memcontrol.c 190.8 KB
Newer Older
B
Balbir Singh 已提交
1 2 3 4 5
/* memcontrol.c - Memory Controller
 *
 * Copyright IBM Corporation, 2007
 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
 *
6 7 8
 * Copyright 2007 OpenVZ SWsoft Inc
 * Author: Pavel Emelianov <xemul@openvz.org>
 *
9 10 11 12
 * Memory thresholds
 * Copyright (C) 2009 Nokia Corporation
 * Author: Kirill A. Shutemov
 *
13 14 15 16
 * Kernel Memory Controller
 * Copyright (C) 2012 Parallels Inc. and Google Inc.
 * Authors: Glauber Costa and Suleiman Souhlal
 *
B
Balbir Singh 已提交
17 18 19 20 21 22 23 24 25 26 27 28 29 30
 * 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>
31
#include <linux/mm.h>
32
#include <linux/hugetlb.h>
K
KAMEZAWA Hiroyuki 已提交
33
#include <linux/pagemap.h>
34
#include <linux/smp.h>
35
#include <linux/page-flags.h>
36
#include <linux/backing-dev.h>
37 38
#include <linux/bit_spinlock.h>
#include <linux/rcupdate.h>
39
#include <linux/limits.h>
40
#include <linux/export.h>
41
#include <linux/mutex.h>
42
#include <linux/rbtree.h>
43
#include <linux/slab.h>
44
#include <linux/swap.h>
45
#include <linux/swapops.h>
46
#include <linux/spinlock.h>
47
#include <linux/eventfd.h>
48
#include <linux/poll.h>
49
#include <linux/sort.h>
50
#include <linux/fs.h>
51
#include <linux/seq_file.h>
52
#include <linux/vmpressure.h>
53
#include <linux/mm_inline.h>
54
#include <linux/page_cgroup.h>
55
#include <linux/cpu.h>
56
#include <linux/oom.h>
57
#include <linux/lockdep.h>
58
#include <linux/file.h>
K
KAMEZAWA Hiroyuki 已提交
59
#include "internal.h"
G
Glauber Costa 已提交
60
#include <net/sock.h>
M
Michal Hocko 已提交
61
#include <net/ip.h>
G
Glauber Costa 已提交
62
#include <net/tcp_memcontrol.h>
63
#include "slab.h"
B
Balbir Singh 已提交
64

65 66
#include <asm/uaccess.h>

67 68
#include <trace/events/vmscan.h>

69 70
struct cgroup_subsys memory_cgrp_subsys __read_mostly;
EXPORT_SYMBOL(memory_cgrp_subsys);
71

72
#define MEM_CGROUP_RECLAIM_RETRIES	5
73
static struct mem_cgroup *root_mem_cgroup __read_mostly;
B
Balbir Singh 已提交
74

A
Andrew Morton 已提交
75
#ifdef CONFIG_MEMCG_SWAP
L
Li Zefan 已提交
76
/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
77
int do_swap_account __read_mostly;
78 79

/* for remember boot option*/
A
Andrew Morton 已提交
80
#ifdef CONFIG_MEMCG_SWAP_ENABLED
81 82 83 84 85
static int really_do_swap_account __initdata = 1;
#else
static int really_do_swap_account __initdata = 0;
#endif

86
#else
87
#define do_swap_account		0
88 89 90
#endif


91 92 93
static const char * const mem_cgroup_stat_names[] = {
	"cache",
	"rss",
94
	"rss_huge",
95
	"mapped_file",
96
	"writeback",
97 98 99
	"swap",
};

100 101 102
enum mem_cgroup_events_index {
	MEM_CGROUP_EVENTS_PGPGIN,	/* # of pages paged in */
	MEM_CGROUP_EVENTS_PGPGOUT,	/* # of pages paged out */
103 104
	MEM_CGROUP_EVENTS_PGFAULT,	/* # of page-faults */
	MEM_CGROUP_EVENTS_PGMAJFAULT,	/* # of major page-faults */
105 106
	MEM_CGROUP_EVENTS_NSTATS,
};
107 108 109 110 111 112 113 114

static const char * const mem_cgroup_events_names[] = {
	"pgpgin",
	"pgpgout",
	"pgfault",
	"pgmajfault",
};

115 116 117 118 119 120 121 122
static const char * const mem_cgroup_lru_names[] = {
	"inactive_anon",
	"active_anon",
	"inactive_file",
	"active_file",
	"unevictable",
};

123 124 125 126 127 128 129 130
/*
 * 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,
131
	MEM_CGROUP_TARGET_SOFTLIMIT,
132
	MEM_CGROUP_TARGET_NUMAINFO,
133 134
	MEM_CGROUP_NTARGETS,
};
135 136 137
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
#define NUMAINFO_EVENTS_TARGET	1024
138

139
struct mem_cgroup_stat_cpu {
140
	long count[MEM_CGROUP_STAT_NSTATS];
141
	unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
142
	unsigned long nr_page_events;
143
	unsigned long targets[MEM_CGROUP_NTARGETS];
144 145
};

146
struct mem_cgroup_reclaim_iter {
M
Michal Hocko 已提交
147 148 149 150
	/*
	 * last scanned hierarchy member. Valid only if last_dead_count
	 * matches memcg->dead_count of the hierarchy root group.
	 */
151
	struct mem_cgroup *last_visited;
152
	int last_dead_count;
M
Michal Hocko 已提交
153

154 155 156 157
	/* scan generation, increased every round-trip */
	unsigned int generation;
};

158 159 160 161
/*
 * per-zone information in memory controller.
 */
struct mem_cgroup_per_zone {
162
	struct lruvec		lruvec;
163
	unsigned long		lru_size[NR_LRU_LISTS];
K
KOSAKI Motohiro 已提交
164

165 166
	struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];

167 168 169 170
	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;
171
	struct mem_cgroup	*memcg;		/* Back pointer, we cannot */
172
						/* use container_of	   */
173 174 175 176 177 178
};

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

179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198
/*
 * 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;

199 200 201 202 203
struct mem_cgroup_threshold {
	struct eventfd_ctx *eventfd;
	u64 threshold;
};

K
KAMEZAWA Hiroyuki 已提交
204
/* For threshold */
205
struct mem_cgroup_threshold_ary {
206
	/* An array index points to threshold just below or equal to usage. */
207
	int current_threshold;
208 209 210 211 212
	/* Size of entries[] */
	unsigned int size;
	/* Array of thresholds */
	struct mem_cgroup_threshold entries[0];
};
213 214 215 216 217 218 219 220 221 222 223 224

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;
};

K
KAMEZAWA Hiroyuki 已提交
225 226 227 228 229
/* for OOM */
struct mem_cgroup_eventfd_list {
	struct list_head list;
	struct eventfd_ctx *eventfd;
};
230

231 232 233
/*
 * cgroup_event represents events which userspace want to receive.
 */
234
struct mem_cgroup_event {
235
	/*
236
	 * memcg which the event belongs to.
237
	 */
238
	struct mem_cgroup *memcg;
239 240 241 242 243 244 245 246
	/*
	 * 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;
247 248 249 250 251
	/*
	 * 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.
	 */
252
	int (*register_event)(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
253
			      struct eventfd_ctx *eventfd, const char *args);
254 255 256 257 258
	/*
	 * 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.
	 */
259
	void (*unregister_event)(struct mem_cgroup *memcg,
260
				 struct eventfd_ctx *eventfd);
261 262 263 264 265 266 267 268 269 270
	/*
	 * 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;
};

271 272
static void mem_cgroup_threshold(struct mem_cgroup *memcg);
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
273

B
Balbir Singh 已提交
274 275 276 277 278 279 280
/*
 * 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
281 282 283
 * 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.
B
Balbir Singh 已提交
284 285 286 287 288 289 290
 */
struct mem_cgroup {
	struct cgroup_subsys_state css;
	/*
	 * the counter to account for memory usage
	 */
	struct res_counter res;
291

292 293 294
	/* vmpressure notifications */
	struct vmpressure vmpressure;

295 296 297 298
	/*
	 * the counter to account for mem+swap usage.
	 */
	struct res_counter memsw;
299

300 301 302 303
	/*
	 * the counter to account for kernel memory usage.
	 */
	struct res_counter kmem;
304 305 306 307
	/*
	 * Should the accounting and control be hierarchical, per subtree?
	 */
	bool use_hierarchy;
308
	unsigned long kmem_account_flags; /* See KMEM_ACCOUNTED_*, below */
309 310 311

	bool		oom_lock;
	atomic_t	under_oom;
312
	atomic_t	oom_wakeups;
313

314
	int	swappiness;
315 316
	/* OOM-Killer disable */
	int		oom_kill_disable;
K
KOSAKI Motohiro 已提交
317

318 319 320
	/* set when res.limit == memsw.limit */
	bool		memsw_is_minimum;

321 322 323 324
	/* protect arrays of thresholds */
	struct mutex thresholds_lock;

	/* thresholds for memory usage. RCU-protected */
325
	struct mem_cgroup_thresholds thresholds;
326

327
	/* thresholds for mem+swap usage. RCU-protected */
328
	struct mem_cgroup_thresholds memsw_thresholds;
329

K
KAMEZAWA Hiroyuki 已提交
330 331
	/* For oom notifier event fd */
	struct list_head oom_notify;
332

333 334 335 336
	/*
	 * Should we move charges of a task when a task is moved into this
	 * mem_cgroup ? And what type of charges should we move ?
	 */
A
Andrew Morton 已提交
337
	unsigned long move_charge_at_immigrate;
338 339 340 341
	/*
	 * set > 0 if pages under this cgroup are moving to other cgroup.
	 */
	atomic_t	moving_account;
342 343
	/* taken only while moving_account > 0 */
	spinlock_t	move_lock;
344
	/*
345
	 * percpu counter.
346
	 */
347
	struct mem_cgroup_stat_cpu __percpu *stat;
348 349 350 351 352 353
	/*
	 * 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;
G
Glauber Costa 已提交
354

M
Michal Hocko 已提交
355
	atomic_t	dead_count;
M
Michal Hocko 已提交
356
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
357
	struct cg_proto tcp_mem;
G
Glauber Costa 已提交
358
#endif
359 360 361 362 363 364 365 366
#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
367 368 369 370 371 372 373

	int last_scanned_node;
#if MAX_NUMNODES > 1
	nodemask_t	scan_nodes;
	atomic_t	numainfo_events;
	atomic_t	numainfo_updating;
#endif
374

375 376 377 378
	/* List of events which userspace want to receive */
	struct list_head event_list;
	spinlock_t event_list_lock;

379 380
	struct mem_cgroup_per_node *nodeinfo[0];
	/* WARNING: nodeinfo must be the last member here */
B
Balbir Singh 已提交
381 382
};

383 384
/* internal only representation about the status of kmem accounting. */
enum {
385
	KMEM_ACCOUNTED_ACTIVE, /* accounted by this cgroup itself */
386
	KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */
387 388 389 390 391 392 393
};

#ifdef CONFIG_MEMCG_KMEM
static inline void memcg_kmem_set_active(struct mem_cgroup *memcg)
{
	set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}
394 395 396 397 398 399 400 401

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)
{
402 403 404 405 406
	/*
	 * Our caller must use css_get() first, because memcg_uncharge_kmem()
	 * will call css_put() if it sees the memcg is dead.
	 */
	smp_wmb();
407 408 409 410 411 412 413 414 415
	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);
}
416 417
#endif

418 419
/* Stuffs for move charges at task migration. */
/*
420 421
 * Types of charges to be moved. "move_charge_at_immitgrate" and
 * "immigrate_flags" are treated as a left-shifted bitmap of these types.
422 423
 */
enum move_type {
424
	MOVE_CHARGE_TYPE_ANON,	/* private anonymous page and swap of it */
425
	MOVE_CHARGE_TYPE_FILE,	/* file page(including tmpfs) and swap of it */
426 427 428
	NR_MOVE_TYPE,
};

429 430
/* "mc" and its members are protected by cgroup_mutex */
static struct move_charge_struct {
431
	spinlock_t	  lock; /* for from, to */
432 433
	struct mem_cgroup *from;
	struct mem_cgroup *to;
434
	unsigned long immigrate_flags;
435
	unsigned long precharge;
436
	unsigned long moved_charge;
437
	unsigned long moved_swap;
438 439 440
	struct task_struct *moving_task;	/* a task moving charges */
	wait_queue_head_t waitq;		/* a waitq for other context */
} mc = {
441
	.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
442 443
	.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
444

D
Daisuke Nishimura 已提交
445 446
static bool move_anon(void)
{
447
	return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags);
D
Daisuke Nishimura 已提交
448 449
}

450 451
static bool move_file(void)
{
452
	return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags);
453 454
}

455 456 457 458
/*
 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
 * limit reclaim to prevent infinite loops, if they ever occur.
 */
459
#define	MEM_CGROUP_MAX_RECLAIM_LOOPS		100
460
#define	MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS	2
461

462 463
enum charge_type {
	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
464
	MEM_CGROUP_CHARGE_TYPE_ANON,
K
KAMEZAWA Hiroyuki 已提交
465
	MEM_CGROUP_CHARGE_TYPE_SWAPOUT,	/* for accounting swapcache */
K
KAMEZAWA Hiroyuki 已提交
466
	MEM_CGROUP_CHARGE_TYPE_DROP,	/* a page was unused swap cache */
467 468 469
	NR_CHARGE_TYPE,
};

470
/* for encoding cft->private value on file */
G
Glauber Costa 已提交
471 472 473 474
enum res_type {
	_MEM,
	_MEMSWAP,
	_OOM_TYPE,
475
	_KMEM,
G
Glauber Costa 已提交
476 477
};

478 479
#define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
#define MEMFILE_TYPE(val)	((val) >> 16 & 0xffff)
480
#define MEMFILE_ATTR(val)	((val) & 0xffff)
K
KAMEZAWA Hiroyuki 已提交
481 482
/* Used for OOM nofiier */
#define OOM_CONTROL		(0)
483

484 485 486 487 488 489 490 491
/*
 * 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)

492 493 494 495 496 497 498
/*
 * 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);

499 500
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
{
501
	return s ? container_of(s, struct mem_cgroup, css) : NULL;
502 503
}

504 505 506 507 508 509 510 511 512 513 514 515 516
/* 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;
}

517 518 519 520 521
static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
{
	return (memcg == root_mem_cgroup);
}

522 523 524 525 526 527
/*
 * 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

L
Li Zefan 已提交
528 529 530 531 532 533 534 535 536 537 538 539 540
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;

541
	css = css_from_id(id - 1, &memory_cgrp_subsys);
L
Li Zefan 已提交
542 543 544
	return mem_cgroup_from_css(css);
}

G
Glauber Costa 已提交
545
/* Writing them here to avoid exposing memcg's inner layout */
M
Michal Hocko 已提交
546
#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
G
Glauber Costa 已提交
547 548 549

void sock_update_memcg(struct sock *sk)
{
550
	if (mem_cgroup_sockets_enabled) {
G
Glauber Costa 已提交
551
		struct mem_cgroup *memcg;
552
		struct cg_proto *cg_proto;
G
Glauber Costa 已提交
553 554 555

		BUG_ON(!sk->sk_prot->proto_cgroup);

556 557 558 559 560 561 562 563 564 565
		/* 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));
566
			css_get(&sk->sk_cgrp->memcg->css);
567 568 569
			return;
		}

G
Glauber Costa 已提交
570 571
		rcu_read_lock();
		memcg = mem_cgroup_from_task(current);
572
		cg_proto = sk->sk_prot->proto_cgroup(memcg);
573 574
		if (!mem_cgroup_is_root(memcg) &&
		    memcg_proto_active(cg_proto) && css_tryget(&memcg->css)) {
575
			sk->sk_cgrp = cg_proto;
G
Glauber Costa 已提交
576 577 578 579 580 581 582 583
		}
		rcu_read_unlock();
	}
}
EXPORT_SYMBOL(sock_update_memcg);

void sock_release_memcg(struct sock *sk)
{
584
	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
G
Glauber Costa 已提交
585 586 587
		struct mem_cgroup *memcg;
		WARN_ON(!sk->sk_cgrp->memcg);
		memcg = sk->sk_cgrp->memcg;
588
		css_put(&sk->sk_cgrp->memcg->css);
G
Glauber Costa 已提交
589 590
	}
}
G
Glauber Costa 已提交
591 592 593 594 595 596

struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
{
	if (!memcg || mem_cgroup_is_root(memcg))
		return NULL;

597
	return &memcg->tcp_mem;
G
Glauber Costa 已提交
598 599
}
EXPORT_SYMBOL(tcp_proto_cgroup);
G
Glauber Costa 已提交
600

601 602
static void disarm_sock_keys(struct mem_cgroup *memcg)
{
603
	if (!memcg_proto_activated(&memcg->tcp_mem))
604 605 606 607 608 609 610 611 612
		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 1082 1083 1084 1085
		/*
		 * Page cache insertions can happen withou an
		 * actual mm context, e.g. during disk probing
		 * on boot, loopback IO, acct() writes etc.
		 */
		if (unlikely(!mm))
1086
			memcg = root_mem_cgroup;
1087 1088 1089 1090 1091
		else {
			memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
			if (unlikely(!memcg))
				memcg = root_mem_cgroup;
		}
1092
	} while (!css_tryget(&memcg->css));
1093
	rcu_read_unlock();
1094
	return memcg;
1095 1096
}

1097 1098 1099 1100 1101 1102 1103
/*
 * 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,
1104
		struct mem_cgroup *last_visited)
1105
{
1106
	struct cgroup_subsys_state *prev_css, *next_css;
1107

1108
	prev_css = last_visited ? &last_visited->css : NULL;
1109
skip_node:
1110
	next_css = css_next_descendant_pre(prev_css, &root->css);
1111 1112 1113 1114 1115 1116 1117

	/*
	 * 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.
1118 1119 1120 1121 1122 1123 1124 1125
	 *
	 * 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.
1126
	 */
1127
	if (next_css) {
1128 1129
		if ((next_css == &root->css) ||
		    ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)))
1130
			return mem_cgroup_from_css(next_css);
1131 1132 1133

		prev_css = next_css;
		goto skip_node;
1134 1135 1136 1137 1138
	}

	return NULL;
}

1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
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;
1167 1168 1169 1170 1171 1172 1173 1174 1175

		/*
		 * 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))
1176 1177 1178 1179 1180 1181 1182 1183
			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,
1184
				   struct mem_cgroup *root,
1185 1186
				   int sequence)
{
1187 1188
	/* root reference counting symmetric to mem_cgroup_iter_load */
	if (last_visited && last_visited != root)
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200
		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;
}

1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217
/**
 * 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.
 */
1218
struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
1219
				   struct mem_cgroup *prev,
1220
				   struct mem_cgroup_reclaim_cookie *reclaim)
K
KAMEZAWA Hiroyuki 已提交
1221
{
1222
	struct mem_cgroup *memcg = NULL;
1223
	struct mem_cgroup *last_visited = NULL;
1224

1225 1226
	if (mem_cgroup_disabled())
		return NULL;
1227

1228 1229
	if (!root)
		root = root_mem_cgroup;
K
KAMEZAWA Hiroyuki 已提交
1230

1231
	if (prev && !reclaim)
1232
		last_visited = prev;
K
KAMEZAWA Hiroyuki 已提交
1233

1234 1235
	if (!root->use_hierarchy && root != root_mem_cgroup) {
		if (prev)
1236
			goto out_css_put;
1237
		return root;
1238
	}
K
KAMEZAWA Hiroyuki 已提交
1239

1240
	rcu_read_lock();
1241
	while (!memcg) {
1242
		struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
1243
		int uninitialized_var(seq);
1244

1245 1246 1247 1248 1249 1250 1251
		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];
1252
			if (prev && reclaim->generation != iter->generation) {
M
Michal Hocko 已提交
1253
				iter->last_visited = NULL;
1254 1255
				goto out_unlock;
			}
M
Michal Hocko 已提交
1256

1257
			last_visited = mem_cgroup_iter_load(iter, root, &seq);
1258
		}
K
KAMEZAWA Hiroyuki 已提交
1259

1260
		memcg = __mem_cgroup_iter_next(root, last_visited);
K
KAMEZAWA Hiroyuki 已提交
1261

1262
		if (reclaim) {
1263 1264
			mem_cgroup_iter_update(iter, last_visited, memcg, root,
					seq);
1265

M
Michal Hocko 已提交
1266
			if (!memcg)
1267 1268 1269 1270
				iter->generation++;
			else if (!prev && memcg)
				reclaim->generation = iter->generation;
		}
1271

1272
		if (prev && !memcg)
1273
			goto out_unlock;
1274
	}
1275 1276
out_unlock:
	rcu_read_unlock();
1277 1278 1279 1280
out_css_put:
	if (prev && prev != root)
		css_put(&prev->css);

1281
	return memcg;
K
KAMEZAWA Hiroyuki 已提交
1282
}
K
KAMEZAWA Hiroyuki 已提交
1283

1284 1285 1286 1287 1288 1289 1290
/**
 * 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)
1291 1292 1293 1294 1295 1296
{
	if (!root)
		root = root_mem_cgroup;
	if (prev && prev != root)
		css_put(&prev->css);
}
K
KAMEZAWA Hiroyuki 已提交
1297

1298 1299 1300 1301 1302 1303
/*
 * 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)		\
1304
	for (iter = mem_cgroup_iter(root, NULL, NULL);	\
1305
	     iter != NULL;				\
1306
	     iter = mem_cgroup_iter(root, iter, NULL))
1307

1308
#define for_each_mem_cgroup(iter)			\
1309
	for (iter = mem_cgroup_iter(NULL, NULL, NULL);	\
1310
	     iter != NULL;				\
1311
	     iter = mem_cgroup_iter(NULL, iter, NULL))
K
KAMEZAWA Hiroyuki 已提交
1312

1313
void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
1314
{
1315
	struct mem_cgroup *memcg;
1316 1317

	rcu_read_lock();
1318 1319
	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
	if (unlikely(!memcg))
1320 1321 1322 1323
		goto out;

	switch (idx) {
	case PGFAULT:
1324 1325 1326 1327
		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
		break;
	case PGMAJFAULT:
		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
1328 1329 1330 1331 1332 1333 1334
		break;
	default:
		BUG();
	}
out:
	rcu_read_unlock();
}
1335
EXPORT_SYMBOL(__mem_cgroup_count_vm_event);
1336

1337 1338 1339
/**
 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
 * @zone: zone of the wanted lruvec
1340
 * @memcg: memcg of the wanted lruvec
1341 1342 1343 1344 1345 1346 1347 1348 1349
 *
 * 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;
1350
	struct lruvec *lruvec;
1351

1352 1353 1354 1355
	if (mem_cgroup_disabled()) {
		lruvec = &zone->lruvec;
		goto out;
	}
1356 1357

	mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
1358 1359 1360 1361 1362 1363 1364 1365 1366 1367
	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;
1368 1369
}

K
KAMEZAWA Hiroyuki 已提交
1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382
/*
 * 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.
 */
1383

1384
/**
1385
 * mem_cgroup_page_lruvec - return lruvec for adding an lru page
1386
 * @page: the page
1387
 * @zone: zone of the page
1388
 */
1389
struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
K
KAMEZAWA Hiroyuki 已提交
1390 1391
{
	struct mem_cgroup_per_zone *mz;
1392 1393
	struct mem_cgroup *memcg;
	struct page_cgroup *pc;
1394
	struct lruvec *lruvec;
1395

1396 1397 1398 1399
	if (mem_cgroup_disabled()) {
		lruvec = &zone->lruvec;
		goto out;
	}
1400

K
KAMEZAWA Hiroyuki 已提交
1401
	pc = lookup_page_cgroup(page);
1402
	memcg = pc->mem_cgroup;
1403 1404

	/*
1405
	 * Surreptitiously switch any uncharged offlist page to root:
1406 1407 1408 1409 1410 1411 1412
	 * 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.
	 */
1413
	if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
1414 1415
		pc->mem_cgroup = memcg = root_mem_cgroup;

1416
	mz = page_cgroup_zoneinfo(memcg, page);
1417 1418 1419 1420 1421 1422 1423 1424 1425 1426
	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
1427
}
1428

1429
/**
1430 1431 1432 1433
 * 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
1434
 *
1435 1436
 * This function must be called when a page is added to or removed from an
 * lru list.
1437
 */
1438 1439
void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
				int nr_pages)
1440 1441
{
	struct mem_cgroup_per_zone *mz;
1442
	unsigned long *lru_size;
1443 1444 1445 1446

	if (mem_cgroup_disabled())
		return;

1447 1448 1449 1450
	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
1451
}
1452

1453
/*
1454
 * Checks whether given mem is same or in the root_mem_cgroup's
1455 1456
 * hierarchy subtree
 */
1457 1458
bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
				  struct mem_cgroup *memcg)
1459
{
1460 1461
	if (root_memcg == memcg)
		return true;
1462
	if (!root_memcg->use_hierarchy || !memcg)
1463
		return false;
1464
	return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
1465 1466 1467 1468 1469 1470 1471
}

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

1472
	rcu_read_lock();
1473
	ret = __mem_cgroup_same_or_subtree(root_memcg, memcg);
1474 1475
	rcu_read_unlock();
	return ret;
1476 1477
}

1478 1479
bool task_in_mem_cgroup(struct task_struct *task,
			const struct mem_cgroup *memcg)
1480
{
1481
	struct mem_cgroup *curr = NULL;
1482
	struct task_struct *p;
1483
	bool ret;
1484

1485
	p = find_lock_task_mm(task);
1486
	if (p) {
1487
		curr = get_mem_cgroup_from_mm(p->mm);
1488 1489 1490 1491 1492 1493 1494
		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.
		 */
1495
		rcu_read_lock();
1496 1497 1498
		curr = mem_cgroup_from_task(task);
		if (curr)
			css_get(&curr->css);
1499
		rcu_read_unlock();
1500
	}
1501
	/*
1502
	 * We should check use_hierarchy of "memcg" not "curr". Because checking
1503
	 * use_hierarchy of "curr" here make this function true if hierarchy is
1504 1505
	 * enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
	 * hierarchy(even if use_hierarchy is disabled in "memcg").
1506
	 */
1507
	ret = mem_cgroup_same_or_subtree(memcg, curr);
1508
	css_put(&curr->css);
1509 1510 1511
	return ret;
}

1512
int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
1513
{
1514
	unsigned long inactive_ratio;
1515
	unsigned long inactive;
1516
	unsigned long active;
1517
	unsigned long gb;
1518

1519 1520
	inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
	active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
1521

1522 1523 1524 1525 1526 1527
	gb = (inactive + active) >> (30 - PAGE_SHIFT);
	if (gb)
		inactive_ratio = int_sqrt(10 * gb);
	else
		inactive_ratio = 1;

1528
	return inactive * inactive_ratio < active;
1529 1530
}

1531 1532 1533
#define mem_cgroup_from_res_counter(counter, member)	\
	container_of(counter, struct mem_cgroup, member)

1534
/**
1535
 * mem_cgroup_margin - calculate chargeable space of a memory cgroup
W
Wanpeng Li 已提交
1536
 * @memcg: the memory cgroup
1537
 *
1538
 * Returns the maximum amount of memory @mem can be charged with, in
1539
 * pages.
1540
 */
1541
static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
1542
{
1543 1544
	unsigned long long margin;

1545
	margin = res_counter_margin(&memcg->res);
1546
	if (do_swap_account)
1547
		margin = min(margin, res_counter_margin(&memcg->memsw));
1548
	return margin >> PAGE_SHIFT;
1549 1550
}

1551
int mem_cgroup_swappiness(struct mem_cgroup *memcg)
K
KOSAKI Motohiro 已提交
1552 1553
{
	/* root ? */
T
Tejun Heo 已提交
1554
	if (!css_parent(&memcg->css))
K
KOSAKI Motohiro 已提交
1555 1556
		return vm_swappiness;

1557
	return memcg->swappiness;
K
KOSAKI Motohiro 已提交
1558 1559
}

1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573
/*
 * 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.
 */
1574 1575 1576 1577

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

1578
static void mem_cgroup_start_move(struct mem_cgroup *memcg)
1579
{
1580
	atomic_inc(&memcg_moving);
1581
	atomic_inc(&memcg->moving_account);
1582 1583 1584
	synchronize_rcu();
}

1585
static void mem_cgroup_end_move(struct mem_cgroup *memcg)
1586
{
1587 1588 1589 1590
	/*
	 * Now, mem_cgroup_clear_mc() may call this function with NULL.
	 * We check NULL in callee rather than caller.
	 */
1591 1592
	if (memcg) {
		atomic_dec(&memcg_moving);
1593
		atomic_dec(&memcg->moving_account);
1594
	}
1595
}
1596

1597 1598 1599
/*
 * 2 routines for checking "mem" is under move_account() or not.
 *
1600 1601
 * mem_cgroup_stolen() -  checking whether a cgroup is mc.from or not. This
 *			  is used for avoiding races in accounting.  If true,
1602 1603 1604 1605 1606 1607 1608
 *			  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".
 */

1609
static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
1610 1611
{
	VM_BUG_ON(!rcu_read_lock_held());
1612
	return atomic_read(&memcg->moving_account) > 0;
1613
}
1614

1615
static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
1616
{
1617 1618
	struct mem_cgroup *from;
	struct mem_cgroup *to;
1619
	bool ret = false;
1620 1621 1622 1623 1624 1625 1626 1627 1628
	/*
	 * 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;
1629

1630 1631
	ret = mem_cgroup_same_or_subtree(memcg, from)
		|| mem_cgroup_same_or_subtree(memcg, to);
1632 1633
unlock:
	spin_unlock(&mc.lock);
1634 1635 1636
	return ret;
}

1637
static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
1638 1639
{
	if (mc.moving_task && current != mc.moving_task) {
1640
		if (mem_cgroup_under_move(memcg)) {
1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652
			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;
}

1653 1654 1655 1656
/*
 * 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.
1657
 * see mem_cgroup_stolen(), too.
1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670
 */
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);
}

1671
#define K(x) ((x) << (PAGE_SHIFT-10))
1672
/**
1673
 * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
1674 1675 1676 1677 1678 1679 1680 1681
 * @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
1682
	/* oom_info_lock ensures that parallel ooms do not interleave */
1683
	static DEFINE_MUTEX(oom_info_lock);
1684 1685
	struct mem_cgroup *iter;
	unsigned int i;
1686

1687
	if (!p)
1688 1689
		return;

1690
	mutex_lock(&oom_info_lock);
1691 1692
	rcu_read_lock();

T
Tejun Heo 已提交
1693 1694 1695 1696 1697
	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");
1698 1699 1700

	rcu_read_unlock();

1701
	pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n",
1702 1703 1704
		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));
1705
	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n",
1706 1707 1708
		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));
1709
	pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n",
1710 1711 1712
		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));
1713 1714

	for_each_mem_cgroup_tree(iter, memcg) {
T
Tejun Heo 已提交
1715 1716
		pr_info("Memory cgroup stats for ");
		pr_cont_cgroup_path(iter->css.cgroup);
1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731
		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");
	}
1732
	mutex_unlock(&oom_info_lock);
1733 1734
}

1735 1736 1737 1738
/*
 * This function returns the number of memcg under hierarchy tree. Returns
 * 1(self count) if no children.
 */
1739
static int mem_cgroup_count_children(struct mem_cgroup *memcg)
1740 1741
{
	int num = 0;
K
KAMEZAWA Hiroyuki 已提交
1742 1743
	struct mem_cgroup *iter;

1744
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
1745
		num++;
1746 1747 1748
	return num;
}

D
David Rientjes 已提交
1749 1750 1751
/*
 * Return the memory (and swap, if configured) limit for a memcg.
 */
1752
static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
D
David Rientjes 已提交
1753 1754 1755
{
	u64 limit;

1756 1757
	limit = res_counter_read_u64(&memcg->res, RES_LIMIT);

D
David Rientjes 已提交
1758
	/*
1759
	 * Do not consider swap space if we cannot swap due to swappiness
D
David Rientjes 已提交
1760
	 */
1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774
	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
1775 1776
}

1777 1778
static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
				     int order)
1779 1780 1781 1782 1783 1784 1785
{
	struct mem_cgroup *iter;
	unsigned long chosen_points = 0;
	unsigned long totalpages;
	unsigned int points = 0;
	struct task_struct *chosen = NULL;

1786
	/*
1787 1788 1789
	 * 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.
1790
	 */
1791
	if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
1792 1793 1794 1795 1796
		set_thread_flag(TIF_MEMDIE);
		return;
	}

	check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
1797 1798
	totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
	for_each_mem_cgroup_tree(iter, memcg) {
1799
		struct css_task_iter it;
1800 1801
		struct task_struct *task;

1802 1803
		css_task_iter_start(&iter->css, &it);
		while ((task = css_task_iter_next(&it))) {
1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815
			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:
1816
				css_task_iter_end(&it);
1817 1818 1819 1820 1821 1822 1823 1824
				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);
1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836
			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);
1837
		}
1838
		css_task_iter_end(&it);
1839 1840 1841 1842 1843 1844 1845 1846 1847
	}

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

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 1875 1876 1877 1878 1879 1880 1881 1882 1883
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;
}

1884 1885
/**
 * test_mem_cgroup_node_reclaimable
W
Wanpeng Li 已提交
1886
 * @memcg: the target memcg
1887 1888 1889 1890 1891 1892 1893
 * @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.
 */
1894
static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
1895 1896
		int nid, bool noswap)
{
1897
	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
1898 1899 1900
		return true;
	if (noswap || !total_swap_pages)
		return false;
1901
	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
1902 1903 1904 1905
		return true;
	return false;

}
1906
#if MAX_NUMNODES > 1
1907 1908 1909 1910 1911 1912 1913

/*
 * 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.
 *
 */
1914
static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
1915 1916
{
	int nid;
1917 1918 1919 1920
	/*
	 * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
	 * pagein/pageout changes since the last update.
	 */
1921
	if (!atomic_read(&memcg->numainfo_events))
1922
		return;
1923
	if (atomic_inc_return(&memcg->numainfo_updating) > 1)
1924 1925 1926
		return;

	/* make a nodemask where this memcg uses memory from */
1927
	memcg->scan_nodes = node_states[N_MEMORY];
1928

1929
	for_each_node_mask(nid, node_states[N_MEMORY]) {
1930

1931 1932
		if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
			node_clear(nid, memcg->scan_nodes);
1933
	}
1934

1935 1936
	atomic_set(&memcg->numainfo_events, 0);
	atomic_set(&memcg->numainfo_updating, 0);
1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950
}

/*
 * 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.
 */
1951
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1952 1953 1954
{
	int node;

1955 1956
	mem_cgroup_may_update_nodemask(memcg);
	node = memcg->last_scanned_node;
1957

1958
	node = next_node(node, memcg->scan_nodes);
1959
	if (node == MAX_NUMNODES)
1960
		node = first_node(memcg->scan_nodes);
1961 1962 1963 1964 1965 1966 1967 1968 1969
	/*
	 * 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();

1970
	memcg->last_scanned_node = node;
1971 1972 1973
	return node;
}

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 2000 2001 2002 2003 2004 2005 2006 2007 2008
/*
 * 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;
}

2009
#else
2010
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
2011 2012 2013
{
	return 0;
}
2014

2015 2016 2017 2018
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
	return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
}
2019 2020
#endif

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 2060 2061 2062 2063 2064 2065 2066 2067 2068
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;
2069
	}
2070 2071
	mem_cgroup_iter_break(root_memcg, victim);
	return total;
2072 2073
}

2074 2075 2076 2077 2078 2079
#ifdef CONFIG_LOCKDEP
static struct lockdep_map memcg_oom_lock_dep_map = {
	.name = "memcg_oom_lock",
};
#endif

2080 2081
static DEFINE_SPINLOCK(memcg_oom_lock);

K
KAMEZAWA Hiroyuki 已提交
2082 2083 2084 2085
/*
 * Check OOM-Killer is already running under our hierarchy.
 * If someone is running, return false.
 */
2086
static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
2087
{
2088
	struct mem_cgroup *iter, *failed = NULL;
2089

2090 2091
	spin_lock(&memcg_oom_lock);

2092
	for_each_mem_cgroup_tree(iter, memcg) {
2093
		if (iter->oom_lock) {
2094 2095 2096 2097 2098
			/*
			 * this subtree of our hierarchy is already locked
			 * so we cannot give a lock.
			 */
			failed = iter;
2099 2100
			mem_cgroup_iter_break(memcg, iter);
			break;
2101 2102
		} else
			iter->oom_lock = true;
K
KAMEZAWA Hiroyuki 已提交
2103
	}
K
KAMEZAWA Hiroyuki 已提交
2104

2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115
	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;
2116
		}
2117 2118
	} else
		mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
2119 2120 2121 2122

	spin_unlock(&memcg_oom_lock);

	return !failed;
2123
}
2124

2125
static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
2126
{
K
KAMEZAWA Hiroyuki 已提交
2127 2128
	struct mem_cgroup *iter;

2129
	spin_lock(&memcg_oom_lock);
2130
	mutex_release(&memcg_oom_lock_dep_map, 1, _RET_IP_);
2131
	for_each_mem_cgroup_tree(iter, memcg)
2132
		iter->oom_lock = false;
2133
	spin_unlock(&memcg_oom_lock);
2134 2135
}

2136
static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
2137 2138 2139
{
	struct mem_cgroup *iter;

2140
	for_each_mem_cgroup_tree(iter, memcg)
2141 2142 2143
		atomic_inc(&iter->under_oom);
}

2144
static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
2145 2146 2147
{
	struct mem_cgroup *iter;

K
KAMEZAWA Hiroyuki 已提交
2148 2149 2150 2151 2152
	/*
	 * 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.
	 */
2153
	for_each_mem_cgroup_tree(iter, memcg)
2154
		atomic_add_unless(&iter->under_oom, -1, 0);
2155 2156
}

K
KAMEZAWA Hiroyuki 已提交
2157 2158
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);

K
KAMEZAWA Hiroyuki 已提交
2159
struct oom_wait_info {
2160
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
2161 2162 2163 2164 2165 2166
	wait_queue_t	wait;
};

static int memcg_oom_wake_function(wait_queue_t *wait,
	unsigned mode, int sync, void *arg)
{
2167 2168
	struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
	struct mem_cgroup *oom_wait_memcg;
K
KAMEZAWA Hiroyuki 已提交
2169 2170 2171
	struct oom_wait_info *oom_wait_info;

	oom_wait_info = container_of(wait, struct oom_wait_info, wait);
2172
	oom_wait_memcg = oom_wait_info->memcg;
K
KAMEZAWA Hiroyuki 已提交
2173 2174

	/*
2175
	 * Both of oom_wait_info->memcg and wake_memcg are stable under us.
K
KAMEZAWA Hiroyuki 已提交
2176 2177
	 * Then we can use css_is_ancestor without taking care of RCU.
	 */
2178 2179
	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
2180 2181 2182 2183
		return 0;
	return autoremove_wake_function(wait, mode, sync, arg);
}

2184
static void memcg_wakeup_oom(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
2185
{
2186
	atomic_inc(&memcg->oom_wakeups);
2187 2188
	/* for filtering, pass "memcg" as argument. */
	__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
K
KAMEZAWA Hiroyuki 已提交
2189 2190
}

2191
static void memcg_oom_recover(struct mem_cgroup *memcg)
2192
{
2193 2194
	if (memcg && atomic_read(&memcg->under_oom))
		memcg_wakeup_oom(memcg);
2195 2196
}

2197
static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
2198
{
2199 2200
	if (!current->memcg_oom.may_oom)
		return;
K
KAMEZAWA Hiroyuki 已提交
2201
	/*
2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213
	 * 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
2214
	 */
2215 2216 2217 2218
	css_get(&memcg->css);
	current->memcg_oom.memcg = memcg;
	current->memcg_oom.gfp_mask = mask;
	current->memcg_oom.order = order;
2219 2220 2221 2222
}

/**
 * mem_cgroup_oom_synchronize - complete memcg OOM handling
2223
 * @handle: actually kill/wait or just clean up the OOM state
2224
 *
2225 2226
 * This has to be called at the end of a page fault if the memcg OOM
 * handler was enabled.
2227
 *
2228
 * Memcg supports userspace OOM handling where failed allocations must
2229 2230 2231 2232
 * 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
2233
 * the end of the page fault to complete the OOM handling.
2234 2235
 *
 * Returns %true if an ongoing memcg OOM situation was detected and
2236
 * completed, %false otherwise.
2237
 */
2238
bool mem_cgroup_oom_synchronize(bool handle)
2239
{
2240
	struct mem_cgroup *memcg = current->memcg_oom.memcg;
2241
	struct oom_wait_info owait;
2242
	bool locked;
2243 2244 2245

	/* OOM is global, do not handle */
	if (!memcg)
2246
		return false;
2247

2248 2249
	if (!handle)
		goto cleanup;
2250 2251 2252 2253 2254 2255

	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
2256

2257
	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270
	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 {
2271
		schedule();
2272 2273 2274 2275 2276
		mem_cgroup_unmark_under_oom(memcg);
		finish_wait(&memcg_oom_waitq, &owait.wait);
	}

	if (locked) {
2277 2278 2279 2280 2281 2282 2283 2284
		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);
	}
2285 2286
cleanup:
	current->memcg_oom.memcg = NULL;
2287
	css_put(&memcg->css);
K
KAMEZAWA Hiroyuki 已提交
2288
	return true;
2289 2290
}

2291 2292 2293
/*
 * Currently used to update mapped file statistics, but the routine can be
 * generalized to update other statistics as well.
2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310
 *
 * 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
2311 2312
 * small, we check mm->moving_account and detect there are possibility of race
 * If there is, we take a lock.
2313
 */
2314

2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327
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
2328
	 * need to take move_lock_mem_cgroup(). Because we already hold
2329
	 * rcu_read_lock(), any calls to move_account will be delayed until
2330
	 * rcu_read_unlock() if mem_cgroup_stolen() == true.
2331
	 */
2332
	if (!mem_cgroup_stolen(memcg))
2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349
		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
2350
	 * should take move_lock_mem_cgroup().
2351 2352 2353 2354
	 */
	move_unlock_mem_cgroup(pc->mem_cgroup, flags);
}

2355
void mem_cgroup_update_page_stat(struct page *page,
S
Sha Zhengju 已提交
2356
				 enum mem_cgroup_stat_index idx, int val)
2357
{
2358
	struct mem_cgroup *memcg;
2359
	struct page_cgroup *pc = lookup_page_cgroup(page);
2360
	unsigned long uninitialized_var(flags);
2361

2362
	if (mem_cgroup_disabled())
2363
		return;
2364

2365
	VM_BUG_ON(!rcu_read_lock_held());
2366 2367
	memcg = pc->mem_cgroup;
	if (unlikely(!memcg || !PageCgroupUsed(pc)))
2368
		return;
2369

2370
	this_cpu_add(memcg->stat->count[idx], val);
2371
}
2372

2373 2374 2375 2376
/*
 * size of first charge trial. "32" comes from vmscan.c's magic value.
 * TODO: maybe necessary to use big numbers in big irons.
 */
2377
#define CHARGE_BATCH	32U
2378 2379
struct memcg_stock_pcp {
	struct mem_cgroup *cached; /* this never be root cgroup */
2380
	unsigned int nr_pages;
2381
	struct work_struct work;
2382
	unsigned long flags;
2383
#define FLUSHING_CACHED_CHARGE	0
2384 2385
};
static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
2386
static DEFINE_MUTEX(percpu_charge_mutex);
2387

2388 2389 2390 2391 2392 2393 2394 2395 2396 2397
/**
 * 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.
2398
 */
2399
static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2400 2401 2402 2403
{
	struct memcg_stock_pcp *stock;
	bool ret = true;

2404 2405 2406
	if (nr_pages > CHARGE_BATCH)
		return false;

2407
	stock = &get_cpu_var(memcg_stock);
2408 2409
	if (memcg == stock->cached && stock->nr_pages >= nr_pages)
		stock->nr_pages -= nr_pages;
2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422
	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;

2423 2424 2425 2426
	if (stock->nr_pages) {
		unsigned long bytes = stock->nr_pages * PAGE_SIZE;

		res_counter_uncharge(&old->res, bytes);
2427
		if (do_swap_account)
2428 2429
			res_counter_uncharge(&old->memsw, bytes);
		stock->nr_pages = 0;
2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441
	}
	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);
2442
	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
2443 2444
}

2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455
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);
	}
}

2456 2457
/*
 * Cache charges(val) which is from res_counter, to local per_cpu area.
2458
 * This will be consumed by consume_stock() function, later.
2459
 */
2460
static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2461 2462 2463
{
	struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);

2464
	if (stock->cached != memcg) { /* reset if necessary */
2465
		drain_stock(stock);
2466
		stock->cached = memcg;
2467
	}
2468
	stock->nr_pages += nr_pages;
2469 2470 2471 2472
	put_cpu_var(memcg_stock);
}

/*
2473
 * Drains all per-CPU charge caches for given root_memcg resp. subtree
2474 2475
 * of the hierarchy under it. sync flag says whether we should block
 * until the work is done.
2476
 */
2477
static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
2478
{
2479
	int cpu, curcpu;
2480

2481 2482
	/* Notify other cpus that system-wide "drain" is running */
	get_online_cpus();
2483
	curcpu = get_cpu();
2484 2485
	for_each_online_cpu(cpu) {
		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2486
		struct mem_cgroup *memcg;
2487

2488 2489
		memcg = stock->cached;
		if (!memcg || !stock->nr_pages)
2490
			continue;
2491
		if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
2492
			continue;
2493 2494 2495 2496 2497 2498
		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);
		}
2499
	}
2500
	put_cpu();
2501 2502 2503 2504 2505 2506

	if (!sync)
		goto out;

	for_each_online_cpu(cpu) {
		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2507
		if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
2508 2509 2510
			flush_work(&stock->work);
	}
out:
A
Andrew Morton 已提交
2511
	put_online_cpus();
2512 2513 2514 2515 2516 2517 2518 2519
}

/*
 * 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.
 */
2520
static void drain_all_stock_async(struct mem_cgroup *root_memcg)
2521
{
2522 2523 2524 2525 2526
	/*
	 * If someone calls draining, avoid adding more kworker runs.
	 */
	if (!mutex_trylock(&percpu_charge_mutex))
		return;
2527
	drain_all_stock(root_memcg, false);
2528
	mutex_unlock(&percpu_charge_mutex);
2529 2530 2531
}

/* This is a synchronous drain interface. */
2532
static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
2533 2534
{
	/* called when force_empty is called */
2535
	mutex_lock(&percpu_charge_mutex);
2536
	drain_all_stock(root_memcg, true);
2537
	mutex_unlock(&percpu_charge_mutex);
2538 2539
}

2540 2541 2542 2543
/*
 * This function drains percpu counter value from DEAD cpu and
 * move it to local cpu. Note that this function can be preempted.
 */
2544
static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
2545 2546 2547
{
	int i;

2548
	spin_lock(&memcg->pcp_counter_lock);
2549
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
2550
		long x = per_cpu(memcg->stat->count[i], cpu);
2551

2552 2553
		per_cpu(memcg->stat->count[i], cpu) = 0;
		memcg->nocpu_base.count[i] += x;
2554
	}
2555
	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
2556
		unsigned long x = per_cpu(memcg->stat->events[i], cpu);
2557

2558 2559
		per_cpu(memcg->stat->events[i], cpu) = 0;
		memcg->nocpu_base.events[i] += x;
2560
	}
2561
	spin_unlock(&memcg->pcp_counter_lock);
2562 2563
}

2564
static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
2565 2566 2567 2568 2569
					unsigned long action,
					void *hcpu)
{
	int cpu = (unsigned long)hcpu;
	struct memcg_stock_pcp *stock;
2570
	struct mem_cgroup *iter;
2571

2572
	if (action == CPU_ONLINE)
2573 2574
		return NOTIFY_OK;

2575
	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
2576
		return NOTIFY_OK;
2577

2578
	for_each_mem_cgroup(iter)
2579 2580
		mem_cgroup_drain_pcp_counter(iter, cpu);

2581 2582 2583 2584 2585
	stock = &per_cpu(memcg_stock, cpu);
	drain_stock(stock);
	return NOTIFY_OK;
}

2586

2587
/* See mem_cgroup_try_charge() for details */
2588 2589 2590 2591 2592 2593 2594
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. */
};

2595
static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
2596
				unsigned int nr_pages, unsigned int min_pages,
2597
				bool invoke_oom)
2598
{
2599
	unsigned long csize = nr_pages * PAGE_SIZE;
2600 2601 2602 2603 2604
	struct mem_cgroup *mem_over_limit;
	struct res_counter *fail_res;
	unsigned long flags = 0;
	int ret;

2605
	ret = res_counter_charge(&memcg->res, csize, &fail_res);
2606 2607 2608 2609

	if (likely(!ret)) {
		if (!do_swap_account)
			return CHARGE_OK;
2610
		ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
2611 2612 2613
		if (likely(!ret))
			return CHARGE_OK;

2614
		res_counter_uncharge(&memcg->res, csize);
2615 2616 2617 2618
		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);
2619 2620 2621 2622
	/*
	 * Never reclaim on behalf of optional batching, retry with a
	 * single page instead.
	 */
2623
	if (nr_pages > min_pages)
2624 2625 2626 2627 2628
		return CHARGE_RETRY;

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

2629 2630 2631
	if (gfp_mask & __GFP_NORETRY)
		return CHARGE_NOMEM;

2632
	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
2633
	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
2634
		return CHARGE_RETRY;
2635
	/*
2636 2637 2638 2639 2640 2641 2642
	 * 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.
2643
	 */
2644
	if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret)
2645 2646 2647 2648 2649 2650 2651 2652 2653
		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;

2654 2655
	if (invoke_oom)
		mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize));
2656

2657
	return CHARGE_NOMEM;
2658 2659
}

2660 2661 2662 2663 2664
/**
 * 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
2665
 *
2666 2667
 * Returns 0 if @memcg was charged successfully, -EINTR if the charge
 * was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed.
2668
 */
2669 2670 2671 2672
static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
				 gfp_t gfp_mask,
				 unsigned int nr_pages,
				 bool oom)
2673
{
2674
	unsigned int batch = max(CHARGE_BATCH, nr_pages);
2675 2676
	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
	int ret;
2677

2678 2679
	if (mem_cgroup_is_root(memcg))
		goto done;
K
KAMEZAWA Hiroyuki 已提交
2680
	/*
2681 2682 2683 2684
	 * 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
2685
	 */
2686 2687
	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
		     fatal_signal_pending(current)))
K
KAMEZAWA Hiroyuki 已提交
2688
		goto bypass;
2689

2690
	if (unlikely(task_in_memcg_oom(current)))
2691
		goto nomem;
2692

2693 2694
	if (gfp_mask & __GFP_NOFAIL)
		oom = false;
K
KAMEZAWA Hiroyuki 已提交
2695
again:
2696 2697
	if (consume_stock(memcg, nr_pages))
		goto done;
2698

2699
	do {
2700
		bool invoke_oom = oom && !nr_oom_retries;
2701

2702
		/* If killed, bypass charge */
2703
		if (fatal_signal_pending(current))
2704
			goto bypass;
2705

2706 2707
		ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
					   nr_pages, invoke_oom);
2708 2709 2710 2711
		switch (ret) {
		case CHARGE_OK:
			break;
		case CHARGE_RETRY: /* not in OOM situation but retry */
2712
			batch = nr_pages;
K
KAMEZAWA Hiroyuki 已提交
2713
			goto again;
2714 2715 2716
		case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
			goto nomem;
		case CHARGE_NOMEM: /* OOM routine works */
2717
			if (!oom || invoke_oom)
K
KAMEZAWA Hiroyuki 已提交
2718
				goto nomem;
2719 2720
			nr_oom_retries--;
			break;
2721
		}
2722 2723
	} while (ret != CHARGE_OK);

2724
	if (batch > nr_pages)
2725
		refill_stock(memcg, batch - nr_pages);
2726
done:
2727 2728
	return 0;
nomem:
2729
	if (!(gfp_mask & __GFP_NOFAIL))
2730
		return -ENOMEM;
K
KAMEZAWA Hiroyuki 已提交
2731
bypass:
2732
	return -EINTR;
2733
}
2734

2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763
/**
 * 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;
}

2764 2765 2766 2767 2768
/*
 * 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().
 */
2769
static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
2770
				       unsigned int nr_pages)
2771
{
2772
	if (!mem_cgroup_is_root(memcg)) {
2773 2774
		unsigned long bytes = nr_pages * PAGE_SIZE;

2775
		res_counter_uncharge(&memcg->res, bytes);
2776
		if (do_swap_account)
2777
			res_counter_uncharge(&memcg->memsw, bytes);
2778
	}
2779 2780
}

2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798
/*
 * 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);
}

2799 2800
/*
 * A helper function to get mem_cgroup from ID. must be called under
T
Tejun Heo 已提交
2801 2802 2803
 * 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.)
2804 2805 2806 2807 2808 2809
 */
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
2810
	return mem_cgroup_from_id(id);
2811 2812
}

2813
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2814
{
2815
	struct mem_cgroup *memcg = NULL;
2816
	struct page_cgroup *pc;
2817
	unsigned short id;
2818 2819
	swp_entry_t ent;

2820
	VM_BUG_ON_PAGE(!PageLocked(page), page);
2821 2822

	pc = lookup_page_cgroup(page);
2823
	lock_page_cgroup(pc);
2824
	if (PageCgroupUsed(pc)) {
2825 2826 2827
		memcg = pc->mem_cgroup;
		if (memcg && !css_tryget(&memcg->css))
			memcg = NULL;
2828
	} else if (PageSwapCache(page)) {
2829
		ent.val = page_private(page);
2830
		id = lookup_swap_cgroup_id(ent);
2831
		rcu_read_lock();
2832 2833 2834
		memcg = mem_cgroup_lookup(id);
		if (memcg && !css_tryget(&memcg->css))
			memcg = NULL;
2835
		rcu_read_unlock();
2836
	}
2837
	unlock_page_cgroup(pc);
2838
	return memcg;
2839 2840
}

2841
static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
2842
				       struct page *page,
2843
				       unsigned int nr_pages,
2844 2845
				       enum charge_type ctype,
				       bool lrucare)
2846
{
2847
	struct page_cgroup *pc = lookup_page_cgroup(page);
2848
	struct zone *uninitialized_var(zone);
2849
	struct lruvec *lruvec;
2850
	bool was_on_lru = false;
2851
	bool anon;
2852

2853
	lock_page_cgroup(pc);
2854
	VM_BUG_ON_PAGE(PageCgroupUsed(pc), page);
2855 2856 2857 2858
	/*
	 * we don't need page_cgroup_lock about tail pages, becase they are not
	 * accessed by any other context at this point.
	 */
2859 2860 2861 2862 2863 2864 2865 2866 2867

	/*
	 * 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)) {
2868
			lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2869
			ClearPageLRU(page);
2870
			del_page_from_lru_list(page, lruvec, page_lru(page));
2871 2872 2873 2874
			was_on_lru = true;
		}
	}

2875
	pc->mem_cgroup = memcg;
2876 2877 2878 2879 2880 2881
	/*
	 * 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
2882
	 */
K
KAMEZAWA Hiroyuki 已提交
2883
	smp_wmb();
2884
	SetPageCgroupUsed(pc);
2885

2886 2887
	if (lrucare) {
		if (was_on_lru) {
2888
			lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2889
			VM_BUG_ON_PAGE(PageLRU(page), page);
2890
			SetPageLRU(page);
2891
			add_page_to_lru_list(page, lruvec, page_lru(page));
2892 2893 2894 2895
		}
		spin_unlock_irq(&zone->lru_lock);
	}

2896
	if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON)
2897 2898 2899 2900
		anon = true;
	else
		anon = false;

2901
	mem_cgroup_charge_statistics(memcg, page, anon, nr_pages);
2902
	unlock_page_cgroup(pc);
2903

2904
	/*
2905 2906 2907
	 * "charge_statistics" updated event counter. Then, check it.
	 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
	 * if they exceeds softlimit.
2908
	 */
2909
	memcg_check_events(memcg, page);
2910
}
2911

2912 2913
static DEFINE_MUTEX(set_limit_mutex);

2914
#ifdef CONFIG_MEMCG_KMEM
2915 2916
static DEFINE_MUTEX(activate_kmem_mutex);

2917 2918 2919
static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
{
	return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
2920
		memcg_kmem_is_active(memcg);
2921 2922
}

G
Glauber Costa 已提交
2923 2924 2925 2926 2927 2928 2929 2930 2931 2932
/*
 * 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;
2933
	return cache_from_memcg_idx(cachep, memcg_cache_id(p->memcg));
G
Glauber Costa 已提交
2934 2935
}

2936
#ifdef CONFIG_SLABINFO
2937
static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v)
2938
{
2939
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955
	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

2956
int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
2957 2958 2959 2960 2961 2962 2963 2964
{
	struct res_counter *fail_res;
	int ret = 0;

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

2965 2966
	ret = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT,
				    oom_gfp_allowed(gfp));
2967 2968
	if (ret == -EINTR)  {
		/*
2969
		 * mem_cgroup_try_charge() chosed to bypass to root due to
2970 2971 2972 2973 2974 2975 2976 2977 2978
		 * 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
2979
		 * mem_cgroup_try_charge() above. Tasks that were already
2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993
		 * 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;
}

2994
void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
2995 2996 2997 2998
{
	res_counter_uncharge(&memcg->res, size);
	if (do_swap_account)
		res_counter_uncharge(&memcg->memsw, size);
2999 3000 3001 3002 3003

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

3004 3005 3006 3007 3008 3009 3010 3011
	/*
	 * 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().
	 */
3012
	if (memcg_kmem_test_and_clear_dead(memcg))
3013
		css_put(&memcg->css);
3014 3015
}

3016 3017 3018 3019 3020 3021 3022 3023 3024 3025
/*
 * 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;
}

3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051
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);
}

3052 3053
static void kmem_cache_destroy_work_func(struct work_struct *w);

3054 3055 3056 3057
int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
{
	struct memcg_cache_params *cur_params = s->memcg_params;

3058
	VM_BUG_ON(!is_root_cache(s));
3059 3060 3061

	if (num_groups > memcg_limited_groups_array_size) {
		int i;
3062
		struct memcg_cache_params *new_params;
3063 3064 3065
		ssize_t size = memcg_caches_array_size(num_groups);

		size *= sizeof(void *);
3066
		size += offsetof(struct memcg_cache_params, memcg_caches);
3067

3068 3069
		new_params = kzalloc(size, GFP_KERNEL);
		if (!new_params)
3070 3071
			return -ENOMEM;

3072
		new_params->is_root_cache = true;
3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085

		/*
		 * 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;
3086
			new_params->memcg_caches[i] =
3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098
						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.
		 */
3099 3100 3101
		rcu_assign_pointer(s->memcg_params, new_params);
		if (cur_params)
			kfree_rcu(cur_params, rcu_head);
3102 3103 3104 3105
	}
	return 0;
}

3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128
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);
}

3129 3130
int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
			     struct kmem_cache *root_cache)
3131
{
3132
	size_t size;
3133 3134 3135 3136

	if (!memcg_kmem_enabled())
		return 0;

3137 3138
	if (!memcg) {
		size = offsetof(struct memcg_cache_params, memcg_caches);
3139
		size += memcg_limited_groups_array_size * sizeof(void *);
3140 3141
	} else
		size = sizeof(struct memcg_cache_params);
3142

3143 3144 3145 3146
	s->memcg_params = kzalloc(size, GFP_KERNEL);
	if (!s->memcg_params)
		return -ENOMEM;

G
Glauber Costa 已提交
3147
	if (memcg) {
3148
		s->memcg_params->memcg = memcg;
G
Glauber Costa 已提交
3149
		s->memcg_params->root_cache = root_cache;
3150 3151
		INIT_WORK(&s->memcg_params->destroy,
				kmem_cache_destroy_work_func);
3152
		css_get(&memcg->css);
3153 3154 3155
	} else
		s->memcg_params->is_root_cache = true;

3156 3157 3158
	return 0;
}

3159 3160
void memcg_free_cache_params(struct kmem_cache *s)
{
3161 3162 3163 3164
	if (!s->memcg_params)
		return;
	if (!s->memcg_params->is_root_cache)
		css_put(&s->memcg_params->memcg->css);
3165 3166 3167
	kfree(s->memcg_params);
}

3168
void memcg_register_cache(struct kmem_cache *s)
3169
{
3170 3171 3172 3173
	struct kmem_cache *root;
	struct mem_cgroup *memcg;
	int id;

3174 3175 3176
	if (is_root_cache(s))
		return;

3177 3178 3179 3180 3181 3182
	/*
	 * Holding the slab_mutex assures nobody will touch the memcg_caches
	 * array while we are modifying it.
	 */
	lockdep_assert_held(&slab_mutex);

3183 3184 3185 3186
	root = s->memcg_params->root_cache;
	memcg = s->memcg_params->memcg;
	id = memcg_cache_id(memcg);

3187
	/*
3188 3189 3190
	 * 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.
3191
	 */
3192 3193
	smp_wmb();

3194 3195 3196 3197 3198
	/*
	 * 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.
	 */
3199
	VM_BUG_ON(root->memcg_params->memcg_caches[id]);
3200
	root->memcg_params->memcg_caches[id] = s;
3201 3202 3203 3204

	mutex_lock(&memcg->slab_caches_mutex);
	list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
	mutex_unlock(&memcg->slab_caches_mutex);
3205
}
3206

3207 3208 3209 3210 3211 3212 3213 3214
void memcg_unregister_cache(struct kmem_cache *s)
{
	struct kmem_cache *root;
	struct mem_cgroup *memcg;
	int id;

	if (is_root_cache(s))
		return;
3215

3216 3217 3218 3219 3220 3221
	/*
	 * Holding the slab_mutex assures nobody will touch the memcg_caches
	 * array while we are modifying it.
	 */
	lockdep_assert_held(&slab_mutex);

3222
	root = s->memcg_params->root_cache;
3223 3224
	memcg = s->memcg_params->memcg;
	id = memcg_cache_id(memcg);
3225 3226 3227 3228 3229

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

3230 3231 3232 3233 3234
	/*
	 * 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.
	 */
3235
	VM_BUG_ON(root->memcg_params->memcg_caches[id] != s);
3236
	root->memcg_params->memcg_caches[id] = NULL;
3237 3238
}

3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269
/*
 * 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
3270 3271 3272 3273 3274 3275 3276 3277 3278
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
3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294
	/*
	 * 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
	 */
3295
	if (atomic_read(&cachep->memcg_params->nr_pages) != 0)
G
Glauber Costa 已提交
3296
		kmem_cache_shrink(cachep);
3297
	else
G
Glauber Costa 已提交
3298 3299 3300 3301 3302 3303 3304 3305
		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
3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325
	/*
	 * 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
3326 3327 3328 3329 3330 3331 3332
	/*
	 * 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);
}

3333
int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
3334 3335
{
	struct kmem_cache *c;
3336
	int i, failed = 0;
3337 3338 3339 3340 3341 3342 3343 3344

	/*
	 * 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,
3345 3346
	 * we'll take the activate_kmem_mutex to protect ourselves against
	 * this.
3347
	 */
3348
	mutex_lock(&activate_kmem_mutex);
3349 3350
	for_each_memcg_cache_index(i) {
		c = cache_from_memcg_idx(s, i);
3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367
		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
3368
		cancel_work_sync(&c->memcg_params->destroy);
3369
		kmem_cache_destroy(c);
3370 3371 3372

		if (cache_from_memcg_idx(s, i))
			failed++;
3373
	}
3374
	mutex_unlock(&activate_kmem_mutex);
3375
	return failed;
3376 3377
}

G
Glauber Costa 已提交
3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394
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);
}

3395 3396 3397 3398 3399 3400
struct create_work {
	struct mem_cgroup *memcg;
	struct kmem_cache *cachep;
	struct work_struct work;
};

3401 3402
static void memcg_create_cache_work_func(struct work_struct *w)
{
3403 3404 3405
	struct create_work *cw = container_of(w, struct create_work, work);
	struct mem_cgroup *memcg = cw->memcg;
	struct kmem_cache *cachep = cw->cachep;
3406

3407
	kmem_cache_create_memcg(memcg, cachep);
3408
	css_put(&memcg->css);
3409 3410 3411 3412 3413 3414
	kfree(cw);
}

/*
 * Enqueue the creation of a per-memcg kmem_cache.
 */
3415 3416
static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
					 struct kmem_cache *cachep)
3417 3418 3419 3420
{
	struct create_work *cw;

	cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
3421 3422
	if (cw == NULL) {
		css_put(&memcg->css);
3423 3424 3425 3426 3427 3428 3429 3430 3431 3432
		return;
	}

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

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

3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450
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();
}
3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467
/*
 * 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;
3468
	struct kmem_cache *memcg_cachep;
3469 3470 3471 3472

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

3473 3474 3475
	if (!current->mm || current->memcg_kmem_skip_account)
		return cachep;

3476 3477 3478 3479
	rcu_read_lock();
	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));

	if (!memcg_can_account_kmem(memcg))
3480
		goto out;
3481

3482 3483 3484
	memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));
	if (likely(memcg_cachep)) {
		cachep = memcg_cachep;
3485
		goto out;
3486 3487
	}

3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514
	/* 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;
3515 3516 3517
}
EXPORT_SYMBOL(__memcg_kmem_get_cache);

3518 3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532 3533 3534 3535 3536 3537 3538
/*
 * 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;
3539 3540 3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552 3553

	/*
	 * 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
3554 3555 3556
	 *	memcg_stop_kmem_account();
	 *	kmalloc(<large_number>)
	 *	memcg_resume_kmem_account();
3557 3558 3559 3560 3561 3562 3563 3564 3565 3566
	 *
	 * 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;

3567
	memcg = get_mem_cgroup_from_mm(current->mm);
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 3621 3622 3623 3624 3625 3626 3627 3628 3629

	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;

3630
	VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
3631 3632
	memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
}
G
Glauber Costa 已提交
3633 3634 3635 3636
#else
static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
}
3637 3638
#endif /* CONFIG_MEMCG_KMEM */

3639 3640
#ifdef CONFIG_TRANSPARENT_HUGEPAGE

3641
#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
3642 3643
/*
 * Because tail pages are not marked as "used", set it. We're under
3644 3645 3646
 * 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.
3647
 */
3648
void mem_cgroup_split_huge_fixup(struct page *head)
3649 3650
{
	struct page_cgroup *head_pc = lookup_page_cgroup(head);
3651
	struct page_cgroup *pc;
3652
	struct mem_cgroup *memcg;
3653
	int i;
3654

3655 3656
	if (mem_cgroup_disabled())
		return;
3657 3658

	memcg = head_pc->mem_cgroup;
3659 3660
	for (i = 1; i < HPAGE_PMD_NR; i++) {
		pc = head_pc + i;
3661
		pc->mem_cgroup = memcg;
3662 3663 3664
		smp_wmb();/* see __commit_charge() */
		pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
	}
3665 3666
	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
		       HPAGE_PMD_NR);
3667
}
3668
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3669

3670
/**
3671
 * mem_cgroup_move_account - move account of the page
3672
 * @page: the page
3673
 * @nr_pages: number of regular pages (>1 for huge pages)
3674 3675 3676 3677 3678
 * @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
3679
 * - page is not on LRU (isolate_page() is useful.)
3680
 * - compound_lock is held when nr_pages > 1
3681
 *
3682 3683
 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
 * from old cgroup.
3684
 */
3685 3686 3687 3688
static int mem_cgroup_move_account(struct page *page,
				   unsigned int nr_pages,
				   struct page_cgroup *pc,
				   struct mem_cgroup *from,
3689
				   struct mem_cgroup *to)
3690
{
3691 3692
	unsigned long flags;
	int ret;
3693
	bool anon = PageAnon(page);
3694

3695
	VM_BUG_ON(from == to);
3696
	VM_BUG_ON_PAGE(PageLRU(page), page);
3697 3698 3699 3700 3701 3702 3703
	/*
	 * 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;
3704
	if (nr_pages > 1 && !PageTransHuge(page))
3705 3706 3707 3708 3709 3710 3711 3712
		goto out;

	lock_page_cgroup(pc);

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

3713
	move_lock_mem_cgroup(from, &flags);
3714

3715 3716 3717 3718 3719 3720
	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);
	}
3721

3722 3723 3724 3725 3726 3727
	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);
	}
3728

3729
	mem_cgroup_charge_statistics(from, page, anon, -nr_pages);
3730

3731
	/* caller should have done css_get */
K
KAMEZAWA Hiroyuki 已提交
3732
	pc->mem_cgroup = to;
3733
	mem_cgroup_charge_statistics(to, page, anon, nr_pages);
3734
	move_unlock_mem_cgroup(from, &flags);
3735 3736
	ret = 0;
unlock:
3737
	unlock_page_cgroup(pc);
3738 3739 3740
	/*
	 * check events
	 */
3741 3742
	memcg_check_events(to, page);
	memcg_check_events(from, page);
3743
out:
3744 3745 3746
	return ret;
}

3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766
/**
 * 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.
3767
 */
3768 3769
static int mem_cgroup_move_parent(struct page *page,
				  struct page_cgroup *pc,
3770
				  struct mem_cgroup *child)
3771 3772
{
	struct mem_cgroup *parent;
3773
	unsigned int nr_pages;
3774
	unsigned long uninitialized_var(flags);
3775 3776
	int ret;

3777
	VM_BUG_ON(mem_cgroup_is_root(child));
3778

3779 3780 3781 3782 3783
	ret = -EBUSY;
	if (!get_page_unless_zero(page))
		goto out;
	if (isolate_lru_page(page))
		goto put;
3784

3785
	nr_pages = hpage_nr_pages(page);
K
KAMEZAWA Hiroyuki 已提交
3786

3787 3788 3789 3790 3791 3792
	parent = parent_mem_cgroup(child);
	/*
	 * If no parent, move charges to root cgroup.
	 */
	if (!parent)
		parent = root_mem_cgroup;
3793

3794
	if (nr_pages > 1) {
3795
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3796
		flags = compound_lock_irqsave(page);
3797
	}
3798

3799
	ret = mem_cgroup_move_account(page, nr_pages,
3800
				pc, child, parent);
3801 3802
	if (!ret)
		__mem_cgroup_cancel_local_charge(child, nr_pages);
3803

3804
	if (nr_pages > 1)
3805
		compound_unlock_irqrestore(page, flags);
K
KAMEZAWA Hiroyuki 已提交
3806
	putback_lru_page(page);
3807
put:
3808
	put_page(page);
3809
out:
3810 3811 3812
	return ret;
}

3813
int mem_cgroup_charge_anon(struct page *page,
3814
			      struct mm_struct *mm, gfp_t gfp_mask)
3815
{
3816
	unsigned int nr_pages = 1;
3817
	struct mem_cgroup *memcg;
3818
	bool oom = true;
A
Andrea Arcangeli 已提交
3819

3820 3821 3822 3823 3824 3825 3826
	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
3827
	if (PageTransHuge(page)) {
3828
		nr_pages <<= compound_order(page);
3829
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3830 3831 3832 3833 3834
		/*
		 * 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
3835
	}
3836

3837 3838 3839
	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);
	if (!memcg)
		return -ENOMEM;
3840 3841
	__mem_cgroup_commit_charge(memcg, page, nr_pages,
				   MEM_CGROUP_CHARGE_TYPE_ANON, false);
3842 3843 3844
	return 0;
}

3845 3846 3847
/*
 * While swap-in, try_charge -> commit or cancel, the page is locked.
 * And when try_charge() successfully returns, one refcnt to memcg without
3848
 * struct page_cgroup is acquired. This refcnt will be consumed by
3849 3850
 * "commit()" or removed by "cancel()"
 */
3851 3852 3853 3854
static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
					  struct page *page,
					  gfp_t mask,
					  struct mem_cgroup **memcgp)
3855
{
3856
	struct mem_cgroup *memcg = NULL;
3857
	struct page_cgroup *pc;
3858
	int ret;
3859

3860 3861 3862 3863 3864 3865 3866 3867 3868
	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))
3869 3870 3871
		goto out;
	if (do_swap_account)
		memcg = try_get_mem_cgroup_from_page(page);
3872
	if (!memcg)
3873 3874
		memcg = get_mem_cgroup_from_mm(mm);
	ret = mem_cgroup_try_charge(memcg, mask, 1, true);
3875
	css_put(&memcg->css);
3876
	if (ret == -EINTR)
3877 3878 3879 3880 3881 3882
		memcg = root_mem_cgroup;
	else if (ret)
		return ret;
out:
	*memcgp = memcg;
	return 0;
3883 3884
}

3885 3886 3887
int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
				 gfp_t gfp_mask, struct mem_cgroup **memcgp)
{
3888 3889
	if (mem_cgroup_disabled()) {
		*memcgp = NULL;
3890
		return 0;
3891
	}
3892 3893 3894 3895 3896 3897 3898
	/*
	 * 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)) {
3899
		struct mem_cgroup *memcg;
3900

3901 3902 3903 3904 3905
		memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
		if (!memcg)
			return -ENOMEM;
		*memcgp = memcg;
		return 0;
3906
	}
3907 3908 3909
	return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
}

3910 3911 3912 3913 3914 3915 3916 3917 3918
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
3919
static void
3920
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
D
Daisuke Nishimura 已提交
3921
					enum charge_type ctype)
3922
{
3923
	if (mem_cgroup_disabled())
3924
		return;
3925
	if (!memcg)
3926
		return;
3927

3928
	__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
3929 3930 3931
	/*
	 * Now swap is on-memory. This means this page may be
	 * counted both as mem and swap....double count.
3932 3933 3934
	 * 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.
3935
	 */
3936
	if (do_swap_account && PageSwapCache(page)) {
3937
		swp_entry_t ent = {.val = page_private(page)};
3938
		mem_cgroup_uncharge_swap(ent);
3939
	}
3940 3941
}

3942 3943
void mem_cgroup_commit_charge_swapin(struct page *page,
				     struct mem_cgroup *memcg)
D
Daisuke Nishimura 已提交
3944
{
3945
	__mem_cgroup_commit_charge_swapin(page, memcg,
3946
					  MEM_CGROUP_CHARGE_TYPE_ANON);
D
Daisuke Nishimura 已提交
3947 3948
}

3949
int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
3950
				gfp_t gfp_mask)
3951
{
3952
	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
3953
	struct mem_cgroup *memcg;
3954 3955
	int ret;

3956
	if (mem_cgroup_disabled())
3957 3958 3959 3960
		return 0;
	if (PageCompound(page))
		return 0;

3961
	if (PageSwapCache(page)) { /* shmem */
3962 3963
		ret = __mem_cgroup_try_charge_swapin(mm, page,
						     gfp_mask, &memcg);
3964 3965 3966 3967
		if (ret)
			return ret;
		__mem_cgroup_commit_charge_swapin(page, memcg, type);
		return 0;
3968
	}
3969

3970 3971 3972
	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
	if (!memcg)
		return -ENOMEM;
3973 3974
	__mem_cgroup_commit_charge(memcg, page, 1, type, false);
	return 0;
3975 3976
}

3977
static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
3978 3979
				   unsigned int nr_pages,
				   const enum charge_type ctype)
3980 3981 3982
{
	struct memcg_batch_info *batch = NULL;
	bool uncharge_memsw = true;
3983

3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994
	/* 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)
3995
		batch->memcg = memcg;
3996 3997
	/*
	 * do_batch > 0 when unmapping pages or inode invalidate/truncate.
L
Lucas De Marchi 已提交
3998
	 * In those cases, all pages freed continuously can be expected to be in
3999 4000 4001 4002 4003 4004 4005 4006
	 * 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;

4007
	if (nr_pages > 1)
A
Andrea Arcangeli 已提交
4008 4009
		goto direct_uncharge;

4010 4011 4012 4013 4014
	/*
	 * 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.
	 */
4015
	if (batch->memcg != memcg)
4016 4017
		goto direct_uncharge;
	/* remember freed charge and uncharge it later */
4018
	batch->nr_pages++;
4019
	if (uncharge_memsw)
4020
		batch->memsw_nr_pages++;
4021 4022
	return;
direct_uncharge:
4023
	res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
4024
	if (uncharge_memsw)
4025 4026 4027
		res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
	if (unlikely(batch->memcg != memcg))
		memcg_oom_recover(memcg);
4028
}
4029

4030
/*
4031
 * uncharge if !page_mapped(page)
4032
 */
4033
static struct mem_cgroup *
4034 4035
__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
			     bool end_migration)
4036
{
4037
	struct mem_cgroup *memcg = NULL;
4038 4039
	unsigned int nr_pages = 1;
	struct page_cgroup *pc;
4040
	bool anon;
4041

4042
	if (mem_cgroup_disabled())
4043
		return NULL;
4044

A
Andrea Arcangeli 已提交
4045
	if (PageTransHuge(page)) {
4046
		nr_pages <<= compound_order(page);
4047
		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
A
Andrea Arcangeli 已提交
4048
	}
4049
	/*
4050
	 * Check if our page_cgroup is valid
4051
	 */
4052
	pc = lookup_page_cgroup(page);
4053
	if (unlikely(!PageCgroupUsed(pc)))
4054
		return NULL;
4055

4056
	lock_page_cgroup(pc);
K
KAMEZAWA Hiroyuki 已提交
4057

4058
	memcg = pc->mem_cgroup;
4059

K
KAMEZAWA Hiroyuki 已提交
4060 4061 4062
	if (!PageCgroupUsed(pc))
		goto unlock_out;

4063 4064
	anon = PageAnon(page);

K
KAMEZAWA Hiroyuki 已提交
4065
	switch (ctype) {
4066
	case MEM_CGROUP_CHARGE_TYPE_ANON:
4067 4068 4069 4070 4071
		/*
		 * 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.
		 */
4072 4073
		anon = true;
		/* fallthrough */
K
KAMEZAWA Hiroyuki 已提交
4074
	case MEM_CGROUP_CHARGE_TYPE_DROP:
4075
		/* See mem_cgroup_prepare_migration() */
4076 4077 4078 4079 4080 4081 4082 4083 4084 4085
		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
4086 4087 4088 4089 4090 4091 4092 4093 4094 4095 4096
			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;
4097
	}
K
KAMEZAWA Hiroyuki 已提交
4098

4099
	mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages);
K
KAMEZAWA Hiroyuki 已提交
4100

4101
	ClearPageCgroupUsed(pc);
4102 4103 4104 4105 4106 4107
	/*
	 * 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.
	 */
4108

4109
	unlock_page_cgroup(pc);
K
KAMEZAWA Hiroyuki 已提交
4110
	/*
4111
	 * even after unlock, we have memcg->res.usage here and this memcg
L
Li Zefan 已提交
4112
	 * will never be freed, so it's safe to call css_get().
K
KAMEZAWA Hiroyuki 已提交
4113
	 */
4114
	memcg_check_events(memcg, page);
K
KAMEZAWA Hiroyuki 已提交
4115
	if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
4116
		mem_cgroup_swap_statistics(memcg, true);
L
Li Zefan 已提交
4117
		css_get(&memcg->css);
K
KAMEZAWA Hiroyuki 已提交
4118
	}
4119 4120 4121 4122 4123 4124
	/*
	 * 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))
4125
		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
4126

4127
	return memcg;
K
KAMEZAWA Hiroyuki 已提交
4128 4129 4130

unlock_out:
	unlock_page_cgroup(pc);
4131
	return NULL;
4132 4133
}

4134 4135
void mem_cgroup_uncharge_page(struct page *page)
{
4136 4137 4138
	/* early check. */
	if (page_mapped(page))
		return;
4139
	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150 4151
	/*
	 * 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.
	 */
4152 4153
	if (PageSwapCache(page))
		return;
4154
	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
4155 4156 4157 4158
}

void mem_cgroup_uncharge_cache_page(struct page *page)
{
4159 4160
	VM_BUG_ON_PAGE(page_mapped(page), page);
	VM_BUG_ON_PAGE(page->mapping, page);
4161
	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
4162 4163
}

4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176 4177
/*
 * 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;
4178 4179
		current->memcg_batch.nr_pages = 0;
		current->memcg_batch.memsw_nr_pages = 0;
4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199
	}
}

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.
	 */
4200 4201 4202 4203 4204 4205
	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);
4206
	memcg_oom_recover(batch->memcg);
4207 4208 4209 4210
	/* forget this pointer (for sanity check) */
	batch->memcg = NULL;
}

4211
#ifdef CONFIG_SWAP
4212
/*
4213
 * called after __delete_from_swap_cache() and drop "page" account.
4214 4215
 * memcg information is recorded to swap_cgroup of "ent"
 */
K
KAMEZAWA Hiroyuki 已提交
4216 4217
void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
4218 4219
{
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
4220 4221 4222 4223 4224
	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;

4225
	memcg = __mem_cgroup_uncharge_common(page, ctype, false);
4226

K
KAMEZAWA Hiroyuki 已提交
4227 4228
	/*
	 * record memcg information,  if swapout && memcg != NULL,
L
Li Zefan 已提交
4229
	 * css_get() was called in uncharge().
K
KAMEZAWA Hiroyuki 已提交
4230 4231
	 */
	if (do_swap_account && swapout && memcg)
L
Li Zefan 已提交
4232
		swap_cgroup_record(ent, mem_cgroup_id(memcg));
4233
}
4234
#endif
4235

A
Andrew Morton 已提交
4236
#ifdef CONFIG_MEMCG_SWAP
4237 4238 4239 4240 4241
/*
 * 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
4242
{
4243
	struct mem_cgroup *memcg;
4244
	unsigned short id;
4245 4246 4247 4248

	if (!do_swap_account)
		return;

4249 4250 4251
	id = swap_cgroup_record(ent, 0);
	rcu_read_lock();
	memcg = mem_cgroup_lookup(id);
4252
	if (memcg) {
4253 4254 4255 4256
		/*
		 * We uncharge this because swap is freed.
		 * This memcg can be obsolete one. We avoid calling css_tryget
		 */
4257
		if (!mem_cgroup_is_root(memcg))
4258
			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
4259
		mem_cgroup_swap_statistics(memcg, false);
L
Li Zefan 已提交
4260
		css_put(&memcg->css);
4261
	}
4262
	rcu_read_unlock();
K
KAMEZAWA Hiroyuki 已提交
4263
}
4264 4265 4266 4267 4268 4269 4270 4271 4272 4273 4274 4275 4276 4277 4278 4279

/**
 * 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,
4280
				struct mem_cgroup *from, struct mem_cgroup *to)
4281 4282 4283
{
	unsigned short old_id, new_id;

L
Li Zefan 已提交
4284 4285
	old_id = mem_cgroup_id(from);
	new_id = mem_cgroup_id(to);
4286 4287 4288

	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
		mem_cgroup_swap_statistics(from, false);
4289
		mem_cgroup_swap_statistics(to, true);
4290
		/*
4291 4292 4293
		 * 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
4294 4295 4296 4297 4298 4299
		 * 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().
4300
		 */
L
Li Zefan 已提交
4301
		css_get(&to->css);
4302 4303 4304 4305 4306 4307
		return 0;
	}
	return -EINVAL;
}
#else
static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
4308
				struct mem_cgroup *from, struct mem_cgroup *to)
4309 4310 4311
{
	return -EINVAL;
}
4312
#endif
K
KAMEZAWA Hiroyuki 已提交
4313

4314
/*
4315 4316
 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
 * page belongs to.
4317
 */
4318 4319
void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
				  struct mem_cgroup **memcgp)
4320
{
4321
	struct mem_cgroup *memcg = NULL;
4322
	unsigned int nr_pages = 1;
4323
	struct page_cgroup *pc;
4324
	enum charge_type ctype;
4325

4326
	*memcgp = NULL;
4327

4328
	if (mem_cgroup_disabled())
4329
		return;
4330

4331 4332 4333
	if (PageTransHuge(page))
		nr_pages <<= compound_order(page);

4334 4335 4336
	pc = lookup_page_cgroup(page);
	lock_page_cgroup(pc);
	if (PageCgroupUsed(pc)) {
4337 4338
		memcg = pc->mem_cgroup;
		css_get(&memcg->css);
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 4369
		/*
		 * 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);
4370
	}
4371
	unlock_page_cgroup(pc);
4372 4373 4374 4375
	/*
	 * If the page is not charged at this point,
	 * we return here.
	 */
4376
	if (!memcg)
4377
		return;
4378

4379
	*memcgp = memcg;
4380 4381 4382 4383 4384 4385 4386
	/*
	 * 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))
4387
		ctype = MEM_CGROUP_CHARGE_TYPE_ANON;
4388
	else
4389
		ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
4390 4391 4392 4393 4394
	/*
	 * 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.
	 */
4395
	__mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false);
4396
}
4397

4398
/* remove redundant charge if migration failed*/
4399
void mem_cgroup_end_migration(struct mem_cgroup *memcg,
4400
	struct page *oldpage, struct page *newpage, bool migration_ok)
4401
{
4402
	struct page *used, *unused;
4403
	struct page_cgroup *pc;
4404
	bool anon;
4405

4406
	if (!memcg)
4407
		return;
4408

4409
	if (!migration_ok) {
4410 4411
		used = oldpage;
		unused = newpage;
4412
	} else {
4413
		used = newpage;
4414 4415
		unused = oldpage;
	}
4416
	anon = PageAnon(used);
4417 4418 4419 4420
	__mem_cgroup_uncharge_common(unused,
				     anon ? MEM_CGROUP_CHARGE_TYPE_ANON
				     : MEM_CGROUP_CHARGE_TYPE_CACHE,
				     true);
4421
	css_put(&memcg->css);
4422
	/*
4423 4424 4425
	 * 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.
4426
	 */
4427 4428 4429 4430 4431
	pc = lookup_page_cgroup(oldpage);
	lock_page_cgroup(pc);
	ClearPageCgroupMigration(pc);
	unlock_page_cgroup(pc);

4432
	/*
4433 4434 4435 4436 4437 4438
	 * 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)
4439
	 */
4440
	if (anon)
4441
		mem_cgroup_uncharge_page(used);
4442
}
4443

4444 4445 4446 4447 4448 4449 4450 4451
/*
 * 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)
{
4452
	struct mem_cgroup *memcg = NULL;
4453 4454 4455 4456 4457 4458 4459 4460 4461
	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);
4462 4463
	if (PageCgroupUsed(pc)) {
		memcg = pc->mem_cgroup;
4464
		mem_cgroup_charge_statistics(memcg, oldpage, false, -1);
4465 4466
		ClearPageCgroupUsed(pc);
	}
4467 4468
	unlock_page_cgroup(pc);

4469 4470 4471 4472 4473 4474
	/*
	 * When called from shmem_replace_page(), in some cases the
	 * oldpage has already been charged, and in some cases not.
	 */
	if (!memcg)
		return;
4475 4476 4477 4478 4479
	/*
	 * 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.
	 */
4480
	__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
4481 4482
}

4483 4484 4485 4486 4487 4488
#ifdef CONFIG_DEBUG_VM
static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
{
	struct page_cgroup *pc;

	pc = lookup_page_cgroup(page);
4489 4490 4491 4492 4493
	/*
	 * 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().
	 */
4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512
	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) {
4513 4514
		pr_alert("pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
			 pc, pc->flags, pc->mem_cgroup);
4515 4516 4517 4518
	}
}
#endif

4519
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
4520
				unsigned long long val)
4521
{
4522
	int retry_count;
4523
	u64 memswlimit, memlimit;
4524
	int ret = 0;
4525 4526
	int children = mem_cgroup_count_children(memcg);
	u64 curusage, oldusage;
4527
	int enlarge;
4528 4529 4530 4531 4532 4533 4534 4535 4536

	/*
	 * 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);
4537

4538
	enlarge = 0;
4539
	while (retry_count) {
4540 4541 4542 4543
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
4544 4545 4546
		/*
		 * Rather than hide all in some function, I do this in
		 * open coded manner. You see what this really does.
4547
		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
4548 4549 4550 4551 4552 4553
		 */
		mutex_lock(&set_limit_mutex);
		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
		if (memswlimit < val) {
			ret = -EINVAL;
			mutex_unlock(&set_limit_mutex);
4554 4555
			break;
		}
4556 4557 4558 4559 4560

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

4561
		ret = res_counter_set_limit(&memcg->res, val);
4562 4563 4564 4565 4566 4567
		if (!ret) {
			if (memswlimit == val)
				memcg->memsw_is_minimum = true;
			else
				memcg->memsw_is_minimum = false;
		}
4568 4569 4570 4571 4572
		mutex_unlock(&set_limit_mutex);

		if (!ret)
			break;

4573 4574
		mem_cgroup_reclaim(memcg, GFP_KERNEL,
				   MEM_CGROUP_RECLAIM_SHRINK);
4575 4576
		curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
		/* Usage is reduced ? */
A
Andrew Morton 已提交
4577
		if (curusage >= oldusage)
4578 4579 4580
			retry_count--;
		else
			oldusage = curusage;
4581
	}
4582 4583
	if (!ret && enlarge)
		memcg_oom_recover(memcg);
4584

4585 4586 4587
	return ret;
}

L
Li Zefan 已提交
4588 4589
static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
					unsigned long long val)
4590
{
4591
	int retry_count;
4592
	u64 memlimit, memswlimit, oldusage, curusage;
4593 4594
	int children = mem_cgroup_count_children(memcg);
	int ret = -EBUSY;
4595
	int enlarge = 0;
4596

4597
	/* see mem_cgroup_resize_res_limit */
A
Andrew Morton 已提交
4598
	retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
4599
	oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
4600 4601 4602 4603 4604 4605 4606 4607
	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.
4608
		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
4609 4610 4611 4612 4613 4614 4615 4616
		 */
		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;
		}
4617 4618 4619
		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
		if (memswlimit < val)
			enlarge = 1;
4620
		ret = res_counter_set_limit(&memcg->memsw, val);
4621 4622 4623 4624 4625 4626
		if (!ret) {
			if (memlimit == val)
				memcg->memsw_is_minimum = true;
			else
				memcg->memsw_is_minimum = false;
		}
4627 4628 4629 4630 4631
		mutex_unlock(&set_limit_mutex);

		if (!ret)
			break;

4632 4633 4634
		mem_cgroup_reclaim(memcg, GFP_KERNEL,
				   MEM_CGROUP_RECLAIM_NOSWAP |
				   MEM_CGROUP_RECLAIM_SHRINK);
4635
		curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
4636
		/* Usage is reduced ? */
4637
		if (curusage >= oldusage)
4638
			retry_count--;
4639 4640
		else
			oldusage = curusage;
4641
	}
4642 4643
	if (!ret && enlarge)
		memcg_oom_recover(memcg);
4644 4645 4646
	return ret;
}

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 4738
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;
}

4739 4740 4741 4742 4743 4744 4745
/**
 * 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
 *
4746
 * Traverse a specified page_cgroup list and try to drop them all.  This doesn't
4747 4748
 * reclaim the pages page themselves - pages are moved to the parent (or root)
 * group.
4749
 */
4750
static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
K
KAMEZAWA Hiroyuki 已提交
4751
				int node, int zid, enum lru_list lru)
4752
{
4753
	struct lruvec *lruvec;
4754
	unsigned long flags;
4755
	struct list_head *list;
4756 4757
	struct page *busy;
	struct zone *zone;
4758

K
KAMEZAWA Hiroyuki 已提交
4759
	zone = &NODE_DATA(node)->node_zones[zid];
4760 4761
	lruvec = mem_cgroup_zone_lruvec(zone, memcg);
	list = &lruvec->lists[lru];
4762

4763
	busy = NULL;
4764
	do {
4765
		struct page_cgroup *pc;
4766 4767
		struct page *page;

K
KAMEZAWA Hiroyuki 已提交
4768
		spin_lock_irqsave(&zone->lru_lock, flags);
4769
		if (list_empty(list)) {
K
KAMEZAWA Hiroyuki 已提交
4770
			spin_unlock_irqrestore(&zone->lru_lock, flags);
4771
			break;
4772
		}
4773 4774 4775
		page = list_entry(list->prev, struct page, lru);
		if (busy == page) {
			list_move(&page->lru, list);
4776
			busy = NULL;
K
KAMEZAWA Hiroyuki 已提交
4777
			spin_unlock_irqrestore(&zone->lru_lock, flags);
4778 4779
			continue;
		}
K
KAMEZAWA Hiroyuki 已提交
4780
		spin_unlock_irqrestore(&zone->lru_lock, flags);
4781

4782
		pc = lookup_page_cgroup(page);
4783

4784
		if (mem_cgroup_move_parent(page, pc, memcg)) {
4785
			/* found lock contention or "pc" is obsolete. */
4786
			busy = page;
4787 4788 4789
			cond_resched();
		} else
			busy = NULL;
4790
	} while (!list_empty(list));
4791 4792 4793
}

/*
4794 4795
 * make mem_cgroup's charge to be 0 if there is no task by moving
 * all the charges and pages to the parent.
4796
 * This enables deleting this mem_cgroup.
4797 4798
 *
 * Caller is responsible for holding css reference on the memcg.
4799
 */
4800
static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
4801
{
4802
	int node, zid;
4803
	u64 usage;
4804

4805
	do {
4806 4807
		/* This is for making all *used* pages to be on LRU. */
		lru_add_drain_all();
4808 4809
		drain_all_stock_sync(memcg);
		mem_cgroup_start_move(memcg);
4810
		for_each_node_state(node, N_MEMORY) {
4811
			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
H
Hugh Dickins 已提交
4812 4813
				enum lru_list lru;
				for_each_lru(lru) {
4814
					mem_cgroup_force_empty_list(memcg,
H
Hugh Dickins 已提交
4815
							node, zid, lru);
4816
				}
4817
			}
4818
		}
4819 4820
		mem_cgroup_end_move(memcg);
		memcg_oom_recover(memcg);
4821
		cond_resched();
4822

4823
		/*
4824 4825 4826 4827 4828
		 * 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.
		 *
4829 4830 4831 4832 4833 4834
		 * 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.
		 */
4835 4836 4837
		usage = res_counter_read_u64(&memcg->res, RES_USAGE) -
			res_counter_read_u64(&memcg->kmem, RES_USAGE);
	} while (usage > 0);
4838 4839
}

4840 4841
static inline bool memcg_has_children(struct mem_cgroup *memcg)
{
4842 4843 4844 4845 4846 4847 4848 4849 4850 4851
	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);
4852 4853
}

4854 4855 4856 4857 4858 4859 4860 4861 4862 4863
/*
 * 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;
4864

4865
	/* returns EBUSY if there is a task or if we come here twice. */
4866
	if (cgroup_has_tasks(cgrp) || !list_empty(&cgrp->children))
4867 4868
		return -EBUSY;

4869 4870
	/* we call try-to-free pages for make this cgroup empty */
	lru_add_drain_all();
4871
	/* try to free all pages in this cgroup */
4872
	while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
4873
		int progress;
4874

4875 4876 4877
		if (signal_pending(current))
			return -EINTR;

4878
		progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
4879
						false);
4880
		if (!progress) {
4881
			nr_retries--;
4882
			/* maybe some writeback is necessary */
4883
			congestion_wait(BLK_RW_ASYNC, HZ/10);
4884
		}
4885 4886

	}
K
KAMEZAWA Hiroyuki 已提交
4887
	lru_add_drain();
4888 4889 4890
	mem_cgroup_reparent_charges(memcg);

	return 0;
4891 4892
}

4893 4894
static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css,
					unsigned int event)
4895
{
4896
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4897

4898 4899
	if (mem_cgroup_is_root(memcg))
		return -EINVAL;
4900
	return mem_cgroup_force_empty(memcg);
4901 4902
}

4903 4904
static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
				     struct cftype *cft)
4905
{
4906
	return mem_cgroup_from_css(css)->use_hierarchy;
4907 4908
}

4909 4910
static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
				      struct cftype *cft, u64 val)
4911 4912
{
	int retval = 0;
4913
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
4914
	struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css));
4915

4916
	mutex_lock(&memcg_create_mutex);
4917 4918 4919 4920

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

4921
	/*
4922
	 * If parent's use_hierarchy is set, we can't make any modifications
4923 4924 4925 4926 4927 4928
	 * 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.
	 */
4929
	if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
4930
				(val == 1 || val == 0)) {
4931
		if (list_empty(&memcg->css.cgroup->children))
4932
			memcg->use_hierarchy = val;
4933 4934 4935 4936
		else
			retval = -EBUSY;
	} else
		retval = -EINVAL;
4937 4938

out:
4939
	mutex_unlock(&memcg_create_mutex);
4940 4941 4942 4943

	return retval;
}

4944

4945
static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
4946
					       enum mem_cgroup_stat_index idx)
4947
{
K
KAMEZAWA Hiroyuki 已提交
4948
	struct mem_cgroup *iter;
4949
	long val = 0;
4950

4951
	/* Per-cpu values can be negative, use a signed accumulator */
4952
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
4953 4954 4955 4956 4957
		val += mem_cgroup_read_stat(iter, idx);

	if (val < 0) /* race ? */
		val = 0;
	return val;
4958 4959
}

4960
static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
4961
{
K
KAMEZAWA Hiroyuki 已提交
4962
	u64 val;
4963

4964
	if (!mem_cgroup_is_root(memcg)) {
4965
		if (!swap)
4966
			return res_counter_read_u64(&memcg->res, RES_USAGE);
4967
		else
4968
			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
4969 4970
	}

4971 4972 4973 4974
	/*
	 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
	 * as well as in MEM_CGROUP_STAT_RSS_HUGE.
	 */
4975 4976
	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
4977

K
KAMEZAWA Hiroyuki 已提交
4978
	if (swap)
4979
		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
4980 4981 4982 4983

	return val << PAGE_SHIFT;
}

4984 4985
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
				   struct cftype *cft)
B
Balbir Singh 已提交
4986
{
4987
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4988
	u64 val;
4989
	int name;
G
Glauber Costa 已提交
4990
	enum res_type type;
4991 4992 4993

	type = MEMFILE_TYPE(cft->private);
	name = MEMFILE_ATTR(cft->private);
4994

4995 4996
	switch (type) {
	case _MEM:
4997
		if (name == RES_USAGE)
4998
			val = mem_cgroup_usage(memcg, false);
4999
		else
5000
			val = res_counter_read_u64(&memcg->res, name);
5001 5002
		break;
	case _MEMSWAP:
5003
		if (name == RES_USAGE)
5004
			val = mem_cgroup_usage(memcg, true);
5005
		else
5006
			val = res_counter_read_u64(&memcg->memsw, name);
5007
		break;
5008 5009 5010
	case _KMEM:
		val = res_counter_read_u64(&memcg->kmem, name);
		break;
5011 5012 5013
	default:
		BUG();
	}
5014

5015
	return val;
B
Balbir Singh 已提交
5016
}
5017 5018

#ifdef CONFIG_MEMCG_KMEM
5019 5020 5021 5022 5023 5024 5025 5026 5027 5028 5029 5030 5031 5032 5033 5034
/* 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();

5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046
	/*
	 * 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.
	 */
5047
	mutex_lock(&memcg_create_mutex);
5048
	if (cgroup_has_tasks(memcg->css.cgroup) || memcg_has_children(memcg))
5049 5050 5051 5052
		err = -EBUSY;
	mutex_unlock(&memcg_create_mutex);
	if (err)
		goto out;
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 5086
	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);
5087
out:
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 5115
	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);
5116 5117 5118
	return ret;
}

5119
static int memcg_propagate_kmem(struct mem_cgroup *memcg)
5120
{
5121
	int ret = 0;
5122
	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
5123

5124 5125
	if (!parent)
		return 0;
5126

5127
	mutex_lock(&activate_kmem_mutex);
5128
	/*
5129 5130
	 * If the parent cgroup is not kmem-active now, it cannot be activated
	 * after this point, because it has at least one child already.
5131
	 */
5132 5133 5134
	if (memcg_kmem_is_active(parent))
		ret = __memcg_activate_kmem(memcg, RES_COUNTER_MAX);
	mutex_unlock(&activate_kmem_mutex);
5135
	return ret;
5136
}
5137 5138 5139 5140 5141 5142
#else
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
				   unsigned long long val)
{
	return -EINVAL;
}
5143
#endif /* CONFIG_MEMCG_KMEM */
5144

5145 5146 5147 5148
/*
 * The user of this function is...
 * RES_LIMIT.
 */
5149
static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft,
5150
			    char *buffer)
B
Balbir Singh 已提交
5151
{
5152
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
G
Glauber Costa 已提交
5153 5154
	enum res_type type;
	int name;
5155 5156 5157
	unsigned long long val;
	int ret;

5158 5159
	type = MEMFILE_TYPE(cft->private);
	name = MEMFILE_ATTR(cft->private);
5160

5161
	switch (name) {
5162
	case RES_LIMIT:
5163 5164 5165 5166
		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
			ret = -EINVAL;
			break;
		}
5167 5168
		/* This function does all necessary parse...reuse it */
		ret = res_counter_memparse_write_strategy(buffer, &val);
5169 5170 5171
		if (ret)
			break;
		if (type == _MEM)
5172
			ret = mem_cgroup_resize_limit(memcg, val);
5173
		else if (type == _MEMSWAP)
5174
			ret = mem_cgroup_resize_memsw_limit(memcg, val);
5175
		else if (type == _KMEM)
5176
			ret = memcg_update_kmem_limit(memcg, val);
5177 5178
		else
			return -EINVAL;
5179
		break;
5180 5181 5182 5183 5184 5185 5186 5187 5188 5189 5190 5191 5192 5193
	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;
5194 5195 5196 5197 5198
	default:
		ret = -EINVAL; /* should be BUG() ? */
		break;
	}
	return ret;
B
Balbir Singh 已提交
5199 5200
}

5201 5202 5203 5204 5205 5206 5207 5208 5209 5210
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
5211 5212
	while (css_parent(&memcg->css)) {
		memcg = mem_cgroup_from_css(css_parent(&memcg->css));
5213 5214 5215 5216 5217 5218 5219 5220 5221 5222 5223 5224
		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;
}

5225
static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
5226
{
5227
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
G
Glauber Costa 已提交
5228 5229
	int name;
	enum res_type type;
5230

5231 5232
	type = MEMFILE_TYPE(event);
	name = MEMFILE_ATTR(event);
5233

5234
	switch (name) {
5235
	case RES_MAX_USAGE:
5236
		if (type == _MEM)
5237
			res_counter_reset_max(&memcg->res);
5238
		else if (type == _MEMSWAP)
5239
			res_counter_reset_max(&memcg->memsw);
5240 5241 5242 5243
		else if (type == _KMEM)
			res_counter_reset_max(&memcg->kmem);
		else
			return -EINVAL;
5244 5245
		break;
	case RES_FAILCNT:
5246
		if (type == _MEM)
5247
			res_counter_reset_failcnt(&memcg->res);
5248
		else if (type == _MEMSWAP)
5249
			res_counter_reset_failcnt(&memcg->memsw);
5250 5251 5252 5253
		else if (type == _KMEM)
			res_counter_reset_failcnt(&memcg->kmem);
		else
			return -EINVAL;
5254 5255
		break;
	}
5256

5257
	return 0;
5258 5259
}

5260
static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
5261 5262
					struct cftype *cft)
{
5263
	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
5264 5265
}

5266
#ifdef CONFIG_MMU
5267
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
5268 5269
					struct cftype *cft, u64 val)
{
5270
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5271 5272 5273

	if (val >= (1 << NR_MOVE_TYPE))
		return -EINVAL;
5274

5275
	/*
5276 5277 5278 5279
	 * 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.
5280
	 */
5281
	memcg->move_charge_at_immigrate = val;
5282 5283
	return 0;
}
5284
#else
5285
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
5286 5287 5288 5289 5290
					struct cftype *cft, u64 val)
{
	return -ENOSYS;
}
#endif
5291

5292
#ifdef CONFIG_NUMA
5293
static int memcg_numa_stat_show(struct seq_file *m, void *v)
5294
{
5295 5296 5297 5298 5299 5300 5301 5302 5303 5304 5305 5306
	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;
5307
	int nid;
5308
	unsigned long nr;
5309
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
5310

5311 5312 5313 5314 5315 5316 5317 5318 5319
	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');
5320 5321
	}

5322 5323 5324 5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335 5336
	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');
5337 5338 5339 5340 5341 5342
	}

	return 0;
}
#endif /* CONFIG_NUMA */

5343 5344 5345 5346 5347
static inline void mem_cgroup_lru_names_not_uptodate(void)
{
	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
}

5348
static int memcg_stat_show(struct seq_file *m, void *v)
5349
{
5350
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
5351 5352
	struct mem_cgroup *mi;
	unsigned int i;
5353

5354
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
5355
		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
5356
			continue;
5357 5358
		seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
			   mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
5359
	}
L
Lee Schermerhorn 已提交
5360

5361 5362 5363 5364 5365 5366 5367 5368
	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
5369
	/* Hierarchical information */
5370 5371
	{
		unsigned long long limit, memsw_limit;
5372
		memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
5373
		seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
5374
		if (do_swap_account)
5375 5376
			seq_printf(m, "hierarchical_memsw_limit %llu\n",
				   memsw_limit);
5377
	}
K
KOSAKI Motohiro 已提交
5378

5379 5380 5381
	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
		long long val = 0;

5382
		if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
5383
			continue;
5384 5385 5386 5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397 5398 5399 5400 5401 5402 5403
		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);
5404
	}
K
KAMEZAWA Hiroyuki 已提交
5405

K
KOSAKI Motohiro 已提交
5406 5407 5408 5409
#ifdef CONFIG_DEBUG_VM
	{
		int nid, zid;
		struct mem_cgroup_per_zone *mz;
5410
		struct zone_reclaim_stat *rstat;
K
KOSAKI Motohiro 已提交
5411 5412 5413 5414 5415
		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++) {
5416
				mz = mem_cgroup_zoneinfo(memcg, nid, zid);
5417
				rstat = &mz->lruvec.reclaim_stat;
K
KOSAKI Motohiro 已提交
5418

5419 5420 5421 5422
				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
5423
			}
5424 5425 5426 5427
		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
5428 5429 5430
	}
#endif

5431 5432 5433
	return 0;
}

5434 5435
static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
				      struct cftype *cft)
K
KOSAKI Motohiro 已提交
5436
{
5437
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
K
KOSAKI Motohiro 已提交
5438

5439
	return mem_cgroup_swappiness(memcg);
K
KOSAKI Motohiro 已提交
5440 5441
}

5442 5443
static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
				       struct cftype *cft, u64 val)
K
KOSAKI Motohiro 已提交
5444
{
5445
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
5446
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
K
KOSAKI Motohiro 已提交
5447

T
Tejun Heo 已提交
5448
	if (val > 100 || !parent)
K
KOSAKI Motohiro 已提交
5449 5450
		return -EINVAL;

5451
	mutex_lock(&memcg_create_mutex);
5452

K
KOSAKI Motohiro 已提交
5453
	/* If under hierarchy, only empty-root can set this value */
5454
	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
5455
		mutex_unlock(&memcg_create_mutex);
K
KOSAKI Motohiro 已提交
5456
		return -EINVAL;
5457
	}
K
KOSAKI Motohiro 已提交
5458 5459 5460

	memcg->swappiness = val;

5461
	mutex_unlock(&memcg_create_mutex);
5462

K
KOSAKI Motohiro 已提交
5463 5464 5465
	return 0;
}

5466 5467 5468 5469 5470 5471 5472 5473
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)
5474
		t = rcu_dereference(memcg->thresholds.primary);
5475
	else
5476
		t = rcu_dereference(memcg->memsw_thresholds.primary);
5477 5478 5479 5480 5481 5482 5483

	if (!t)
		goto unlock;

	usage = mem_cgroup_usage(memcg, swap);

	/*
5484
	 * current_threshold points to threshold just below or equal to usage.
5485 5486 5487
	 * If it's not true, a threshold was crossed after last
	 * call of __mem_cgroup_threshold().
	 */
5488
	i = t->current_threshold;
5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499 5500 5501 5502 5503 5504 5505 5506 5507 5508 5509 5510 5511

	/*
	 * 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 */
5512
	t->current_threshold = i - 1;
5513 5514 5515 5516 5517 5518
unlock:
	rcu_read_unlock();
}

static void mem_cgroup_threshold(struct mem_cgroup *memcg)
{
5519 5520 5521 5522 5523 5524 5525
	while (memcg) {
		__mem_cgroup_threshold(memcg, false);
		if (do_swap_account)
			__mem_cgroup_threshold(memcg, true);

		memcg = parent_mem_cgroup(memcg);
	}
5526 5527 5528 5529 5530 5531 5532
}

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

5533 5534 5535 5536 5537 5538 5539
	if (_a->threshold > _b->threshold)
		return 1;

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

	return 0;
5540 5541
}

5542
static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
5543 5544 5545
{
	struct mem_cgroup_eventfd_list *ev;

5546
	list_for_each_entry(ev, &memcg->oom_notify, list)
K
KAMEZAWA Hiroyuki 已提交
5547 5548 5549 5550
		eventfd_signal(ev->eventfd, 1);
	return 0;
}

5551
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
K
KAMEZAWA Hiroyuki 已提交
5552
{
K
KAMEZAWA Hiroyuki 已提交
5553 5554
	struct mem_cgroup *iter;

5555
	for_each_mem_cgroup_tree(iter, memcg)
K
KAMEZAWA Hiroyuki 已提交
5556
		mem_cgroup_oom_notify_cb(iter);
K
KAMEZAWA Hiroyuki 已提交
5557 5558
}

5559
static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5560
	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
5561
{
5562 5563
	struct mem_cgroup_thresholds *thresholds;
	struct mem_cgroup_threshold_ary *new;
5564
	u64 threshold, usage;
5565
	int i, size, ret;
5566 5567 5568 5569 5570 5571

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

	mutex_lock(&memcg->thresholds_lock);
5572

5573
	if (type == _MEM)
5574
		thresholds = &memcg->thresholds;
5575
	else if (type == _MEMSWAP)
5576
		thresholds = &memcg->memsw_thresholds;
5577 5578 5579 5580 5581 5582
	else
		BUG();

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

	/* Check if a threshold crossed before adding a new one */
5583
	if (thresholds->primary)
5584 5585
		__mem_cgroup_threshold(memcg, type == _MEMSWAP);

5586
	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
5587 5588

	/* Allocate memory for new array of thresholds */
5589
	new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
5590
			GFP_KERNEL);
5591
	if (!new) {
5592 5593 5594
		ret = -ENOMEM;
		goto unlock;
	}
5595
	new->size = size;
5596 5597

	/* Copy thresholds (if any) to new array */
5598 5599
	if (thresholds->primary) {
		memcpy(new->entries, thresholds->primary->entries, (size - 1) *
5600
				sizeof(struct mem_cgroup_threshold));
5601 5602
	}

5603
	/* Add new threshold */
5604 5605
	new->entries[size - 1].eventfd = eventfd;
	new->entries[size - 1].threshold = threshold;
5606 5607

	/* Sort thresholds. Registering of new threshold isn't time-critical */
5608
	sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
5609 5610 5611
			compare_thresholds, NULL);

	/* Find current threshold */
5612
	new->current_threshold = -1;
5613
	for (i = 0; i < size; i++) {
5614
		if (new->entries[i].threshold <= usage) {
5615
			/*
5616 5617
			 * new->current_threshold will not be used until
			 * rcu_assign_pointer(), so it's safe to increment
5618 5619
			 * it here.
			 */
5620
			++new->current_threshold;
5621 5622
		} else
			break;
5623 5624
	}

5625 5626 5627 5628 5629
	/* Free old spare buffer and save old primary buffer as spare */
	kfree(thresholds->spare);
	thresholds->spare = thresholds->primary;

	rcu_assign_pointer(thresholds->primary, new);
5630

5631
	/* To be sure that nobody uses thresholds */
5632 5633 5634 5635 5636 5637 5638 5639
	synchronize_rcu();

unlock:
	mutex_unlock(&memcg->thresholds_lock);

	return ret;
}

5640
static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5641 5642
	struct eventfd_ctx *eventfd, const char *args)
{
5643
	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
T
Tejun Heo 已提交
5644 5645
}

5646
static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5647 5648
	struct eventfd_ctx *eventfd, const char *args)
{
5649
	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
T
Tejun Heo 已提交
5650 5651
}

5652
static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5653
	struct eventfd_ctx *eventfd, enum res_type type)
5654
{
5655 5656
	struct mem_cgroup_thresholds *thresholds;
	struct mem_cgroup_threshold_ary *new;
5657
	u64 usage;
5658
	int i, j, size;
5659 5660 5661

	mutex_lock(&memcg->thresholds_lock);
	if (type == _MEM)
5662
		thresholds = &memcg->thresholds;
5663
	else if (type == _MEMSWAP)
5664
		thresholds = &memcg->memsw_thresholds;
5665 5666 5667
	else
		BUG();

5668 5669 5670
	if (!thresholds->primary)
		goto unlock;

5671 5672 5673 5674 5675 5676
	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 */
5677 5678 5679
	size = 0;
	for (i = 0; i < thresholds->primary->size; i++) {
		if (thresholds->primary->entries[i].eventfd != eventfd)
5680 5681 5682
			size++;
	}

5683
	new = thresholds->spare;
5684

5685 5686
	/* Set thresholds array to NULL if we don't have thresholds */
	if (!size) {
5687 5688
		kfree(new);
		new = NULL;
5689
		goto swap_buffers;
5690 5691
	}

5692
	new->size = size;
5693 5694

	/* Copy thresholds and find current threshold */
5695 5696 5697
	new->current_threshold = -1;
	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
		if (thresholds->primary->entries[i].eventfd == eventfd)
5698 5699
			continue;

5700
		new->entries[j] = thresholds->primary->entries[i];
5701
		if (new->entries[j].threshold <= usage) {
5702
			/*
5703
			 * new->current_threshold will not be used
5704 5705 5706
			 * until rcu_assign_pointer(), so it's safe to increment
			 * it here.
			 */
5707
			++new->current_threshold;
5708 5709 5710 5711
		}
		j++;
	}

5712
swap_buffers:
5713 5714
	/* Swap primary and spare array */
	thresholds->spare = thresholds->primary;
5715 5716 5717 5718 5719 5720
	/* If all events are unregistered, free the spare array */
	if (!new) {
		kfree(thresholds->spare);
		thresholds->spare = NULL;
	}

5721
	rcu_assign_pointer(thresholds->primary, new);
5722

5723
	/* To be sure that nobody uses thresholds */
5724
	synchronize_rcu();
5725
unlock:
5726 5727
	mutex_unlock(&memcg->thresholds_lock);
}
5728

5729
static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5730 5731
	struct eventfd_ctx *eventfd)
{
5732
	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
T
Tejun Heo 已提交
5733 5734
}

5735
static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5736 5737
	struct eventfd_ctx *eventfd)
{
5738
	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
T
Tejun Heo 已提交
5739 5740
}

5741
static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5742
	struct eventfd_ctx *eventfd, const char *args)
K
KAMEZAWA Hiroyuki 已提交
5743 5744 5745 5746 5747 5748 5749
{
	struct mem_cgroup_eventfd_list *event;

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

5750
	spin_lock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5751 5752 5753 5754 5755

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

	/* already in OOM ? */
5756
	if (atomic_read(&memcg->under_oom))
K
KAMEZAWA Hiroyuki 已提交
5757
		eventfd_signal(eventfd, 1);
5758
	spin_unlock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5759 5760 5761 5762

	return 0;
}

5763
static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
T
Tejun Heo 已提交
5764
	struct eventfd_ctx *eventfd)
K
KAMEZAWA Hiroyuki 已提交
5765 5766 5767
{
	struct mem_cgroup_eventfd_list *ev, *tmp;

5768
	spin_lock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5769

5770
	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
K
KAMEZAWA Hiroyuki 已提交
5771 5772 5773 5774 5775 5776
		if (ev->eventfd == eventfd) {
			list_del(&ev->list);
			kfree(ev);
		}
	}

5777
	spin_unlock(&memcg_oom_lock);
K
KAMEZAWA Hiroyuki 已提交
5778 5779
}

5780
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
5781
{
5782
	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
5783

5784 5785
	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));
5786 5787 5788
	return 0;
}

5789
static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
5790 5791
	struct cftype *cft, u64 val)
{
5792
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
T
Tejun Heo 已提交
5793
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
5794 5795

	/* cannot set to root cgroup and only 0 and 1 are allowed */
T
Tejun Heo 已提交
5796
	if (!parent || !((val == 0) || (val == 1)))
5797 5798
		return -EINVAL;

5799
	mutex_lock(&memcg_create_mutex);
5800
	/* oom-kill-disable is a flag for subhierarchy. */
5801
	if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
5802
		mutex_unlock(&memcg_create_mutex);
5803 5804
		return -EINVAL;
	}
5805
	memcg->oom_kill_disable = val;
5806
	if (!val)
5807
		memcg_oom_recover(memcg);
5808
	mutex_unlock(&memcg_create_mutex);
5809 5810 5811
	return 0;
}

A
Andrew Morton 已提交
5812
#ifdef CONFIG_MEMCG_KMEM
5813
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
5814
{
5815 5816
	int ret;

5817
	memcg->kmemcg_id = -1;
5818 5819 5820
	ret = memcg_propagate_kmem(memcg);
	if (ret)
		return ret;
5821

5822
	return mem_cgroup_sockets_init(memcg, ss);
5823
}
5824

5825
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
G
Glauber Costa 已提交
5826
{
5827
	mem_cgroup_sockets_destroy(memcg);
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 5853
}

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);
5854 5855 5856 5857 5858 5859 5860

	memcg_kmem_mark_dead(memcg);

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

	if (memcg_kmem_test_and_clear_dead(memcg))
5861
		css_put(&memcg->css);
G
Glauber Costa 已提交
5862
}
5863
#else
5864
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
5865 5866 5867
{
	return 0;
}
G
Glauber Costa 已提交
5868

5869 5870 5871 5872 5873
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
5874 5875
{
}
5876 5877
#endif

5878 5879 5880 5881 5882 5883 5884 5885 5886 5887 5888 5889 5890
/*
 * 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.
 */

5891 5892 5893 5894 5895
/*
 * Unregister event and free resources.
 *
 * Gets called from workqueue.
 */
5896
static void memcg_event_remove(struct work_struct *work)
5897
{
5898 5899
	struct mem_cgroup_event *event =
		container_of(work, struct mem_cgroup_event, remove);
5900
	struct mem_cgroup *memcg = event->memcg;
5901 5902 5903

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

5904
	event->unregister_event(memcg, event->eventfd);
5905 5906 5907 5908 5909 5910

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

	eventfd_ctx_put(event->eventfd);
	kfree(event);
5911
	css_put(&memcg->css);
5912 5913 5914 5915 5916 5917 5918
}

/*
 * Gets called on POLLHUP on eventfd when user closes it.
 *
 * Called with wqh->lock held and interrupts disabled.
 */
5919 5920
static int memcg_event_wake(wait_queue_t *wait, unsigned mode,
			    int sync, void *key)
5921
{
5922 5923
	struct mem_cgroup_event *event =
		container_of(wait, struct mem_cgroup_event, wait);
5924
	struct mem_cgroup *memcg = event->memcg;
5925 5926 5927 5928 5929 5930 5931 5932 5933 5934 5935 5936
	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.
		 */
5937
		spin_lock(&memcg->event_list_lock);
5938 5939 5940 5941 5942 5943 5944 5945
		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);
		}
5946
		spin_unlock(&memcg->event_list_lock);
5947 5948 5949 5950 5951
	}

	return 0;
}

5952
static void memcg_event_ptable_queue_proc(struct file *file,
5953 5954
		wait_queue_head_t *wqh, poll_table *pt)
{
5955 5956
	struct mem_cgroup_event *event =
		container_of(pt, struct mem_cgroup_event, pt);
5957 5958 5959 5960 5961 5962

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

/*
5963 5964
 * DO NOT USE IN NEW FILES.
 *
5965 5966 5967 5968 5969
 * 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.
 */
5970
static int memcg_write_event_control(struct cgroup_subsys_state *css,
5971
				     struct cftype *cft, char *buffer)
5972
{
5973
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5974
	struct mem_cgroup_event *event;
5975 5976 5977 5978
	struct cgroup_subsys_state *cfile_css;
	unsigned int efd, cfd;
	struct fd efile;
	struct fd cfile;
5979
	const char *name;
5980 5981 5982 5983 5984 5985 5986 5987 5988 5989 5990 5991 5992 5993 5994 5995 5996
	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;

5997
	event->memcg = memcg;
5998
	INIT_LIST_HEAD(&event->list);
5999 6000 6001
	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);
6002 6003 6004 6005 6006 6007 6008 6009 6010 6011 6012 6013 6014 6015 6016 6017 6018 6019 6020 6021 6022 6023 6024 6025 6026

	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;

6027 6028 6029 6030 6031
	/*
	 * 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.
6032 6033
	 *
	 * DO NOT ADD NEW FILES.
6034 6035 6036 6037 6038 6039 6040 6041 6042 6043 6044 6045 6046
	 */
	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
6047 6048
		event->register_event = memsw_cgroup_usage_register_event;
		event->unregister_event = memsw_cgroup_usage_unregister_event;
6049 6050 6051 6052 6053
	} else {
		ret = -EINVAL;
		goto out_put_cfile;
	}

6054
	/*
6055 6056 6057
	 * 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.
6058
	 */
6059 6060
	cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent,
					&memory_cgrp_subsys);
6061
	ret = -EINVAL;
6062
	if (IS_ERR(cfile_css))
6063
		goto out_put_cfile;
6064 6065
	if (cfile_css != css) {
		css_put(cfile_css);
6066
		goto out_put_cfile;
6067
	}
6068

6069
	ret = event->register_event(memcg, event->eventfd, buffer);
6070 6071 6072 6073 6074
	if (ret)
		goto out_put_css;

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

6075 6076 6077
	spin_lock(&memcg->event_list_lock);
	list_add(&event->list, &memcg->event_list);
	spin_unlock(&memcg->event_list_lock);
6078 6079 6080 6081 6082 6083 6084

	fdput(cfile);
	fdput(efile);

	return 0;

out_put_css:
6085
	css_put(css);
6086 6087 6088 6089 6090 6091 6092 6093 6094 6095 6096 6097
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
6098 6099
static struct cftype mem_cgroup_files[] = {
	{
6100
		.name = "usage_in_bytes",
6101
		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
6102
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6103
	},
6104 6105
	{
		.name = "max_usage_in_bytes",
6106
		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
6107
		.trigger = mem_cgroup_reset,
6108
		.read_u64 = mem_cgroup_read_u64,
6109
	},
B
Balbir Singh 已提交
6110
	{
6111
		.name = "limit_in_bytes",
6112
		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
6113
		.write_string = mem_cgroup_write,
6114
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6115
	},
6116 6117 6118 6119
	{
		.name = "soft_limit_in_bytes",
		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
		.write_string = mem_cgroup_write,
6120
		.read_u64 = mem_cgroup_read_u64,
6121
	},
B
Balbir Singh 已提交
6122 6123
	{
		.name = "failcnt",
6124
		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
6125
		.trigger = mem_cgroup_reset,
6126
		.read_u64 = mem_cgroup_read_u64,
B
Balbir Singh 已提交
6127
	},
6128 6129
	{
		.name = "stat",
6130
		.seq_show = memcg_stat_show,
6131
	},
6132 6133 6134 6135
	{
		.name = "force_empty",
		.trigger = mem_cgroup_force_empty_write,
	},
6136 6137
	{
		.name = "use_hierarchy",
6138
		.flags = CFTYPE_INSANE,
6139 6140 6141
		.write_u64 = mem_cgroup_hierarchy_write,
		.read_u64 = mem_cgroup_hierarchy_read,
	},
6142
	{
6143 6144
		.name = "cgroup.event_control",		/* XXX: for compat */
		.write_string = memcg_write_event_control,
6145 6146 6147
		.flags = CFTYPE_NO_PREFIX,
		.mode = S_IWUGO,
	},
K
KOSAKI Motohiro 已提交
6148 6149 6150 6151 6152
	{
		.name = "swappiness",
		.read_u64 = mem_cgroup_swappiness_read,
		.write_u64 = mem_cgroup_swappiness_write,
	},
6153 6154 6155 6156 6157
	{
		.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
6158 6159
	{
		.name = "oom_control",
6160
		.seq_show = mem_cgroup_oom_control_read,
6161
		.write_u64 = mem_cgroup_oom_control_write,
K
KAMEZAWA Hiroyuki 已提交
6162 6163
		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
	},
6164 6165 6166
	{
		.name = "pressure_level",
	},
6167 6168 6169
#ifdef CONFIG_NUMA
	{
		.name = "numa_stat",
6170
		.seq_show = memcg_numa_stat_show,
6171 6172
	},
#endif
6173 6174 6175 6176 6177
#ifdef CONFIG_MEMCG_KMEM
	{
		.name = "kmem.limit_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
		.write_string = mem_cgroup_write,
6178
		.read_u64 = mem_cgroup_read_u64,
6179 6180 6181 6182
	},
	{
		.name = "kmem.usage_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
6183
		.read_u64 = mem_cgroup_read_u64,
6184 6185 6186 6187 6188
	},
	{
		.name = "kmem.failcnt",
		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
		.trigger = mem_cgroup_reset,
6189
		.read_u64 = mem_cgroup_read_u64,
6190 6191 6192 6193 6194
	},
	{
		.name = "kmem.max_usage_in_bytes",
		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
		.trigger = mem_cgroup_reset,
6195
		.read_u64 = mem_cgroup_read_u64,
6196
	},
6197 6198 6199
#ifdef CONFIG_SLABINFO
	{
		.name = "kmem.slabinfo",
6200
		.seq_show = mem_cgroup_slabinfo_read,
6201 6202
	},
#endif
6203
#endif
6204
	{ },	/* terminate */
6205
};
6206

6207 6208 6209 6210 6211
#ifdef CONFIG_MEMCG_SWAP
static struct cftype memsw_cgroup_files[] = {
	{
		.name = "memsw.usage_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
6212
		.read_u64 = mem_cgroup_read_u64,
6213 6214 6215 6216 6217
	},
	{
		.name = "memsw.max_usage_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
		.trigger = mem_cgroup_reset,
6218
		.read_u64 = mem_cgroup_read_u64,
6219 6220 6221 6222 6223
	},
	{
		.name = "memsw.limit_in_bytes",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
		.write_string = mem_cgroup_write,
6224
		.read_u64 = mem_cgroup_read_u64,
6225 6226 6227 6228 6229
	},
	{
		.name = "memsw.failcnt",
		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
		.trigger = mem_cgroup_reset,
6230
		.read_u64 = mem_cgroup_read_u64,
6231 6232 6233 6234
	},
	{ },	/* terminate */
};
#endif
6235
static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
6236 6237
{
	struct mem_cgroup_per_node *pn;
6238
	struct mem_cgroup_per_zone *mz;
6239
	int zone, tmp = node;
6240 6241 6242 6243 6244 6245 6246 6247
	/*
	 * 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.
	 */
6248 6249
	if (!node_state(node, N_NORMAL_MEMORY))
		tmp = -1;
6250
	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
6251 6252
	if (!pn)
		return 1;
6253 6254 6255

	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
		mz = &pn->zoneinfo[zone];
6256
		lruvec_init(&mz->lruvec);
6257 6258
		mz->usage_in_excess = 0;
		mz->on_tree = false;
6259
		mz->memcg = memcg;
6260
	}
6261
	memcg->nodeinfo[node] = pn;
6262 6263 6264
	return 0;
}

6265
static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
6266
{
6267
	kfree(memcg->nodeinfo[node]);
6268 6269
}

6270 6271
static struct mem_cgroup *mem_cgroup_alloc(void)
{
6272
	struct mem_cgroup *memcg;
6273
	size_t size;
6274

6275 6276
	size = sizeof(struct mem_cgroup);
	size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
6277

6278
	memcg = kzalloc(size, GFP_KERNEL);
6279
	if (!memcg)
6280 6281
		return NULL;

6282 6283
	memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
	if (!memcg->stat)
6284
		goto out_free;
6285 6286
	spin_lock_init(&memcg->pcp_counter_lock);
	return memcg;
6287 6288

out_free:
6289
	kfree(memcg);
6290
	return NULL;
6291 6292
}

6293
/*
6294 6295 6296 6297 6298 6299 6300 6301
 * 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.
6302
 */
6303 6304

static void __mem_cgroup_free(struct mem_cgroup *memcg)
6305
{
6306
	int node;
6307

6308
	mem_cgroup_remove_from_trees(memcg);
6309 6310 6311 6312 6313 6314

	for_each_node(node)
		free_mem_cgroup_per_zone_info(memcg, node);

	free_percpu(memcg->stat);

6315 6316 6317 6318 6319 6320 6321 6322 6323 6324 6325
	/*
	 * 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.
	 */
6326
	disarm_static_keys(memcg);
6327
	kfree(memcg);
6328
}
6329

6330 6331 6332
/*
 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
 */
G
Glauber Costa 已提交
6333
struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
6334
{
6335
	if (!memcg->res.parent)
6336
		return NULL;
6337
	return mem_cgroup_from_res_counter(memcg->res.parent, res);
6338
}
G
Glauber Costa 已提交
6339
EXPORT_SYMBOL(parent_mem_cgroup);
6340

6341 6342 6343 6344 6345 6346 6347 6348 6349 6350 6351 6352 6353 6354 6355 6356 6357 6358 6359 6360 6361 6362 6363
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
6364
static struct cgroup_subsys_state * __ref
6365
mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
B
Balbir Singh 已提交
6366
{
6367
	struct mem_cgroup *memcg;
K
KAMEZAWA Hiroyuki 已提交
6368
	long error = -ENOMEM;
6369
	int node;
B
Balbir Singh 已提交
6370

6371 6372
	memcg = mem_cgroup_alloc();
	if (!memcg)
K
KAMEZAWA Hiroyuki 已提交
6373
		return ERR_PTR(error);
6374

B
Bob Liu 已提交
6375
	for_each_node(node)
6376
		if (alloc_mem_cgroup_per_zone_info(memcg, node))
6377
			goto free_out;
6378

6379
	/* root ? */
6380
	if (parent_css == NULL) {
6381
		root_mem_cgroup = memcg;
6382 6383 6384
		res_counter_init(&memcg->res, NULL);
		res_counter_init(&memcg->memsw, NULL);
		res_counter_init(&memcg->kmem, NULL);
6385
	}
6386

6387 6388 6389 6390 6391
	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);
6392
	vmpressure_init(&memcg->vmpressure);
6393 6394
	INIT_LIST_HEAD(&memcg->event_list);
	spin_lock_init(&memcg->event_list_lock);
6395 6396 6397 6398 6399 6400 6401 6402 6403

	return &memcg->css;

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

static int
6404
mem_cgroup_css_online(struct cgroup_subsys_state *css)
6405
{
6406 6407
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
6408

6409 6410 6411
	if (css->cgroup->id > MEM_CGROUP_ID_MAX)
		return -ENOSPC;

T
Tejun Heo 已提交
6412
	if (!parent)
6413 6414
		return 0;

6415
	mutex_lock(&memcg_create_mutex);
6416 6417 6418 6419 6420 6421

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

	if (parent->use_hierarchy) {
6422 6423
		res_counter_init(&memcg->res, &parent->res);
		res_counter_init(&memcg->memsw, &parent->memsw);
6424
		res_counter_init(&memcg->kmem, &parent->kmem);
6425

6426
		/*
6427 6428
		 * No need to take a reference to the parent because cgroup
		 * core guarantees its existence.
6429
		 */
6430
	} else {
6431 6432
		res_counter_init(&memcg->res, NULL);
		res_counter_init(&memcg->memsw, NULL);
6433
		res_counter_init(&memcg->kmem, NULL);
6434 6435 6436 6437 6438
		/*
		 * Deeper hierachy with use_hierarchy == false doesn't make
		 * much sense so let cgroup subsystem know about this
		 * unfortunate state in our controller.
		 */
6439
		if (parent != root_mem_cgroup)
6440
			memory_cgrp_subsys.broken_hierarchy = true;
6441
	}
6442
	mutex_unlock(&memcg_create_mutex);
6443

6444
	return memcg_init_kmem(memcg, &memory_cgrp_subsys);
B
Balbir Singh 已提交
6445 6446
}

M
Michal Hocko 已提交
6447 6448 6449 6450 6451 6452 6453 6454
/*
 * 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)))
6455
		mem_cgroup_iter_invalidate(parent);
M
Michal Hocko 已提交
6456 6457 6458 6459 6460 6461

	/*
	 * if the root memcg is not hierarchical we have to check it
	 * explicitely.
	 */
	if (!root_mem_cgroup->use_hierarchy)
6462
		mem_cgroup_iter_invalidate(root_mem_cgroup);
M
Michal Hocko 已提交
6463 6464
}

6465
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
6466
{
6467
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6468
	struct mem_cgroup_event *event, *tmp;
6469
	struct cgroup_subsys_state *iter;
6470 6471 6472 6473 6474 6475

	/*
	 * Unregister events and notify userspace.
	 * Notify userspace about cgroup removing only after rmdir of cgroup
	 * directory to avoid race between userspace and kernelspace.
	 */
6476 6477
	spin_lock(&memcg->event_list_lock);
	list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
6478 6479 6480
		list_del_init(&event->list);
		schedule_work(&event->remove);
	}
6481
	spin_unlock(&memcg->event_list_lock);
6482

6483 6484
	kmem_cgroup_css_offline(memcg);

M
Michal Hocko 已提交
6485
	mem_cgroup_invalidate_reclaim_iterators(memcg);
6486 6487 6488 6489 6490 6491 6492 6493

	/*
	 * 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
6494
	mem_cgroup_destroy_all_caches(memcg);
6495
	vmpressure_cleanup(&memcg->vmpressure);
6496 6497
}

6498
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
B
Balbir Singh 已提交
6499
{
6500
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
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 6536
	/*
	 * 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);
6537

6538
	memcg_destroy_kmem(memcg);
6539
	__mem_cgroup_free(memcg);
B
Balbir Singh 已提交
6540 6541
}

6542
#ifdef CONFIG_MMU
6543
/* Handlers for move charge at task migration. */
6544 6545
#define PRECHARGE_COUNT_AT_ONCE	256
static int mem_cgroup_do_precharge(unsigned long count)
6546
{
6547 6548
	int ret = 0;
	int batch_count = PRECHARGE_COUNT_AT_ONCE;
6549
	struct mem_cgroup *memcg = mc.to;
6550

6551
	if (mem_cgroup_is_root(memcg)) {
6552 6553 6554 6555 6556 6557 6558 6559
		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;
		/*
6560
		 * "memcg" cannot be under rmdir() because we've already checked
6561 6562 6563 6564
		 * 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().
		 */
6565
		if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
6566
			goto one_by_one;
6567
		if (do_swap_account && res_counter_charge(&memcg->memsw,
6568
						PAGE_SIZE * count, &dummy)) {
6569
			res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
6570 6571 6572 6573 6574 6575 6576 6577 6578 6579 6580 6581 6582 6583 6584 6585
			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();
		}
6586
		ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
6587
		if (ret)
6588
			/* mem_cgroup_clear_mc() will do uncharge later */
6589
			return ret;
6590 6591
		mc.precharge++;
	}
6592 6593 6594 6595
	return ret;
}

/**
6596
 * get_mctgt_type - get target type of moving charge
6597 6598 6599
 * @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
6600
 * @target: the pointer the target page or swap ent will be stored(can be NULL)
6601 6602 6603 6604 6605 6606
 *
 * 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).
6607 6608 6609
 *   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.
6610 6611 6612 6613 6614
 *
 * Called with pte lock held.
 */
union mc_target {
	struct page	*page;
6615
	swp_entry_t	ent;
6616 6617 6618
};

enum mc_target_type {
6619
	MC_TARGET_NONE = 0,
6620
	MC_TARGET_PAGE,
6621
	MC_TARGET_SWAP,
6622 6623
};

D
Daisuke Nishimura 已提交
6624 6625
static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
						unsigned long addr, pte_t ptent)
6626
{
D
Daisuke Nishimura 已提交
6627
	struct page *page = vm_normal_page(vma, addr, ptent);
6628

D
Daisuke Nishimura 已提交
6629 6630 6631 6632
	if (!page || !page_mapped(page))
		return NULL;
	if (PageAnon(page)) {
		/* we don't move shared anon */
6633
		if (!move_anon())
D
Daisuke Nishimura 已提交
6634
			return NULL;
6635 6636
	} else if (!move_file())
		/* we ignore mapcount for file pages */
D
Daisuke Nishimura 已提交
6637 6638 6639 6640 6641 6642 6643
		return NULL;
	if (!get_page_unless_zero(page))
		return NULL;

	return page;
}

6644
#ifdef CONFIG_SWAP
D
Daisuke Nishimura 已提交
6645 6646 6647 6648 6649 6650 6651 6652
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;
6653 6654 6655 6656
	/*
	 * Because lookup_swap_cache() updates some statistics counter,
	 * we call find_get_page() with swapper_space directly.
	 */
6657
	page = find_get_page(swap_address_space(ent), ent.val);
D
Daisuke Nishimura 已提交
6658 6659 6660 6661 6662
	if (do_swap_account)
		entry->val = ent.val;

	return page;
}
6663 6664 6665 6666 6667 6668 6669
#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
6670

6671 6672 6673 6674 6675 6676 6677 6678 6679 6680 6681 6682 6683 6684 6685 6686 6687 6688 6689
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). */
6690 6691
#ifdef CONFIG_SWAP
	/* shmem/tmpfs may report page out on swap: account for that too. */
6692 6693 6694 6695 6696 6697 6698 6699 6700 6701 6702 6703
	if (shmem_mapping(mapping)) {
		page = find_get_entry(mapping, pgoff);
		if (radix_tree_exceptional_entry(page)) {
			swp_entry_t swp = radix_to_swp_entry(page);
			if (do_swap_account)
				*entry = swp;
			page = find_get_page(swap_address_space(swp), swp.val);
		}
	} else
		page = find_get_page(mapping, pgoff);
#else
	page = find_get_page(mapping, pgoff);
6704
#endif
6705 6706 6707
	return page;
}

6708
static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
D
Daisuke Nishimura 已提交
6709 6710 6711 6712
		unsigned long addr, pte_t ptent, union mc_target *target)
{
	struct page *page = NULL;
	struct page_cgroup *pc;
6713
	enum mc_target_type ret = MC_TARGET_NONE;
D
Daisuke Nishimura 已提交
6714 6715 6716 6717 6718 6719
	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);
6720 6721
	else if (pte_none(ptent) || pte_file(ptent))
		page = mc_handle_file_pte(vma, addr, ptent, &ent);
D
Daisuke Nishimura 已提交
6722 6723

	if (!page && !ent.val)
6724
		return ret;
6725 6726 6727 6728 6729 6730 6731 6732 6733 6734 6735 6736 6737 6738 6739
	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
6740 6741
	/* 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
6742
	    mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
6743 6744 6745
		ret = MC_TARGET_SWAP;
		if (target)
			target->ent = ent;
6746 6747 6748 6749
	}
	return ret;
}

6750 6751 6752 6753 6754 6755 6756 6757 6758 6759 6760 6761 6762 6763
#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);
6764
	VM_BUG_ON_PAGE(!page || !PageHead(page), page);
6765 6766 6767 6768 6769 6770 6771 6772 6773 6774 6775 6776 6777 6778 6779 6780 6781 6782 6783 6784
	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

6785 6786 6787 6788 6789 6790 6791 6792
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;

6793
	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
6794 6795
		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
			mc.precharge += HPAGE_PMD_NR;
6796
		spin_unlock(ptl);
6797
		return 0;
6798
	}
6799

6800 6801
	if (pmd_trans_unstable(pmd))
		return 0;
6802 6803
	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
	for (; addr != end; pte++, addr += PAGE_SIZE)
6804
		if (get_mctgt_type(vma, addr, *pte, NULL))
6805 6806 6807 6808
			mc.precharge++;	/* increment precharge temporarily */
	pte_unmap_unlock(pte - 1, ptl);
	cond_resched();

6809 6810 6811
	return 0;
}

6812 6813 6814 6815 6816
static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
{
	unsigned long precharge;
	struct vm_area_struct *vma;

6817
	down_read(&mm->mmap_sem);
6818 6819 6820 6821 6822 6823 6824 6825 6826 6827 6828
	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);
	}
6829
	up_read(&mm->mmap_sem);
6830 6831 6832 6833 6834 6835 6836 6837 6838

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

	return precharge;
}

static int mem_cgroup_precharge_mc(struct mm_struct *mm)
{
6839 6840 6841 6842 6843
	unsigned long precharge = mem_cgroup_count_precharge(mm);

	VM_BUG_ON(mc.moving_task);
	mc.moving_task = current;
	return mem_cgroup_do_precharge(precharge);
6844 6845
}

6846 6847
/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
static void __mem_cgroup_clear_mc(void)
6848
{
6849 6850
	struct mem_cgroup *from = mc.from;
	struct mem_cgroup *to = mc.to;
L
Li Zefan 已提交
6851
	int i;
6852

6853
	/* we must uncharge all the leftover precharges from mc.to */
6854 6855 6856 6857 6858 6859 6860 6861 6862 6863 6864
	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;
6865
	}
6866 6867 6868 6869 6870 6871
	/* 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
6872 6873 6874

		for (i = 0; i < mc.moved_swap; i++)
			css_put(&mc.from->css);
6875 6876 6877 6878 6879 6880 6881 6882 6883

		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
6884
		/* we've already done css_get(mc.to) */
6885 6886
		mc.moved_swap = 0;
	}
6887 6888 6889 6890 6891 6892 6893 6894 6895 6896 6897 6898 6899 6900 6901
	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();
6902
	spin_lock(&mc.lock);
6903 6904
	mc.from = NULL;
	mc.to = NULL;
6905
	spin_unlock(&mc.lock);
6906
	mem_cgroup_end_move(from);
6907 6908
}

6909
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
6910
				 struct cgroup_taskset *tset)
6911
{
6912
	struct task_struct *p = cgroup_taskset_first(tset);
6913
	int ret = 0;
6914
	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6915
	unsigned long move_charge_at_immigrate;
6916

6917 6918 6919 6920 6921 6922 6923
	/*
	 * 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) {
6924 6925 6926
		struct mm_struct *mm;
		struct mem_cgroup *from = mem_cgroup_from_task(p);

6927
		VM_BUG_ON(from == memcg);
6928 6929 6930 6931 6932

		mm = get_task_mm(p);
		if (!mm)
			return 0;
		/* We move charges only when we move a owner of the mm */
6933 6934 6935 6936
		if (mm->owner == p) {
			VM_BUG_ON(mc.from);
			VM_BUG_ON(mc.to);
			VM_BUG_ON(mc.precharge);
6937
			VM_BUG_ON(mc.moved_charge);
6938
			VM_BUG_ON(mc.moved_swap);
6939
			mem_cgroup_start_move(from);
6940
			spin_lock(&mc.lock);
6941
			mc.from = from;
6942
			mc.to = memcg;
6943
			mc.immigrate_flags = move_charge_at_immigrate;
6944
			spin_unlock(&mc.lock);
6945
			/* We set mc.moving_task later */
6946 6947 6948 6949

			ret = mem_cgroup_precharge_mc(mm);
			if (ret)
				mem_cgroup_clear_mc();
6950 6951
		}
		mmput(mm);
6952 6953 6954 6955
	}
	return ret;
}

6956
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
6957
				     struct cgroup_taskset *tset)
6958
{
6959
	mem_cgroup_clear_mc();
6960 6961
}

6962 6963 6964
static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
				unsigned long addr, unsigned long end,
				struct mm_walk *walk)
6965
{
6966 6967 6968 6969
	int ret = 0;
	struct vm_area_struct *vma = walk->private;
	pte_t *pte;
	spinlock_t *ptl;
6970 6971 6972 6973
	enum mc_target_type target_type;
	union mc_target target;
	struct page *page;
	struct page_cgroup *pc;
6974

6975 6976 6977 6978 6979 6980 6981 6982 6983 6984
	/*
	 * 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.
	 */
6985
	if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
6986
		if (mc.precharge < HPAGE_PMD_NR) {
6987
			spin_unlock(ptl);
6988 6989 6990 6991 6992 6993 6994 6995
			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,
6996
							pc, mc.from, mc.to)) {
6997 6998 6999 7000 7001 7002 7003
					mc.precharge -= HPAGE_PMD_NR;
					mc.moved_charge += HPAGE_PMD_NR;
				}
				putback_lru_page(page);
			}
			put_page(page);
		}
7004
		spin_unlock(ptl);
7005
		return 0;
7006 7007
	}

7008 7009
	if (pmd_trans_unstable(pmd))
		return 0;
7010 7011 7012 7013
retry:
	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
	for (; addr != end; addr += PAGE_SIZE) {
		pte_t ptent = *(pte++);
7014
		swp_entry_t ent;
7015 7016 7017 7018

		if (!mc.precharge)
			break;

7019
		switch (get_mctgt_type(vma, addr, ptent, &target)) {
7020 7021 7022 7023 7024
		case MC_TARGET_PAGE:
			page = target.page;
			if (isolate_lru_page(page))
				goto put;
			pc = lookup_page_cgroup(page);
7025
			if (!mem_cgroup_move_account(page, 1, pc,
7026
						     mc.from, mc.to)) {
7027
				mc.precharge--;
7028 7029
				/* we uncharge from mc.from later. */
				mc.moved_charge++;
7030 7031
			}
			putback_lru_page(page);
7032
put:			/* get_mctgt_type() gets the page */
7033 7034
			put_page(page);
			break;
7035 7036
		case MC_TARGET_SWAP:
			ent = target.ent;
7037
			if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
7038
				mc.precharge--;
7039 7040 7041
				/* we fixup refcnts and charges later. */
				mc.moved_swap++;
			}
7042
			break;
7043 7044 7045 7046 7047 7048 7049 7050 7051 7052 7053 7054 7055 7056
		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.
		 */
7057
		ret = mem_cgroup_do_precharge(1);
7058 7059 7060 7061 7062 7063 7064 7065 7066 7067 7068 7069
		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();
7070 7071 7072 7073 7074 7075 7076 7077 7078 7079 7080 7081 7082
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;
	}
7083 7084 7085 7086 7087 7088 7089 7090 7091 7092 7093 7094 7095 7096 7097 7098 7099 7100
	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;
	}
7101
	up_read(&mm->mmap_sem);
7102 7103
}

7104
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
7105
				 struct cgroup_taskset *tset)
B
Balbir Singh 已提交
7106
{
7107
	struct task_struct *p = cgroup_taskset_first(tset);
7108
	struct mm_struct *mm = get_task_mm(p);
7109 7110

	if (mm) {
7111 7112
		if (mc.to)
			mem_cgroup_move_charge(mm);
7113 7114
		mmput(mm);
	}
7115 7116
	if (mc.to)
		mem_cgroup_clear_mc();
B
Balbir Singh 已提交
7117
}
7118
#else	/* !CONFIG_MMU */
7119
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
7120
				 struct cgroup_taskset *tset)
7121 7122 7123
{
	return 0;
}
7124
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
7125
				     struct cgroup_taskset *tset)
7126 7127
{
}
7128
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
7129
				 struct cgroup_taskset *tset)
7130 7131 7132
{
}
#endif
B
Balbir Singh 已提交
7133

7134 7135 7136 7137
/*
 * Cgroup retains root cgroups across [un]mount cycles making it necessary
 * to verify sane_behavior flag on each mount attempt.
 */
7138
static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
7139 7140 7141 7142 7143 7144
{
	/*
	 * 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.
	 */
7145 7146
	if (cgroup_sane_behavior(root_css->cgroup))
		mem_cgroup_from_css(root_css)->use_hierarchy = true;
7147 7148
}

7149
struct cgroup_subsys memory_cgrp_subsys = {
7150
	.css_alloc = mem_cgroup_css_alloc,
7151
	.css_online = mem_cgroup_css_online,
7152 7153
	.css_offline = mem_cgroup_css_offline,
	.css_free = mem_cgroup_css_free,
7154 7155
	.can_attach = mem_cgroup_can_attach,
	.cancel_attach = mem_cgroup_cancel_attach,
B
Balbir Singh 已提交
7156
	.attach = mem_cgroup_move_task,
7157
	.bind = mem_cgroup_bind,
7158
	.base_cftypes = mem_cgroup_files,
7159
	.early_init = 0,
B
Balbir Singh 已提交
7160
};
7161

A
Andrew Morton 已提交
7162
#ifdef CONFIG_MEMCG_SWAP
7163 7164
static int __init enable_swap_account(char *s)
{
7165
	if (!strcmp(s, "1"))
7166
		really_do_swap_account = 1;
7167
	else if (!strcmp(s, "0"))
7168 7169 7170
		really_do_swap_account = 0;
	return 1;
}
7171
__setup("swapaccount=", enable_swap_account);
7172

7173 7174
static void __init memsw_file_init(void)
{
7175
	WARN_ON(cgroup_add_cftypes(&memory_cgrp_subsys, memsw_cgroup_files));
7176 7177 7178 7179 7180 7181 7182 7183
}

static void __init enable_swap_cgroup(void)
{
	if (!mem_cgroup_disabled() && really_do_swap_account) {
		do_swap_account = 1;
		memsw_file_init();
	}
7184
}
7185

7186
#else
7187
static void __init enable_swap_cgroup(void)
7188 7189
{
}
7190
#endif
7191 7192

/*
7193 7194 7195 7196 7197 7198
 * 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.
7199 7200 7201 7202
 */
static int __init mem_cgroup_init(void)
{
	hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
7203
	enable_swap_cgroup();
7204
	mem_cgroup_soft_limit_tree_init();
7205
	memcg_stock_init();
7206 7207 7208
	return 0;
}
subsys_initcall(mem_cgroup_init);