4316
 */
4317 4318
void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
				  struct mem_cgroup **memcgp)
4319
{
4320
	struct mem_cgroup *memcg = NULL;
4321
	unsigned int nr_pages = 1;
4322
	struct page_cgroup *pc;
4323
	enum charge_type ctype;
4324

4325
	*memcgp = NULL;
4326

4327
	if (mem_cgroup_disabled())
4328
		return;
4329

4330 4331 4332
	if (PageTransHuge(page))
		nr_pages <<= compound_order(page);

4333 4334 4335
	pc = lookup_page_cgroup(page);
	lock_page_cgroup(pc);
	if (PageCgroupUsed(pc)) {
4336 4337
		memcg = pc->mem_cgroup;
		css_get(&memcg->css);
4338 4339 4340 4341 4342 4343 4344 4345 4346 4347 4348 4349 4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367 4368
		/*
		 * At migrating an anonymous page, its mapcount goes down
		 * to 0 and uncharge() will be called. But, even if it's fully
		 * unmapped, migration may fail and this page has to be
		 * charged again. We set MIGRATION flag here and delay uncharge
		 * until end_migration() is called
		 *
		 * Corner Case Thinking
		 * A)
		 * When the old page was mapped as Anon and it's unmap-and-freed
		 * while migration was ongoing.
		 * If unmap finds the old page, uncharge() of it will be delayed
		 * until end_migration(). If unmap finds a new page, it's
		 * uncharged when it make mapcount to be 1->0. If unmap code
		 * finds swap_migration_entry, the new page will not be mapped
		 * and end_migration() will find it(mapcount==0).
		 *
		 * B)
		 * When the old page was mapped but migraion fails, the kernel
		 * remaps it. A charge for it is kept by MIGRATION flag even
		 * if mapcount goes down to 0. We can do remap successfully
		 * without charging it again.
		 *
		 * C)
		 * The "old" page is under lock_page() until the end of
		 * migration, so, the old page itself will not be swapped-out.
		 * If the new page is swapped out before end_migraton, our
		 * hook to usual swap-out path will catch the event.
		 */
		if (PageAnon(page))
			SetPageCgroupMigration(pc);
4369
	}
4370
	unlock_page_cgroup(pc);
4371 4372 4373 4374
	/*
	 * If the page is not charged at this point,
	 * we return here.
	 */
4375
	if (!memcg)
4376
		return;
4377

4378
	*memcgp = memcg;
4379 4380 4381 4382 4383 4384 4385
	/*
	 * We charge new page before it's used/mapped. So, even if unlock_page()
	 * is called before end_migration, we can catch all events on this new
	 * page. In the case new page is migrated but not remapped, new page's
	 * mapcount will be finally 0 and we call uncharge in end_migration().
	 */
	if (PageAnon(page))
4386
		ctype = MEM_CGROUP_CHARGE_TYPE_ANON;
4387
	else
4388
		ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
4389 4390 4391 4392 4393
	/*
	 * The page is committed to the memcg, but it's not actually
	 * charged to the res_counter since we plan on replacing the
	 * old one and only one page is going to be left afterwards.
	 */
4394
	__mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false);
4395
}
4396

4397
/* remove redundant charge if migration failed*/
4398
void mem_cgroup_end_migration(struct mem_cgroup *memcg,
4399
	struct page *oldpage, struct page *newpage, bool migration_ok)
4400
{
4401
	struct page *used, *unused;
4402
	struct page_cgroup *pc;
4403
	bool anon;
4404

4405
	if (!memcg)
4406
		return;
4407

4408
	if (!migration_ok) {
4409 4410
		used = oldpage;
		unused = newpage;
4411
	} else {
4412
		used = newpage;
4413 4414
		unused = oldpage;
	}
4415
	anon = PageAnon(used);
4416 4417 4418 4419
	__mem_cgroup_uncharge_common(unused,
				     anon ? MEM_CGROUP_CHARGE_TYPE_ANON
				     : MEM_CGROUP_CHARGE_TYPE_CACHE,
				     true);
4420
	css_put(&memcg->css);
4421
	/*
4422 4423 4424
	 * We disallowed uncharge of pages under migration because mapcount
	 * of the page goes down to zero, temporarly.
	 * Clear the flag and check the page should be charged.
4425
	 */
4426 4427 4428 4429 4430
	pc = lookup_page_cgroup(oldpage);
	lock_page_cgroup(pc);
	ClearPageCgroupMigration(pc);
	unlock_page_cgroup(pc);

4431
	/*
4432 4433 4434 4435 4436 4437
	 * If a page is a file cache, radix-tree replacement is very atomic
	 * and we can skip this check. When it was an Anon page, its mapcount
	 * goes down to 0. But because we added MIGRATION flage, it's not
	 * uncharged yet. There are several case but page->mapcount check
	 * and USED bit check in mem_cgroup_uncharge_page() will do enough
	 * check. (see prepare_charge() also)
4438
	 */
4439
	if (anon)
4440
		mem_cgroup_uncharge_page(used);
4441
}
4442

4443 4444 4445 4446 4447 4448 4449 4450
/*
 * At replace page cache, newpage is not under any memcg but it's on
 * LRU. So, this function doesn't touch res_counter but handles LRU
 * in correct way. Both pages are locked so we cannot race with uncharge.
 */
void mem_cgroup_replace_page_cache(struct page *oldpage,
				  struct page *newpage)
{
4451
	struct mem_cgroup *memcg = NULL;
4452 4453 4454 4455 4456 4457 4458 4459 4460
	struct page_cgroup *pc;
	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;

	if (mem_cgroup_disabled())
		return;

	pc = lookup_page_cgroup(oldpage);
	/* fix accounting on old pages */
	lock_page_cgroup(pc);
4461 4462
	if (PageCgroupUsed(pc)) {
		memcg = pc->mem_cgroup;
4463
		mem_cgroup_charge_statistics(memcg, oldpage, false, -1);
4464 4465
		ClearPageCgroupUsed(pc);
	}
4466 4467
	unlock_page_cgroup(pc);

4468 4469 4470 4471 4472 4473
	/*
	 * When called from shmem_replace_page(), in some cases the
	 * oldpage has already been charged, and in some cases not.
	 */
	if (!memcg)
		return;
4474 4475 4476 4477 4478
	/*
	 * Even if newpage->mapping was NULL before starting replacement,
	 * the newpage may be on LRU(or pagevec for LRU) already. We lock
	 * LRU while we overwrite pc->mem_cgroup.
	 */
4479
	__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
4480 4481
}

4482 4483 4484 4485 4486 4487
#ifdef CONFIG_DEBUG_VM
static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
{
	struct page_cgroup *pc;

	pc = lookup_page_cgroup(page);
4488 4489 4490 4491 4492
	/*
	 * Can be NULL while feeding pages into the page allocator for
	 * the first time, i.e. during boot or memory hotplug;
	 * or when mem_cgroup_disabled().
	 */
4493 4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511
	if (likely(pc) && PageCgroupUsed(pc))
		return pc;
	return NULL;
}

bool mem_cgroup_bad_page_check(struct page *page)
{
	if (mem_cgroup_disabled())
		return false;

	return lookup_page_cgroup_used(page) != NULL;
}

void mem_cgroup_print_bad_page(struct page *page)
{
	struct page_cgroup *pc;

	pc = lookup_page_cgroup_used(page);
	if (pc) {
4512 4513
		pr_alert("pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
			 pc, pc->flags, pc->mem_cgroup);
4514 4515 4516 4517
	}
}
#endif

4518
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
4519
				unsigned long long val)
4520
{
4521
	int retry_count;
4522
	u64 memswlimit, memlimit;
4523
	int ret = 0;
4524 4525
	int children = mem_cgroup_count_children(memcg);
	u64 curusage, oldusage;
4526
	int enlarge;
4527 4528 4529 4530 4531 4532 4533 4534 4535

	/*
	 * For keeping hierarchical_reclaim simple, how long we should retry
	 * is depends on callers. We set our retry-count to be function
	 * of # of children which we should visit in this loop.
	 */
	retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;

	oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
4536

4537
	enlarge = 0;
4538
	while (retry_count) {
4539 4540 4541 4542
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
4543 4544 4545
		/*
		 * Rather than hide all in some function, I do this in
		 * open coded manner. You see what this really does.
4546
		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
4547 4548 4549 4550 4551 4552
		 */
		mutex_lock(&set_limit_mutex);
		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
		if (memswlimit < val) {
			ret = -EINVAL;
			mutex_unlock(&set_limit_mutex);
4553 4554
			break;
		}
4555 4556 4557 4558 4559

		memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
		if (memlimit < val)
			enlarge = 1;

4560
		ret = res_counter_set_limit(&memcg->res, val);
4561 4562 4563 4564 4565 4566
		if (!ret) {
			if (memswlimit == val)
				memcg->memsw_is_minimum = true;
			else
				memcg->memsw_is_minimum = false;
		}
4567 4568 4569 4570 4571
		mutex_unlock(&set_limit_mutex);

		if (!ret)
			break;

4572 4573
		mem_cgroup_reclaim(memcg, GFP_KERNEL,
				   MEM_CGROUP_RECLAIM_SHRINK);
4574 4575
		curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
		/* Usage is reduced ? */
A
Andrew Morton 已提交
4576
		if (curusage >= oldusage)
4577 4578 4579
			retry_count--;
		else
			oldusage = curusage;
4580
	}
4581 4582
	if (!ret && enlarge)
		memcg_oom_recover(memcg);
4583

4584 4585 4586
	return ret;
}

L
Li Zefan 已提交
4587 4588
static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
					unsigned long long val)
4589
{
4590
	int retry_count;
4591
	u64 memlimit, memswlimit, oldusage, curusage;
4592 4593
	int children = mem_cgroup_count_children(memcg);
	int ret = -EBUSY;
4594
	int enlarge = 0;
4595

4596
	/* see mem_cgroup_resize_res_limit */
A
Andrew Morton 已提交
4597
	retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
4598
	oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
4599 4600 4601 4602 4603 4604 4605 4606
	while (retry_count) {
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
		/*
		 * Rather than hide all in some function, I do this in
		 * open coded manner. You see what this really does.
4607
		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
4608 4609 4610 4611 4612 4613 4614 4615
		 */
		mutex_lock(&set_limit_mutex);
		memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
		if (memlimit > val) {
			ret = -EINVAL;
			mutex_unlock(&set_limit_mutex);
			break;
		}
4616 4617 4618
		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
		if (memswlimit < val)
			enlarge = 1;
4619
		ret = res_counter_set_limit(&memcg->memsw, val);
4620 4621 4622 4623 4624 4625
		if (!ret) {
			if (memlimit == val)
				memcg->memsw_is_minimum = true;
			else
				memcg->memsw_is_minimum = false;
		}
4626 4627 4628 4629 4630
		mutex_unlock(&set_limit_mutex);

		if (!ret)
			break;

4631 4632 4633
		mem_cgroup_reclaim(memcg, GFP_KERNEL,
				   MEM_CGROUP_RECLAIM_NOSWAP |
				   MEM_CGROUP_RECLAIM_SHRINK);
4634
		curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
4635
		/* Usage is reduced ? */
4636
		if (curusage >= oldusage)
4637
			retry_count--;
4638 4639
		else
			oldusage = curusage;
4640
	}
4641 4642
	if (!ret && enlarge)
		memcg_oom_recover(memcg);
4643 4644 4645
	return ret;
}

4646 4647 4648 4649 4650 4651 4652 4653 4654 4655 4656 4657 4658 4659 4660 4661 4662 4663 4664 4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 4687 4688 4689 4690 4691 4692 4693 4694 4695 4696 4697 4698 4699 4700 4701 4702 4703 4704 4705 4706 4707 4708 4709 4710 4711 4712 4713 4714 4715 4716 4717 4718 4719 4720 4721 4722 4723 4724 4725 4726 4727 4728 4729 4730 4731 4732 4733 4734 4735 4736 4737
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
					    gfp_t gfp_mask,
					    unsigned long *total_scanned)
{
	unsigned long nr_reclaimed = 0;
	struct mem_cgroup_per_zone *mz, *next_mz = NULL;
	unsigned long reclaimed;
	int loop = 0;
	struct mem_cgroup_tree_per_zone *mctz;
	unsigned long long excess;
	unsigned long nr_scanned;

	if (order > 0)
		return 0;

	mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
	/*
	 * This loop can run a while, specially if mem_cgroup's continuously
	 * keep exceeding their soft limit and putting the system under
	 * pressure
	 */
	do {
		if (next_mz)
			mz = next_mz;
		else
			mz = mem_cgroup_largest_soft_limit_node(mctz);
		if (!mz)
			break;

		nr_scanned = 0;
		reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
						    gfp_mask, &nr_scanned);
		nr_reclaimed += reclaimed;
		*total_scanned += nr_scanned;
		spin_lock(&mctz->lock);

		/*
		 * If we failed to reclaim anything from this memory cgroup
		 * it is time to move on to the next cgroup
		 */
		next_mz = NULL;
		if (!reclaimed) {
			do {
				/*
				 * Loop until we find yet another one.
				 *
				 * By the time we get the soft_limit lock
				 * again, someone might have aded the
				 * group back on the RB tree. Iterate to
				 * make sure we get a different mem.
				 * mem_cgroup_largest_soft_limit_node returns
				 * NULL if no other cgroup is present on
				 * the tree
				 */
				next_mz =
				__mem_cgroup_largest_soft_limit_node(mctz);
				if (next_mz == mz)
					css_put(&next_mz->memcg->css);
				else /* next_mz == NULL or other memcg */
					break;
			} while (1);
		}
		__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
		excess = res_counter_soft_limit_excess(&mz->memcg->res);
		/*
		 * One school of thought says that we should not add
		 * back the node to the tree if reclaim returns 0.
		 * But our reclaim could return 0, simply because due
		 * to priority we are exposing a smaller subset of
		 * memory to reclaim from. Consider this as a longer
		 * term TODO.
		 */
		/* If excess == 0, no tree ops */
		__mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess);
		spin_unlock(&mctz->lock);
		css_put(&mz->memcg->css);
		loop++;
		/*
		 * Could not reclaim anything and there are no more
		 * mem cgroups to try or we seem to be looping without
		 * reclaiming anything.
		 */
		if (!nr_reclaimed &&
			(next_mz == NULL ||
			loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
			break;
	} while (!nr_reclaimed);
	if (next_mz)
		css_put(&next_mz->memcg->css);
	return nr_reclaimed;
}

4738 4739 4740 4741 4742 4743 4744
/**
 * mem_cgroup_force_empty_list - clears LRU of a group
 * @memcg: group to clear
 * @node: NUMA node
 * @zid: zone id
 * @lru: lru to to clear
 *
4745
 * Traverse a specified page_cgroup list and try to drop them all.  This doesn't
4746 4747
 * reclaim the pages page themselves - pages are moved to the parent (or root)
 * group.
4748
 */
4749
static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
K
KAMEZAWA Hiroyuki 已提交
4750
				int node, int zid, enum lru_list lru)
4751
{
4752
	struct lruvec *lruvec;
4753
	unsigned long flags;
4754
	struct list_head *list;
4755 4756
	struct page *busy;
	struct zone *zone;
4757

K
KAMEZAWA Hiroyuki 已提交
4758
	zone = &NODE_DATA(node)->node_zones[zid];
4759 4760
	lruvec = mem_cgroup_zone_lruvec(zone, memcg);
	list = &lruvec->lists[lru];
4761

4762
	busy = NULL;
4763
	do {
4764
		struct page_cgroup *pc;
4765 4766
		struct page *page;

K
KAMEZAWA Hiroyuki 已提交
4767
		spin_lock_irqsave(&zone->lru_lock, flags);
4768
		if (list_empty(list)) {
K
KAMEZAWA Hiroyuki 已提交
4769
			spin_unlock_irqrestore(&zone->lru_lock, flags);
4770
			break;
4771
		}
4772 4773 4774
		page = list_entry(list->prev, struct page, lru);
		if (busy == page) {
			list_move(&page->lru, list);
4775
			busy = NULL;
K
KAMEZAWA Hiroyuki 已提交
4776
			spin_unlock_irqrestore(&zone->lru_lock, flags);
4777 4778
			continue;
		}
K
KAMEZAWA Hiroyuki 已提交
4779
		spin_unlock_irqrestore(&zone->lru_lock, flags);
4780

4781
		pc = lookup_page_cgroup(page);
4782

4783
		if (mem_cgroup_move_parent(page, pc, memcg)) {
4784
			/* found lock contention or "pc" is obsolete. */
4785
			busy = page;
4786 4787 4788
			cond_resched();
		} else
			busy = NULL;
4789
	} while (!list_empty(list));
4790 4791 4792
}

/*
4793 4794
 * make mem_cgroup's charge to be 0 if there is no task by moving
 * all the charges and pages to the parent.
4795
 * This enables deleting this mem_cgroup.
4796 4797
 *
 * Caller is responsible for holding css reference on the memcg.
4798
 */
4799
static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
4800
{
4801
	int node, zid;
4802
	u64 usage;
4803

4804
	do {
4805 4806
		/* This is for making all *used* pages to be on LRU. */
		lru_add_drain_all();
4807 4808
		drain_all_stock_sync(memcg);
		mem_cgroup_start_move(memcg);
4809
		for_each_node_state(node, N_MEMORY) {
4810
			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
H
Hugh Dickins 已提交
4811 4812
				enum lru_list lru;
				for_each_lru(lru) {
4813
					mem_cgroup_force_empty_list(memcg,
H
Hugh Dickins 已提交
4814
							node, zid, lru);
4815
				}
4816
			}
4817
		}
4818 4819
		mem_cgroup_end_move(memcg);
		memcg_oom_recover(memcg);
4820
		cond_resched();
4821

4822
		/*
4823 4824 4825 4826 4827
		 * Kernel memory may not necessarily be trackable to a specific
		 * process. So they are not migrated, and therefore we can't
		 * expect their value to drop to 0 here.
		 * Having res filled up with kmem only is enough.
		 *
4828 4829 4830 4831 4832 4833
		 * This is a safety check because mem_cgroup_force_empty_list
		 * could have raced with mem_cgroup_replace_page_cache callers
		 * so the lru seemed empty but the page could have been added
		 * right after the check. RES_USAGE should be safe as we always
		 * charge before adding to the LRU.
		 */
4834 4835 4836
		usage = res_counter_read_u64(&memcg->res, RES_USAGE) -
			res_counter_read_u64(&memcg->kmem, RES_USAGE);
	} while (usage > 0);
4837 4838
}

4839 4840
static inline bool memcg_has_children(struct mem_cgroup *memcg)
{
4841 4842 4843 4844 4845 4846 4847 4848 4849 4850
	lockdep_assert_held(&memcg_create_mutex);
	/*
	 * The lock does not prevent addition or deletion to the list
	 * of children, but it prevents a new child from being
	 * initialized based on this parent in css_online(), so it's
	 * enough to decide whether hierarchically inherited
	 * attributes can still be changed or not.
	 */
	return memcg->use_hierarchy &&
		!list_empty(&memcg->css.cgroup->children);
4851 4852
}

4853 4854 4855 4856 4857 4858 4859 4860 4861 4862
/*
 * Reclaims as many pages from the given memcg as possible and moves
 * the rest to the parent.
 *
 * Caller is responsible for holding css reference for memcg.
 */
static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
{
	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
	struct cgroup *cgrp = memcg->css.cgroup;
4863

4864
	/* returns EBUSY if there is a task or if we come here twice. */
4865
	if (cgroup_has_tasks(cgrp) || !list_empty(&cgrp->children))
4866 4867
		return -EBUSY;

4868 4869
	/* we call try-to-free pages for make this cgroup empty */
	lru_add_drain_all();
4870
	/* try to free all pages in this cgroup */
4871
	while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
4872
		int progress;
4873

4874 4875 4876
		if (signal_pending(current))
			return -EINTR;

4877
		progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
4878
						false);
4879
		if (!progress) {
4880
			nr_retries--;
4881
			/* maybe some writeback is necessary */
4882
			congestion_wait(BLK_RW_ASYNC, HZ/10);
4883
		}
4884 4885

	}
K
KAMEZAWA Hiroyuki 已提交
4886
	lru_add_drain();
4887 4888 4889
	mem_cgroup_reparent_charges(memcg);

	return 0;
4890 4891
}

4892 4893
static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css,
					unsigned int event)
4894
{
4895
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4896

4897 4898
	if (mem_cgroup_is_root(memcg))
		return -EINVAL;
4899
	return mem_cgroup_force_empty(memcg);
4900 4901
}

4902 4903
static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
				     struct cftype *cft)
4904
{
4905
	return mem_cgroup_from_css(css)->use_hierarchy;
4906 4907
}

4908 4909
static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
				      struct cftype *cft, u64 val)
4910 4911
{
	int retval = 0;
4912
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
4913
	struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css));
4914

4915
	mutex_lock(&memcg_create_mutex);
4916 4917 4918 4919

	if (memcg->use_hierarchy == val)
		goto out;

4920
	/*
4921
	 * If parent's use_hierarchy is set, we can't make any modifications
4922 4923 4924 4925 4926 4927
	 * in the child subtrees. If it is unset, then the change can
	 * occur, provided the current cgroup has no children.
	 *
	 * For the root cgroup, parent_mem is NULL, we allow value to be
	 * set if there are no children.
	 */
4928
	if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
4929
				(val == 1 || val == 0)) {
4930
		if (list_empty(&memcg->css.cgroup->children))
4931
			memcg->use_hierarchy = val;
4932 4933 4934 4935
		else
			retval = -EBUSY;
	} else
		retval = -EINVAL;
4936 4937

out:
4938
	mutex_unlock(&memcg_create_mutex);
4939 4940 4941 4942

	return retval;
}

4943

4944
static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
4945
					       enum mem_cgroup_stat_index idx)
4946
{
K
KAMEZAWA Hiroyuki 已提交
4947
	struct mem_cgroup *iter;
4948
	long val = 0;
4949

4950
	/* Per-cpu values can be negative, use a signed accumulator */
4951
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
4952 4953 4954 4955 4956
		val += mem_cgroup_read_stat(iter, idx);

	if (val < 0) /* race ? */
		val = 0;
	return val;
4957 4958
}

4959
static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
4960
{
K
KAMEZAWA Hiroyuki 已提交
4961
	u64 val;
4962

4963
	if (!mem_cgroup_is_root(memcg)) {
4964
		if (!swap)
4965
			return res_counter_read_u64(&memcg->res, RES_USAGE);
4966
		else
4967
			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
4968 4969
	}

4970 4971 4972 4973
	/*
	 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
	 * as well as in MEM_CGROUP_STAT_RSS_HUGE.
	 */
4974 4975
	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
4976

K
KAMEZAWA Hiroyuki 已提交
4977
	if (swap)
4978
		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
4979 4980 4981 4982

	return val << PAGE_SHIFT;
}

4983 4984
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
				   struct cftype *cft)
B
Balbir Singh 已提交
4985
{
4986
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4987
	u64 val;
4988
	int name;
G
Glauber Costa 已提交
4989
	enum res_type type;
4990 4991 4992

	type = MEMFILE_TYPE(cft->private);
	name = MEMFILE_ATTR(cft->private);
4993

4994 4995
	switch (type) {
	case _MEM:
4996
		if (name == RES_USAGE)
4997
			val = mem_cgroup_usage(memcg, false);
4998
		else
4999
			val = res_counter_read_u64(&memcg->res, name);
5000 5001
		break;
	case _MEMSWAP:
5002
		if (name == RES_USAGE)
5003
			val = mem_cgroup_usage(memcg, true);
5004
		else
5005
			val = res_counter_read_u64(&memcg->memsw, name);
5006
		break;
5007 5008 5009
	case _KMEM:
		val = res_counter_read_u64(&memcg->kmem, name);
		break;
5010 5011 5012
	default:
		BUG();
	}
5013

5014
	return val;
B
Balbir Singh 已提交
5015
}
5016 5017

#ifdef CONFIG_MEMCG_KMEM
5018 5019 5020 5021 5022 5023 5024 5025 5026 5027 5028 5029 5030 5031 5032 5033
/* should be called with activate_kmem_mutex held */
static int __memcg_activate_kmem(struct mem_cgroup *memcg,
				 unsigned long long limit)
{
	int err = 0;
	int memcg_id;

	if (memcg_kmem_is_active(memcg))
		return 0;

	/*
	 * We are going to allocate memory for data shared by all memory
	 * cgroups so let's stop accounting here.
	 */
	memcg_stop_kmem_account();

5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045
	/*
	 * For simplicity, we won't allow this to be disabled.  It also can't
	 * be changed if the cgroup has children already, or if tasks had
	 * already joined.
	 *
	 * If tasks join before we set the limit, a person looking at
	 * kmem.usage_in_bytes will have no way to determine when it took
	 * place, which makes the value quite meaningless.
	 *
	 * After it first became limited, changes in the value of the limit are
	 * of course permitted.
	 */
5046
	mutex_lock(&memcg_create_mutex);
5047
	if (cgroup_has_tasks(memcg->css.cgroup) || memcg_has_children(memcg))
5048 5049 5050 5051
		err = -EBUSY;
	mutex_unlock(&memcg_create_mutex);
	if (err)
		goto out;
5052

5053 5054 5055 5056 5057 5058 5059 5060 5061 5062 5063 5064 5065 5066 5067 5068 5069 5070 5071 5072 5073 5074 5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085
	memcg_id = ida_simple_get(&kmem_limited_groups,
				  0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
	if (memcg_id < 0) {
		err = memcg_id;
		goto out;
	}

	/*
	 * Make sure we have enough space for this cgroup in each root cache's
	 * memcg_params.
	 */
	err = memcg_update_all_caches(memcg_id + 1);
	if (err)
		goto out_rmid;

	memcg->kmemcg_id = memcg_id;
	INIT_LIST_HEAD(&memcg->memcg_slab_caches);
	mutex_init(&memcg->slab_caches_mutex);

	/*
	 * We couldn't have accounted to this cgroup, because it hasn't got the
	 * active bit set yet, so this should succeed.
	 */
	err = res_counter_set_limit(&memcg->kmem, limit);
	VM_BUG_ON(err);

	static_key_slow_inc(&memcg_kmem_enabled_key);
	/*
	 * Setting the active bit after enabling static branching will
	 * guarantee no one starts accounting before all call sites are
	 * patched.
	 */
	memcg_kmem_set_active(memcg);
5086
out:
5087 5088 5089 5090 5091 5092 5093 5094 5095 5096 5097 5098 5099 5100 5101 5102 5103 5104 5105 5106 5107 5108 5109 5110 5111 5112 5113 5114
	memcg_resume_kmem_account();
	return err;

out_rmid:
	ida_simple_remove(&kmem_limited_groups, memcg_id);
	goto out;
}

static int memcg_activate_kmem(struct mem_cgroup *memcg,
			       unsigned long long limit)
{
	int ret;

	mutex_lock(&activate_kmem_mutex);
	ret = __memcg_activate_kmem(memcg, limit);
	mutex_unlock(&activate_kmem_mutex);
	return ret;
}

static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
				   unsigned long long val)
{
	int ret;

	if (!memcg_kmem_is_active(memcg))
		ret = memcg_activate_kmem(memcg, val);
	else
		ret = res_counter_set_limit(&memcg->kmem, val);
5115 5116 5117
	return ret;
}

5118
static int memcg_propagate_kmem(struct mem_cgroup *memcg)
5119
{
5120
	int ret = 0;
5121
	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
5122

5123 5124
	if (!parent)
		return 0;
5125

5126
	mutex_lock(&activate_kmem_mutex);
5127
	/*
5128 5129
	 * If the parent cgroup is not kmem-active now, it cannot be activated
	 * after this point, because it has at least one child already.
5130
	 */
5131 5132 5133
	if (memcg_kmem_is_active(parent))
		ret = __memcg_activate_kmem(memcg, RES_COUNTER_MAX);
	mutex_unlock(&activate_kmem_mutex);
5134
	return ret;
5135
}
5136 5137 5138 5139 5140 5141
#else
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
				   unsigned long long val)
{
	return -EINVAL;
}
5142
#endif /* CONFIG_MEMCG_KMEM */
5143

5144 5145 5146 5147
/*
 * The user of this function is...
 * RES_LIMIT.
 */
5148
static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft,
5149
			    char *buffer)
B
Balbir Singh 已提交
5150
{
5151
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
G
Glauber Costa 已提交
5152 5153
	enum res_type type;
	int name;
5154 5155 5156
	unsigned long long val;
	int ret;

5157 5158
	type = MEMFILE_TYPE(cft->private);
	name = MEMFILE_ATTR(cft->private);
5159

5160
	switch (name) {
5161
	case RES_LIMIT:
5162 5163 5164 5165
		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
			ret = -EINVAL;
			break;
		}
5166 5167
		/* This function does all necessary parse...reuse it */
		ret = res_counter_memparse_write_strategy(buffer, &val);
5168 5169 5170
		if (ret)
			break;
		if (type == _MEM)
5171
			ret = mem_cgroup_resize_limit(memcg, val);
5172
		else if (type == _MEMSWAP)
5173
			ret = mem_cgroup_resize_memsw_limit(memcg, val);
5174
		else if (type == _KMEM)
5175
			ret = memcg_update_kmem_limit(memcg, val);
5176 5177
		else
			return -EINVAL;
5178
		break;
5179 5180 5181 5182 5183 5184 5185 5186 5187 5188 5189 5190 5191 5192
	case RES_SOFT_LIMIT:
		ret = res_counter_memparse_write_strategy(buffer, &val);
		if (ret)
			break;
		/*
		 * For memsw, soft limits are hard to implement in terms
		 * of semantics, for now, we support soft limits for
		 * control without swap
		 */
		if (type == _MEM)
			ret = res_counter_set_soft_limit(&memcg->res, val);
		else
			ret = -EINVAL;
		break;
5193 5194 5195 5196 5197
	default:
		ret = -EINVAL; /* should be BUG() ? */
		break;
	}
	return ret;
B
Balbir Singh 已提交
5198 5199
}

5200 5201 5202 5203 5204 5205 5206 5207 5208 5209
static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
		unsigned long long *mem_limit, unsigned long long *memsw_limit)
{
	unsigned long long min_limit, min_memsw_limit, tmp;

	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
	if (!memcg->use_hierarchy)
		goto out;

T
Tejun Heo 已提交
5210 5211
	while (css_parent(&memcg->css)) {
		memcg = mem_cgroup_from_css(css_parent(&memcg->css));
5212 5213 5214 5215 5216 5217 5218 5219 5220 5221 5222 5223
		if (!memcg->use_hierarchy)
			break;
		tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
		min_limit = min(min_limit, tmp);
		tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
		min_memsw_limit = min(min_memsw_limit, tmp);
	}
out:
	*mem_limit = min_limit;
	*memsw_limit = min_memsw_limit;
}

5224
static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
5225
{
5226
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
G
Glauber Costa 已提交
5227 5228
	int name;
	enum res_type type;
5229

5230 5231
	type = MEMFILE_TYPE(event);
	name = MEMFILE_ATTR(event);
5232

5233
	switch (name) {
5234
	case RES_MAX_USAGE:
5235
		if (type == _MEM)
5236
			res_counter_reset_max(&memcg->res);
5237
		else if (type == _MEMSWAP)
5238
			res_counter_reset_max(&memcg->memsw);
5239 5240 5241 5242
		else if (type == _KMEM)
			res_counter_reset_max(&memcg->kmem);
		else
			return -EINVAL;
5243 5244
		break;
	case RES_FAILCNT:
5245
		if (type == _MEM)
5246
			res_counter_reset_failcnt(&memcg->res);
5247
		else if (type == _MEMSWAP)
5248
			res_counter_reset_failcnt(&memcg->memsw);
5249 5250 5251 5252
		else if (type == _KMEM)
			res_counter_reset_failcnt(&memcg->kmem);
		else
			return -EINVAL;
5253 5254
		break;
	}
5255

5256
	return 0;
5257 5258
}

5259
static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
5260 5261
					struct cftype *cft)
{
5262
	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
5263 5264
}

5265
#ifdef CONFIG_MMU
5266
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
5267 5268
					struct cftype *cft, u64 val)
{
5269
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5270 5271 5272

	if (val >= (1 << NR_MOVE_TYPE))
		return -EINVAL;
5273

5274
	/*
5275 5276 5277 5278
	 * No kind of locking is needed in here, because ->can_attach() will
	 * check this value once in the beginning of the process, and then carry
	 * on with stale data. This means that changes to this value will only
	 * affect task migrations starting after the change.
5279
	 */
5280
	memcg->move_charge_at_immigrate = val;
5281 5282
	return 0;
}
5283
#else
5284
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
5285 5286 5287 5288 5289
					struct cftype *cft, u64 val)
{
	return -ENOSYS;
}
#endif
5290

5291
#ifdef CONFIG_NUMA
5292
static int memcg_numa_stat_show(struct seq_file *m, void *v)
5293
{
5294 5295 5296 5297 5298 5299 5300 5301 5302 5303 5304 5305
	struct numa_stat {
		const char *name;
		unsigned int lru_mask;
	};

	static const struct numa_stat stats[] = {
		{ "total", LRU_ALL },
		{ "file", LRU_ALL_FILE },
		{ "anon", LRU_ALL_ANON },
		{ "unevictable", BIT(LRU_UNEVICTABLE) },
	};
	const struct numa_stat *stat;
5306
	int nid;
5307
	unsigned long nr;
5308
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
5309

5310 5311 5312 5313 5314 5315 5316 5317 5318
	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
		nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask);
		seq_printf(m, "%s=%lu", stat->name, nr);
		for_each_node_state(nid, N_MEMORY) {
			nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
							  stat->lru_mask);
			seq_printf(m, " N%d=%lu", nid, nr);
		}
		seq_putc(m, '\n');
5319 5320
	}

5321 5322 5323 5324 5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335
	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
		struct mem_cgroup *iter;

		nr = 0;
		for_each_mem_cgroup_tree(iter, memcg)
			nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask);
		seq_printf(m, "hierarchical_%s=%lu", stat->name, nr);
		for_each_node_state(nid, N_MEMORY) {
			nr = 0;
			for_each_mem_cgroup_tree(iter, memcg)
				nr += mem_cgroup_node_nr_lru_pages(
					iter, nid, stat->lru_mask);
			seq_printf(m, " N%d=%lu", nid, nr);
		}
		seq_putc(m, '\n');
5336 5337 5338 5339 5340 5341
	}

	return 0;
}
#endif /* CONFIG_NUMA */

5342 5343 5344 5345 5346
static inline void mem_cgroup_lru_names_not_uptodate(void)
{
	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
}

5347
static int memcg_stat_show(struct seq_file *m, void *v)
5348
{
5349
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
5350 5351
	struct mem_cgroup *mi;
	unsigned int i;
5352

5353
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
5354
		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
5355
			continue;
5356 5357
		seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
			   mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
5358
	}
L
Lee Schermerhorn 已提交
5359

5360 5361 5362 5363 5364 5365 5366 5367
	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
		seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i],
			   mem_cgroup_read_events(memcg, i));

	for (i = 0; i < NR_LRU_LISTS; i++)
		seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
			   mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);

K
KAMEZAWA Hiroyuki 已提交
5368
	/* Hierarchical information */
5369 5370
	{
		unsigned long long limit, memsw_limit;
5371
		memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
5372
		seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
5373
		if (do_swap_account)
5374 5375
			seq_printf(m, "hierarchical_memsw_limit %llu\n",
				   memsw_limit);
5376
	}
K
KOSAKI Motohiro 已提交
5377

5378 5379 5380
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
		long long val = 0;

5381
		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
5382
			continue;
5383 5384 5385 5386 5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397 5398 5399 5400 5401 5402
		for_each_mem_cgroup_tree(mi, memcg)
			val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
		seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val);
	}

	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
		unsigned long long val = 0;

		for_each_mem_cgroup_tree(mi, memcg)
			val += mem_cgroup_read_events(mi, i);
		seq_printf(m, "total_%s %llu\n",
			   mem_cgroup_events_names[i], val);
	}

	for (i = 0; i < NR_LRU_LISTS; i++) {
		unsigned long long val = 0;

		for_each_mem_cgroup_tree(mi, memcg)
			val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
		seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val);
5403
	}
K
KAMEZAWA Hiroyuki 已提交
5404

K
KOSAKI Motohiro 已提交
5405 5406 5407 5408
#ifdef CONFIG_DEBUG_VM
	{
		int nid, zid;
		struct mem_cgroup_per_zone *mz;
5409
		struct zone_reclaim_stat *rstat;
K
KOSAKI Motohiro 已提交
5410 5411 5412 5413 5414
		unsigned long recent_rotated[2] = {0, 0};
		unsigned long recent_scanned[2] = {0, 0};

		for_each_online_node(nid)
			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
5415
				mz = mem_cgroup_zoneinfo(memcg, nid, zid);
5416
				rstat = &mz->lruvec.reclaim_stat;
K
KOSAKI Motohiro 已提交
5417

5418 5419 5420 5421
				recent_rotated[0] += rstat->recent_rotated[0];
				recent_rotated[1] += rstat->recent_rotated[1];
				recent_scanned[0] += rstat->recent_scanned[0];
				recent_scanned[1] += rstat->recent_scanned[1];
K
KOSAKI Motohiro 已提交
5422
			}
5423 5424 5425 5426
		seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
		seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
		seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
		seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
K
KOSAKI Motohiro 已提交
5427 5428 5429
	}
#endif

5430 5431 5432
	return 0;
}

5433 5434
static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
				      struct cftype *cft)
K
KOSAKI Motohiro 已提交
5435
{
5436
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
K
KOSAKI Motohiro 已提交
5437

5438
	return mem_cgroup_swappiness(memcg);
K
KOSAKI Motohiro 已提交
5439 5440
}

5441 5442
static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
				       struct cftype *cft, u64 val)
K
KOSAKI Motohiro 已提交
5443
{
5444
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
5445
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
K
KOSAKI Motohiro 已提交
5446

T
Tejun Heo 已提交
5447
	if (val > 100 || !parent)
K
KOSAKI Motohiro 已提交
5448 5449
		return -EINVAL;

5450
	mutex_lock(&memcg_create_mutex);
5451

K
KOSAKI Motohiro 已提交
5452
	/* If under hierarchy, only empty-root can set this value */
5453
	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
5454
		mutex_unlock(&memcg_create_mutex);
K
KOSAKI Motohiro 已提交
5455
		return -EINVAL;
5456
	}
K
KOSAKI Motohiro 已提交
5457 5458 5459

	memcg->swappiness = val;

5460
	mutex_unlock(&memcg_create_mutex);
5461

K
KOSAKI Motohiro 已提交
5462 5463 5464
	return 0;
}

5465 5466 5467 5468 5469 5470 5471 5472
static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
{
	struct mem_cgroup_threshold_ary *t;
	u64 usage;
	int i;

	rcu_read_lock();
	if (!swap)
5473
		t = rcu_dereference(memcg->thresholds.primary);
5474
	else
5475
		t = rcu_dereference(memcg->memsw_thresholds.primary);
5476 5477 5478 5479 5480 5481 5482

	if (!t)
		goto unlock;

	usage = mem_cgroup_usage(memcg, swap);

	/*
5483
	 * current_threshold points to threshold just below or equal to usage.
5484 5485 5486
	 * If it's not true, a threshold was crossed after last
	 * call of __mem_cgroup_threshold().
	 */
5487
	i = t->current_threshold;
5488 5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499 5500 5501 5502 5503 5504 5505 5506 5507 5508 5509 5510

	/*
	 * Iterate backward over array of thresholds starting from
	 * current_threshold and check if a threshold is crossed.
	 * If none of thresholds below usage is crossed, we read
	 * only one element of the array here.
	 */
	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
		eventfd_signal(t->entries[i].eventfd, 1);

	/* i = current_threshold + 1 */
	i++;

	/*
	 * Iterate forward over array of thresholds starting from
	 * current_threshold+1 and check if a threshold is crossed.
	 * If none of thresholds above usage is crossed, we read
	 * only one element of the array here.
	 */
	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
		eventfd_signal(t->entries[i].eventfd, 1);

	/* Update current_threshold */
5511
	t->current_threshold = i - 1;
5512 5513 5514 5515 5516 5517
unlock:
	rcu_read_unlock();
}

static void mem_cgroup_threshold(struct mem_cgroup *memcg)
{
5518 5519 5520 5521 5522 5523 5524
	while (memcg) {
		__mem_cgroup_threshold(memcg, false);
		if (do_swap_account)
			__mem_cgroup_threshold(memcg, true);

		memcg = parent_mem_cgroup(memcg);
	}
5525 5526 5527 5528 5529 5530 5531
}

static int compare_thresholds(const void *a, const void *b)
{
	const struct mem_cgroup_threshold *_a = a;
	const struct mem_cgroup_threshold *_b = b;

5532 5533 5534 5535 5536 5537 5538
	if (_a->threshold > _b->threshold)
		return 1;

	if (_a->threshold < _b->threshold)
		return -1;

	return 0;
5539 5540
}

5541
static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
5542 5543 5544
{
	struct mem_cgroup_eventfd_list *ev;

5545
	list_for_each_entry(ev, &memcg->oom_notify, list)
K
KAMEZAWA Hiroyuki 已提交
5546 5547 5548 5549
		eventfd_signal(ev->eventfd, 1);
	return 0;
}

5550
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
5551
{
K
KAMEZAWA Hiroyuki 已提交
5552 5553
	struct mem_cgroup *iter;

5554
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
5555
		mem_cgroup_oom_notify_cb(iter);
K
KAMEZAWA Hiroyuki 已提交
5556 5557
}

5558
static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5559
	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
5560
{
5561 5562
	struct mem_cgroup_thresholds *thresholds;
	struct mem_cgroup_threshold_ary *new;
5563
	u64 threshold, usage;
5564
	int i, size, ret;
5565 5566 5567 5568 5569 5570

	ret = res_counter_memparse_write_strategy(args, &threshold);
	if (ret)
		return ret;

	mutex_lock(&memcg->thresholds_lock);
5571

5572
	if (type == _MEM)
5573
		thresholds = &memcg->thresholds;
5574
	else if (type == _MEMSWAP)
5575
		thresholds = &memcg->memsw_thresholds;
5576 5577 5578 5579 5580 5581
	else
		BUG();

	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);

	/* Check if a threshold crossed before adding a new one */
5582
	if (thresholds->primary)
5583 5584
		__mem_cgroup_threshold(memcg, type == _MEMSWAP);

5585
	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
5586 5587

	/* Allocate memory for new array of thresholds */
5588
	new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
5589
			GFP_KERNEL);
5590
	if (!new) {
5591 5592 5593
		ret = -ENOMEM;
		goto unlock;
	}
5594
	new->size = size;
5595 5596

	/* Copy thresholds (if any) to new array */
5597 5598
	if (thresholds->primary) {
		memcpy(new->entries, thresholds->primary->entries, (size - 1) *
5599
				sizeof(struct mem_cgroup_threshold));
5600 5601
	}

5602
	/* Add new threshold */
5603 5604
	new->entries[size - 1].eventfd = eventfd;
	new->entries[size - 1].threshold = threshold;
5605 5606

	/* Sort thresholds. Registering of new threshold isn't time-critical */
5607
	sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
5608 5609 5610
			compare_thresholds, NULL);

	/* Find current threshold */
5611
	new->current_threshold = -1;
5612
	for (i = 0; i < size; i++) {
5613
		if (new->entries[i].threshold <= usage) {
5614
			/*
5615 5616
			 * new->current_threshold will not be used until
			 * rcu_assign_pointer(), so it's safe to increment
5617 5618
			 * it here.
			 */
5619
			++new->current_threshold;
5620 5621
		} else
			break;
5622 5623
	}

5624 5625 5626 5627 5628
	/* Free old spare buffer and save old primary buffer as spare */
	kfree(thresholds->spare);
	thresholds->spare = thresholds->primary;

	rcu_assign_pointer(thresholds->primary, new);
5629

5630
	/* To be sure that nobody uses thresholds */
5631 5632 5633 5634 5635 5636 5637 5638
	synchronize_rcu();

unlock:
	mutex_unlock(&memcg->thresholds_lock);

	return ret;
}

5639
static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5640 5641
	struct eventfd_ctx *eventfd, const char *args)
{
5642
	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
T
Tejun Heo 已提交
5643 5644
}

5645
static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5646 5647
	struct eventfd_ctx *eventfd, const char *args)
{
5648
	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
T
Tejun Heo 已提交
5649 5650
}

5651
static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5652
	struct eventfd_ctx *eventfd, enum res_type type)
5653
{
5654 5655
	struct mem_cgroup_thresholds *thresholds;
	struct mem_cgroup_threshold_ary *new;
5656
	u64 usage;
5657
	int i, j, size;
5658 5659 5660

	mutex_lock(&memcg->thresholds_lock);
	if (type == _MEM)
5661
		thresholds = &memcg->thresholds;
5662
	else if (type == _MEMSWAP)
5663
		thresholds = &memcg->memsw_thresholds;
5664 5665 5666
	else
		BUG();

5667 5668 5669
	if (!thresholds->primary)
		goto unlock;

5670 5671 5672 5673 5674 5675
	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);

	/* Check if a threshold crossed before removing */
	__mem_cgroup_threshold(memcg, type == _MEMSWAP);

	/* Calculate new number of threshold */
5676 5677 5678
	size = 0;
	for (i = 0; i < thresholds->primary->size; i++) {
		if (thresholds->primary->entries[i].eventfd != eventfd)
5679 5680 5681
			size++;
	}

5682
	new = thresholds->spare;
5683

5684 5685
	/* Set thresholds array to NULL if we don't have thresholds */
	if (!size) {
5686 5687
		kfree(new);
		new = NULL;
5688
		goto swap_buffers;
5689 5690
	}

5691
	new->size = size;
5692 5693

	/* Copy thresholds and find current threshold */
5694 5695 5696
	new->current_threshold = -1;
	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
		if (thresholds->primary->entries[i].eventfd == eventfd)
5697 5698
			continue;

5699
		new->entries[j] = thresholds->primary->entries[i];
5700
		if (new->entries[j].threshold <= usage) {
5701
			/*
5702
			 * new->current_threshold will not be used
5703 5704 5705
			 * until rcu_assign_pointer(), so it's safe to increment
			 * it here.
			 */
5706
			++new->current_threshold;
5707 5708 5709 5710
		}
		j++;
	}

5711
swap_buffers:
5712 5713
	/* Swap primary and spare array */
	thresholds->spare = thresholds->primary;
5714 5715 5716 5717 5718 5719
	/* If all events are unregistered, free the spare array */
	if (!new) {
		kfree(thresholds->spare);
		thresholds->spare = NULL;
	}

5720
	rcu_assign_pointer(thresholds->primary, new);
5721

5722
	/* To be sure that nobody uses thresholds */
5723
	synchronize_rcu();
5724
unlock:
5725 5726
	mutex_unlock(&memcg->thresholds_lock);
}
5727

5728
static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5729 5730
	struct eventfd_ctx *eventfd)
{
5731
	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
T
Tejun Heo 已提交
5732 5733
}

5734
static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5735 5736
	struct eventfd_ctx *eventfd)
{
5737
	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
T
Tejun Heo 已提交
5738 5739
}

5740
static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5741
	struct eventfd_ctx *eventfd, const char *args)
K
KAMEZAWA Hiroyuki 已提交
5742 5743 5744 5745 5746 5747 5748
{
	struct mem_cgroup_eventfd_list *event;

	event = kmalloc(sizeof(*event),	GFP_KERNEL);
	if (!event)
		return -ENOMEM;

5749
	spin_lock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5750 5751 5752 5753 5754

	event->eventfd = eventfd;
	list_add(&event->list, &memcg->oom_notify);

	/* already in OOM ? */
5755
	if (atomic_read(&memcg->under_oom))
K
KAMEZAWA Hiroyuki 已提交
5756
		eventfd_signal(eventfd, 1);
5757
	spin_unlock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5758 5759 5760 5761

	return 0;
}

5762
static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5763
	struct eventfd_ctx *eventfd)
K
KAMEZAWA Hiroyuki 已提交
5764 5765 5766
{
	struct mem_cgroup_eventfd_list *ev, *tmp;

5767
	spin_lock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5768

5769
	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
K
KAMEZAWA Hiroyuki 已提交
5770 5771 5772 5773 5774 5775
		if (ev->eventfd == eventfd) {
			list_del(&ev->list);
			kfree(ev);
		}
	}

5776
	spin_unlock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5777 5778
}

5779
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
5780
{
5781
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
5782

5783 5784
	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
	seq_printf(sf, "under_oom %d\n", (bool)atomic_read(&memcg->under_oom));
5785 5786 5787
	return 0;
}

5788
static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
5789 5790
	struct cftype *cft, u64 val)
{
5791
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
5792
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
5793 5794

	/* cannot set to root cgroup and only 0 and 1 are allowed */
T
Tejun Heo 已提交
5795
	if (!parent || !((val == 0) || (val == 1)))
5796 5797
		return -EINVAL;

5798
	mutex_lock(&memcg_create_mutex);
5799
	/* oom-kill-disable is a flag for subhierarchy. */
5800
	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
5801
		mutex_unlock(&memcg_create_mutex);
5802 5803
		return -EINVAL;
	}
5804
	memcg->oom_kill_disable = val;
5805
	if (!val)
5806
		memcg_oom_recover(memcg);
5807
	mutex_unlock(&memcg_create_mutex);
5808 5809 5810
	return 0;
}

A
Andrew Morton 已提交
5811
#ifdef CONFIG_MEMCG_KMEM
5812
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
5813
{
5814 5815
	int ret;

5816
	memcg->kmemcg_id = -1;
5817 5818 5819
	ret = memcg_propagate_kmem(memcg);
	if (ret)
		return ret;
5820

5821
	return mem_cgroup_sockets_init(memcg, ss);
5822
}
5823

5824
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
G
Glauber Costa 已提交
5825
{
5826
	mem_cgroup_sockets_destroy(memcg);
5827 5828 5829 5830 5831 5832 5833 5834 5835 5836 5837 5838 5839 5840 5841 5842 5843 5844 5845 5846 5847 5848 5849 5850 5851 5852
}

static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
{
	if (!memcg_kmem_is_active(memcg))
		return;

	/*
	 * kmem charges can outlive the cgroup. In the case of slab
	 * pages, for instance, a page contain objects from various
	 * processes. As we prevent from taking a reference for every
	 * such allocation we have to be careful when doing uncharge
	 * (see memcg_uncharge_kmem) and here during offlining.
	 *
	 * The idea is that that only the _last_ uncharge which sees
	 * the dead memcg will drop the last reference. An additional
	 * reference is taken here before the group is marked dead
	 * which is then paired with css_put during uncharge resp. here.
	 *
	 * Although this might sound strange as this path is called from
	 * css_offline() when the referencemight have dropped down to 0
	 * and shouldn't be incremented anymore (css_tryget would fail)
	 * we do not have other options because of the kmem allocations
	 * lifetime.
	 */
	css_get(&memcg->css);
5853 5854 5855 5856 5857 5858 5859

	memcg_kmem_mark_dead(memcg);

	if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0)
		return;

	if (memcg_kmem_test_and_clear_dead(memcg))
5860
		css_put(&memcg->css);
G
Glauber Costa 已提交
5861
}
5862
#else
5863
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
5864 5865 5866
{
	return 0;
}
G
Glauber Costa 已提交
5867

5868 5869 5870 5871 5872
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
{
}

static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
G
Glauber Costa 已提交
5873 5874
{
}
5875 5876
#endif

5877 5878 5879 5880 5881 5882 5883 5884 5885 5886 5887 5888 5889
/*
 * DO NOT USE IN NEW FILES.
 *
 * "cgroup.event_control" implementation.
 *
 * This is way over-engineered.  It tries to support fully configurable
 * events for each user.  Such level of flexibility is completely
 * unnecessary especially in the light of the planned unified hierarchy.
 *
 * Please deprecate this and replace with something simpler if at all
 * possible.
 */

5890 5891 5892 5893 5894
/*
 * Unregister event and free resources.
 *
 * Gets called from workqueue.
 */
5895
static void memcg_event_remove(struct work_struct *work)
5896
{
5897 5898
	struct mem_cgroup_event *event =
		container_of(work, struct mem_cgroup_event, remove);
5899
	struct mem_cgroup *memcg = event->memcg;
5900 5901 5902

	remove_wait_queue(event->wqh, &event->wait);

5903
	event->unregister_event(memcg, event->eventfd);
5904 5905 5906 5907 5908 5909

	/* Notify userspace the event is going away. */
	eventfd_signal(event->eventfd, 1);

	eventfd_ctx_put(event->eventfd);
	kfree(event);
5910
	css_put(&memcg->css);
5911 5912 5913 5914 5915 5916 5917
}

/*
 * Gets called on POLLHUP on eventfd when user closes it.
 *
 * Called with wqh->lock held and interrupts disabled.
 */
5918 5919
static int memcg_event_wake(wait_queue_t *wait, unsigned mode,
			    int sync, void *key)
5920
{
5921 5922
	struct mem_cgroup_event *event =
		container_of(wait, struct mem_cgroup_event, wait);
5923
	struct mem_cgroup *memcg = event->memcg;
5924 5925 5926 5927 5928 5929 5930 5931 5932 5933 5934 5935
	unsigned long flags = (unsigned long)key;

	if (flags & POLLHUP) {
		/*
		 * If the event has been detached at cgroup removal, we
		 * can simply return knowing the other side will cleanup
		 * for us.
		 *
		 * We can't race against event freeing since the other
		 * side will require wqh->lock via remove_wait_queue(),
		 * which we hold.
		 */
5936
		spin_lock(&memcg->event_list_lock);
5937 5938 5939 5940 5941 5942 5943 5944
		if (!list_empty(&event->list)) {
			list_del_init(&event->list);
			/*
			 * We are in atomic context, but cgroup_event_remove()
			 * may sleep, so we have to call it in workqueue.
			 */
			schedule_work(&event->remove);
		}
5945
		spin_unlock(&memcg->event_list_lock);
5946 5947 5948 5949 5950
	}

	return 0;
}

5951
static void memcg_event_ptable_queue_proc(struct file *file,
5952 5953
		wait_queue_head_t *wqh, poll_table *pt)
{
5954 5955
	struct mem_cgroup_event *event =
		container_of(pt, struct mem_cgroup_event, pt);
5956 5957 5958 5959 5960 5961

	event->wqh = wqh;
	add_wait_queue(wqh, &event->wait);
}

/*
5962 5963
 * DO NOT USE IN NEW FILES.
 *
5964 5965 5966 5967 5968
 * Parse input and register new cgroup event handler.
 *
 * Input must be in format '<event_fd> <control_fd> <args>'.
 * Interpretation of args is defined by control file implementation.
 */
5969
static int memcg_write_event_control(struct cgroup_subsys_state *css,
5970
				     struct cftype *cft, char *buffer)
5971
{
5972
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5973
	struct mem_cgroup_event *event;
5974 5975 5976 5977
	struct cgroup_subsys_state *cfile_css;
	unsigned int efd, cfd;
	struct fd efile;
	struct fd cfile;
5978
	const char *name;
5979 5980 5981 5982 5983 5984 5985 5986 5987 5988 5989 5990 5991 5992 5993 5994 5995
	char *endp;
	int ret;

	efd = simple_strtoul(buffer, &endp, 10);
	if (*endp != ' ')
		return -EINVAL;
	buffer = endp + 1;

	cfd = simple_strtoul(buffer, &endp, 10);
	if ((*endp != ' ') && (*endp != '\0'))
		return -EINVAL;
	buffer = endp + 1;

	event = kzalloc(sizeof(*event), GFP_KERNEL);
	if (!event)
		return -ENOMEM;

5996
	event->memcg = memcg;
5997
	INIT_LIST_HEAD(&event->list);
5998 5999 6000
	init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
	init_waitqueue_func_entry(&event->wait, memcg_event_wake);
	INIT_WORK(&event->remove, memcg_event_remove);
6001 6002 6003 6004 6005 6006 6007 6008 6009 6010 6011 6012 6013 6014 6015 6016 6017 6018 6019 6020 6021 6022 6023 6024 6025

	efile = fdget(efd);
	if (!efile.file) {
		ret = -EBADF;
		goto out_kfree;
	}

	event->eventfd = eventfd_ctx_fileget(efile.file);
	if (IS_ERR(event->eventfd)) {
		ret = PTR_ERR(event->eventfd);
		goto out_put_efile;
	}

	cfile = fdget(cfd);
	if (!cfile.file) {
		ret = -EBADF;
		goto out_put_eventfd;
	}

	/* the process need read permission on control file */
	/* AV: shouldn't we check that it's been opened for read instead? */
	ret = inode_permission(file_inode(cfile.file), MAY_READ);
	if (ret < 0)
		goto out_put_cfile;

6026 6027 6028 6029 6030
	/*
	 * Determine the event callbacks and set them in @event.  This used
	 * to be done via struct cftype but cgroup core no longer knows
	 * about these events.  The following is crude but the whole thing
	 * is for compatibility anyway.
6031 6032
	 *
	 * DO NOT ADD NEW FILES.
6033 6034 6035 6036 6037 6038 6039 6040 6041 6042 6043 6044 6045
	 */
	name = cfile.file->f_dentry->d_name.name;

	if (!strcmp(name, "memory.usage_in_bytes")) {
		event->register_event = mem_cgroup_usage_register_event;
		event->unregister_event = mem_cgroup_usage_unregister_event;
	} else if (!strcmp(name, "memory.oom_control")) {
		event->register_event = mem_cgroup_oom_register_event;
		event->unregister_event = mem_cgroup_oom_unregister_event;
	} else if (!strcmp(name, "memory.pressure_level")) {
		event->register_event = vmpressure_register_event;
		event->unregister_event = vmpressure_unregister_event;
	} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
T
Tejun Heo 已提交
6046 6047
		event->register_event = memsw_cgroup_usage_register_event;
		event->unregister_event = memsw_cgroup_usage_unregister_event;
6048 6049 6050 6051 6052
	} else {
		ret = -EINVAL;
		goto out_put_cfile;
	}

6053
	/*
6054 6055 6056
	 * Verify @cfile should belong to @css.  Also, remaining events are
	 * automatically removed on cgroup destruction but the removal is
	 * asynchronous, so take an extra ref on @css.
6057
	 */
6058 6059
	cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent,
					&memory_cgrp_subsys);
6060
	ret = -EINVAL;
6061
	if (IS_ERR(cfile_css))
6062
		goto out_put_cfile;
6063 6064
	if (cfile_css != css) {
		css_put(cfile_css);
6065
		goto out_put_cfile;
6066
	}
6067

6068
	ret = event->register_event(memcg, event->eventfd, buffer);
6069 6070 6071 6072 6073
	if (ret)
		goto out_put_css;

	efile.file->f_op->poll(efile.file, &event->pt);

6074 6075 6076
	spin_lock(&memcg->event_list_lock);
	list_add(&event->list, &memcg->event_list);
	spin_unlock(&memcg->event_list_lock);
6077 6078 6079 6080 6081 6082 6083

	fdput(cfile);
	fdput(efile);

	return 0;

out_put_css:
6084
	css_put(css);
6085 6086 6087 6088 6089 6090 6091 6092 6093 6094 6095 6096
out_put_cfile:
	fdput(cfile);
out_put_eventfd:
	eventfd_ctx_put(event->eventfd);
out_put_efile:
	fdput(efile);
out_kfree:
	kfree(event);

	return ret;
}

B
Balbir Singh 已提交
6097 6098
static struct cftype mem_cgroup_files[] = {
	{
6099
		.name = "usage_in_bytes",
6100
		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
6101
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6102
	},
6103 6104
	{
		.name = "max_usage_in_bytes",
6105
		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
6106
		.trigger = mem_cgroup_reset,
6107
		.read_u64 = mem_cgroup_read_u64,
6108
	},
B
Balbir Singh 已提交
6109
	{
6110
		.name = "limit_in_bytes",
6111
		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
6112
		.write_string = mem_cgroup_write,
6113
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6114
	},
6115 6116 6117 6118
	{
		.name = "soft_limit_in_bytes",
		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
		.write_string = mem_cgroup_write,
6119
		.read_u64 = mem_cgroup_read_u64,
6120
	},
B
Balbir Singh 已提交
6121 6122
	{
		.name = "failcnt",
6123
		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
6124
		.trigger = mem_cgroup_reset,
6125
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6126
	},
6127 6128
	{
		.name = "stat",
6129
		.seq_show = memcg_stat_show,
6130
	},
6131 6132 6133 6134
	{
		.name = "force_empty",
		.trigger = mem_cgroup_force_empty_write,
	},
6135 6136
	{
		.name = "use_hierarchy",
6137
		.flags = CFTYPE_INSANE,
6138 6139 6140
		.write_u64 = mem_cgroup_hierarchy_write,
		.read_u64 = mem_cgroup_hierarchy_read,
	},
6141
	{
6142 6143
		.name = "cgroup.event_control",		/* XXX: for compat */
		.write_string = memcg_write_event_control,
6144 6145 6146
		.flags = CFTYPE_NO_PREFIX,
		.mode = S_IWUGO,
	},
K
KOSAKI Motohiro 已提交
6147 6148 6149 6150 6151
	{
		.name = "swappiness",
		.read_u64 = mem_cgroup_swappiness_read,
		.write_u64 = mem_cgroup_swappiness_write,
	},
6152 6153 6154 6155 6156
	{
		.name = "move_charge_at_immigrate",
		.read_u64 = mem_cgroup_move_charge_read,
		.write_u64 = mem_cgroup_move_charge_write,
	},
K
KAMEZAWA Hiroyuki 已提交
6157 6158
	{
		.name = "oom_control",
6159
		.seq_show = mem_cgroup_oom_control_read,
6160
		.write_u64 = mem_cgroup_oom_control_write,
K
KAMEZAWA Hiroyuki 已提交
6161 6162
		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
	},
6163 6164 6165
	{
		.name = "pressure_level",
	},
6166 6167 6168
#ifdef CONFIG_NUMA
	{
		.name = "numa_stat",
6169
		.seq_show = memcg_numa_stat_show,
6170 6171
	},
#endif
6172 6173 6174 6175 6176
#ifdef CONFIG_MEMCG_KMEM
	{
		.name = "kmem.limit_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
		.write_string = mem_cgroup_write,
6177
		.read_u64 = mem_cgroup_read_u64,
6178 6179 6180 6181
	},
	{
		.name = "kmem.usage_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
6182
		.read_u64 = mem_cgroup_read_u64,
6183 6184 6185 6186 6187
	},
	{
		.name = "kmem.failcnt",
		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
		.trigger = mem_cgroup_reset,
6188
		.read_u64 = mem_cgroup_read_u64,
6189 6190 6191 6192 6193
	},
	{
		.name = "kmem.max_usage_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
		.trigger = mem_cgroup_reset,
6194
		.read_u64 = mem_cgroup_read_u64,
6195
	},
6196 6197 6198
#ifdef CONFIG_SLABINFO
	{
		.name = "kmem.slabinfo",
6199
		.seq_show = mem_cgroup_slabinfo_read,
6200 6201
	},
#endif
6202
#endif
6203
	{ },	/* terminate */
6204
};
6205

6206 6207 6208 6209 6210
#ifdef CONFIG_MEMCG_SWAP
static struct cftype memsw_cgroup_files[] = {
	{
		.name = "memsw.usage_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
6211
		.read_u64 = mem_cgroup_read_u64,
6212 6213 6214 6215 6216
	},
	{
		.name = "memsw.max_usage_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
		.trigger = mem_cgroup_reset,
6217
		.read_u64 = mem_cgroup_read_u64,
6218 6219 6220 6221 6222
	},
	{
		.name = "memsw.limit_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
		.write_string = mem_cgroup_write,
6223
		.read_u64 = mem_cgroup_read_u64,
6224 6225 6226 6227 6228
	},
	{
		.name = "memsw.failcnt",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
		.trigger = mem_cgroup_reset,
6229
		.read_u64 = mem_cgroup_read_u64,
6230 6231 6232 6233
	},
	{ },	/* terminate */
};
#endif
6234
static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
6235 6236
{
	struct mem_cgroup_per_node *pn;
6237
	struct mem_cgroup_per_zone *mz;
6238
	int zone, tmp = node;
6239 6240 6241 6242 6243 6244 6245 6246
	/*
	 * This routine is called against possible nodes.
	 * But it's BUG to call kmalloc() against offline node.
	 *
	 * TODO: this routine can waste much memory for nodes which will
	 *       never be onlined. It's better to use memory hotplug callback
	 *       function.
	 */
6247 6248
	if (!node_state(node, N_NORMAL_MEMORY))
		tmp = -1;
6249
	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
6250 6251
	if (!pn)
		return 1;
6252 6253 6254

	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
		mz = &pn->zoneinfo[zone];
6255
		lruvec_init(&mz->lruvec);
6256 6257
		mz->usage_in_excess = 0;
		mz->on_tree = false;
6258
		mz->memcg = memcg;
6259
	}
6260
	memcg->nodeinfo[node] = pn;
6261 6262 6263
	return 0;
}

6264
static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
6265
{
6266
	kfree(memcg->nodeinfo[node]);
6267 6268
}

6269 6270
static struct mem_cgroup *mem_cgroup_alloc(void)
{
6271
	struct mem_cgroup *memcg;
6272
	size_t size;
6273

6274 6275
	size = sizeof(struct mem_cgroup);
	size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
6276

6277
	memcg = kzalloc(size, GFP_KERNEL);
6278
	if (!memcg)
6279 6280
		return NULL;

6281 6282
	memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
	if (!memcg->stat)
6283
		goto out_free;
6284 6285
	spin_lock_init(&memcg->pcp_counter_lock);
	return memcg;
6286 6287

out_free:
6288
	kfree(memcg);
6289
	return NULL;
6290 6291
}

6292
/*
6293 6294 6295 6296 6297 6298 6299 6300
 * At destroying mem_cgroup, references from swap_cgroup can remain.
 * (scanning all at force_empty is too costly...)
 *
 * Instead of clearing all references at force_empty, we remember
 * the number of reference from swap_cgroup and free mem_cgroup when
 * it goes down to 0.
 *
 * Removal of cgroup itself succeeds regardless of refs from swap.
6301
 */
6302 6303

static void __mem_cgroup_free(struct mem_cgroup *memcg)
6304
{
6305
	int node;
6306

6307
	mem_cgroup_remove_from_trees(memcg);
6308 6309 6310 6311 6312 6313

	for_each_node(node)
		free_mem_cgroup_per_zone_info(memcg, node);

	free_percpu(memcg->stat);

6314 6315 6316 6317 6318 6319 6320 6321 6322 6323 6324
	/*
	 * We need to make sure that (at least for now), the jump label
	 * destruction code runs outside of the cgroup lock. This is because
	 * get_online_cpus(), which is called from the static_branch update,
	 * can't be called inside the cgroup_lock. cpusets are the ones
	 * enforcing this dependency, so if they ever change, we might as well.
	 *
	 * schedule_work() will guarantee this happens. Be careful if you need
	 * to move this code around, and make sure it is outside
	 * the cgroup_lock.
	 */
6325
	disarm_static_keys(memcg);
6326
	kfree(memcg);
6327
}
6328

6329 6330 6331
/*
 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
 */
G
Glauber Costa 已提交
6332
struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
6333
{
6334
	if (!memcg->res.parent)
6335
		return NULL;
6336
	return mem_cgroup_from_res_counter(memcg->res.parent, res);
6337
}
G
Glauber Costa 已提交
6338
EXPORT_SYMBOL(parent_mem_cgroup);
6339

6340 6341 6342 6343 6344 6345 6346 6347 6348 6349 6350 6351 6352 6353 6354 6355 6356 6357 6358 6359 6360 6361 6362
static void __init mem_cgroup_soft_limit_tree_init(void)
{
	struct mem_cgroup_tree_per_node *rtpn;
	struct mem_cgroup_tree_per_zone *rtpz;
	int tmp, node, zone;

	for_each_node(node) {
		tmp = node;
		if (!node_state(node, N_NORMAL_MEMORY))
			tmp = -1;
		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
		BUG_ON(!rtpn);

		soft_limit_tree.rb_tree_per_node[node] = rtpn;

		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
			rtpz = &rtpn->rb_tree_per_zone[zone];
			rtpz->rb_root = RB_ROOT;
			spin_lock_init(&rtpz->lock);
		}
	}
}

L
Li Zefan 已提交
6363
static struct cgroup_subsys_state * __ref
6364
mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
B
Balbir Singh 已提交
6365
{
6366
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
6367
	long error = -ENOMEM;
6368
	int node;
B
Balbir Singh 已提交
6369

6370 6371
	memcg = mem_cgroup_alloc();
	if (!memcg)
K
KAMEZAWA Hiroyuki 已提交
6372
		return ERR_PTR(error);
6373

B
Bob Liu 已提交
6374
	for_each_node(node)
6375
		if (alloc_mem_cgroup_per_zone_info(memcg, node))
6376
			goto free_out;
6377

6378
	/* root ? */
6379
	if (parent_css == NULL) {
6380
		root_mem_cgroup = memcg;
6381 6382 6383
		res_counter_init(&memcg->res, NULL);
		res_counter_init(&memcg->memsw, NULL);
		res_counter_init(&memcg->kmem, NULL);
6384
	}
6385

6386 6387 6388 6389 6390
	memcg->last_scanned_node = MAX_NUMNODES;
	INIT_LIST_HEAD(&memcg->oom_notify);
	memcg->move_charge_at_immigrate = 0;
	mutex_init(&memcg->thresholds_lock);
	spin_lock_init(&memcg->move_lock);
6391
	vmpressure_init(&memcg->vmpressure);
6392 6393
	INIT_LIST_HEAD(&memcg->event_list);
	spin_lock_init(&memcg->event_list_lock);
6394 6395 6396 6397 6398 6399 6400 6401 6402

	return &memcg->css;

free_out:
	__mem_cgroup_free(memcg);
	return ERR_PTR(error);
}

static int
6403
mem_cgroup_css_online(struct cgroup_subsys_state *css)
6404
{
6405 6406
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
6407

6408 6409 6410
	if (css->cgroup->id > MEM_CGROUP_ID_MAX)
		return -ENOSPC;

T
Tejun Heo 已提交
6411
	if (!parent)
6412 6413
		return 0;

6414
	mutex_lock(&memcg_create_mutex);
6415 6416 6417 6418 6419 6420

	memcg->use_hierarchy = parent->use_hierarchy;
	memcg->oom_kill_disable = parent->oom_kill_disable;
	memcg->swappiness = mem_cgroup_swappiness(parent);

	if (parent->use_hierarchy) {
6421 6422
		res_counter_init(&memcg->res, &parent->res);
		res_counter_init(&memcg->memsw, &parent->memsw);
6423
		res_counter_init(&memcg->kmem, &parent->kmem);
6424

6425
		/*
6426 6427
		 * No need to take a reference to the parent because cgroup
		 * core guarantees its existence.
6428
		 */
6429
	} else {
6430 6431
		res_counter_init(&memcg->res, NULL);
		res_counter_init(&memcg->memsw, NULL);
6432
		res_counter_init(&memcg->kmem, NULL);
6433 6434 6435 6436 6437
		/*
		 * Deeper hierachy with use_hierarchy == false doesn't make
		 * much sense so let cgroup subsystem know about this
		 * unfortunate state in our controller.
		 */
6438
		if (parent != root_mem_cgroup)
6439
			memory_cgrp_subsys.broken_hierarchy = true;
6440
	}
6441
	mutex_unlock(&memcg_create_mutex);
6442

6443
	return memcg_init_kmem(memcg, &memory_cgrp_subsys);
B
Balbir Singh 已提交
6444 6445
}

M
Michal Hocko 已提交
6446 6447 6448 6449 6450 6451 6452 6453
/*
 * Announce all parents that a group from their hierarchy is gone.
 */
static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg)
{
	struct mem_cgroup *parent = memcg;

	while ((parent = parent_mem_cgroup(parent)))
6454
		mem_cgroup_iter_invalidate(parent);
M
Michal Hocko 已提交
6455 6456 6457 6458 6459 6460

	/*
	 * if the root memcg is not hierarchical we have to check it
	 * explicitely.
	 */
	if (!root_mem_cgroup->use_hierarchy)
6461
		mem_cgroup_iter_invalidate(root_mem_cgroup);
M
Michal Hocko 已提交
6462 6463
}

6464
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
6465
{
6466
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6467
	struct mem_cgroup_event *event, *tmp;
6468
	struct cgroup_subsys_state *iter;
6469 6470 6471 6472 6473 6474

	/*
	 * Unregister events and notify userspace.
	 * Notify userspace about cgroup removing only after rmdir of cgroup
	 * directory to avoid race between userspace and kernelspace.
	 */
6475 6476
	spin_lock(&memcg->event_list_lock);
	list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
6477 6478 6479
		list_del_init(&event->list);
		schedule_work(&event->remove);
	}
6480
	spin_unlock(&memcg->event_list_lock);
6481

6482 6483
	kmem_cgroup_css_offline(memcg);

M
Michal Hocko 已提交
6484
	mem_cgroup_invalidate_reclaim_iterators(memcg);
6485 6486 6487 6488 6489 6490 6491 6492

	/*
	 * This requires that offlining is serialized.  Right now that is
	 * guaranteed because css_killed_work_fn() holds the cgroup_mutex.
	 */
	css_for_each_descendant_post(iter, css)
		mem_cgroup_reparent_charges(mem_cgroup_from_css(iter));

G
Glauber Costa 已提交
6493
	mem_cgroup_destroy_all_caches(memcg);
6494
	vmpressure_cleanup(&memcg->vmpressure);
6495 6496
}

6497
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
B
Balbir Singh 已提交
6498
{
6499
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6500 6501 6502 6503 6504 6505 6506 6507 6508 6509 6510 6511 6512 6513 6514 6515 6516 6517 6518 6519 6520 6521 6522 6523 6524 6525 6526 6527 6528 6529 6530 6531 6532 6533 6534 6535
	/*
	 * XXX: css_offline() would be where we should reparent all
	 * memory to prepare the cgroup for destruction.  However,
	 * memcg does not do css_tryget() and res_counter charging
	 * under the same RCU lock region, which means that charging
	 * could race with offlining.  Offlining only happens to
	 * cgroups with no tasks in them but charges can show up
	 * without any tasks from the swapin path when the target
	 * memcg is looked up from the swapout record and not from the
	 * current task as it usually is.  A race like this can leak
	 * charges and put pages with stale cgroup pointers into
	 * circulation:
	 *
	 * #0                        #1
	 *                           lookup_swap_cgroup_id()
	 *                           rcu_read_lock()
	 *                           mem_cgroup_lookup()
	 *                           css_tryget()
	 *                           rcu_read_unlock()
	 * disable css_tryget()
	 * call_rcu()
	 *   offline_css()
	 *     reparent_charges()
	 *                           res_counter_charge()
	 *                           css_put()
	 *                             css_free()
	 *                           pc->mem_cgroup = dead memcg
	 *                           add page to lru
	 *
	 * The bulk of the charges are still moved in offline_css() to
	 * avoid pinning a lot of pages in case a long-term reference
	 * like a swapout record is deferring the css_free() to long
	 * after offlining.  But this makes sure we catch any charges
	 * made after offlining:
	 */
	mem_cgroup_reparent_charges(memcg);
6536

6537
	memcg_destroy_kmem(memcg);
6538
	__mem_cgroup_free(memcg);
B
Balbir Singh 已提交
6539 6540
}

6541
#ifdef CONFIG_MMU
6542
/* Handlers for move charge at task migration. */
6543 6544
#define PRECHARGE_COUNT_AT_ONCE	256
static int mem_cgroup_do_precharge(unsigned long count)
6545
{
6546 6547
	int ret = 0;
	int batch_count = PRECHARGE_COUNT_AT_ONCE;
6548
	struct mem_cgroup *memcg = mc.to;
6549

6550
	if (mem_cgroup_is_root(memcg)) {
6551 6552 6553 6554 6555 6556 6557 6558
		mc.precharge += count;
		/* we don't need css_get for root */
		return ret;
	}
	/* try to charge at once */
	if (count > 1) {
		struct res_counter *dummy;
		/*
6559
		 * "memcg" cannot be under rmdir() because we've already checked
6560 6561 6562 6563
		 * by cgroup_lock_live_cgroup() that it is not removed and we
		 * are still under the same cgroup_mutex. So we can postpone
		 * css_get().
		 */
6564
		if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
6565
			goto one_by_one;
6566
		if (do_swap_account && res_counter_charge(&memcg->memsw,
6567
						PAGE_SIZE * count, &dummy)) {
6568
			res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
6569 6570 6571 6572 6573 6574 6575 6576 6577 6578 6579 6580 6581 6582 6583 6584
			goto one_by_one;
		}
		mc.precharge += count;
		return ret;
	}
one_by_one:
	/* fall back to one by one charge */
	while (count--) {
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
		if (!batch_count--) {
			batch_count = PRECHARGE_COUNT_AT_ONCE;
			cond_resched();
		}
6585
		ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
6586
		if (ret)
6587
			/* mem_cgroup_clear_mc() will do uncharge later */
6588
			return ret;
6589 6590
		mc.precharge++;
	}
6591 6592 6593 6594
	return ret;
}

/**
6595
 * get_mctgt_type - get target type of moving charge
6596 6597 6598
 * @vma: the vma the pte to be checked belongs
 * @addr: the address corresponding to the pte to be checked
 * @ptent: the pte to be checked
6599
 * @target: the pointer the target page or swap ent will be stored(can be NULL)
6600 6601 6602 6603 6604 6605
 *
 * Returns
 *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
 *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
 *     move charge. if @target is not NULL, the page is stored in target->page
 *     with extra refcnt got(Callers should handle it).
6606 6607 6608
 *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
 *     target for charge migration. if @target is not NULL, the entry is stored
 *     in target->ent.
6609 6610 6611 6612 6613
 *
 * Called with pte lock held.
 */
union mc_target {
	struct page	*page;
6614
	swp_entry_t	ent;
6615 6616 6617
};

enum mc_target_type {
6618
	MC_TARGET_NONE = 0,
6619
	MC_TARGET_PAGE,
6620
	MC_TARGET_SWAP,
6621 6622
};

D
Daisuke Nishimura 已提交
6623 6624
static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
						unsigned long addr, pte_t ptent)
6625
{
D
Daisuke Nishimura 已提交
6626
	struct page *page = vm_normal_page(vma, addr, ptent);
6627

D
Daisuke Nishimura 已提交
6628 6629 6630 6631
	if (!page || !page_mapped(page))
		return NULL;
	if (PageAnon(page)) {
		/* we don't move shared anon */
6632
		if (!move_anon())
D
Daisuke Nishimura 已提交
6633
			return NULL;
6634 6635
	} else if (!move_file())
		/* we ignore mapcount for file pages */
D
Daisuke Nishimura 已提交
6636 6637 6638 6639 6640 6641 6642
		return NULL;
	if (!get_page_unless_zero(page))
		return NULL;

	return page;
}

6643
#ifdef CONFIG_SWAP
D
Daisuke Nishimura 已提交
6644 6645 6646 6647 6648 6649 6650 6651
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
			unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
	struct page *page = NULL;
	swp_entry_t ent = pte_to_swp_entry(ptent);

	if (!move_anon() || non_swap_entry(ent))
		return NULL;
6652 6653 6654 6655
	/*
	 * Because lookup_swap_cache() updates some statistics counter,
	 * we call find_get_page() with swapper_space directly.
	 */
6656
	page = find_get_page(swap_address_space(ent), ent.val);
D
Daisuke Nishimura 已提交
6657 6658 6659 6660 6661
	if (do_swap_account)
		entry->val = ent.val;

	return page;
}
6662 6663 6664 6665 6666 6667 6668
#else
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
			unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
	return NULL;
}
#endif
D
Daisuke Nishimura 已提交
6669

6670 6671 6672 6673 6674 6675 6676 6677 6678 6679 6680 6681 6682 6683 6684 6685 6686 6687 6688
static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
			unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
	struct page *page = NULL;
	struct address_space *mapping;
	pgoff_t pgoff;

	if (!vma->vm_file) /* anonymous vma */
		return NULL;
	if (!move_file())
		return NULL;

	mapping = vma->vm_file->f_mapping;
	if (pte_none(ptent))
		pgoff = linear_page_index(vma, addr);
	else /* pte_file(ptent) is true */
		pgoff = pte_to_pgoff(ptent);

	/* page is moved even if it's not RSS of this task(page-faulted). */
6689 6690 6691 6692 6693 6694
	page = find_get_page(mapping, pgoff);

#ifdef CONFIG_SWAP
	/* shmem/tmpfs may report page out on swap: account for that too. */
	if (radix_tree_exceptional_entry(page)) {
		swp_entry_t swap = radix_to_swp_entry(page);
6695
		if (do_swap_account)
6696
			*entry = swap;
6697
		page = find_get_page(swap_address_space(swap), swap.val);
6698
	}
6699
#endif
6700 6701 6702
	return page;
}

6703
static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
D
Daisuke Nishimura 已提交
6704 6705 6706 6707
		unsigned long addr, pte_t ptent, union mc_target *target)
{
	struct page *page = NULL;
	struct page_cgroup *pc;
6708
	enum mc_target_type ret = MC_TARGET_NONE;
D
Daisuke Nishimura 已提交
6709 6710 6711 6712 6713 6714
	swp_entry_t ent = { .val = 0 };

	if (pte_present(ptent))
		page = mc_handle_present_pte(vma, addr, ptent);
	else if (is_swap_pte(ptent))
		page = mc_handle_swap_pte(vma, addr, ptent, &ent);
6715 6716
	else if (pte_none(ptent) || pte_file(ptent))
		page = mc_handle_file_pte(vma, addr, ptent, &ent);
D
Daisuke Nishimura 已提交
6717 6718

	if (!page && !ent.val)
6719
		return ret;
6720 6721 6722 6723 6724 6725 6726 6727 6728 6729 6730 6731 6732 6733 6734
	if (page) {
		pc = lookup_page_cgroup(page);
		/*
		 * Do only loose check w/o page_cgroup lock.
		 * mem_cgroup_move_account() checks the pc is valid or not under
		 * the lock.
		 */
		if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
			ret = MC_TARGET_PAGE;
			if (target)
				target->page = page;
		}
		if (!ret || !target)
			put_page(page);
	}
D
Daisuke Nishimura 已提交
6735 6736
	/* There is a swap entry and a page doesn't exist or isn't charged */
	if (ent.val && !ret &&
L
Li Zefan 已提交
6737
	    mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
6738 6739 6740
		ret = MC_TARGET_SWAP;
		if (target)
			target->ent = ent;
6741 6742 6743 6744
	}
	return ret;
}

6745 6746 6747 6748 6749 6750 6751 6752 6753 6754 6755 6756 6757 6758
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
 * We don't consider swapping or file mapped pages because THP does not
 * support them for now.
 * Caller should make sure that pmd_trans_huge(pmd) is true.
 */
static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
		unsigned long addr, pmd_t pmd, union mc_target *target)
{
	struct page *page = NULL;
	struct page_cgroup *pc;
	enum mc_target_type ret = MC_TARGET_NONE;

	page = pmd_page(pmd);
6759
	VM_BUG_ON_PAGE(!page || !PageHead(page), page);
6760 6761 6762 6763 6764 6765 6766 6767 6768 6769 6770 6771 6772 6773 6774 6775 6776 6777 6778 6779
	if (!move_anon())
		return ret;
	pc = lookup_page_cgroup(page);
	if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
		ret = MC_TARGET_PAGE;
		if (target) {
			get_page(page);
			target->page = page;
		}
	}
	return ret;
}
#else
static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
		unsigned long addr, pmd_t pmd, union mc_target *target)
{
	return MC_TARGET_NONE;
}
#endif

6780 6781 6782 6783 6784 6785 6786 6787
static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
					unsigned long addr, unsigned long end,
					struct mm_walk *walk)
{
	struct vm_area_struct *vma = walk->private;
	pte_t *pte;
	spinlock_t *ptl;

6788
	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
6789 6790
		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
			mc.precharge += HPAGE_PMD_NR;
6791
		spin_unlock(ptl);
6792
		return 0;
6793
	}
6794

6795 6796
	if (pmd_trans_unstable(pmd))
		return 0;
6797 6798
	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
	for (; addr != end; pte++, addr += PAGE_SIZE)
6799
		if (get_mctgt_type(vma, addr, *pte, NULL))
6800 6801 6802 6803
			mc.precharge++;	/* increment precharge temporarily */
	pte_unmap_unlock(pte - 1, ptl);
	cond_resched();

6804 6805 6806
	return 0;
}

6807 6808 6809 6810 6811
static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
{
	unsigned long precharge;
	struct vm_area_struct *vma;

6812
	down_read(&mm->mmap_sem);
6813 6814 6815 6816 6817 6818 6819 6820 6821 6822 6823
	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		struct mm_walk mem_cgroup_count_precharge_walk = {
			.pmd_entry = mem_cgroup_count_precharge_pte_range,
			.mm = mm,
			.private = vma,
		};
		if (is_vm_hugetlb_page(vma))
			continue;
		walk_page_range(vma->vm_start, vma->vm_end,
					&mem_cgroup_count_precharge_walk);
	}
6824
	up_read(&mm->mmap_sem);
6825 6826 6827 6828 6829 6830 6831 6832 6833

	precharge = mc.precharge;
	mc.precharge = 0;

	return precharge;
}

static int mem_cgroup_precharge_mc(struct mm_struct *mm)
{
6834 6835 6836 6837 6838
	unsigned long precharge = mem_cgroup_count_precharge(mm);

	VM_BUG_ON(mc.moving_task);
	mc.moving_task = current;
	return mem_cgroup_do_precharge(precharge);
6839 6840
}

6841 6842
/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
static void __mem_cgroup_clear_mc(void)
6843
{
6844 6845
	struct mem_cgroup *from = mc.from;
	struct mem_cgroup *to = mc.to;
L
Li Zefan 已提交
6846
	int i;
6847

6848
	/* we must uncharge all the leftover precharges from mc.to */
6849 6850 6851 6852 6853 6854 6855 6856 6857 6858 6859
	if (mc.precharge) {
		__mem_cgroup_cancel_charge(mc.to, mc.precharge);
		mc.precharge = 0;
	}
	/*
	 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
	 * we must uncharge here.
	 */
	if (mc.moved_charge) {
		__mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
		mc.moved_charge = 0;
6860
	}
6861 6862 6863 6864 6865 6866
	/* we must fixup refcnts and charges */
	if (mc.moved_swap) {
		/* uncharge swap account from the old cgroup */
		if (!mem_cgroup_is_root(mc.from))
			res_counter_uncharge(&mc.from->memsw,
						PAGE_SIZE * mc.moved_swap);
L
Li Zefan 已提交
6867 6868 6869

		for (i = 0; i < mc.moved_swap; i++)
			css_put(&mc.from->css);
6870 6871 6872 6873 6874 6875 6876 6877 6878

		if (!mem_cgroup_is_root(mc.to)) {
			/*
			 * we charged both to->res and to->memsw, so we should
			 * uncharge to->res.
			 */
			res_counter_uncharge(&mc.to->res,
						PAGE_SIZE * mc.moved_swap);
		}
L
Li Zefan 已提交
6879
		/* we've already done css_get(mc.to) */
6880 6881
		mc.moved_swap = 0;
	}
6882 6883 6884 6885 6886 6887 6888 6889 6890 6891 6892 6893 6894 6895 6896
	memcg_oom_recover(from);
	memcg_oom_recover(to);
	wake_up_all(&mc.waitq);
}

static void mem_cgroup_clear_mc(void)
{
	struct mem_cgroup *from = mc.from;

	/*
	 * we must clear moving_task before waking up waiters at the end of
	 * task migration.
	 */
	mc.moving_task = NULL;
	__mem_cgroup_clear_mc();
6897
	spin_lock(&mc.lock);
6898 6899
	mc.from = NULL;
	mc.to = NULL;
6900
	spin_unlock(&mc.lock);
6901
	mem_cgroup_end_move(from);
6902 6903
}

6904
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
6905
				 struct cgroup_taskset *tset)
6906
{
6907
	struct task_struct *p = cgroup_taskset_first(tset);
6908
	int ret = 0;
6909
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6910
	unsigned long move_charge_at_immigrate;
6911

6912 6913 6914 6915 6916 6917 6918
	/*
	 * We are now commited to this value whatever it is. Changes in this
	 * tunable will only affect upcoming migrations, not the current one.
	 * So we need to save it, and keep it going.
	 */
	move_charge_at_immigrate  = memcg->move_charge_at_immigrate;
	if (move_charge_at_immigrate) {
6919 6920 6921
		struct mm_struct *mm;
		struct mem_cgroup *from = mem_cgroup_from_task(p);

6922
		VM_BUG_ON(from == memcg);
6923 6924 6925 6926 6927

		mm = get_task_mm(p);
		if (!mm)
			return 0;
		/* We move charges only when we move a owner of the mm */
6928 6929 6930 6931
		if (mm->owner == p) {
			VM_BUG_ON(mc.from);
			VM_BUG_ON(mc.to);
			VM_BUG_ON(mc.precharge);
6932
			VM_BUG_ON(mc.moved_charge);
6933
			VM_BUG_ON(mc.moved_swap);
6934
			mem_cgroup_start_move(from);
6935
			spin_lock(&mc.lock);
6936
			mc.from = from;
6937
			mc.to = memcg;
6938
			mc.immigrate_flags = move_charge_at_immigrate;
6939
			spin_unlock(&mc.lock);
6940
			/* We set mc.moving_task later */
6941 6942 6943 6944

			ret = mem_cgroup_precharge_mc(mm);
			if (ret)
				mem_cgroup_clear_mc();
6945 6946
		}
		mmput(mm);
6947 6948 6949 6950
	}
	return ret;
}

6951
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
6952
				     struct cgroup_taskset *tset)
6953
{
6954
	mem_cgroup_clear_mc();
6955 6956
}

6957 6958 6959
static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
				unsigned long addr, unsigned long end,
				struct mm_walk *walk)
6960
{
6961 6962 6963 6964
	int ret = 0;
	struct vm_area_struct *vma = walk->private;
	pte_t *pte;
	spinlock_t *ptl;
6965 6966 6967 6968
	enum mc_target_type target_type;
	union mc_target target;
	struct page *page;
	struct page_cgroup *pc;
6969

6970 6971 6972 6973 6974 6975 6976 6977 6978 6979
	/*
	 * We don't take compound_lock() here but no race with splitting thp
	 * happens because:
	 *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
	 *    under splitting, which means there's no concurrent thp split,
	 *  - if another thread runs into split_huge_page() just after we
	 *    entered this if-block, the thread must wait for page table lock
	 *    to be unlocked in __split_huge_page_splitting(), where the main
	 *    part of thp split is not executed yet.
	 */
6980
	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
6981
		if (mc.precharge < HPAGE_PMD_NR) {
6982
			spin_unlock(ptl);
6983 6984 6985 6986 6987 6988 6989 6990
			return 0;
		}
		target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
		if (target_type == MC_TARGET_PAGE) {
			page = target.page;
			if (!isolate_lru_page(page)) {
				pc = lookup_page_cgroup(page);
				if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
6991
							pc, mc.from, mc.to)) {
6992 6993 6994 6995 6996 6997 6998
					mc.precharge -= HPAGE_PMD_NR;
					mc.moved_charge += HPAGE_PMD_NR;
				}
				putback_lru_page(page);
			}
			put_page(page);
		}
6999
		spin_unlock(ptl);
7000
		return 0;
7001 7002
	}

7003 7004
	if (pmd_trans_unstable(pmd))
		return 0;
7005 7006 7007 7008
retry:
	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
	for (; addr != end; addr += PAGE_SIZE) {
		pte_t ptent = *(pte++);
7009
		swp_entry_t ent;
7010 7011 7012 7013

		if (!mc.precharge)
			break;

7014
		switch (get_mctgt_type(vma, addr, ptent, &target)) {
7015 7016 7017 7018 7019
		case MC_TARGET_PAGE:
			page = target.page;
			if (isolate_lru_page(page))
				goto put;
			pc = lookup_page_cgroup(page);
7020
			if (!mem_cgroup_move_account(page, 1, pc,
7021
						     mc.from, mc.to)) {
7022
				mc.precharge--;
7023 7024
				/* we uncharge from mc.from later. */
				mc.moved_charge++;
7025 7026
			}
			putback_lru_page(page);
7027
put:			/* get_mctgt_type() gets the page */
7028 7029
			put_page(page);
			break;
7030 7031
		case MC_TARGET_SWAP:
			ent = target.ent;
7032
			if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
7033
				mc.precharge--;
7034 7035 7036
				/* we fixup refcnts and charges later. */
				mc.moved_swap++;
			}
7037
			break;
7038 7039 7040 7041 7042 7043 7044 7045 7046 7047 7048 7049 7050 7051
		default:
			break;
		}
	}
	pte_unmap_unlock(pte - 1, ptl);
	cond_resched();

	if (addr != end) {
		/*
		 * We have consumed all precharges we got in can_attach().
		 * We try charge one by one, but don't do any additional
		 * charges to mc.to if we have failed in charge once in attach()
		 * phase.
		 */
7052
		ret = mem_cgroup_do_precharge(1);
7053 7054 7055 7056 7057 7058 7059 7060 7061 7062 7063 7064
		if (!ret)
			goto retry;
	}

	return ret;
}

static void mem_cgroup_move_charge(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	lru_add_drain_all();
7065 7066 7067 7068 7069 7070 7071 7072 7073 7074 7075 7076 7077
retry:
	if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
		/*
		 * Someone who are holding the mmap_sem might be waiting in
		 * waitq. So we cancel all extra charges, wake up all waiters,
		 * and retry. Because we cancel precharges, we might not be able
		 * to move enough charges, but moving charge is a best-effort
		 * feature anyway, so it wouldn't be a big problem.
		 */
		__mem_cgroup_clear_mc();
		cond_resched();
		goto retry;
	}
7078 7079 7080 7081 7082 7083 7084 7085 7086 7087 7088 7089 7090 7091 7092 7093 7094 7095
	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		int ret;
		struct mm_walk mem_cgroup_move_charge_walk = {
			.pmd_entry = mem_cgroup_move_charge_pte_range,
			.mm = mm,
			.private = vma,
		};
		if (is_vm_hugetlb_page(vma))
			continue;
		ret = walk_page_range(vma->vm_start, vma->vm_end,
						&mem_cgroup_move_charge_walk);
		if (ret)
			/*
			 * means we have consumed all precharges and failed in
			 * doing additional charge. Just abandon here.
			 */
			break;
	}
7096
	up_read(&mm->mmap_sem);
7097 7098
}

7099
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
7100
				 struct cgroup_taskset *tset)
B
Balbir Singh 已提交
7101
{
7102
	struct task_struct *p = cgroup_taskset_first(tset);
7103
	struct mm_struct *mm = get_task_mm(p);
7104 7105

	if (mm) {
7106 7107
		if (mc.to)
			mem_cgroup_move_charge(mm);
7108 7109
		mmput(mm);
	}
7110 7111
	if (mc.to)
		mem_cgroup_clear_mc();
B
Balbir Singh 已提交
7112
}
7113
#else	/* !CONFIG_MMU */
7114
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
7115
				 struct cgroup_taskset *tset)
7116 7117 7118
{
	return 0;
}
7119
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
7120
				     struct cgroup_taskset *tset)
7121 7122
{
}
7123
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
7124
				 struct cgroup_taskset *tset)
7125 7126 7127
{
}
#endif
B
Balbir Singh 已提交
7128

7129 7130 7131 7132
/*
 * Cgroup retains root cgroups across [un]mount cycles making it necessary
 * to verify sane_behavior flag on each mount attempt.
 */
7133
static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
7134 7135 7136 7137 7138 7139
{
	/*
	 * use_hierarchy is forced with sane_behavior.  cgroup core
	 * guarantees that @root doesn't have any children, so turning it
	 * on for the root memcg is enough.
	 */
7140 7141
	if (cgroup_sane_behavior(root_css->cgroup))
		mem_cgroup_from_css(root_css)->use_hierarchy = true;
7142 7143
}

7144
struct cgroup_subsys memory_cgrp_subsys = {
7145
	.css_alloc = mem_cgroup_css_alloc,
7146
	.css_online = mem_cgroup_css_online,
7147 7148
	.css_offline = mem_cgroup_css_offline,
	.css_free = mem_cgroup_css_free,
7149 7150
	.can_attach = mem_cgroup_can_attach,
	.cancel_attach = mem_cgroup_cancel_attach,
B
Balbir Singh 已提交
7151
	.attach = mem_cgroup_move_task,
7152
	.bind = mem_cgroup_bind,
7153
	.base_cftypes = mem_cgroup_files,
7154
	.early_init = 0,
B
Balbir Singh 已提交
7155
};
7156

A
Andrew Morton 已提交
7157
#ifdef CONFIG_MEMCG_SWAP
7158 7159
static int __init enable_swap_account(char *s)
{
7160
	if (!strcmp(s, "1"))
7161
		really_do_swap_account = 1;
7162
	else if (!strcmp(s, "0"))
7163 7164 7165
		really_do_swap_account = 0;
	return 1;
}
7166
__setup("swapaccount=", enable_swap_account);
7167

7168 7169
static void __init memsw_file_init(void)
{
7170
	WARN_ON(cgroup_add_cftypes(&memory_cgrp_subsys, memsw_cgroup_files));
7171 7172 7173 7174 7175 7176 7177 7178
}

static void __init enable_swap_cgroup(void)
{
	if (!mem_cgroup_disabled() && really_do_swap_account) {
		do_swap_account = 1;
		memsw_file_init();
	}
7179
}
7180

7181
#else
7182
static void __init enable_swap_cgroup(void)
7183 7184
{
}
7185
#endif
7186 7187

/*
7188 7189 7190 7191 7192 7193
 * subsys_initcall() for memory controller.
 *
 * Some parts like hotcpu_notifier() have to be initialized from this context
 * because of lock dependencies (cgroup_lock -> cpu hotplug) but basically
 * everything that doesn't depend on a specific mem_cgroup structure should
 * be initialized from here.
7194 7195 7196 7197
 */
static int __init mem_cgroup_init(void)
{
	hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
7198
	enable_swap_cgroup();
7199
	mem_cgroup_soft_limit_tree_init();
7200
	memcg_stock_init();
7201 7202 7203
	return 0;
}
subsys_initcall(mem_cgroup_init);