cpuset.c 74.5 KB
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/*
 *  kernel/cpuset.c
 *
 *  Processor and Memory placement constraints for sets of tasks.
 *
 *  Copyright (C) 2003 BULL SA.
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 *  Copyright (C) 2004-2007 Silicon Graphics, Inc.
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 *  Copyright (C) 2006 Google, Inc
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 *
 *  Portions derived from Patrick Mochel's sysfs code.
 *  sysfs is Copyright (c) 2001-3 Patrick Mochel
 *
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 *  2003-10-10 Written by Simon Derr.
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 *  2003-10-22 Updates by Stephen Hemminger.
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 *  2004 May-July Rework by Paul Jackson.
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 *  2006 Rework by Paul Menage to use generic cgroups
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 *  2008 Rework of the scheduler domains and CPU hotplug handling
 *       by Max Krasnyansky
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 *
 *  This file is subject to the terms and conditions of the GNU General Public
 *  License.  See the file COPYING in the main directory of the Linux
 *  distribution for more details.
 */

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/cpuset.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/list.h>
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#include <linux/mempolicy.h>
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#include <linux/mm.h>
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#include <linux/memory.h>
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#include <linux/export.h>
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#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
#include <linux/seq_file.h>
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#include <linux/security.h>
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#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>

#include <asm/uaccess.h>
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#include <linux/atomic.h>
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#include <linux/mutex.h>
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#include <linux/workqueue.h>
#include <linux/cgroup.h>
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#include <linux/wait.h>
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/*
 * Tracks how many cpusets are currently defined in system.
 * When there is only one cpuset (the root cpuset) we can
 * short circuit some hooks.
 */
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int number_of_cpusets __read_mostly;
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/* See "Frequency meter" comments, below. */

struct fmeter {
	int cnt;		/* unprocessed events count */
	int val;		/* most recent output value */
	time_t time;		/* clock (secs) when val computed */
	spinlock_t lock;	/* guards read or write of above */
};

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struct cpuset {
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	struct cgroup_subsys_state css;

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	unsigned long flags;		/* "unsigned long" so bitops work */
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	cpumask_var_t cpus_allowed;	/* CPUs allowed to tasks in cpuset */
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	nodemask_t mems_allowed;	/* Memory Nodes allowed to tasks */

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	/*
	 * This is old Memory Nodes tasks took on.
	 *
	 * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
	 * - A new cpuset's old_mems_allowed is initialized when some
	 *   task is moved into it.
	 * - old_mems_allowed is used in cpuset_migrate_mm() when we change
	 *   cpuset.mems_allowed and have tasks' nodemask updated, and
	 *   then old_mems_allowed is updated to mems_allowed.
	 */
	nodemask_t old_mems_allowed;

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	struct fmeter fmeter;		/* memory_pressure filter */
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	/*
	 * Tasks are being attached to this cpuset.  Used to prevent
	 * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
	 */
	int attach_in_progress;

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	/* partition number for rebuild_sched_domains() */
	int pn;
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	/* for custom sched domain */
	int relax_domain_level;
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};

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static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
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{
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	return css ? container_of(css, struct cpuset, css) : NULL;
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}

/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
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	return css_cs(task_css(task, cpuset_cgrp_id));
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}

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static inline struct cpuset *parent_cs(struct cpuset *cs)
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{
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	return css_cs(css_parent(&cs->css));
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}

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#ifdef CONFIG_NUMA
static inline bool task_has_mempolicy(struct task_struct *task)
{
	return task->mempolicy;
}
#else
static inline bool task_has_mempolicy(struct task_struct *task)
{
	return false;
}
#endif


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/* bits in struct cpuset flags field */
typedef enum {
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	CS_ONLINE,
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	CS_CPU_EXCLUSIVE,
	CS_MEM_EXCLUSIVE,
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	CS_MEM_HARDWALL,
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	CS_MEMORY_MIGRATE,
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	CS_SCHED_LOAD_BALANCE,
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	CS_SPREAD_PAGE,
	CS_SPREAD_SLAB,
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} cpuset_flagbits_t;

/* convenient tests for these bits */
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static inline bool is_cpuset_online(const struct cpuset *cs)
{
	return test_bit(CS_ONLINE, &cs->flags);
}

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static inline int is_cpu_exclusive(const struct cpuset *cs)
{
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	return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
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}

static inline int is_mem_exclusive(const struct cpuset *cs)
{
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	return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
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}

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static inline int is_mem_hardwall(const struct cpuset *cs)
{
	return test_bit(CS_MEM_HARDWALL, &cs->flags);
}

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static inline int is_sched_load_balance(const struct cpuset *cs)
{
	return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}

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static inline int is_memory_migrate(const struct cpuset *cs)
{
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	return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
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}

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static inline int is_spread_page(const struct cpuset *cs)
{
	return test_bit(CS_SPREAD_PAGE, &cs->flags);
}

static inline int is_spread_slab(const struct cpuset *cs)
{
	return test_bit(CS_SPREAD_SLAB, &cs->flags);
}

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static struct cpuset top_cpuset = {
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	.flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
		  (1 << CS_MEM_EXCLUSIVE)),
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};

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/**
 * cpuset_for_each_child - traverse online children of a cpuset
 * @child_cs: loop cursor pointing to the current child
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 * @pos_css: used for iteration
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 * @parent_cs: target cpuset to walk children of
 *
 * Walk @child_cs through the online children of @parent_cs.  Must be used
 * with RCU read locked.
 */
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#define cpuset_for_each_child(child_cs, pos_css, parent_cs)		\
	css_for_each_child((pos_css), &(parent_cs)->css)		\
		if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
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/**
 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
 * @des_cs: loop cursor pointing to the current descendant
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 * @pos_css: used for iteration
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 * @root_cs: target cpuset to walk ancestor of
 *
 * Walk @des_cs through the online descendants of @root_cs.  Must be used
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 * with RCU read locked.  The caller may modify @pos_css by calling
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 * css_rightmost_descendant() to skip subtree.  @root_cs is included in the
 * iteration and the first node to be visited.
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 */
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#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs)	\
	css_for_each_descendant_pre((pos_css), &(root_cs)->css)		\
		if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
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/*
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 * There are two global mutexes guarding cpuset structures - cpuset_mutex
 * and callback_mutex.  The latter may nest inside the former.  We also
 * require taking task_lock() when dereferencing a task's cpuset pointer.
 * See "The task_lock() exception", at the end of this comment.
 *
 * A task must hold both mutexes to modify cpusets.  If a task holds
 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
 * is the only task able to also acquire callback_mutex and be able to
 * modify cpusets.  It can perform various checks on the cpuset structure
 * first, knowing nothing will change.  It can also allocate memory while
 * just holding cpuset_mutex.  While it is performing these checks, various
 * callback routines can briefly acquire callback_mutex to query cpusets.
 * Once it is ready to make the changes, it takes callback_mutex, blocking
 * everyone else.
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 *
 * Calls to the kernel memory allocator can not be made while holding
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 * callback_mutex, as that would risk double tripping on callback_mutex
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 * from one of the callbacks into the cpuset code from within
 * __alloc_pages().
 *
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 * If a task is only holding callback_mutex, then it has read-only
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 * access to cpusets.
 *
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 * Now, the task_struct fields mems_allowed and mempolicy may be changed
 * by other task, we use alloc_lock in the task_struct fields to protect
 * them.
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 *
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 * The cpuset_common_file_read() handlers only hold callback_mutex across
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 * small pieces of code, such as when reading out possibly multi-word
 * cpumasks and nodemasks.
 *
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 * Accessing a task's cpuset should be done in accordance with the
 * guidelines for accessing subsystem state in kernel/cgroup.c
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 */

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static DEFINE_MUTEX(cpuset_mutex);
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static DEFINE_MUTEX(callback_mutex);
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/*
 * CPU / memory hotplug is handled asynchronously.
 */
static void cpuset_hotplug_workfn(struct work_struct *work);
static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);

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static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);

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/*
 * This is ugly, but preserves the userspace API for existing cpuset
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 * users. If someone tries to mount the "cpuset" filesystem, we
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 * silently switch it to mount "cgroup" instead
 */
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static struct dentry *cpuset_mount(struct file_system_type *fs_type,
			 int flags, const char *unused_dev_name, void *data)
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{
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	struct file_system_type *cgroup_fs = get_fs_type("cgroup");
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	struct dentry *ret = ERR_PTR(-ENODEV);
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	if (cgroup_fs) {
		char mountopts[] =
			"cpuset,noprefix,"
			"release_agent=/sbin/cpuset_release_agent";
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		ret = cgroup_fs->mount(cgroup_fs, flags,
					   unused_dev_name, mountopts);
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		put_filesystem(cgroup_fs);
	}
	return ret;
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}

static struct file_system_type cpuset_fs_type = {
	.name = "cpuset",
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	.mount = cpuset_mount,
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};

/*
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 * Return in pmask the portion of a cpusets's cpus_allowed that
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 * are online.  If none are online, walk up the cpuset hierarchy
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 * until we find one that does have some online cpus.  The top
 * cpuset always has some cpus online.
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of cpu_online_mask.
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 *
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 * Call with callback_mutex held.
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 */
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static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
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{
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	while (!cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
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		cs = parent_cs(cs);
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	cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
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}

/*
 * Return in *pmask the portion of a cpusets's mems_allowed that
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 * are online, with memory.  If none are online with memory, walk
 * up the cpuset hierarchy until we find one that does have some
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 * online mems.  The top cpuset always has some mems online.
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of node_states[N_MEMORY].
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 *
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 * Call with callback_mutex held.
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 */
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static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
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{
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	while (!nodes_intersects(cs->mems_allowed, node_states[N_MEMORY]))
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		cs = parent_cs(cs);
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	nodes_and(*pmask, cs->mems_allowed, node_states[N_MEMORY]);
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}

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/*
 * update task's spread flag if cpuset's page/slab spread flag is set
 *
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 * Called with callback_mutex/cpuset_mutex held
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 */
static void cpuset_update_task_spread_flag(struct cpuset *cs,
					struct task_struct *tsk)
{
	if (is_spread_page(cs))
		tsk->flags |= PF_SPREAD_PAGE;
	else
		tsk->flags &= ~PF_SPREAD_PAGE;
	if (is_spread_slab(cs))
		tsk->flags |= PF_SPREAD_SLAB;
	else
		tsk->flags &= ~PF_SPREAD_SLAB;
}

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/*
 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
 *
 * One cpuset is a subset of another if all its allowed CPUs and
 * Memory Nodes are a subset of the other, and its exclusive flags
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 * are only set if the other's are set.  Call holding cpuset_mutex.
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 */

static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
{
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	return	cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
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		nodes_subset(p->mems_allowed, q->mems_allowed) &&
		is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
		is_mem_exclusive(p) <= is_mem_exclusive(q);
}

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/**
 * alloc_trial_cpuset - allocate a trial cpuset
 * @cs: the cpuset that the trial cpuset duplicates
 */
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static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
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{
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	struct cpuset *trial;

	trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
	if (!trial)
		return NULL;

	if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
		kfree(trial);
		return NULL;
	}
	cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);

	return trial;
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}

/**
 * free_trial_cpuset - free the trial cpuset
 * @trial: the trial cpuset to be freed
 */
static void free_trial_cpuset(struct cpuset *trial)
{
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	free_cpumask_var(trial->cpus_allowed);
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	kfree(trial);
}

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/*
 * validate_change() - Used to validate that any proposed cpuset change
 *		       follows the structural rules for cpusets.
 *
 * If we replaced the flag and mask values of the current cpuset
 * (cur) with those values in the trial cpuset (trial), would
 * our various subset and exclusive rules still be valid?  Presumes
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 * cpuset_mutex held.
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 *
 * 'cur' is the address of an actual, in-use cpuset.  Operations
 * such as list traversal that depend on the actual address of the
 * cpuset in the list must use cur below, not trial.
 *
 * 'trial' is the address of bulk structure copy of cur, with
 * perhaps one or more of the fields cpus_allowed, mems_allowed,
 * or flags changed to new, trial values.
 *
 * Return 0 if valid, -errno if not.
 */

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static int validate_change(struct cpuset *cur, struct cpuset *trial)
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{
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	struct cgroup_subsys_state *css;
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	struct cpuset *c, *par;
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	int ret;

	rcu_read_lock();
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	/* Each of our child cpusets must be a subset of us */
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	ret = -EBUSY;
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	cpuset_for_each_child(c, css, cur)
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		if (!is_cpuset_subset(c, trial))
			goto out;
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	/* Remaining checks don't apply to root cpuset */
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	ret = 0;
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	if (cur == &top_cpuset)
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		goto out;
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	par = parent_cs(cur);
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	/* We must be a subset of our parent cpuset */
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	ret = -EACCES;
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	if (!is_cpuset_subset(trial, par))
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		goto out;
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	/*
	 * If either I or some sibling (!= me) is exclusive, we can't
	 * overlap
	 */
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	ret = -EINVAL;
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	cpuset_for_each_child(c, css, par) {
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		if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
		    c != cur &&
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		    cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
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			goto out;
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		if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
		    c != cur &&
		    nodes_intersects(trial->mems_allowed, c->mems_allowed))
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			goto out;
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	}

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	/*
	 * Cpusets with tasks - existing or newly being attached - can't
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	 * be changed to have empty cpus_allowed or mems_allowed.
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	 */
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	ret = -ENOSPC;
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	if ((cgroup_has_tasks(cur->css.cgroup) || cur->attach_in_progress)) {
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		if (!cpumask_empty(cur->cpus_allowed) &&
		    cpumask_empty(trial->cpus_allowed))
			goto out;
		if (!nodes_empty(cur->mems_allowed) &&
		    nodes_empty(trial->mems_allowed))
			goto out;
	}
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	ret = 0;
out:
	rcu_read_unlock();
	return ret;
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}

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#ifdef CONFIG_SMP
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/*
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 * Helper routine for generate_sched_domains().
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 * Do cpusets a, b have overlapping cpus_allowed masks?
 */
static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
{
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	return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
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}

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static void
update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
{
	if (dattr->relax_domain_level < c->relax_domain_level)
		dattr->relax_domain_level = c->relax_domain_level;
	return;
}

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static void update_domain_attr_tree(struct sched_domain_attr *dattr,
				    struct cpuset *root_cs)
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{
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	struct cpuset *cp;
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	struct cgroup_subsys_state *pos_css;
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	rcu_read_lock();
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	cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
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		if (cp == root_cs)
			continue;

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		/* skip the whole subtree if @cp doesn't have any CPU */
		if (cpumask_empty(cp->cpus_allowed)) {
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			pos_css = css_rightmost_descendant(pos_css);
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			continue;
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		}
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		if (is_sched_load_balance(cp))
			update_domain_attr(dattr, cp);
	}
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	rcu_read_unlock();
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}

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/*
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 * generate_sched_domains()
 *
 * This function builds a partial partition of the systems CPUs
 * A 'partial partition' is a set of non-overlapping subsets whose
 * union is a subset of that set.
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 * The output of this function needs to be passed to kernel/sched/core.c
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 * partition_sched_domains() routine, which will rebuild the scheduler's
 * load balancing domains (sched domains) as specified by that partial
 * partition.
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 *
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 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
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 * for a background explanation of this.
 *
 * Does not return errors, on the theory that the callers of this
 * routine would rather not worry about failures to rebuild sched
 * domains when operating in the severe memory shortage situations
 * that could cause allocation failures below.
 *
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 * Must be called with cpuset_mutex held.
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 *
 * The three key local variables below are:
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 *    q  - a linked-list queue of cpuset pointers, used to implement a
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 *	   top-down scan of all cpusets.  This scan loads a pointer
 *	   to each cpuset marked is_sched_load_balance into the
 *	   array 'csa'.  For our purposes, rebuilding the schedulers
 *	   sched domains, we can ignore !is_sched_load_balance cpusets.
 *  csa  - (for CpuSet Array) Array of pointers to all the cpusets
 *	   that need to be load balanced, for convenient iterative
 *	   access by the subsequent code that finds the best partition,
 *	   i.e the set of domains (subsets) of CPUs such that the
 *	   cpus_allowed of every cpuset marked is_sched_load_balance
 *	   is a subset of one of these domains, while there are as
 *	   many such domains as possible, each as small as possible.
 * doms  - Conversion of 'csa' to an array of cpumasks, for passing to
561
 *	   the kernel/sched/core.c routine partition_sched_domains() in a
P
Paul Jackson 已提交
562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579
 *	   convenient format, that can be easily compared to the prior
 *	   value to determine what partition elements (sched domains)
 *	   were changed (added or removed.)
 *
 * Finding the best partition (set of domains):
 *	The triple nested loops below over i, j, k scan over the
 *	load balanced cpusets (using the array of cpuset pointers in
 *	csa[]) looking for pairs of cpusets that have overlapping
 *	cpus_allowed, but which don't have the same 'pn' partition
 *	number and gives them in the same partition number.  It keeps
 *	looping on the 'restart' label until it can no longer find
 *	any such pairs.
 *
 *	The union of the cpus_allowed masks from the set of
 *	all cpusets having the same 'pn' value then form the one
 *	element of the partition (one sched domain) to be passed to
 *	partition_sched_domains().
 */
580
static int generate_sched_domains(cpumask_var_t **domains,
581
			struct sched_domain_attr **attributes)
P
Paul Jackson 已提交
582 583 584 585 586
{
	struct cpuset *cp;	/* scans q */
	struct cpuset **csa;	/* array of all cpuset ptrs */
	int csn;		/* how many cpuset ptrs in csa so far */
	int i, j, k;		/* indices for partition finding loops */
587
	cpumask_var_t *doms;	/* resulting partition; i.e. sched domains */
588
	struct sched_domain_attr *dattr;  /* attributes for custom domains */
589
	int ndoms = 0;		/* number of sched domains in result */
590
	int nslot;		/* next empty doms[] struct cpumask slot */
591
	struct cgroup_subsys_state *pos_css;
P
Paul Jackson 已提交
592 593

	doms = NULL;
594
	dattr = NULL;
595
	csa = NULL;
P
Paul Jackson 已提交
596 597 598

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
599 600
		ndoms = 1;
		doms = alloc_sched_domains(ndoms);
P
Paul Jackson 已提交
601
		if (!doms)
602 603
			goto done;

604 605 606
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
607
			update_domain_attr_tree(dattr, &top_cpuset);
608
		}
609
		cpumask_copy(doms[0], top_cpuset.cpus_allowed);
610 611

		goto done;
P
Paul Jackson 已提交
612 613 614 615 616 617 618
	}

	csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
	if (!csa)
		goto done;
	csn = 0;

619
	rcu_read_lock();
620
	cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
621 622
		if (cp == &top_cpuset)
			continue;
623
		/*
624 625 626 627 628 629
		 * Continue traversing beyond @cp iff @cp has some CPUs and
		 * isn't load balancing.  The former is obvious.  The
		 * latter: All child cpusets contain a subset of the
		 * parent's cpus, so just skip them, and then we call
		 * update_domain_attr_tree() to calc relax_domain_level of
		 * the corresponding sched domain.
630
		 */
631 632
		if (!cpumask_empty(cp->cpus_allowed) &&
		    !is_sched_load_balance(cp))
633
			continue;
634

635 636 637 638
		if (is_sched_load_balance(cp))
			csa[csn++] = cp;

		/* skip @cp's subtree */
639
		pos_css = css_rightmost_descendant(pos_css);
640 641
	}
	rcu_read_unlock();
P
Paul Jackson 已提交
642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669

	for (i = 0; i < csn; i++)
		csa[i]->pn = i;
	ndoms = csn;

restart:
	/* Find the best partition (set of sched domains) */
	for (i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
		int apn = a->pn;

		for (j = 0; j < csn; j++) {
			struct cpuset *b = csa[j];
			int bpn = b->pn;

			if (apn != bpn && cpusets_overlap(a, b)) {
				for (k = 0; k < csn; k++) {
					struct cpuset *c = csa[k];

					if (c->pn == bpn)
						c->pn = apn;
				}
				ndoms--;	/* one less element */
				goto restart;
			}
		}
	}

670 671 672 673
	/*
	 * Now we know how many domains to create.
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
	 */
674
	doms = alloc_sched_domains(ndoms);
675
	if (!doms)
676 677 678 679 680 681
		goto done;

	/*
	 * The rest of the code, including the scheduler, can deal with
	 * dattr==NULL case. No need to abort if alloc fails.
	 */
682
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
P
Paul Jackson 已提交
683 684 685

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
686
		struct cpumask *dp;
P
Paul Jackson 已提交
687 688
		int apn = a->pn;

689 690 691 692 693
		if (apn < 0) {
			/* Skip completed partitions */
			continue;
		}

694
		dp = doms[nslot];
695 696 697 698

		if (nslot == ndoms) {
			static int warnings = 10;
			if (warnings) {
699 700
				pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
					nslot, ndoms, csn, i, apn);
701
				warnings--;
P
Paul Jackson 已提交
702
			}
703 704
			continue;
		}
P
Paul Jackson 已提交
705

706
		cpumask_clear(dp);
707 708 709 710 711 712
		if (dattr)
			*(dattr + nslot) = SD_ATTR_INIT;
		for (j = i; j < csn; j++) {
			struct cpuset *b = csa[j];

			if (apn == b->pn) {
713
				cpumask_or(dp, dp, b->cpus_allowed);
714 715 716 717 718
				if (dattr)
					update_domain_attr_tree(dattr + nslot, b);

				/* Done with this partition */
				b->pn = -1;
P
Paul Jackson 已提交
719 720
			}
		}
721
		nslot++;
P
Paul Jackson 已提交
722 723 724
	}
	BUG_ON(nslot != ndoms);

725 726 727
done:
	kfree(csa);

728 729 730 731 732 733 734
	/*
	 * Fallback to the default domain if kmalloc() failed.
	 * See comments in partition_sched_domains().
	 */
	if (doms == NULL)
		ndoms = 1;

735 736 737 738 739 740 741 742
	*domains    = doms;
	*attributes = dattr;
	return ndoms;
}

/*
 * Rebuild scheduler domains.
 *
743 744 745 746 747
 * If the flag 'sched_load_balance' of any cpuset with non-empty
 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
 * which has that flag enabled, or if any cpuset with a non-empty
 * 'cpus' is removed, then call this routine to rebuild the
 * scheduler's dynamic sched domains.
748
 *
749
 * Call with cpuset_mutex held.  Takes get_online_cpus().
750
 */
751
static void rebuild_sched_domains_locked(void)
752 753
{
	struct sched_domain_attr *attr;
754
	cpumask_var_t *doms;
755 756
	int ndoms;

757
	lockdep_assert_held(&cpuset_mutex);
758
	get_online_cpus();
759

760 761 762 763 764 765 766 767
	/*
	 * We have raced with CPU hotplug. Don't do anything to avoid
	 * passing doms with offlined cpu to partition_sched_domains().
	 * Anyways, hotplug work item will rebuild sched domains.
	 */
	if (!cpumask_equal(top_cpuset.cpus_allowed, cpu_active_mask))
		goto out;

768 769 770 771 772
	/* Generate domain masks and attrs */
	ndoms = generate_sched_domains(&doms, &attr);

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);
773
out:
774
	put_online_cpus();
775
}
776
#else /* !CONFIG_SMP */
777
static void rebuild_sched_domains_locked(void)
778 779 780
{
}
#endif /* CONFIG_SMP */
P
Paul Jackson 已提交
781

782 783
void rebuild_sched_domains(void)
{
784
	mutex_lock(&cpuset_mutex);
785
	rebuild_sched_domains_locked();
786
	mutex_unlock(&cpuset_mutex);
P
Paul Jackson 已提交
787 788
}

789 790 791
/*
 * effective_cpumask_cpuset - return nearest ancestor with non-empty cpus
 * @cs: the cpuset in interest
C
Cliff Wickman 已提交
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
 * A cpuset's effective cpumask is the cpumask of the nearest ancestor
 * with non-empty cpus. We use effective cpumask whenever:
 * - we update tasks' cpus_allowed. (they take on the ancestor's cpumask
 *   if the cpuset they reside in has no cpus)
 * - we want to retrieve task_cs(tsk)'s cpus_allowed.
 *
 * Called with cpuset_mutex held. cpuset_cpus_allowed_fallback() is an
 * exception. See comments there.
 */
static struct cpuset *effective_cpumask_cpuset(struct cpuset *cs)
{
	while (cpumask_empty(cs->cpus_allowed))
		cs = parent_cs(cs);
	return cs;
}

/*
 * effective_nodemask_cpuset - return nearest ancestor with non-empty mems
 * @cs: the cpuset in interest
 *
 * A cpuset's effective nodemask is the nodemask of the nearest ancestor
 * with non-empty memss. We use effective nodemask whenever:
 * - we update tasks' mems_allowed. (they take on the ancestor's nodemask
 *   if the cpuset they reside in has no mems)
 * - we want to retrieve task_cs(tsk)'s mems_allowed.
 *
 * Called with cpuset_mutex held.
820
 */
821
static struct cpuset *effective_nodemask_cpuset(struct cpuset *cs)
C
Cliff Wickman 已提交
822
{
823 824 825
	while (nodes_empty(cs->mems_allowed))
		cs = parent_cs(cs);
	return cs;
C
Cliff Wickman 已提交
826
}
827

828 829 830 831
/**
 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
 *
832 833 834
 * Iterate through each task of @cs updating its cpus_allowed to the
 * effective cpuset's.  As this function is called with cpuset_mutex held,
 * cpuset membership stays stable.
835
 */
836
static void update_tasks_cpumask(struct cpuset *cs)
837
{
838 839 840 841 842 843 844 845
	struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
	struct css_task_iter it;
	struct task_struct *task;

	css_task_iter_start(&cs->css, &it);
	while ((task = css_task_iter_next(&it)))
		set_cpus_allowed_ptr(task, cpus_cs->cpus_allowed);
	css_task_iter_end(&it);
846 847
}

848 849 850 851 852 853 854 855 856 857
/*
 * update_tasks_cpumask_hier - Update the cpumasks of tasks in the hierarchy.
 * @root_cs: the root cpuset of the hierarchy
 * @update_root: update root cpuset or not?
 *
 * This will update cpumasks of tasks in @root_cs and all other empty cpusets
 * which take on cpumask of @root_cs.
 *
 * Called with cpuset_mutex held
 */
858
static void update_tasks_cpumask_hier(struct cpuset *root_cs, bool update_root)
859 860
{
	struct cpuset *cp;
861
	struct cgroup_subsys_state *pos_css;
862 863

	rcu_read_lock();
864
	cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
865 866 867 868 869 870 871 872 873
		if (cp == root_cs) {
			if (!update_root)
				continue;
		} else {
			/* skip the whole subtree if @cp have some CPU */
			if (!cpumask_empty(cp->cpus_allowed)) {
				pos_css = css_rightmost_descendant(pos_css);
				continue;
			}
874
		}
875
		if (!css_tryget_online(&cp->css))
876 877 878
			continue;
		rcu_read_unlock();

879
		update_tasks_cpumask(cp);
880 881 882 883 884 885 886

		rcu_read_lock();
		css_put(&cp->css);
	}
	rcu_read_unlock();
}

C
Cliff Wickman 已提交
887 888 889
/**
 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 * @cs: the cpuset to consider
890
 * @trialcs: trial cpuset
C
Cliff Wickman 已提交
891 892
 * @buf: buffer of cpu numbers written to this cpuset
 */
893 894
static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
			  const char *buf)
L
Linus Torvalds 已提交
895
{
C
Cliff Wickman 已提交
896 897
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
898

899
	/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
900 901 902
	if (cs == &top_cpuset)
		return -EACCES;

903
	/*
904
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
905 906 907
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
908
	 */
909
	if (!*buf) {
910
		cpumask_clear(trialcs->cpus_allowed);
911
	} else {
912
		retval = cpulist_parse(buf, trialcs->cpus_allowed);
913 914
		if (retval < 0)
			return retval;
915

916
		if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
917
			return -EINVAL;
918
	}
P
Paul Jackson 已提交
919

P
Paul Menage 已提交
920
	/* Nothing to do if the cpus didn't change */
921
	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
P
Paul Menage 已提交
922
		return 0;
C
Cliff Wickman 已提交
923

924 925 926 927
	retval = validate_change(cs, trialcs);
	if (retval < 0)
		return retval;

928
	is_load_balanced = is_sched_load_balance(trialcs);
P
Paul Jackson 已提交
929

930
	mutex_lock(&callback_mutex);
931
	cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
932
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
933

934
	update_tasks_cpumask_hier(cs, true);
C
Cliff Wickman 已提交
935

P
Paul Menage 已提交
936
	if (is_load_balanced)
937
		rebuild_sched_domains_locked();
938
	return 0;
L
Linus Torvalds 已提交
939 940
}

941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958
/*
 * cpuset_migrate_mm
 *
 *    Migrate memory region from one set of nodes to another.
 *
 *    Temporarilly set tasks mems_allowed to target nodes of migration,
 *    so that the migration code can allocate pages on these nodes.
 *
 *    While the mm_struct we are migrating is typically from some
 *    other task, the task_struct mems_allowed that we are hacking
 *    is for our current task, which must allocate new pages for that
 *    migrating memory region.
 */

static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
							const nodemask_t *to)
{
	struct task_struct *tsk = current;
959
	struct cpuset *mems_cs;
960 961 962 963 964

	tsk->mems_allowed = *to;

	do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);

965
	rcu_read_lock();
966 967
	mems_cs = effective_nodemask_cpuset(task_cs(tsk));
	guarantee_online_mems(mems_cs, &tsk->mems_allowed);
968
	rcu_read_unlock();
969 970
}

971
/*
972 973 974 975 976 977 978 979 980 981 982
 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
 * @tsk: the task to change
 * @newmems: new nodes that the task will be set
 *
 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
 * we structure updates as setting all new allowed nodes, then clearing newly
 * disallowed ones.
 */
static void cpuset_change_task_nodemask(struct task_struct *tsk,
					nodemask_t *newmems)
{
983
	bool need_loop;
984

985 986 987 988 989 990 991 992 993 994
	/*
	 * Allow tasks that have access to memory reserves because they have
	 * been OOM killed to get memory anywhere.
	 */
	if (unlikely(test_thread_flag(TIF_MEMDIE)))
		return;
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return;

	task_lock(tsk);
995 996
	/*
	 * Determine if a loop is necessary if another thread is doing
997
	 * read_mems_allowed_begin().  If at least one node remains unchanged and
998 999 1000 1001 1002
	 * tsk does not have a mempolicy, then an empty nodemask will not be
	 * possible when mems_allowed is larger than a word.
	 */
	need_loop = task_has_mempolicy(tsk) ||
			!nodes_intersects(*newmems, tsk->mems_allowed);
1003

1004 1005
	if (need_loop) {
		local_irq_disable();
1006
		write_seqcount_begin(&tsk->mems_allowed_seq);
1007
	}
1008

1009 1010
	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
1011 1012

	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1013
	tsk->mems_allowed = *newmems;
1014

1015
	if (need_loop) {
1016
		write_seqcount_end(&tsk->mems_allowed_seq);
1017 1018
		local_irq_enable();
	}
1019

1020
	task_unlock(tsk);
1021 1022
}

1023 1024
static void *cpuset_being_rebound;

1025 1026 1027 1028
/**
 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
 *
1029 1030 1031
 * Iterate through each task of @cs updating its mems_allowed to the
 * effective cpuset's.  As this function is called with cpuset_mutex held,
 * cpuset membership stays stable.
1032
 */
1033
static void update_tasks_nodemask(struct cpuset *cs)
L
Linus Torvalds 已提交
1034
{
1035
	static nodemask_t newmems;	/* protected by cpuset_mutex */
1036
	struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
1037 1038
	struct css_task_iter it;
	struct task_struct *task;
1039

1040
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
1041

1042
	guarantee_online_mems(mems_cs, &newmems);
1043

1044
	/*
1045 1046 1047 1048
	 * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
	 * take while holding tasklist_lock.  Forks can happen - the
	 * mpol_dup() cpuset_being_rebound check will catch such forks,
	 * and rebind their vma mempolicies too.  Because we still hold
1049
	 * the global cpuset_mutex, we know that no other rebind effort
1050
	 * will be contending for the global variable cpuset_being_rebound.
1051
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1052
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1053
	 */
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
	css_task_iter_start(&cs->css, &it);
	while ((task = css_task_iter_next(&it))) {
		struct mm_struct *mm;
		bool migrate;

		cpuset_change_task_nodemask(task, &newmems);

		mm = get_task_mm(task);
		if (!mm)
			continue;

		migrate = is_memory_migrate(cs);

		mpol_rebind_mm(mm, &cs->mems_allowed);
		if (migrate)
			cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
		mmput(mm);
	}
	css_task_iter_end(&it);
1073

1074 1075 1076 1077 1078 1079
	/*
	 * All the tasks' nodemasks have been updated, update
	 * cs->old_mems_allowed.
	 */
	cs->old_mems_allowed = newmems;

1080
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1081
	cpuset_being_rebound = NULL;
L
Linus Torvalds 已提交
1082 1083
}

1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
/*
 * update_tasks_nodemask_hier - Update the nodemasks of tasks in the hierarchy.
 * @cs: the root cpuset of the hierarchy
 * @update_root: update the root cpuset or not?
 *
 * This will update nodemasks of tasks in @root_cs and all other empty cpusets
 * which take on nodemask of @root_cs.
 *
 * Called with cpuset_mutex held
 */
1094
static void update_tasks_nodemask_hier(struct cpuset *root_cs, bool update_root)
1095 1096
{
	struct cpuset *cp;
1097
	struct cgroup_subsys_state *pos_css;
1098 1099

	rcu_read_lock();
1100
	cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
1101 1102 1103 1104 1105 1106 1107 1108 1109
		if (cp == root_cs) {
			if (!update_root)
				continue;
		} else {
			/* skip the whole subtree if @cp have some CPU */
			if (!nodes_empty(cp->mems_allowed)) {
				pos_css = css_rightmost_descendant(pos_css);
				continue;
			}
1110
		}
1111
		if (!css_tryget_online(&cp->css))
1112 1113 1114
			continue;
		rcu_read_unlock();

1115
		update_tasks_nodemask(cp);
1116 1117 1118 1119 1120 1121 1122

		rcu_read_lock();
		css_put(&cp->css);
	}
	rcu_read_unlock();
}

1123 1124 1125
/*
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
1126 1127 1128 1129
 * cpusets mems_allowed, and for each task in the cpuset,
 * update mems_allowed and rebind task's mempolicy and any vma
 * mempolicies and if the cpuset is marked 'memory_migrate',
 * migrate the tasks pages to the new memory.
1130
 *
1131
 * Call with cpuset_mutex held.  May take callback_mutex during call.
1132 1133 1134 1135
 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
 * their mempolicies to the cpusets new mems_allowed.
 */
1136 1137
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
			   const char *buf)
1138 1139 1140 1141
{
	int retval;

	/*
1142
	 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1143 1144
	 * it's read-only
	 */
1145 1146 1147 1148
	if (cs == &top_cpuset) {
		retval = -EACCES;
		goto done;
	}
1149 1150 1151 1152 1153 1154 1155 1156

	/*
	 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
	 * Since nodelist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have memory.
	 */
	if (!*buf) {
1157
		nodes_clear(trialcs->mems_allowed);
1158
	} else {
1159
		retval = nodelist_parse(buf, trialcs->mems_allowed);
1160 1161 1162
		if (retval < 0)
			goto done;

1163
		if (!nodes_subset(trialcs->mems_allowed,
1164
				node_states[N_MEMORY])) {
1165 1166 1167
			retval =  -EINVAL;
			goto done;
		}
1168
	}
1169 1170

	if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
1171 1172 1173
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
1174
	retval = validate_change(cs, trialcs);
1175 1176 1177 1178
	if (retval < 0)
		goto done;

	mutex_lock(&callback_mutex);
1179
	cs->mems_allowed = trialcs->mems_allowed;
1180 1181
	mutex_unlock(&callback_mutex);

1182
	update_tasks_nodemask_hier(cs, true);
1183 1184 1185 1186
done:
	return retval;
}

1187 1188 1189 1190 1191
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1192
static int update_relax_domain_level(struct cpuset *cs, s64 val)
1193
{
1194
#ifdef CONFIG_SMP
1195
	if (val < -1 || val >= sched_domain_level_max)
1196
		return -EINVAL;
1197
#endif
1198 1199 1200

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
1201 1202
		if (!cpumask_empty(cs->cpus_allowed) &&
		    is_sched_load_balance(cs))
1203
			rebuild_sched_domains_locked();
1204 1205 1206 1207 1208
	}

	return 0;
}

1209
/**
1210 1211 1212
 * update_tasks_flags - update the spread flags of tasks in the cpuset.
 * @cs: the cpuset in which each task's spread flags needs to be changed
 *
1213 1214 1215
 * Iterate through each task of @cs updating its spread flags.  As this
 * function is called with cpuset_mutex held, cpuset membership stays
 * stable.
1216
 */
1217
static void update_tasks_flags(struct cpuset *cs)
1218
{
1219 1220 1221 1222 1223 1224 1225
	struct css_task_iter it;
	struct task_struct *task;

	css_task_iter_start(&cs->css, &it);
	while ((task = css_task_iter_next(&it)))
		cpuset_update_task_spread_flag(cs, task);
	css_task_iter_end(&it);
1226 1227
}

L
Linus Torvalds 已提交
1228 1229
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
1230 1231 1232
 * bit:		the bit to update (see cpuset_flagbits_t)
 * cs:		the cpuset to update
 * turning_on: 	whether the flag is being set or cleared
1233
 *
1234
 * Call with cpuset_mutex held.
L
Linus Torvalds 已提交
1235 1236
 */

1237 1238
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1239
{
1240
	struct cpuset *trialcs;
R
Rakib Mullick 已提交
1241
	int balance_flag_changed;
1242 1243
	int spread_flag_changed;
	int err;
L
Linus Torvalds 已提交
1244

1245 1246 1247 1248
	trialcs = alloc_trial_cpuset(cs);
	if (!trialcs)
		return -ENOMEM;

L
Linus Torvalds 已提交
1249
	if (turning_on)
1250
		set_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1251
	else
1252
		clear_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1253

1254
	err = validate_change(cs, trialcs);
1255
	if (err < 0)
1256
		goto out;
P
Paul Jackson 已提交
1257 1258

	balance_flag_changed = (is_sched_load_balance(cs) !=
1259
				is_sched_load_balance(trialcs));
P
Paul Jackson 已提交
1260

1261 1262 1263
	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
			|| (is_spread_page(cs) != is_spread_page(trialcs)));

1264
	mutex_lock(&callback_mutex);
1265
	cs->flags = trialcs->flags;
1266
	mutex_unlock(&callback_mutex);
1267

1268
	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1269
		rebuild_sched_domains_locked();
P
Paul Jackson 已提交
1270

1271
	if (spread_flag_changed)
1272
		update_tasks_flags(cs);
1273 1274 1275
out:
	free_trial_cpuset(trialcs);
	return err;
L
Linus Torvalds 已提交
1276 1277
}

1278
/*
A
Adrian Bunk 已提交
1279
 * Frequency meter - How fast is some event occurring?
1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375
 *
 * These routines manage a digitally filtered, constant time based,
 * event frequency meter.  There are four routines:
 *   fmeter_init() - initialize a frequency meter.
 *   fmeter_markevent() - called each time the event happens.
 *   fmeter_getrate() - returns the recent rate of such events.
 *   fmeter_update() - internal routine used to update fmeter.
 *
 * A common data structure is passed to each of these routines,
 * which is used to keep track of the state required to manage the
 * frequency meter and its digital filter.
 *
 * The filter works on the number of events marked per unit time.
 * The filter is single-pole low-pass recursive (IIR).  The time unit
 * is 1 second.  Arithmetic is done using 32-bit integers scaled to
 * simulate 3 decimal digits of precision (multiplied by 1000).
 *
 * With an FM_COEF of 933, and a time base of 1 second, the filter
 * has a half-life of 10 seconds, meaning that if the events quit
 * happening, then the rate returned from the fmeter_getrate()
 * will be cut in half each 10 seconds, until it converges to zero.
 *
 * It is not worth doing a real infinitely recursive filter.  If more
 * than FM_MAXTICKS ticks have elapsed since the last filter event,
 * just compute FM_MAXTICKS ticks worth, by which point the level
 * will be stable.
 *
 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
 * arithmetic overflow in the fmeter_update() routine.
 *
 * Given the simple 32 bit integer arithmetic used, this meter works
 * best for reporting rates between one per millisecond (msec) and
 * one per 32 (approx) seconds.  At constant rates faster than one
 * per msec it maxes out at values just under 1,000,000.  At constant
 * rates between one per msec, and one per second it will stabilize
 * to a value N*1000, where N is the rate of events per second.
 * At constant rates between one per second and one per 32 seconds,
 * it will be choppy, moving up on the seconds that have an event,
 * and then decaying until the next event.  At rates slower than
 * about one in 32 seconds, it decays all the way back to zero between
 * each event.
 */

#define FM_COEF 933		/* coefficient for half-life of 10 secs */
#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
#define FM_MAXCNT 1000000	/* limit cnt to avoid overflow */
#define FM_SCALE 1000		/* faux fixed point scale */

/* Initialize a frequency meter */
static void fmeter_init(struct fmeter *fmp)
{
	fmp->cnt = 0;
	fmp->val = 0;
	fmp->time = 0;
	spin_lock_init(&fmp->lock);
}

/* Internal meter update - process cnt events and update value */
static void fmeter_update(struct fmeter *fmp)
{
	time_t now = get_seconds();
	time_t ticks = now - fmp->time;

	if (ticks == 0)
		return;

	ticks = min(FM_MAXTICKS, ticks);
	while (ticks-- > 0)
		fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
	fmp->time = now;

	fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
	fmp->cnt = 0;
}

/* Process any previous ticks, then bump cnt by one (times scale). */
static void fmeter_markevent(struct fmeter *fmp)
{
	spin_lock(&fmp->lock);
	fmeter_update(fmp);
	fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
	spin_unlock(&fmp->lock);
}

/* Process any previous ticks, then return current value. */
static int fmeter_getrate(struct fmeter *fmp)
{
	int val;

	spin_lock(&fmp->lock);
	fmeter_update(fmp);
	val = fmp->val;
	spin_unlock(&fmp->lock);
	return val;
}

1376 1377
static struct cpuset *cpuset_attach_old_cs;

1378
/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
1379 1380
static int cpuset_can_attach(struct cgroup_subsys_state *css,
			     struct cgroup_taskset *tset)
1381
{
1382
	struct cpuset *cs = css_cs(css);
1383 1384
	struct task_struct *task;
	int ret;
L
Linus Torvalds 已提交
1385

1386 1387 1388
	/* used later by cpuset_attach() */
	cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));

1389 1390
	mutex_lock(&cpuset_mutex);

1391 1392 1393 1394
	/*
	 * We allow to move tasks into an empty cpuset if sane_behavior
	 * flag is set.
	 */
1395
	ret = -ENOSPC;
1396
	if (!cgroup_sane_behavior(css->cgroup) &&
1397
	    (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
1398
		goto out_unlock;
1399

1400
	cgroup_taskset_for_each(task, tset) {
1401
		/*
1402 1403 1404 1405 1406 1407 1408
		 * Kthreads which disallow setaffinity shouldn't be moved
		 * to a new cpuset; we don't want to change their cpu
		 * affinity and isolating such threads by their set of
		 * allowed nodes is unnecessary.  Thus, cpusets are not
		 * applicable for such threads.  This prevents checking for
		 * success of set_cpus_allowed_ptr() on all attached tasks
		 * before cpus_allowed may be changed.
1409
		 */
1410
		ret = -EINVAL;
1411
		if (task->flags & PF_NO_SETAFFINITY)
1412 1413 1414 1415
			goto out_unlock;
		ret = security_task_setscheduler(task);
		if (ret)
			goto out_unlock;
1416
	}
1417

1418 1419 1420 1421 1422
	/*
	 * Mark attach is in progress.  This makes validate_change() fail
	 * changes which zero cpus/mems_allowed.
	 */
	cs->attach_in_progress++;
1423 1424 1425 1426
	ret = 0;
out_unlock:
	mutex_unlock(&cpuset_mutex);
	return ret;
1427
}
1428

1429
static void cpuset_cancel_attach(struct cgroup_subsys_state *css,
1430 1431
				 struct cgroup_taskset *tset)
{
1432
	mutex_lock(&cpuset_mutex);
1433
	css_cs(css)->attach_in_progress--;
1434
	mutex_unlock(&cpuset_mutex);
1435
}
L
Linus Torvalds 已提交
1436

1437
/*
1438
 * Protected by cpuset_mutex.  cpus_attach is used only by cpuset_attach()
1439 1440 1441 1442 1443
 * but we can't allocate it dynamically there.  Define it global and
 * allocate from cpuset_init().
 */
static cpumask_var_t cpus_attach;

1444 1445
static void cpuset_attach(struct cgroup_subsys_state *css,
			  struct cgroup_taskset *tset)
1446
{
1447
	/* static buf protected by cpuset_mutex */
1448
	static nodemask_t cpuset_attach_nodemask_to;
1449
	struct mm_struct *mm;
1450 1451
	struct task_struct *task;
	struct task_struct *leader = cgroup_taskset_first(tset);
1452
	struct cpuset *cs = css_cs(css);
1453
	struct cpuset *oldcs = cpuset_attach_old_cs;
1454 1455
	struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
	struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
1456

1457 1458
	mutex_lock(&cpuset_mutex);

1459 1460 1461 1462
	/* prepare for attach */
	if (cs == &top_cpuset)
		cpumask_copy(cpus_attach, cpu_possible_mask);
	else
1463
		guarantee_online_cpus(cpus_cs, cpus_attach);
1464

1465
	guarantee_online_mems(mems_cs, &cpuset_attach_nodemask_to);
1466

1467
	cgroup_taskset_for_each(task, tset) {
1468 1469 1470 1471 1472 1473 1474 1475 1476
		/*
		 * can_attach beforehand should guarantee that this doesn't
		 * fail.  TODO: have a better way to handle failure here
		 */
		WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));

		cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
		cpuset_update_task_spread_flag(cs, task);
	}
1477

1478 1479 1480 1481 1482
	/*
	 * Change mm, possibly for multiple threads in a threadgroup. This is
	 * expensive and may sleep.
	 */
	cpuset_attach_nodemask_to = cs->mems_allowed;
1483
	mm = get_task_mm(leader);
1484
	if (mm) {
1485 1486
		struct cpuset *mems_oldcs = effective_nodemask_cpuset(oldcs);

1487
		mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1488 1489 1490 1491 1492 1493 1494 1495 1496 1497

		/*
		 * old_mems_allowed is the same with mems_allowed here, except
		 * if this task is being moved automatically due to hotplug.
		 * In that case @mems_allowed has been updated and is empty,
		 * so @old_mems_allowed is the right nodesets that we migrate
		 * mm from.
		 */
		if (is_memory_migrate(cs)) {
			cpuset_migrate_mm(mm, &mems_oldcs->old_mems_allowed,
1498
					  &cpuset_attach_nodemask_to);
1499
		}
1500 1501
		mmput(mm);
	}
1502

1503
	cs->old_mems_allowed = cpuset_attach_nodemask_to;
1504

1505
	cs->attach_in_progress--;
1506 1507
	if (!cs->attach_in_progress)
		wake_up(&cpuset_attach_wq);
1508 1509

	mutex_unlock(&cpuset_mutex);
L
Linus Torvalds 已提交
1510 1511 1512 1513 1514
}

/* The various types of files and directories in a cpuset file system */

typedef enum {
1515
	FILE_MEMORY_MIGRATE,
L
Linus Torvalds 已提交
1516 1517 1518 1519
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
1520
	FILE_MEM_HARDWALL,
P
Paul Jackson 已提交
1521
	FILE_SCHED_LOAD_BALANCE,
1522
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1523 1524
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1525 1526
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
L
Linus Torvalds 已提交
1527 1528
} cpuset_filetype_t;

1529 1530
static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
			    u64 val)
1531
{
1532
	struct cpuset *cs = css_cs(css);
1533
	cpuset_filetype_t type = cft->private;
1534
	int retval = 0;
1535

1536
	mutex_lock(&cpuset_mutex);
1537 1538
	if (!is_cpuset_online(cs)) {
		retval = -ENODEV;
1539
		goto out_unlock;
1540
	}
1541 1542

	switch (type) {
L
Linus Torvalds 已提交
1543
	case FILE_CPU_EXCLUSIVE:
1544
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1545 1546
		break;
	case FILE_MEM_EXCLUSIVE:
1547
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1548
		break;
1549 1550 1551
	case FILE_MEM_HARDWALL:
		retval = update_flag(CS_MEM_HARDWALL, cs, val);
		break;
P
Paul Jackson 已提交
1552
	case FILE_SCHED_LOAD_BALANCE:
1553
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1554
		break;
1555
	case FILE_MEMORY_MIGRATE:
1556
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1557
		break;
1558
	case FILE_MEMORY_PRESSURE_ENABLED:
1559
		cpuset_memory_pressure_enabled = !!val;
1560 1561 1562 1563
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1564
	case FILE_SPREAD_PAGE:
1565
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1566 1567
		break;
	case FILE_SPREAD_SLAB:
1568
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1569
		break;
L
Linus Torvalds 已提交
1570 1571
	default:
		retval = -EINVAL;
1572
		break;
L
Linus Torvalds 已提交
1573
	}
1574 1575
out_unlock:
	mutex_unlock(&cpuset_mutex);
L
Linus Torvalds 已提交
1576 1577 1578
	return retval;
}

1579 1580
static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
			    s64 val)
1581
{
1582
	struct cpuset *cs = css_cs(css);
1583
	cpuset_filetype_t type = cft->private;
1584
	int retval = -ENODEV;
1585

1586 1587 1588
	mutex_lock(&cpuset_mutex);
	if (!is_cpuset_online(cs))
		goto out_unlock;
1589

1590 1591 1592 1593 1594 1595 1596 1597
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, val);
		break;
	default:
		retval = -EINVAL;
		break;
	}
1598 1599
out_unlock:
	mutex_unlock(&cpuset_mutex);
1600 1601 1602
	return retval;
}

1603 1604 1605
/*
 * Common handling for a write to a "cpus" or "mems" file.
 */
1606
static int cpuset_write_resmask(struct cgroup_subsys_state *css,
1607
				struct cftype *cft, char *buf)
1608
{
1609
	struct cpuset *cs = css_cs(css);
1610
	struct cpuset *trialcs;
1611
	int retval = -ENODEV;
1612

1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625
	/*
	 * CPU or memory hotunplug may leave @cs w/o any execution
	 * resources, in which case the hotplug code asynchronously updates
	 * configuration and transfers all tasks to the nearest ancestor
	 * which can execute.
	 *
	 * As writes to "cpus" or "mems" may restore @cs's execution
	 * resources, wait for the previously scheduled operations before
	 * proceeding, so that we don't end up keep removing tasks added
	 * after execution capability is restored.
	 */
	flush_work(&cpuset_hotplug_work);

1626 1627 1628
	mutex_lock(&cpuset_mutex);
	if (!is_cpuset_online(cs))
		goto out_unlock;
1629

1630
	trialcs = alloc_trial_cpuset(cs);
1631 1632
	if (!trialcs) {
		retval = -ENOMEM;
1633
		goto out_unlock;
1634
	}
1635

1636 1637
	switch (cft->private) {
	case FILE_CPULIST:
1638
		retval = update_cpumask(cs, trialcs, buf);
1639 1640
		break;
	case FILE_MEMLIST:
1641
		retval = update_nodemask(cs, trialcs, buf);
1642 1643 1644 1645 1646
		break;
	default:
		retval = -EINVAL;
		break;
	}
1647 1648

	free_trial_cpuset(trialcs);
1649 1650
out_unlock:
	mutex_unlock(&cpuset_mutex);
1651 1652 1653
	return retval;
}

L
Linus Torvalds 已提交
1654 1655 1656 1657 1658 1659 1660 1661
/*
 * These ascii lists should be read in a single call, by using a user
 * buffer large enough to hold the entire map.  If read in smaller
 * chunks, there is no guarantee of atomicity.  Since the display format
 * used, list of ranges of sequential numbers, is variable length,
 * and since these maps can change value dynamically, one could read
 * gibberish by doing partial reads while a list was changing.
 */
1662
static int cpuset_common_seq_show(struct seq_file *sf, void *v)
L
Linus Torvalds 已提交
1663
{
1664 1665
	struct cpuset *cs = css_cs(seq_css(sf));
	cpuset_filetype_t type = seq_cft(sf)->private;
1666 1667 1668
	ssize_t count;
	char *buf, *s;
	int ret = 0;
L
Linus Torvalds 已提交
1669

1670 1671
	count = seq_get_buf(sf, &buf);
	s = buf;
L
Linus Torvalds 已提交
1672

1673
	mutex_lock(&callback_mutex);
L
Linus Torvalds 已提交
1674 1675 1676

	switch (type) {
	case FILE_CPULIST:
1677
		s += cpulist_scnprintf(s, count, cs->cpus_allowed);
L
Linus Torvalds 已提交
1678 1679
		break;
	case FILE_MEMLIST:
1680
		s += nodelist_scnprintf(s, count, cs->mems_allowed);
L
Linus Torvalds 已提交
1681 1682
		break;
	default:
1683 1684
		ret = -EINVAL;
		goto out_unlock;
L
Linus Torvalds 已提交
1685 1686
	}

1687 1688 1689 1690 1691 1692 1693 1694 1695
	if (s < buf + count - 1) {
		*s++ = '\n';
		seq_commit(sf, s - buf);
	} else {
		seq_commit(sf, -1);
	}
out_unlock:
	mutex_unlock(&callback_mutex);
	return ret;
L
Linus Torvalds 已提交
1696 1697
}

1698
static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
1699
{
1700
	struct cpuset *cs = css_cs(css);
1701 1702 1703 1704 1705 1706
	cpuset_filetype_t type = cft->private;
	switch (type) {
	case FILE_CPU_EXCLUSIVE:
		return is_cpu_exclusive(cs);
	case FILE_MEM_EXCLUSIVE:
		return is_mem_exclusive(cs);
1707 1708
	case FILE_MEM_HARDWALL:
		return is_mem_hardwall(cs);
1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723
	case FILE_SCHED_LOAD_BALANCE:
		return is_sched_load_balance(cs);
	case FILE_MEMORY_MIGRATE:
		return is_memory_migrate(cs);
	case FILE_MEMORY_PRESSURE_ENABLED:
		return cpuset_memory_pressure_enabled;
	case FILE_MEMORY_PRESSURE:
		return fmeter_getrate(&cs->fmeter);
	case FILE_SPREAD_PAGE:
		return is_spread_page(cs);
	case FILE_SPREAD_SLAB:
		return is_spread_slab(cs);
	default:
		BUG();
	}
1724 1725 1726

	/* Unreachable but makes gcc happy */
	return 0;
1727
}
L
Linus Torvalds 已提交
1728

1729
static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
1730
{
1731
	struct cpuset *cs = css_cs(css);
1732 1733 1734 1735 1736 1737 1738
	cpuset_filetype_t type = cft->private;
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		return cs->relax_domain_level;
	default:
		BUG();
	}
1739 1740 1741

	/* Unrechable but makes gcc happy */
	return 0;
1742 1743
}

L
Linus Torvalds 已提交
1744 1745 1746 1747 1748

/*
 * for the common functions, 'private' gives the type of file
 */

1749 1750 1751
static struct cftype files[] = {
	{
		.name = "cpus",
1752
		.seq_show = cpuset_common_seq_show,
1753 1754
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * NR_CPUS),
1755 1756 1757 1758 1759
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
1760
		.seq_show = cpuset_common_seq_show,
1761 1762
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * MAX_NUMNODES),
1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779
		.private = FILE_MEMLIST,
	},

	{
		.name = "cpu_exclusive",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_CPU_EXCLUSIVE,
	},

	{
		.name = "mem_exclusive",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_EXCLUSIVE,
	},

1780 1781 1782 1783 1784 1785 1786
	{
		.name = "mem_hardwall",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_HARDWALL,
	},

1787 1788 1789 1790 1791 1792 1793 1794 1795
	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
1796 1797
		.read_s64 = cpuset_read_s64,
		.write_s64 = cpuset_write_s64,
1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812
		.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
	},

	{
		.name = "memory_migrate",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_MIGRATE,
	},

	{
		.name = "memory_pressure",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE,
L
Li Zefan 已提交
1813
		.mode = S_IRUGO,
1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828
	},

	{
		.name = "memory_spread_page",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SPREAD_PAGE,
	},

	{
		.name = "memory_spread_slab",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SPREAD_SLAB,
	},
1829

1830 1831 1832 1833 1834 1835 1836
	{
		.name = "memory_pressure_enabled",
		.flags = CFTYPE_ONLY_ON_ROOT,
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE_ENABLED,
	},
L
Linus Torvalds 已提交
1837

1838 1839
	{ }	/* terminate */
};
L
Linus Torvalds 已提交
1840 1841

/*
1842
 *	cpuset_css_alloc - allocate a cpuset css
L
Li Zefan 已提交
1843
 *	cgrp:	control group that the new cpuset will be part of
L
Linus Torvalds 已提交
1844 1845
 */

1846 1847
static struct cgroup_subsys_state *
cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
L
Linus Torvalds 已提交
1848
{
T
Tejun Heo 已提交
1849
	struct cpuset *cs;
L
Linus Torvalds 已提交
1850

1851
	if (!parent_css)
1852
		return &top_cpuset.css;
1853

T
Tejun Heo 已提交
1854
	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
L
Linus Torvalds 已提交
1855
	if (!cs)
1856
		return ERR_PTR(-ENOMEM);
1857 1858 1859 1860
	if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
		kfree(cs);
		return ERR_PTR(-ENOMEM);
	}
L
Linus Torvalds 已提交
1861

P
Paul Jackson 已提交
1862
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1863
	cpumask_clear(cs->cpus_allowed);
1864
	nodes_clear(cs->mems_allowed);
1865
	fmeter_init(&cs->fmeter);
1866
	cs->relax_domain_level = -1;
L
Linus Torvalds 已提交
1867

T
Tejun Heo 已提交
1868 1869 1870
	return &cs->css;
}

1871
static int cpuset_css_online(struct cgroup_subsys_state *css)
T
Tejun Heo 已提交
1872
{
1873
	struct cpuset *cs = css_cs(css);
T
Tejun Heo 已提交
1874
	struct cpuset *parent = parent_cs(cs);
1875
	struct cpuset *tmp_cs;
1876
	struct cgroup_subsys_state *pos_css;
T
Tejun Heo 已提交
1877 1878 1879 1880

	if (!parent)
		return 0;

1881 1882
	mutex_lock(&cpuset_mutex);

T
Tejun Heo 已提交
1883
	set_bit(CS_ONLINE, &cs->flags);
T
Tejun Heo 已提交
1884 1885 1886 1887
	if (is_spread_page(parent))
		set_bit(CS_SPREAD_PAGE, &cs->flags);
	if (is_spread_slab(parent))
		set_bit(CS_SPREAD_SLAB, &cs->flags);
L
Linus Torvalds 已提交
1888

1889
	number_of_cpusets++;
1890

1891
	if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
1892
		goto out_unlock;
1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906

	/*
	 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
	 * set.  This flag handling is implemented in cgroup core for
	 * histrical reasons - the flag may be specified during mount.
	 *
	 * Currently, if any sibling cpusets have exclusive cpus or mem, we
	 * refuse to clone the configuration - thereby refusing the task to
	 * be entered, and as a result refusing the sys_unshare() or
	 * clone() which initiated it.  If this becomes a problem for some
	 * users who wish to allow that scenario, then this could be
	 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
	 * (and likewise for mems) to the new cgroup.
	 */
1907
	rcu_read_lock();
1908
	cpuset_for_each_child(tmp_cs, pos_css, parent) {
1909 1910
		if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
			rcu_read_unlock();
1911
			goto out_unlock;
1912
		}
1913
	}
1914
	rcu_read_unlock();
1915 1916 1917 1918 1919

	mutex_lock(&callback_mutex);
	cs->mems_allowed = parent->mems_allowed;
	cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
	mutex_unlock(&callback_mutex);
1920 1921
out_unlock:
	mutex_unlock(&cpuset_mutex);
T
Tejun Heo 已提交
1922 1923 1924
	return 0;
}

1925 1926 1927 1928 1929 1930
/*
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
 * will call rebuild_sched_domains_locked().
 */

1931
static void cpuset_css_offline(struct cgroup_subsys_state *css)
T
Tejun Heo 已提交
1932
{
1933
	struct cpuset *cs = css_cs(css);
T
Tejun Heo 已提交
1934

1935
	mutex_lock(&cpuset_mutex);
T
Tejun Heo 已提交
1936 1937 1938 1939 1940

	if (is_sched_load_balance(cs))
		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);

	number_of_cpusets--;
T
Tejun Heo 已提交
1941
	clear_bit(CS_ONLINE, &cs->flags);
T
Tejun Heo 已提交
1942

1943
	mutex_unlock(&cpuset_mutex);
L
Linus Torvalds 已提交
1944 1945
}

1946
static void cpuset_css_free(struct cgroup_subsys_state *css)
L
Linus Torvalds 已提交
1947
{
1948
	struct cpuset *cs = css_cs(css);
L
Linus Torvalds 已提交
1949

1950
	free_cpumask_var(cs->cpus_allowed);
1951
	kfree(cs);
L
Linus Torvalds 已提交
1952 1953
}

1954
struct cgroup_subsys cpuset_cgrp_subsys = {
1955
	.css_alloc = cpuset_css_alloc,
T
Tejun Heo 已提交
1956 1957
	.css_online = cpuset_css_online,
	.css_offline = cpuset_css_offline,
1958
	.css_free = cpuset_css_free,
1959
	.can_attach = cpuset_can_attach,
1960
	.cancel_attach = cpuset_cancel_attach,
1961
	.attach = cpuset_attach,
1962
	.base_cftypes = files,
1963 1964 1965
	.early_init = 1,
};

L
Linus Torvalds 已提交
1966 1967 1968 1969 1970 1971 1972 1973
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1974
	int err = 0;
L
Linus Torvalds 已提交
1975

1976 1977 1978
	if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
		BUG();

1979
	cpumask_setall(top_cpuset.cpus_allowed);
1980
	nodes_setall(top_cpuset.mems_allowed);
L
Linus Torvalds 已提交
1981

1982
	fmeter_init(&top_cpuset.fmeter);
P
Paul Jackson 已提交
1983
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1984
	top_cpuset.relax_domain_level = -1;
L
Linus Torvalds 已提交
1985 1986 1987

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1988 1989
		return err;

1990 1991 1992
	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
		BUG();

1993
	number_of_cpusets = 1;
1994
	return 0;
L
Linus Torvalds 已提交
1995 1996
}

1997
/*
1998
 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1999 2000
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
2001 2002
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
2003
 */
2004 2005 2006 2007 2008 2009 2010 2011
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
T
Tejun Heo 已提交
2012
	parent = parent_cs(cs);
2013
	while (cpumask_empty(parent->cpus_allowed) ||
2014
			nodes_empty(parent->mems_allowed))
T
Tejun Heo 已提交
2015
		parent = parent_cs(parent);
2016

2017
	if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
2018
		pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
T
Tejun Heo 已提交
2019 2020
		pr_cont_cgroup_name(cs->css.cgroup);
		pr_cont("\n");
2021
	}
2022 2023
}

2024
/**
2025
 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
2026
 * @cs: cpuset in interest
2027
 *
2028 2029 2030
 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
 * offline, update @cs accordingly.  If @cs ends up with no CPU or memory,
 * all its tasks are moved to the nearest ancestor with both resources.
2031
 */
2032
static void cpuset_hotplug_update_tasks(struct cpuset *cs)
2033
{
2034
	static cpumask_t off_cpus;
2035
	static nodemask_t off_mems;
2036
	bool is_empty;
2037
	bool sane = cgroup_sane_behavior(cs->css.cgroup);
2038

2039 2040
retry:
	wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
2041

2042
	mutex_lock(&cpuset_mutex);
2043

2044 2045 2046 2047 2048 2049 2050 2051 2052
	/*
	 * We have raced with task attaching. We wait until attaching
	 * is finished, so we won't attach a task to an empty cpuset.
	 */
	if (cs->attach_in_progress) {
		mutex_unlock(&cpuset_mutex);
		goto retry;
	}

2053 2054
	cpumask_andnot(&off_cpus, cs->cpus_allowed, top_cpuset.cpus_allowed);
	nodes_andnot(off_mems, cs->mems_allowed, top_cpuset.mems_allowed);
2055

2056 2057 2058 2059 2060 2061
	mutex_lock(&callback_mutex);
	cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, &off_cpus);
	mutex_unlock(&callback_mutex);

	/*
	 * If sane_behavior flag is set, we need to update tasks' cpumask
2062 2063 2064
	 * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
	 * call update_tasks_cpumask() if the cpuset becomes empty, as
	 * the tasks in it will be migrated to an ancestor.
2065 2066
	 */
	if ((sane && cpumask_empty(cs->cpus_allowed)) ||
2067
	    (!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed)))
2068
		update_tasks_cpumask(cs);
2069

2070 2071 2072 2073 2074 2075
	mutex_lock(&callback_mutex);
	nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
	mutex_unlock(&callback_mutex);

	/*
	 * If sane_behavior flag is set, we need to update tasks' nodemask
2076 2077 2078
	 * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
	 * call update_tasks_nodemask() if the cpuset becomes empty, as
	 * the tasks in it will be migratd to an ancestor.
2079 2080
	 */
	if ((sane && nodes_empty(cs->mems_allowed)) ||
2081
	    (!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed)))
2082
		update_tasks_nodemask(cs);
2083

2084 2085
	is_empty = cpumask_empty(cs->cpus_allowed) ||
		nodes_empty(cs->mems_allowed);
2086

2087 2088 2089
	mutex_unlock(&cpuset_mutex);

	/*
2090 2091 2092 2093
	 * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
	 *
	 * Otherwise move tasks to the nearest ancestor with execution
	 * resources.  This is full cgroup operation which will
2094 2095
	 * also call back into cpuset.  Should be done outside any lock.
	 */
2096
	if (!sane && is_empty)
2097
		remove_tasks_in_empty_cpuset(cs);
2098 2099
}

2100
/**
2101
 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
2102
 *
2103 2104 2105 2106 2107
 * This function is called after either CPU or memory configuration has
 * changed and updates cpuset accordingly.  The top_cpuset is always
 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
 * order to make cpusets transparent (of no affect) on systems that are
 * actively using CPU hotplug but making no active use of cpusets.
2108
 *
2109
 * Non-root cpusets are only affected by offlining.  If any CPUs or memory
2110 2111
 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
 * all descendants.
2112
 *
2113 2114
 * Note that CPU offlining during suspend is ignored.  We don't modify
 * cpusets across suspend/resume cycles at all.
2115
 */
2116
static void cpuset_hotplug_workfn(struct work_struct *work)
2117
{
2118 2119
	static cpumask_t new_cpus;
	static nodemask_t new_mems;
2120
	bool cpus_updated, mems_updated;
2121

2122
	mutex_lock(&cpuset_mutex);
2123

2124 2125 2126
	/* fetch the available cpus/mems and find out which changed how */
	cpumask_copy(&new_cpus, cpu_active_mask);
	new_mems = node_states[N_MEMORY];
2127

2128 2129
	cpus_updated = !cpumask_equal(top_cpuset.cpus_allowed, &new_cpus);
	mems_updated = !nodes_equal(top_cpuset.mems_allowed, new_mems);
2130

2131 2132 2133 2134 2135 2136 2137
	/* synchronize cpus_allowed to cpu_active_mask */
	if (cpus_updated) {
		mutex_lock(&callback_mutex);
		cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
		mutex_unlock(&callback_mutex);
		/* we don't mess with cpumasks of tasks in top_cpuset */
	}
2138

2139 2140 2141 2142 2143
	/* synchronize mems_allowed to N_MEMORY */
	if (mems_updated) {
		mutex_lock(&callback_mutex);
		top_cpuset.mems_allowed = new_mems;
		mutex_unlock(&callback_mutex);
2144
		update_tasks_nodemask(&top_cpuset);
2145
	}
2146

2147 2148
	mutex_unlock(&cpuset_mutex);

2149 2150
	/* if cpus or mems changed, we need to propagate to descendants */
	if (cpus_updated || mems_updated) {
2151
		struct cpuset *cs;
2152
		struct cgroup_subsys_state *pos_css;
2153

2154
		rcu_read_lock();
2155
		cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
2156
			if (cs == &top_cpuset || !css_tryget_online(&cs->css))
2157 2158
				continue;
			rcu_read_unlock();
2159

2160
			cpuset_hotplug_update_tasks(cs);
2161

2162 2163 2164 2165 2166
			rcu_read_lock();
			css_put(&cs->css);
		}
		rcu_read_unlock();
	}
2167

2168
	/* rebuild sched domains if cpus_allowed has changed */
2169 2170
	if (cpus_updated)
		rebuild_sched_domains();
2171 2172
}

2173
void cpuset_update_active_cpus(bool cpu_online)
2174
{
2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186
	/*
	 * We're inside cpu hotplug critical region which usually nests
	 * inside cgroup synchronization.  Bounce actual hotplug processing
	 * to a work item to avoid reverse locking order.
	 *
	 * We still need to do partition_sched_domains() synchronously;
	 * otherwise, the scheduler will get confused and put tasks to the
	 * dead CPU.  Fall back to the default single domain.
	 * cpuset_hotplug_workfn() will rebuild it as necessary.
	 */
	partition_sched_domains(1, NULL, NULL);
	schedule_work(&cpuset_hotplug_work);
2187 2188
}

2189
/*
2190 2191
 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
 * Call this routine anytime after node_states[N_MEMORY] changes.
2192
 * See cpuset_update_active_cpus() for CPU hotplug handling.
2193
 */
2194 2195
static int cpuset_track_online_nodes(struct notifier_block *self,
				unsigned long action, void *arg)
2196
{
2197
	schedule_work(&cpuset_hotplug_work);
2198
	return NOTIFY_OK;
2199
}
2200 2201 2202 2203 2204

static struct notifier_block cpuset_track_online_nodes_nb = {
	.notifier_call = cpuset_track_online_nodes,
	.priority = 10,		/* ??! */
};
2205

L
Linus Torvalds 已提交
2206 2207 2208 2209
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
2210
 */
L
Linus Torvalds 已提交
2211 2212
void __init cpuset_init_smp(void)
{
2213
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2214
	top_cpuset.mems_allowed = node_states[N_MEMORY];
2215
	top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
2216

2217
	register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
L
Linus Torvalds 已提交
2218 2219 2220 2221 2222
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2223
 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
L
Linus Torvalds 已提交
2224
 *
2225
 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
L
Linus Torvalds 已提交
2226
 * attached to the specified @tsk.  Guaranteed to return some non-empty
2227
 * subset of cpu_online_mask, even if this means going outside the
L
Linus Torvalds 已提交
2228 2229 2230
 * tasks cpuset.
 **/

2231
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
L
Linus Torvalds 已提交
2232
{
2233 2234
	struct cpuset *cpus_cs;

2235
	mutex_lock(&callback_mutex);
2236
	rcu_read_lock();
2237 2238
	cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
	guarantee_online_cpus(cpus_cs, pmask);
2239
	rcu_read_unlock();
2240
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
2241 2242
}

2243
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2244
{
2245
	struct cpuset *cpus_cs;
2246 2247

	rcu_read_lock();
2248 2249
	cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
	do_set_cpus_allowed(tsk, cpus_cs->cpus_allowed);
2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264
	rcu_read_unlock();

	/*
	 * We own tsk->cpus_allowed, nobody can change it under us.
	 *
	 * But we used cs && cs->cpus_allowed lockless and thus can
	 * race with cgroup_attach_task() or update_cpumask() and get
	 * the wrong tsk->cpus_allowed. However, both cases imply the
	 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
	 * which takes task_rq_lock().
	 *
	 * If we are called after it dropped the lock we must see all
	 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
	 * set any mask even if it is not right from task_cs() pov,
	 * the pending set_cpus_allowed_ptr() will fix things.
2265 2266 2267
	 *
	 * select_fallback_rq() will fix things ups and set cpu_possible_mask
	 * if required.
2268 2269 2270
	 */
}

L
Linus Torvalds 已提交
2271 2272
void cpuset_init_current_mems_allowed(void)
{
2273
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
2274 2275
}

2276 2277 2278 2279 2280 2281
/**
 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
 *
 * Description: Returns the nodemask_t mems_allowed of the cpuset
 * attached to the specified @tsk.  Guaranteed to return some non-empty
2282
 * subset of node_states[N_MEMORY], even if this means going outside the
2283 2284 2285 2286 2287
 * tasks cpuset.
 **/

nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
2288
	struct cpuset *mems_cs;
2289 2290
	nodemask_t mask;

2291
	mutex_lock(&callback_mutex);
2292
	rcu_read_lock();
2293 2294
	mems_cs = effective_nodemask_cpuset(task_cs(tsk));
	guarantee_online_mems(mems_cs, &mask);
2295
	rcu_read_unlock();
2296
	mutex_unlock(&callback_mutex);
2297 2298 2299 2300

	return mask;
}

2301
/**
2302 2303
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
2304
 *
2305
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
2306
 */
2307
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
2308
{
2309
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
2310 2311
}

2312
/*
2313 2314 2315 2316
 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
 * mem_hardwall ancestor to the specified cpuset.  Call holding
 * callback_mutex.  If no ancestor is mem_exclusive or mem_hardwall
 * (an unusual configuration), then returns the root cpuset.
2317
 */
2318
static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
2319
{
T
Tejun Heo 已提交
2320 2321
	while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
		cs = parent_cs(cs);
2322 2323 2324
	return cs;
}

2325
/**
2326 2327
 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2328
 * @gfp_mask: memory allocation flags
2329
 *
2330 2331 2332 2333 2334 2335
 * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
 * set, yes, we can always allocate.  If node is in our task's mems_allowed,
 * yes.  If it's not a __GFP_HARDWALL request and this node is in the nearest
 * hardwalled cpuset ancestor to this task's cpuset, yes.  If the task has been
 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
 * flag, yes.
2336 2337
 * Otherwise, no.
 *
2338 2339 2340
 * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
 * cpuset_node_allowed_hardwall().  Otherwise, cpuset_node_allowed_softwall()
 * might sleep, and might allow a node from an enclosing cpuset.
2341
 *
2342 2343
 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
 * cpusets, and never sleeps.
2344 2345 2346 2347 2348 2349 2350
 *
 * The __GFP_THISNODE placement logic is really handled elsewhere,
 * by forcibly using a zonelist starting at a specified node, and by
 * (in get_page_from_freelist()) refusing to consider the zones for
 * any node on the zonelist except the first.  By the time any such
 * calls get to this routine, we should just shut up and say 'yes'.
 *
2351
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2352 2353
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2354
 * GFP_KERNEL allocations are not so marked, so can escape to the
2355
 * nearest enclosing hardwalled ancestor cpuset.
2356
 *
2357 2358 2359 2360 2361 2362 2363
 * Scanning up parent cpusets requires callback_mutex.  The
 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
 * current tasks mems_allowed came up empty on the first pass over
 * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
 * cpuset are short of memory, might require taking the callback_mutex
 * mutex.
2364
 *
2365
 * The first call here from mm/page_alloc:get_page_from_freelist()
2366 2367 2368
 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
 * so no allocation on a node outside the cpuset is allowed (unless
 * in interrupt, of course).
2369 2370 2371 2372 2373 2374
 *
 * The second pass through get_page_from_freelist() doesn't even call
 * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
 * in alloc_flags.  That logic and the checks below have the combined
 * affect that:
2375 2376
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2377
 *	TIF_MEMDIE   - any node ok
2378
 *	GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2379
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2380 2381
 *
 * Rule:
2382
 *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2383 2384
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2385
 */
2386
int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2387
{
2388
	struct cpuset *cs;		/* current cpuset ancestors */
2389
	int allowed;			/* is allocation in zone z allowed? */
2390

2391
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2392
		return 1;
2393
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2394 2395
	if (node_isset(node, current->mems_allowed))
		return 1;
2396 2397 2398 2399 2400 2401
	/*
	 * Allow tasks that have access to memory reserves because they have
	 * been OOM killed to get memory anywhere.
	 */
	if (unlikely(test_thread_flag(TIF_MEMDIE)))
		return 1;
2402 2403 2404
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2405 2406 2407
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2408
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2409
	mutex_lock(&callback_mutex);
2410

2411
	rcu_read_lock();
2412
	cs = nearest_hardwall_ancestor(task_cs(current));
2413
	allowed = node_isset(node, cs->mems_allowed);
2414
	rcu_read_unlock();
2415

2416
	mutex_unlock(&callback_mutex);
2417
	return allowed;
L
Linus Torvalds 已提交
2418 2419
}

2420
/*
2421 2422
 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2423 2424
 * @gfp_mask: memory allocation flags
 *
2425 2426 2427 2428 2429
 * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
 * set, yes, we can always allocate.  If node is in our task's mems_allowed,
 * yes.  If the task has been OOM killed and has access to memory reserves as
 * specified by the TIF_MEMDIE flag, yes.
 * Otherwise, no.
2430 2431 2432 2433 2434 2435 2436
 *
 * The __GFP_THISNODE placement logic is really handled elsewhere,
 * by forcibly using a zonelist starting at a specified node, and by
 * (in get_page_from_freelist()) refusing to consider the zones for
 * any node on the zonelist except the first.  By the time any such
 * calls get to this routine, we should just shut up and say 'yes'.
 *
2437 2438
 * Unlike the cpuset_node_allowed_softwall() variant, above,
 * this variant requires that the node be in the current task's
2439 2440 2441 2442
 * mems_allowed or that we're in interrupt.  It does not scan up the
 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
 * It never sleeps.
 */
2443
int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2444 2445 2446 2447 2448
{
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2449 2450 2451 2452 2453 2454
	/*
	 * Allow tasks that have access to memory reserves because they have
	 * been OOM killed to get memory anywhere.
	 */
	if (unlikely(test_thread_flag(TIF_MEMDIE)))
		return 1;
2455 2456 2457
	return 0;
}

2458
/**
2459 2460
 * cpuset_mem_spread_node() - On which node to begin search for a file page
 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484
 *
 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
 * tasks in a cpuset with is_spread_page or is_spread_slab set),
 * and if the memory allocation used cpuset_mem_spread_node()
 * to determine on which node to start looking, as it will for
 * certain page cache or slab cache pages such as used for file
 * system buffers and inode caches, then instead of starting on the
 * local node to look for a free page, rather spread the starting
 * node around the tasks mems_allowed nodes.
 *
 * We don't have to worry about the returned node being offline
 * because "it can't happen", and even if it did, it would be ok.
 *
 * The routines calling guarantee_online_mems() are careful to
 * only set nodes in task->mems_allowed that are online.  So it
 * should not be possible for the following code to return an
 * offline node.  But if it did, that would be ok, as this routine
 * is not returning the node where the allocation must be, only
 * the node where the search should start.  The zonelist passed to
 * __alloc_pages() will include all nodes.  If the slab allocator
 * is passed an offline node, it will fall back to the local node.
 * See kmem_cache_alloc_node().
 */

2485
static int cpuset_spread_node(int *rotor)
2486 2487 2488
{
	int node;

2489
	node = next_node(*rotor, current->mems_allowed);
2490 2491
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
2492
	*rotor = node;
2493 2494
	return node;
}
2495 2496 2497

int cpuset_mem_spread_node(void)
{
2498 2499 2500 2501
	if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
		current->cpuset_mem_spread_rotor =
			node_random(&current->mems_allowed);

2502 2503 2504 2505 2506
	return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
}

int cpuset_slab_spread_node(void)
{
2507 2508 2509 2510
	if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
		current->cpuset_slab_spread_rotor =
			node_random(&current->mems_allowed);

2511 2512 2513
	return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
}

2514 2515
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2516
/**
2517 2518 2519 2520 2521 2522 2523 2524
 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
 * @tsk1: pointer to task_struct of some task.
 * @tsk2: pointer to task_struct of some other task.
 *
 * Description: Return true if @tsk1's mems_allowed intersects the
 * mems_allowed of @tsk2.  Used by the OOM killer to determine if
 * one of the task's memory usage might impact the memory available
 * to the other.
2525 2526
 **/

2527 2528
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2529
{
2530
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2531 2532
}

2533 2534
#define CPUSET_NODELIST_LEN	(256)

2535 2536
/**
 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2537
 * @tsk: pointer to task_struct of some task.
2538 2539
 *
 * Description: Prints @task's name, cpuset name, and cached copy of its
2540
 * mems_allowed to the kernel log.
2541 2542 2543
 */
void cpuset_print_task_mems_allowed(struct task_struct *tsk)
{
2544 2545 2546
	 /* Statically allocated to prevent using excess stack. */
	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
	static DEFINE_SPINLOCK(cpuset_buffer_lock);
2547
	struct cgroup *cgrp;
2548

2549
	spin_lock(&cpuset_buffer_lock);
2550
	rcu_read_lock();
2551

2552
	cgrp = task_cs(tsk)->css.cgroup;
2553 2554
	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
			   tsk->mems_allowed);
2555
	pr_info("%s cpuset=", tsk->comm);
T
Tejun Heo 已提交
2556 2557
	pr_cont_cgroup_name(cgrp);
	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
2558

2559
	rcu_read_unlock();
2560 2561 2562
	spin_unlock(&cpuset_buffer_lock);
}

2563 2564 2565 2566 2567 2568
/*
 * Collection of memory_pressure is suppressed unless
 * this flag is enabled by writing "1" to the special
 * cpuset file 'memory_pressure_enabled' in the root cpuset.
 */

2569
int cpuset_memory_pressure_enabled __read_mostly;
2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590

/**
 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
 *
 * Keep a running average of the rate of synchronous (direct)
 * page reclaim efforts initiated by tasks in each cpuset.
 *
 * This represents the rate at which some task in the cpuset
 * ran low on memory on all nodes it was allowed to use, and
 * had to enter the kernels page reclaim code in an effort to
 * create more free memory by tossing clean pages or swapping
 * or writing dirty pages.
 *
 * Display to user space in the per-cpuset read-only file
 * "memory_pressure".  Value displayed is an integer
 * representing the recent rate of entry into the synchronous
 * (direct) page reclaim by any task attached to the cpuset.
 **/

void __cpuset_memory_pressure_bump(void)
{
2591
	rcu_read_lock();
2592
	fmeter_markevent(&task_cs(current)->fmeter);
2593
	rcu_read_unlock();
2594 2595
}

2596
#ifdef CONFIG_PROC_PID_CPUSET
L
Linus Torvalds 已提交
2597 2598 2599 2600
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2601 2602
 *  - No need to task_lock(tsk) on this tsk->cpuset reference, as it
 *    doesn't really matter if tsk->cpuset changes after we read it,
2603
 *    and we take cpuset_mutex, keeping cpuset_attach() from changing it
2604
 *    anyway.
L
Linus Torvalds 已提交
2605
 */
2606
int proc_cpuset_show(struct seq_file *m, void *unused_v)
L
Linus Torvalds 已提交
2607
{
2608
	struct pid *pid;
L
Linus Torvalds 已提交
2609
	struct task_struct *tsk;
T
Tejun Heo 已提交
2610
	char *buf, *p;
2611
	struct cgroup_subsys_state *css;
2612
	int retval;
L
Linus Torvalds 已提交
2613

2614
	retval = -ENOMEM;
T
Tejun Heo 已提交
2615
	buf = kmalloc(PATH_MAX, GFP_KERNEL);
L
Linus Torvalds 已提交
2616
	if (!buf)
2617 2618 2619
		goto out;

	retval = -ESRCH;
2620 2621
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2622 2623
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2624

T
Tejun Heo 已提交
2625
	retval = -ENAMETOOLONG;
L
Li Zefan 已提交
2626
	rcu_read_lock();
2627
	css = task_css(tsk, cpuset_cgrp_id);
T
Tejun Heo 已提交
2628
	p = cgroup_path(css->cgroup, buf, PATH_MAX);
L
Li Zefan 已提交
2629
	rcu_read_unlock();
T
Tejun Heo 已提交
2630
	if (!p)
L
Li Zefan 已提交
2631
		goto out_put_task;
T
Tejun Heo 已提交
2632
	seq_puts(m, p);
L
Linus Torvalds 已提交
2633
	seq_putc(m, '\n');
T
Tejun Heo 已提交
2634
	retval = 0;
L
Li Zefan 已提交
2635
out_put_task:
2636 2637
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2638
	kfree(buf);
2639
out:
L
Linus Torvalds 已提交
2640 2641
	return retval;
}
2642
#endif /* CONFIG_PROC_PID_CPUSET */
L
Linus Torvalds 已提交
2643

2644
/* Display task mems_allowed in /proc/<pid>/status file. */
2645 2646
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
2647
	seq_puts(m, "Mems_allowed:\t");
2648
	seq_nodemask(m, &task->mems_allowed);
2649 2650
	seq_puts(m, "\n");
	seq_puts(m, "Mems_allowed_list:\t");
2651
	seq_nodemask_list(m, &task->mems_allowed);
2652
	seq_puts(m, "\n");
L
Linus Torvalds 已提交
2653
}