cpuset.c 74.3 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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/*
 * Workqueue for cpuset related tasks.
 *
 * Using kevent workqueue may cause deadlock when memory_migrate
 * is set. So we create a separate workqueue thread for cpuset.
 */
static struct workqueue_struct *cpuset_wq;

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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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/* Forward declare cgroup structures */
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struct cgroup_subsys cpuset_subsys;
struct cpuset;

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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 */

	struct cpuset *parent;		/* my parent */

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	struct fmeter fmeter;		/* memory_pressure filter */
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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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	/* used for walking a cpuset hierarchy */
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	struct list_head stack_list;
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};

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/* Retrieve the cpuset for a cgroup */
static inline struct cpuset *cgroup_cs(struct cgroup *cont)
{
	return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
			    struct cpuset, css);
}

/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
	return container_of(task_subsys_state(task, cpuset_subsys_id),
			    struct cpuset, css);
}

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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 {
	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 */
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 = {
	.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
};

/*
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 * There are two global mutexes guarding cpuset structures.  The first
 * is the main control groups cgroup_mutex, accessed via
 * cgroup_lock()/cgroup_unlock().  The second is the cpuset-specific
 * callback_mutex, below. They can nest.  It is ok to first take
 * cgroup_mutex, then nest callback_mutex.  We also require taking
 * task_lock() when dereferencing a task's cpuset pointer.  See "The
 * task_lock() exception", at the end of this comment.
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 *
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 * A task must hold both mutexes to modify cpusets.  If a task
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 * holds cgroup_mutex, then it blocks others wanting that mutex,
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 * ensuring that it is the only task able to also acquire callback_mutex
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 * and be able to modify cpusets.  It can perform various checks on
 * the cpuset structure first, knowing nothing will change.  It can
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 * also allocate memory while just holding cgroup_mutex.  While it is
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 * performing these checks, various callback routines can briefly
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 * 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(callback_mutex);
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/*
 * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
 * buffers.  They are statically allocated to prevent using excess stack
 * when calling cpuset_print_task_mems_allowed().
 */
#define CPUSET_NAME_LEN		(128)
#define	CPUSET_NODELIST_LEN	(256)
static char cpuset_name[CPUSET_NAME_LEN];
static char cpuset_nodelist[CPUSET_NODELIST_LEN];
static DEFINE_SPINLOCK(cpuset_buffer_lock);

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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
 * until we find one that does have some online cpus.  If we get
 * all the way to the top and still haven't found any online cpus,
 * return cpu_online_map.  Or if passed a NULL cs from an exit'ing
 * task, return cpu_online_map.
 *
 * One way or another, we guarantee to return some non-empty subset
 * of cpu_online_map.
 *
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 * Call with callback_mutex held.
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 */

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static void guarantee_online_cpus(const struct cpuset *cs,
				  struct cpumask *pmask)
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{
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	while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
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		cs = cs->parent;
	if (cs)
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		cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
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	else
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		cpumask_copy(pmask, cpu_online_mask);
	BUG_ON(!cpumask_intersects(pmask, 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
 * online mems.  If we get all the way to the top and still haven't
 * found any online mems, return node_states[N_HIGH_MEMORY].
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of node_states[N_HIGH_MEMORY].
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 *
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 * Call with callback_mutex held.
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 */

static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
{
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	while (cs && !nodes_intersects(cs->mems_allowed,
					node_states[N_HIGH_MEMORY]))
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		cs = cs->parent;
	if (cs)
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		nodes_and(*pmask, cs->mems_allowed,
					node_states[N_HIGH_MEMORY]);
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	else
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		*pmask = node_states[N_HIGH_MEMORY];
	BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
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}

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/*
 * update task's spread flag if cpuset's page/slab spread flag is set
 *
 * Called with callback_mutex/cgroup_mutex held
 */
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 cgroup_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
 */
static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
{
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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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 * cgroup_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.
 */

static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
{
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	struct cgroup *cont;
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	struct cpuset *c, *par;

	/* Each of our child cpusets must be a subset of us */
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	list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
		if (!is_cpuset_subset(cgroup_cs(cont), trial))
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			return -EBUSY;
	}

	/* Remaining checks don't apply to root cpuset */
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	if (cur == &top_cpuset)
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		return 0;

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	par = cur->parent;

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	/* We must be a subset of our parent cpuset */
	if (!is_cpuset_subset(trial, par))
		return -EACCES;

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	/*
	 * If either I or some sibling (!= me) is exclusive, we can't
	 * overlap
	 */
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	list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
		c = cgroup_cs(cont);
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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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			return -EINVAL;
		if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
		    c != cur &&
		    nodes_intersects(trial->mems_allowed, c->mems_allowed))
			return -EINVAL;
	}

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	/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
	if (cgroup_task_count(cur->css.cgroup)) {
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		if (cpumask_empty(trial->cpus_allowed) ||
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		    nodes_empty(trial->mems_allowed)) {
			return -ENOSPC;
		}
	}

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	return 0;
}

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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 *c)
{
	LIST_HEAD(q);

	list_add(&c->stack_list, &q);
	while (!list_empty(&q)) {
		struct cpuset *cp;
		struct cgroup *cont;
		struct cpuset *child;

		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

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		if (cpumask_empty(cp->cpus_allowed))
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			continue;

		if (is_sched_load_balance(cp))
			update_domain_attr(dattr, cp);

		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			list_add_tail(&child->stack_list, &q);
		}
	}
}

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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.
 * The output of this function needs to be passed to kernel/sched.c
 * 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 cgroup_lock 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
 *	   the kernel/sched.c routine partition_sched_domains() in a
 *	   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().
 */
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static int generate_sched_domains(cpumask_var_t **domains,
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			struct sched_domain_attr **attributes)
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{
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	LIST_HEAD(q);		/* queue of cpusets to be scanned */
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	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 */
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	cpumask_var_t *doms;	/* resulting partition; i.e. sched domains */
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	struct sched_domain_attr *dattr;  /* attributes for custom domains */
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	int ndoms = 0;		/* number of sched domains in result */
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	int nslot;		/* next empty doms[] struct cpumask slot */
P
Paul Jackson 已提交
564 565

	doms = NULL;
566
	dattr = NULL;
567
	csa = NULL;
P
Paul Jackson 已提交
568 569 570

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
571 572
		ndoms = 1;
		doms = alloc_sched_domains(ndoms);
P
Paul Jackson 已提交
573
		if (!doms)
574 575
			goto done;

576 577 578
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
579
			update_domain_attr_tree(dattr, &top_cpuset);
580
		}
581
		cpumask_copy(doms[0], top_cpuset.cpus_allowed);
582 583

		goto done;
P
Paul Jackson 已提交
584 585 586 587 588 589 590
	}

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

591 592
	list_add(&top_cpuset.stack_list, &q);
	while (!list_empty(&q)) {
P
Paul Jackson 已提交
593 594
		struct cgroup *cont;
		struct cpuset *child;   /* scans child cpusets of cp */
595

596 597 598
		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

599
		if (cpumask_empty(cp->cpus_allowed))
600 601
			continue;

602 603 604 605 606 607 608
		/*
		 * 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.
		 */
		if (is_sched_load_balance(cp)) {
P
Paul Jackson 已提交
609
			csa[csn++] = cp;
610 611
			continue;
		}
612

P
Paul Jackson 已提交
613 614
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
615
			list_add_tail(&child->stack_list, &q);
P
Paul Jackson 已提交
616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645
		}
  	}

	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;
			}
		}
	}

646 647 648 649
	/*
	 * Now we know how many domains to create.
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
	 */
650
	doms = alloc_sched_domains(ndoms);
651
	if (!doms)
652 653 654 655 656 657
		goto done;

	/*
	 * The rest of the code, including the scheduler, can deal with
	 * dattr==NULL case. No need to abort if alloc fails.
	 */
658
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
P
Paul Jackson 已提交
659 660 661

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
662
		struct cpumask *dp;
P
Paul Jackson 已提交
663 664
		int apn = a->pn;

665 666 667 668 669
		if (apn < 0) {
			/* Skip completed partitions */
			continue;
		}

670
		dp = doms[nslot];
671 672 673 674 675 676 677 678 679 680

		if (nslot == ndoms) {
			static int warnings = 10;
			if (warnings) {
				printk(KERN_WARNING
				 "rebuild_sched_domains confused:"
				  " nslot %d, ndoms %d, csn %d, i %d,"
				  " apn %d\n",
				  nslot, ndoms, csn, i, apn);
				warnings--;
P
Paul Jackson 已提交
681
			}
682 683
			continue;
		}
P
Paul Jackson 已提交
684

685
		cpumask_clear(dp);
686 687 688 689 690 691
		if (dattr)
			*(dattr + nslot) = SD_ATTR_INIT;
		for (j = i; j < csn; j++) {
			struct cpuset *b = csa[j];

			if (apn == b->pn) {
692
				cpumask_or(dp, dp, b->cpus_allowed);
693 694 695 696 697
				if (dattr)
					update_domain_attr_tree(dattr + nslot, b);

				/* Done with this partition */
				b->pn = -1;
P
Paul Jackson 已提交
698 699
			}
		}
700
		nslot++;
P
Paul Jackson 已提交
701 702 703
	}
	BUG_ON(nslot != ndoms);

704 705 706
done:
	kfree(csa);

707 708 709 710 711 712 713
	/*
	 * Fallback to the default domain if kmalloc() failed.
	 * See comments in partition_sched_domains().
	 */
	if (doms == NULL)
		ndoms = 1;

714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731
	*domains    = doms;
	*attributes = dattr;
	return ndoms;
}

/*
 * Rebuild scheduler domains.
 *
 * Call with neither cgroup_mutex held nor within get_online_cpus().
 * Takes both cgroup_mutex and get_online_cpus().
 *
 * Cannot be directly called from cpuset code handling changes
 * to the cpuset pseudo-filesystem, because it cannot be called
 * from code that already holds cgroup_mutex.
 */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
	struct sched_domain_attr *attr;
732
	cpumask_var_t *doms;
733 734
	int ndoms;

735
	get_online_cpus();
736 737 738 739 740 741 742 743 744

	/* Generate domain masks and attrs */
	cgroup_lock();
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);

745
	put_online_cpus();
746
}
747 748 749 750 751
#else /* !CONFIG_SMP */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
}

752
static int generate_sched_domains(cpumask_var_t **domains,
753 754 755 756 757 758
			struct sched_domain_attr **attributes)
{
	*domains = NULL;
	return 1;
}
#endif /* CONFIG_SMP */
P
Paul Jackson 已提交
759

760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782
static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);

/*
 * Rebuild scheduler domains, asynchronously via workqueue.
 *
 * 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.
 *
 * The rebuild_sched_domains() and partition_sched_domains()
 * routines must nest cgroup_lock() inside get_online_cpus(),
 * but such cpuset changes as these must nest that locking the
 * other way, holding cgroup_lock() for much of the code.
 *
 * So in order to avoid an ABBA deadlock, the cpuset code handling
 * these user changes delegates the actual sched domain rebuilding
 * to a separate workqueue thread, which ends up processing the
 * above do_rebuild_sched_domains() function.
 */
static void async_rebuild_sched_domains(void)
{
783
	queue_work(cpuset_wq, &rebuild_sched_domains_work);
784 785 786 787 788 789 790 791 792 793 794 795 796 797
}

/*
 * Accomplishes the same scheduler domain rebuild as the above
 * async_rebuild_sched_domains(), however it directly calls the
 * rebuild routine synchronously rather than calling it via an
 * asynchronous work thread.
 *
 * This can only be called from code that is not holding
 * cgroup_mutex (not nested in a cgroup_lock() call.)
 */
void rebuild_sched_domains(void)
{
	do_rebuild_sched_domains(NULL);
P
Paul Jackson 已提交
798 799
}

C
Cliff Wickman 已提交
800 801 802 803 804
/**
 * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
 * @tsk: task to test
 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
 *
805
 * Call with cgroup_mutex held.  May take callback_mutex during call.
C
Cliff Wickman 已提交
806 807 808
 * Called for each task in a cgroup by cgroup_scan_tasks().
 * Return nonzero if this tasks's cpus_allowed mask should be changed (in other
 * words, if its mask is not equal to its cpuset's mask).
809
 */
810 811
static int cpuset_test_cpumask(struct task_struct *tsk,
			       struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
812
{
813
	return !cpumask_equal(&tsk->cpus_allowed,
C
Cliff Wickman 已提交
814 815
			(cgroup_cs(scan->cg))->cpus_allowed);
}
816

C
Cliff Wickman 已提交
817 818 819 820 821 822 823 824 825 826 827
/**
 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
 * @tsk: task to test
 * @scan: struct cgroup_scanner containing the cgroup of the task
 *
 * Called by cgroup_scan_tasks() for each task in a cgroup whose
 * cpus_allowed mask needs to be changed.
 *
 * We don't need to re-check for the cgroup/cpuset membership, since we're
 * holding cgroup_lock() at this point.
 */
828 829
static void cpuset_change_cpumask(struct task_struct *tsk,
				  struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
830
{
831
	set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
C
Cliff Wickman 已提交
832 833
}

834 835 836
/**
 * 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
837
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
838 839 840 841 842 843
 *
 * Called with cgroup_mutex held
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 *
844 845
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
846
 */
847
static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
848 849 850 851 852 853
{
	struct cgroup_scanner scan;

	scan.cg = cs->css.cgroup;
	scan.test_task = cpuset_test_cpumask;
	scan.process_task = cpuset_change_cpumask;
854 855
	scan.heap = heap;
	cgroup_scan_tasks(&scan);
856 857
}

C
Cliff Wickman 已提交
858 859 860 861 862
/**
 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 * @cs: the cpuset to consider
 * @buf: buffer of cpu numbers written to this cpuset
 */
863 864
static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
			  const char *buf)
L
Linus Torvalds 已提交
865
{
866
	struct ptr_heap heap;
C
Cliff Wickman 已提交
867 868
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
869

870 871 872 873
	/* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
	if (cs == &top_cpuset)
		return -EACCES;

874
	/*
875
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
876 877 878
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
879
	 */
880
	if (!*buf) {
881
		cpumask_clear(trialcs->cpus_allowed);
882
	} else {
883
		retval = cpulist_parse(buf, trialcs->cpus_allowed);
884 885
		if (retval < 0)
			return retval;
886

887
		if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
888
			return -EINVAL;
889
	}
890
	retval = validate_change(cs, trialcs);
891 892
	if (retval < 0)
		return retval;
P
Paul Jackson 已提交
893

P
Paul Menage 已提交
894
	/* Nothing to do if the cpus didn't change */
895
	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
P
Paul Menage 已提交
896
		return 0;
C
Cliff Wickman 已提交
897

898 899 900 901
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval)
		return retval;

902
	is_load_balanced = is_sched_load_balance(trialcs);
P
Paul Jackson 已提交
903

904
	mutex_lock(&callback_mutex);
905
	cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
906
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
907

P
Paul Menage 已提交
908 909
	/*
	 * Scan tasks in the cpuset, and update the cpumasks of any
C
Cliff Wickman 已提交
910
	 * that need an update.
P
Paul Menage 已提交
911
	 */
912 913 914
	update_tasks_cpumask(cs, &heap);

	heap_free(&heap);
C
Cliff Wickman 已提交
915

P
Paul Menage 已提交
916
	if (is_load_balanced)
917
		async_rebuild_sched_domains();
918
	return 0;
L
Linus Torvalds 已提交
919 920
}

921 922 923 924 925 926 927 928
/*
 * 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.
 *
929
 *    Call holding cgroup_mutex, so current's cpuset won't change
930
 *    during this call, as manage_mutex holds off any cpuset_attach()
931 932
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
933
 *    our task's cpuset.
934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949
 *
 *    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;

	tsk->mems_allowed = *to;

	do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);

950
	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
951 952
}

953
/*
954 955 956 957 958 959 960 961 962 963 964
 * 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)
{
965
	bool need_loop;
966

967 968 969 970 971 972 973 974 975 976 977
repeat:
	/*
	 * 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);
978 979 980 981 982 983 984 985
	/*
	 * Determine if a loop is necessary if another thread is doing
	 * get_mems_allowed().  If at least one node remains unchanged and
	 * 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);
986
	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004
	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);

	/*
	 * ensure checking ->mems_allowed_change_disable after setting all new
	 * allowed nodes.
	 *
	 * the read-side task can see an nodemask with new allowed nodes and
	 * old allowed nodes. and if it allocates page when cpuset clears newly
	 * disallowed ones continuous, it can see the new allowed bits.
	 *
	 * And if setting all new allowed nodes is after the checking, setting
	 * all new allowed nodes and clearing newly disallowed ones will be done
	 * continuous, and the read-side task may find no node to alloc page.
	 */
	smp_mb();

	/*
	 * Allocation of memory is very fast, we needn't sleep when waiting
1005
	 * for the read-side.
1006
	 */
1007
	while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
		task_unlock(tsk);
		if (!task_curr(tsk))
			yield();
		goto repeat;
	}

	/*
	 * ensure checking ->mems_allowed_change_disable before clearing all new
	 * disallowed nodes.
	 *
	 * if clearing newly disallowed bits before the checking, the read-side
	 * task may find no node to alloc page.
	 */
	smp_mb();

	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1024
	tsk->mems_allowed = *newmems;
1025
	task_unlock(tsk);
1026 1027 1028 1029 1030 1031
}

/*
 * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
 * of it to cpuset's new mems_allowed, and migrate pages to new nodes if
 * memory_migrate flag is set. Called with cgroup_mutex held.
1032 1033 1034 1035 1036 1037 1038 1039
 */
static void cpuset_change_nodemask(struct task_struct *p,
				   struct cgroup_scanner *scan)
{
	struct mm_struct *mm;
	struct cpuset *cs;
	int migrate;
	const nodemask_t *oldmem = scan->data;
1040
	static nodemask_t newmems;	/* protected by cgroup_mutex */
1041 1042

	cs = cgroup_cs(scan->cg);
1043
	guarantee_online_mems(cs, &newmems);
1044

1045
	cpuset_change_task_nodemask(p, &newmems);
1046

1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058
	mm = get_task_mm(p);
	if (!mm)
		return;

	migrate = is_memory_migrate(cs);

	mpol_rebind_mm(mm, &cs->mems_allowed);
	if (migrate)
		cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
	mmput(mm);
}

1059 1060
static void *cpuset_being_rebound;

1061 1062 1063 1064
/**
 * 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
 * @oldmem: old mems_allowed of cpuset cs
1065
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1066 1067
 *
 * Called with cgroup_mutex held
1068 1069
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
1070
 */
1071 1072
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
				 struct ptr_heap *heap)
L
Linus Torvalds 已提交
1073
{
1074
	struct cgroup_scanner scan;
1075

1076
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
1077

1078 1079 1080
	scan.cg = cs->css.cgroup;
	scan.test_task = NULL;
	scan.process_task = cpuset_change_nodemask;
1081
	scan.heap = heap;
1082
	scan.data = (nodemask_t *)oldmem;
1083 1084

	/*
1085 1086 1087 1088 1089 1090
	 * 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
	 * the global cgroup_mutex, we know that no other rebind effort
	 * will be contending for the global variable cpuset_being_rebound.
1091
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1092
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1093
	 */
1094
	cgroup_scan_tasks(&scan);
1095

1096
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1097
	cpuset_being_rebound = NULL;
L
Linus Torvalds 已提交
1098 1099
}

1100 1101 1102
/*
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
1103 1104 1105 1106
 * 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.
1107 1108 1109 1110 1111 1112
 *
 * Call with cgroup_mutex held.  May take callback_mutex during call.
 * 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.
 */
1113 1114
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
			   const char *buf)
1115
{
1116
	NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
1117
	int retval;
1118
	struct ptr_heap heap;
1119

1120 1121 1122
	if (!oldmem)
		return -ENOMEM;

1123 1124 1125 1126
	/*
	 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
	 * it's read-only
	 */
1127 1128 1129 1130
	if (cs == &top_cpuset) {
		retval = -EACCES;
		goto done;
	}
1131 1132 1133 1134 1135 1136 1137 1138

	/*
	 * 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) {
1139
		nodes_clear(trialcs->mems_allowed);
1140
	} else {
1141
		retval = nodelist_parse(buf, trialcs->mems_allowed);
1142 1143 1144
		if (retval < 0)
			goto done;

1145
		if (!nodes_subset(trialcs->mems_allowed,
1146 1147 1148 1149
				node_states[N_HIGH_MEMORY])) {
			retval =  -EINVAL;
			goto done;
		}
1150
	}
1151 1152
	*oldmem = cs->mems_allowed;
	if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
1153 1154 1155
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
1156
	retval = validate_change(cs, trialcs);
1157 1158 1159
	if (retval < 0)
		goto done;

1160 1161 1162 1163
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval < 0)
		goto done;

1164
	mutex_lock(&callback_mutex);
1165
	cs->mems_allowed = trialcs->mems_allowed;
1166 1167
	mutex_unlock(&callback_mutex);

1168
	update_tasks_nodemask(cs, oldmem, &heap);
1169 1170

	heap_free(&heap);
1171
done:
1172
	NODEMASK_FREE(oldmem);
1173 1174 1175
	return retval;
}

1176 1177 1178 1179 1180
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1181
static int update_relax_domain_level(struct cpuset *cs, s64 val)
1182
{
1183
#ifdef CONFIG_SMP
1184
	if (val < -1 || val >= sched_domain_level_max)
1185
		return -EINVAL;
1186
#endif
1187 1188 1189

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
1190 1191
		if (!cpumask_empty(cs->cpus_allowed) &&
		    is_sched_load_balance(cs))
1192
			async_rebuild_sched_domains();
1193 1194 1195 1196 1197
	}

	return 0;
}

1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237
/*
 * cpuset_change_flag - make a task's spread flags the same as its cpuset's
 * @tsk: task to be updated
 * @scan: struct cgroup_scanner containing the cgroup of the task
 *
 * Called by cgroup_scan_tasks() for each task in a cgroup.
 *
 * We don't need to re-check for the cgroup/cpuset membership, since we're
 * holding cgroup_lock() at this point.
 */
static void cpuset_change_flag(struct task_struct *tsk,
				struct cgroup_scanner *scan)
{
	cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk);
}

/*
 * 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
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
 *
 * Called with cgroup_mutex held
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 *
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
 */
static void update_tasks_flags(struct cpuset *cs, struct ptr_heap *heap)
{
	struct cgroup_scanner scan;

	scan.cg = cs->css.cgroup;
	scan.test_task = NULL;
	scan.process_task = cpuset_change_flag;
	scan.heap = heap;
	cgroup_scan_tasks(&scan);
}

L
Linus Torvalds 已提交
1238 1239
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
1240 1241 1242
 * bit:		the bit to update (see cpuset_flagbits_t)
 * cs:		the cpuset to update
 * turning_on: 	whether the flag is being set or cleared
1243
 *
1244
 * Call with cgroup_mutex held.
L
Linus Torvalds 已提交
1245 1246
 */

1247 1248
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1249
{
1250
	struct cpuset *trialcs;
R
Rakib Mullick 已提交
1251
	int balance_flag_changed;
1252 1253 1254
	int spread_flag_changed;
	struct ptr_heap heap;
	int err;
L
Linus Torvalds 已提交
1255

1256 1257 1258 1259
	trialcs = alloc_trial_cpuset(cs);
	if (!trialcs)
		return -ENOMEM;

L
Linus Torvalds 已提交
1260
	if (turning_on)
1261
		set_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1262
	else
1263
		clear_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1264

1265
	err = validate_change(cs, trialcs);
1266
	if (err < 0)
1267
		goto out;
P
Paul Jackson 已提交
1268

1269 1270 1271 1272
	err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (err < 0)
		goto out;

P
Paul Jackson 已提交
1273
	balance_flag_changed = (is_sched_load_balance(cs) !=
1274
				is_sched_load_balance(trialcs));
P
Paul Jackson 已提交
1275

1276 1277 1278
	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
			|| (is_spread_page(cs) != is_spread_page(trialcs)));

1279
	mutex_lock(&callback_mutex);
1280
	cs->flags = trialcs->flags;
1281
	mutex_unlock(&callback_mutex);
1282

1283
	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1284
		async_rebuild_sched_domains();
P
Paul Jackson 已提交
1285

1286 1287 1288
	if (spread_flag_changed)
		update_tasks_flags(cs, &heap);
	heap_free(&heap);
1289 1290 1291
out:
	free_trial_cpuset(trialcs);
	return err;
L
Linus Torvalds 已提交
1292 1293
}

1294
/*
A
Adrian Bunk 已提交
1295
 * Frequency meter - How fast is some event occurring?
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 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391
 *
 * 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;
}

1392 1393
/*
 * Protected by cgroup_lock. The nodemasks must be stored globally because
1394 1395
 * dynamically allocating them is not allowed in can_attach, and they must
 * persist until attach.
1396 1397 1398 1399 1400
 */
static cpumask_var_t cpus_attach;
static nodemask_t cpuset_attach_nodemask_from;
static nodemask_t cpuset_attach_nodemask_to;

1401
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1402
static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1403
{
1404
	struct cpuset *cs = cgroup_cs(cgrp);
1405 1406
	struct task_struct *task;
	int ret;
L
Linus Torvalds 已提交
1407

1408
	if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
L
Linus Torvalds 已提交
1409
		return -ENOSPC;
1410

1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425
	cgroup_taskset_for_each(task, cgrp, tset) {
		/*
		 * Kthreads bound to specific cpus cannot be moved to a new
		 * cpuset; we cannot 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.
		 */
		if (task->flags & PF_THREAD_BOUND)
			return -EINVAL;
		if ((ret = security_task_setscheduler(task)))
			return ret;
	}
1426

1427
	/* prepare for attach */
1428 1429 1430 1431 1432 1433 1434
	if (cs == &top_cpuset)
		cpumask_copy(cpus_attach, cpu_possible_mask);
	else
		guarantee_online_cpus(cs, cpus_attach);

	guarantee_online_mems(cs, &cpuset_attach_nodemask_to);

1435
	return 0;
1436
}
L
Linus Torvalds 已提交
1437

1438
static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1439 1440
{
	struct mm_struct *mm;
1441 1442
	struct task_struct *task;
	struct task_struct *leader = cgroup_taskset_first(tset);
1443 1444 1445
	struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *oldcs = cgroup_cs(oldcgrp);
1446

1447 1448 1449 1450 1451 1452 1453 1454 1455 1456
	cgroup_taskset_for_each(task, cgrp, tset) {
		/*
		 * 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);
	}
1457

1458 1459 1460 1461 1462 1463
	/*
	 * Change mm, possibly for multiple threads in a threadgroup. This is
	 * expensive and may sleep.
	 */
	cpuset_attach_nodemask_from = oldcs->mems_allowed;
	cpuset_attach_nodemask_to = cs->mems_allowed;
1464
	mm = get_task_mm(leader);
1465
	if (mm) {
1466
		mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1467
		if (is_memory_migrate(cs))
1468 1469
			cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
					  &cpuset_attach_nodemask_to);
1470 1471
		mmput(mm);
	}
L
Linus Torvalds 已提交
1472 1473 1474 1475 1476
}

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

typedef enum {
1477
	FILE_MEMORY_MIGRATE,
L
Linus Torvalds 已提交
1478 1479 1480 1481
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
1482
	FILE_MEM_HARDWALL,
P
Paul Jackson 已提交
1483
	FILE_SCHED_LOAD_BALANCE,
1484
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1485 1486
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1487 1488
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
L
Linus Torvalds 已提交
1489 1490
} cpuset_filetype_t;

1491 1492 1493 1494 1495 1496
static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
	int retval = 0;
	struct cpuset *cs = cgroup_cs(cgrp);
	cpuset_filetype_t type = cft->private;

1497
	if (!cgroup_lock_live_group(cgrp))
1498 1499 1500
		return -ENODEV;

	switch (type) {
L
Linus Torvalds 已提交
1501
	case FILE_CPU_EXCLUSIVE:
1502
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1503 1504
		break;
	case FILE_MEM_EXCLUSIVE:
1505
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1506
		break;
1507 1508 1509
	case FILE_MEM_HARDWALL:
		retval = update_flag(CS_MEM_HARDWALL, cs, val);
		break;
P
Paul Jackson 已提交
1510
	case FILE_SCHED_LOAD_BALANCE:
1511
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1512
		break;
1513
	case FILE_MEMORY_MIGRATE:
1514
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1515
		break;
1516
	case FILE_MEMORY_PRESSURE_ENABLED:
1517
		cpuset_memory_pressure_enabled = !!val;
1518 1519 1520 1521
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1522
	case FILE_SPREAD_PAGE:
1523
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1524 1525
		break;
	case FILE_SPREAD_SLAB:
1526
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1527
		break;
L
Linus Torvalds 已提交
1528 1529
	default:
		retval = -EINVAL;
1530
		break;
L
Linus Torvalds 已提交
1531
	}
1532
	cgroup_unlock();
L
Linus Torvalds 已提交
1533 1534 1535
	return retval;
}

1536 1537 1538 1539 1540 1541
static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
{
	int retval = 0;
	struct cpuset *cs = cgroup_cs(cgrp);
	cpuset_filetype_t type = cft->private;

1542
	if (!cgroup_lock_live_group(cgrp))
1543
		return -ENODEV;
1544

1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, val);
		break;
	default:
		retval = -EINVAL;
		break;
	}
	cgroup_unlock();
	return retval;
}

1557 1558 1559 1560 1561 1562 1563
/*
 * Common handling for a write to a "cpus" or "mems" file.
 */
static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
				const char *buf)
{
	int retval = 0;
1564 1565
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *trialcs;
1566 1567 1568 1569

	if (!cgroup_lock_live_group(cgrp))
		return -ENODEV;

1570
	trialcs = alloc_trial_cpuset(cs);
1571 1572 1573 1574
	if (!trialcs) {
		retval = -ENOMEM;
		goto out;
	}
1575

1576 1577
	switch (cft->private) {
	case FILE_CPULIST:
1578
		retval = update_cpumask(cs, trialcs, buf);
1579 1580
		break;
	case FILE_MEMLIST:
1581
		retval = update_nodemask(cs, trialcs, buf);
1582 1583 1584 1585 1586
		break;
	default:
		retval = -EINVAL;
		break;
	}
1587 1588

	free_trial_cpuset(trialcs);
1589
out:
1590 1591 1592 1593
	cgroup_unlock();
	return retval;
}

L
Linus Torvalds 已提交
1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605
/*
 * 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.
 * A single large read to a buffer that crosses a page boundary is
 * ok, because the result being copied to user land is not recomputed
 * across a page fault.
 */

1606
static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1607
{
1608
	size_t count;
L
Linus Torvalds 已提交
1609

1610
	mutex_lock(&callback_mutex);
1611
	count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1612
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1613

1614
	return count;
L
Linus Torvalds 已提交
1615 1616
}

1617
static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1618
{
1619
	size_t count;
L
Linus Torvalds 已提交
1620

1621
	mutex_lock(&callback_mutex);
1622
	count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
1623
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1624

1625
	return count;
L
Linus Torvalds 已提交
1626 1627
}

1628 1629 1630 1631 1632
static ssize_t cpuset_common_file_read(struct cgroup *cont,
				       struct cftype *cft,
				       struct file *file,
				       char __user *buf,
				       size_t nbytes, loff_t *ppos)
L
Linus Torvalds 已提交
1633
{
1634
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1635 1636 1637 1638 1639
	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

1640
	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
L
Linus Torvalds 已提交
1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657
		return -ENOMEM;

	s = page;

	switch (type) {
	case FILE_CPULIST:
		s += cpuset_sprintf_cpulist(s, cs);
		break;
	case FILE_MEMLIST:
		s += cpuset_sprintf_memlist(s, cs);
		break;
	default:
		retval = -EINVAL;
		goto out;
	}
	*s++ = '\n';

A
Al Viro 已提交
1658
	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
L
Linus Torvalds 已提交
1659 1660 1661 1662 1663
out:
	free_page((unsigned long)page);
	return retval;
}

1664 1665 1666 1667 1668 1669 1670 1671 1672
static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
{
	struct cpuset *cs = cgroup_cs(cont);
	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);
1673 1674
	case FILE_MEM_HARDWALL:
		return is_mem_hardwall(cs);
1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689
	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();
	}
1690 1691 1692

	/* Unreachable but makes gcc happy */
	return 0;
1693
}
L
Linus Torvalds 已提交
1694

1695 1696 1697 1698 1699 1700 1701 1702 1703 1704
static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
{
	struct cpuset *cs = cgroup_cs(cont);
	cpuset_filetype_t type = cft->private;
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		return cs->relax_domain_level;
	default:
		BUG();
	}
1705 1706 1707

	/* Unrechable but makes gcc happy */
	return 0;
1708 1709
}

L
Linus Torvalds 已提交
1710 1711 1712 1713 1714

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

1715 1716 1717 1718
static struct cftype files[] = {
	{
		.name = "cpus",
		.read = cpuset_common_file_read,
1719 1720
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * NR_CPUS),
1721 1722 1723 1724 1725 1726
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
		.read = cpuset_common_file_read,
1727 1728
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * MAX_NUMNODES),
1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745
		.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,
	},

1746 1747 1748 1749 1750 1751 1752
	{
		.name = "mem_hardwall",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_HARDWALL,
	},

1753 1754 1755 1756 1757 1758 1759 1760 1761
	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
1762 1763
		.read_s64 = cpuset_read_s64,
		.write_s64 = cpuset_write_s64,
1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778
		.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,
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Li Zefan 已提交
1779
		.mode = S_IRUGO,
1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794
	},

	{
		.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,
	},
1795 1796
};

1797 1798
static struct cftype cft_memory_pressure_enabled = {
	.name = "memory_pressure_enabled",
1799 1800
	.read_u64 = cpuset_read_u64,
	.write_u64 = cpuset_write_u64,
1801 1802 1803
	.private = FILE_MEMORY_PRESSURE_ENABLED,
};

1804
static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
L
Linus Torvalds 已提交
1805 1806 1807
{
	int err;

1808 1809
	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
	if (err)
L
Linus Torvalds 已提交
1810
		return err;
1811
	/* memory_pressure_enabled is in root cpuset only */
1812
	if (!cont->parent)
1813
		err = cgroup_add_file(cont, ss,
1814 1815
				      &cft_memory_pressure_enabled);
	return err;
L
Linus Torvalds 已提交
1816 1817
}

1818
/*
D
Daniel Lezcano 已提交
1819 1820 1821
 * post_clone() is called during cgroup_create() when the
 * clone_children mount argument was specified.  The cgroup
 * can not yet have any tasks.
1822 1823 1824 1825 1826 1827 1828 1829 1830
 *
 * Currently we refuse to set up the cgroup - thereby
 * refusing the task to be entered, and as a result refusing
 * the sys_unshare() or clone() which initiated it - if any
 * sibling cpusets have exclusive cpus or mem.
 *
 * If this becomes a problem for some users who wish to
 * allow that scenario, then cpuset_post_clone() could be
 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1831 1832
 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
 * held.
1833
 */
1834
static void cpuset_post_clone(struct cgroup *cgroup)
1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847
{
	struct cgroup *parent, *child;
	struct cpuset *cs, *parent_cs;

	parent = cgroup->parent;
	list_for_each_entry(child, &parent->children, sibling) {
		cs = cgroup_cs(child);
		if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
			return;
	}
	cs = cgroup_cs(cgroup);
	parent_cs = cgroup_cs(parent);

1848
	mutex_lock(&callback_mutex);
1849
	cs->mems_allowed = parent_cs->mems_allowed;
1850
	cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
1851
	mutex_unlock(&callback_mutex);
1852 1853 1854
	return;
}

L
Linus Torvalds 已提交
1855 1856
/*
 *	cpuset_create - create a cpuset
1857
 *	cont:	control group that the new cpuset will be part of
L
Linus Torvalds 已提交
1858 1859
 */

1860
static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
L
Linus Torvalds 已提交
1861 1862
{
	struct cpuset *cs;
1863
	struct cpuset *parent;
L
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1864

1865 1866 1867 1868
	if (!cont->parent) {
		return &top_cpuset.css;
	}
	parent = cgroup_cs(cont->parent);
L
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1869 1870
	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
	if (!cs)
1871
		return ERR_PTR(-ENOMEM);
1872 1873 1874 1875
	if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
		kfree(cs);
		return ERR_PTR(-ENOMEM);
	}
L
Linus Torvalds 已提交
1876 1877

	cs->flags = 0;
1878 1879 1880 1881
	if (is_spread_page(parent))
		set_bit(CS_SPREAD_PAGE, &cs->flags);
	if (is_spread_slab(parent))
		set_bit(CS_SPREAD_SLAB, &cs->flags);
P
Paul Jackson 已提交
1882
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1883
	cpumask_clear(cs->cpus_allowed);
1884
	nodes_clear(cs->mems_allowed);
1885
	fmeter_init(&cs->fmeter);
1886
	cs->relax_domain_level = -1;
L
Linus Torvalds 已提交
1887 1888

	cs->parent = parent;
1889
	number_of_cpusets++;
1890
	return &cs->css ;
L
Linus Torvalds 已提交
1891 1892
}

P
Paul Jackson 已提交
1893 1894 1895
/*
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
1896
 * will call async_rebuild_sched_domains().
P
Paul Jackson 已提交
1897 1898
 */

1899
static void cpuset_destroy(struct cgroup *cont)
L
Linus Torvalds 已提交
1900
{
1901
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1902

P
Paul Jackson 已提交
1903
	if (is_sched_load_balance(cs))
1904
		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
P
Paul Jackson 已提交
1905

1906
	number_of_cpusets--;
1907
	free_cpumask_var(cs->cpus_allowed);
1908
	kfree(cs);
L
Linus Torvalds 已提交
1909 1910
}

1911 1912 1913
struct cgroup_subsys cpuset_subsys = {
	.name = "cpuset",
	.create = cpuset_create,
1914
	.destroy = cpuset_destroy,
1915 1916 1917 1918 1919 1920 1921 1922
	.can_attach = cpuset_can_attach,
	.attach = cpuset_attach,
	.populate = cpuset_populate,
	.post_clone = cpuset_post_clone,
	.subsys_id = cpuset_subsys_id,
	.early_init = 1,
};

L
Linus Torvalds 已提交
1923 1924 1925 1926 1927 1928 1929 1930
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1931
	int err = 0;
L
Linus Torvalds 已提交
1932

1933 1934 1935
	if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
		BUG();

1936
	cpumask_setall(top_cpuset.cpus_allowed);
1937
	nodes_setall(top_cpuset.mems_allowed);
L
Linus Torvalds 已提交
1938

1939
	fmeter_init(&top_cpuset.fmeter);
P
Paul Jackson 已提交
1940
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1941
	top_cpuset.relax_domain_level = -1;
L
Linus Torvalds 已提交
1942 1943 1944

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1945 1946
		return err;

1947 1948 1949
	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
		BUG();

1950
	number_of_cpusets = 1;
1951
	return 0;
L
Linus Torvalds 已提交
1952 1953
}

1954 1955 1956 1957 1958 1959 1960 1961
/**
 * cpuset_do_move_task - move a given task to another cpuset
 * @tsk: pointer to task_struct the task to move
 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
 *
 * Called by cgroup_scan_tasks() for each task in a cgroup.
 * Return nonzero to stop the walk through the tasks.
 */
1962 1963
static void cpuset_do_move_task(struct task_struct *tsk,
				struct cgroup_scanner *scan)
1964
{
1965
	struct cgroup *new_cgroup = scan->data;
1966

1967
	cgroup_attach_task(new_cgroup, tsk);
1968 1969 1970 1971 1972 1973 1974
}

/**
 * move_member_tasks_to_cpuset - move tasks from one cpuset to another
 * @from: cpuset in which the tasks currently reside
 * @to: cpuset to which the tasks will be moved
 *
1975 1976
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1977 1978 1979 1980 1981 1982
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 */
static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
{
1983
	struct cgroup_scanner scan;
1984

1985 1986 1987 1988 1989
	scan.cg = from->css.cgroup;
	scan.test_task = NULL; /* select all tasks in cgroup */
	scan.process_task = cpuset_do_move_task;
	scan.heap = NULL;
	scan.data = to->css.cgroup;
1990

1991
	if (cgroup_scan_tasks(&scan))
1992 1993 1994 1995
		printk(KERN_ERR "move_member_tasks_to_cpuset: "
				"cgroup_scan_tasks failed\n");
}

1996
/*
1997
 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1998 1999
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
2000 2001
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
2002
 *
2003 2004
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
2005
 */
2006 2007 2008 2009
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

2010 2011 2012 2013 2014
	/*
	 * The cgroup's css_sets list is in use if there are tasks
	 * in the cpuset; the list is empty if there are none;
	 * the cs->css.refcnt seems always 0.
	 */
2015 2016
	if (list_empty(&cs->css.cgroup->css_sets))
		return;
2017

2018 2019 2020 2021 2022
	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
	parent = cs->parent;
2023
	while (cpumask_empty(parent->cpus_allowed) ||
2024
			nodes_empty(parent->mems_allowed))
2025 2026 2027 2028 2029 2030 2031 2032 2033
		parent = parent->parent;

	move_member_tasks_to_cpuset(cs, parent);
}

/*
 * Walk the specified cpuset subtree and look for empty cpusets.
 * The tasks of such cpuset must be moved to a parent cpuset.
 *
2034
 * Called with cgroup_mutex held.  We take callback_mutex to modify
2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
 * cpus_allowed and mems_allowed.
 *
 * This walk processes the tree from top to bottom, completing one layer
 * before dropping down to the next.  It always processes a node before
 * any of its children.
 *
 * For now, since we lack memory hot unplug, we'll never see a cpuset
 * that has tasks along with an empty 'mems'.  But if we did see such
 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
 */
2045
static void scan_for_empty_cpusets(struct cpuset *root)
2046
{
2047
	LIST_HEAD(queue);
2048 2049
	struct cpuset *cp;	/* scans cpusets being updated */
	struct cpuset *child;	/* scans child cpusets of cp */
2050
	struct cgroup *cont;
2051
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2052

2053 2054 2055
	list_add_tail((struct list_head *)&root->stack_list, &queue);

	while (!list_empty(&queue)) {
2056
		cp = list_first_entry(&queue, struct cpuset, stack_list);
2057 2058 2059 2060 2061
		list_del(queue.next);
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			list_add_tail(&child->stack_list, &queue);
		}
2062 2063

		/* Continue past cpusets with all cpus, mems online */
2064
		if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&
2065 2066 2067
		    nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
			continue;

2068
		oldmems = cp->mems_allowed;
2069

2070
		/* Remove offline cpus and mems from this cpuset. */
2071
		mutex_lock(&callback_mutex);
2072
		cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
2073
			    cpu_active_mask);
2074 2075
		nodes_and(cp->mems_allowed, cp->mems_allowed,
						node_states[N_HIGH_MEMORY]);
2076 2077 2078
		mutex_unlock(&callback_mutex);

		/* Move tasks from the empty cpuset to a parent */
2079
		if (cpumask_empty(cp->cpus_allowed) ||
2080
		     nodes_empty(cp->mems_allowed))
2081
			remove_tasks_in_empty_cpuset(cp);
2082
		else {
2083
			update_tasks_cpumask(cp, NULL);
2084
			update_tasks_nodemask(cp, &oldmems, NULL);
2085
		}
2086 2087 2088
	}
}

2089 2090 2091 2092 2093 2094
/*
 * The top_cpuset tracks what CPUs and Memory Nodes are online,
 * period.  This 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.
 *
2095
 * This routine ensures that top_cpuset.cpus_allowed tracks
2096
 * cpu_active_mask on each CPU hotplug (cpuhp) event.
2097 2098 2099
 *
 * Called within get_online_cpus().  Needs to call cgroup_lock()
 * before calling generate_sched_domains().
2100
 */
2101
void cpuset_update_active_cpus(void)
2102
{
2103
	struct sched_domain_attr *attr;
2104
	cpumask_var_t *doms;
2105 2106 2107
	int ndoms;

	cgroup_lock();
2108
	mutex_lock(&callback_mutex);
2109
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2110
	mutex_unlock(&callback_mutex);
2111 2112 2113 2114 2115 2116
	scan_for_empty_cpusets(&top_cpuset);
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);
2117 2118
}

2119
#ifdef CONFIG_MEMORY_HOTPLUG
2120
/*
2121
 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2122 2123
 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
 * See also the previous routine cpuset_track_online_cpus().
2124
 */
2125 2126
static int cpuset_track_online_nodes(struct notifier_block *self,
				unsigned long action, void *arg)
2127
{
2128
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2129

2130
	cgroup_lock();
2131 2132
	switch (action) {
	case MEM_ONLINE:
2133
		oldmems = top_cpuset.mems_allowed;
2134
		mutex_lock(&callback_mutex);
2135
		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2136
		mutex_unlock(&callback_mutex);
2137
		update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
2138 2139 2140 2141 2142 2143 2144
		break;
	case MEM_OFFLINE:
		/*
		 * needn't update top_cpuset.mems_allowed explicitly because
		 * scan_for_empty_cpusets() will update it.
		 */
		scan_for_empty_cpusets(&top_cpuset);
2145 2146 2147 2148
		break;
	default:
		break;
	}
2149
	cgroup_unlock();
2150

2151
	return NOTIFY_OK;
2152 2153 2154
}
#endif

L
Linus Torvalds 已提交
2155 2156 2157 2158 2159 2160 2161 2162
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
 **/

void __init cpuset_init_smp(void)
{
2163
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2164
	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2165

2166
	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2167 2168 2169

	cpuset_wq = create_singlethread_workqueue("cpuset");
	BUG_ON(!cpuset_wq);
L
Linus Torvalds 已提交
2170 2171 2172 2173 2174
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2175
 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
L
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2176
 *
2177
 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
L
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2178 2179 2180 2181 2182
 * attached to the specified @tsk.  Guaranteed to return some non-empty
 * subset of cpu_online_map, even if this means going outside the
 * tasks cpuset.
 **/

2183
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
L
Linus Torvalds 已提交
2184
{
2185
	mutex_lock(&callback_mutex);
2186
	task_lock(tsk);
2187
	guarantee_online_cpus(task_cs(tsk), pmask);
2188
	task_unlock(tsk);
2189
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
2190 2191
}

2192 2193 2194 2195 2196 2197 2198 2199
int cpuset_cpus_allowed_fallback(struct task_struct *tsk)
{
	const struct cpuset *cs;
	int cpu;

	rcu_read_lock();
	cs = task_cs(tsk);
	if (cs)
2200
		do_set_cpus_allowed(tsk, cs->cpus_allowed);
2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226
	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.
	 */

	cpu = cpumask_any_and(&tsk->cpus_allowed, cpu_active_mask);
	if (cpu >= nr_cpu_ids) {
		/*
		 * Either tsk->cpus_allowed is wrong (see above) or it
		 * is actually empty. The latter case is only possible
		 * if we are racing with remove_tasks_in_empty_cpuset().
		 * Like above we can temporary set any mask and rely on
		 * set_cpus_allowed_ptr() as synchronization point.
		 */
2227
		do_set_cpus_allowed(tsk, cpu_possible_mask);
2228 2229 2230 2231 2232 2233
		cpu = cpumask_any(cpu_active_mask);
	}

	return cpu;
}

L
Linus Torvalds 已提交
2234 2235
void cpuset_init_current_mems_allowed(void)
{
2236
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
2237 2238
}

2239 2240 2241 2242 2243 2244
/**
 * 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
2245
 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2246 2247 2248 2249 2250 2251 2252
 * tasks cpuset.
 **/

nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
	nodemask_t mask;

2253
	mutex_lock(&callback_mutex);
2254
	task_lock(tsk);
2255
	guarantee_online_mems(task_cs(tsk), &mask);
2256
	task_unlock(tsk);
2257
	mutex_unlock(&callback_mutex);
2258 2259 2260 2261

	return mask;
}

2262
/**
2263 2264
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
2265
 *
2266
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
2267
 */
2268
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
2269
{
2270
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
2271 2272
}

2273
/*
2274 2275 2276 2277
 * 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.
2278
 */
2279
static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2280
{
2281
	while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2282 2283 2284 2285
		cs = cs->parent;
	return cs;
}

2286
/**
2287 2288
 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2289
 * @gfp_mask: memory allocation flags
2290
 *
2291 2292 2293 2294 2295 2296
 * 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.
2297 2298
 * Otherwise, no.
 *
2299 2300 2301
 * 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.
2302
 *
2303 2304
 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
 * cpusets, and never sleeps.
2305 2306 2307 2308 2309 2310 2311
 *
 * 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'.
 *
2312
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2313 2314
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2315
 * GFP_KERNEL allocations are not so marked, so can escape to the
2316
 * nearest enclosing hardwalled ancestor cpuset.
2317
 *
2318 2319 2320 2321 2322 2323 2324
 * 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.
2325
 *
2326
 * The first call here from mm/page_alloc:get_page_from_freelist()
2327 2328 2329
 * 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).
2330 2331 2332 2333 2334 2335
 *
 * 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:
2336 2337
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2338
 *	TIF_MEMDIE   - any node ok
2339
 *	GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2340
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2341 2342
 *
 * Rule:
2343
 *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2344 2345
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2346
 */
2347
int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2348
{
2349
	const struct cpuset *cs;	/* current cpuset ancestors */
2350
	int allowed;			/* is allocation in zone z allowed? */
2351

2352
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2353
		return 1;
2354
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2355 2356
	if (node_isset(node, current->mems_allowed))
		return 1;
2357 2358 2359 2360 2361 2362
	/*
	 * 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;
2363 2364 2365
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2366 2367 2368
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2369
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2370
	mutex_lock(&callback_mutex);
2371 2372

	task_lock(current);
2373
	cs = nearest_hardwall_ancestor(task_cs(current));
2374 2375
	task_unlock(current);

2376
	allowed = node_isset(node, cs->mems_allowed);
2377
	mutex_unlock(&callback_mutex);
2378
	return allowed;
L
Linus Torvalds 已提交
2379 2380
}

2381
/*
2382 2383
 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2384 2385
 * @gfp_mask: memory allocation flags
 *
2386 2387 2388 2389 2390
 * 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.
2391 2392 2393 2394 2395 2396 2397
 *
 * 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'.
 *
2398 2399
 * Unlike the cpuset_node_allowed_softwall() variant, above,
 * this variant requires that the node be in the current task's
2400 2401 2402 2403
 * 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.
 */
2404
int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2405 2406 2407 2408 2409
{
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2410 2411 2412 2413 2414 2415
	/*
	 * 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;
2416 2417 2418
	return 0;
}

P
Paul Jackson 已提交
2419 2420 2421 2422 2423 2424 2425 2426
/**
 * cpuset_unlock - release lock on cpuset changes
 *
 * Undo the lock taken in a previous cpuset_lock() call.
 */

void cpuset_unlock(void)
{
2427
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
2428 2429
}

2430
/**
2431 2432
 * 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
2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456
 *
 * 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().
 */

2457
static int cpuset_spread_node(int *rotor)
2458 2459 2460
{
	int node;

2461
	node = next_node(*rotor, current->mems_allowed);
2462 2463
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
2464
	*rotor = node;
2465 2466
	return node;
}
2467 2468 2469

int cpuset_mem_spread_node(void)
{
2470 2471 2472 2473
	if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
		current->cpuset_mem_spread_rotor =
			node_random(&current->mems_allowed);

2474 2475 2476 2477 2478
	return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
}

int cpuset_slab_spread_node(void)
{
2479 2480 2481 2482
	if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
		current->cpuset_slab_spread_rotor =
			node_random(&current->mems_allowed);

2483 2484 2485
	return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
}

2486 2487
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2488
/**
2489 2490 2491 2492 2493 2494 2495 2496
 * 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.
2497 2498
 **/

2499 2500
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2501
{
2502
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2503 2504
}

2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527
/**
 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
 * @task: pointer to task_struct of some task.
 *
 * Description: Prints @task's name, cpuset name, and cached copy of its
 * mems_allowed to the kernel log.  Must hold task_lock(task) to allow
 * dereferencing task_cs(task).
 */
void cpuset_print_task_mems_allowed(struct task_struct *tsk)
{
	struct dentry *dentry;

	dentry = task_cs(tsk)->css.cgroup->dentry;
	spin_lock(&cpuset_buffer_lock);
	snprintf(cpuset_name, CPUSET_NAME_LEN,
		 dentry ? (const char *)dentry->d_name.name : "/");
	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
			   tsk->mems_allowed);
	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
	       tsk->comm, cpuset_name, cpuset_nodelist);
	spin_unlock(&cpuset_buffer_lock);
}

2528 2529 2530 2531 2532 2533
/*
 * 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.
 */

2534
int cpuset_memory_pressure_enabled __read_mostly;
2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556

/**
 * 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)
{
	task_lock(current);
2557
	fmeter_markevent(&task_cs(current)->fmeter);
2558 2559 2560
	task_unlock(current);
}

2561
#ifdef CONFIG_PROC_PID_CPUSET
L
Linus Torvalds 已提交
2562 2563 2564 2565
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2566 2567
 *  - 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,
2568
 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2569
 *    anyway.
L
Linus Torvalds 已提交
2570
 */
P
Paul Jackson 已提交
2571
static int proc_cpuset_show(struct seq_file *m, void *unused_v)
L
Linus Torvalds 已提交
2572
{
2573
	struct pid *pid;
L
Linus Torvalds 已提交
2574 2575
	struct task_struct *tsk;
	char *buf;
2576
	struct cgroup_subsys_state *css;
2577
	int retval;
L
Linus Torvalds 已提交
2578

2579
	retval = -ENOMEM;
L
Linus Torvalds 已提交
2580 2581
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2582 2583 2584
		goto out;

	retval = -ESRCH;
2585 2586
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2587 2588
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2589

2590
	retval = -EINVAL;
2591 2592 2593
	cgroup_lock();
	css = task_subsys_state(tsk, cpuset_subsys_id);
	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
L
Linus Torvalds 已提交
2594
	if (retval < 0)
2595
		goto out_unlock;
L
Linus Torvalds 已提交
2596 2597
	seq_puts(m, buf);
	seq_putc(m, '\n');
2598
out_unlock:
2599
	cgroup_unlock();
2600 2601
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2602
	kfree(buf);
2603
out:
L
Linus Torvalds 已提交
2604 2605 2606 2607 2608
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2609 2610
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
L
Linus Torvalds 已提交
2611 2612
}

2613
const struct file_operations proc_cpuset_operations = {
L
Linus Torvalds 已提交
2614 2615 2616 2617 2618
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
2619
#endif /* CONFIG_PROC_PID_CPUSET */
L
Linus Torvalds 已提交
2620

2621
/* Display task mems_allowed in /proc/<pid>/status file. */
2622 2623 2624
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
	seq_printf(m, "Mems_allowed:\t");
2625
	seq_nodemask(m, &task->mems_allowed);
2626
	seq_printf(m, "\n");
2627
	seq_printf(m, "Mems_allowed_list:\t");
2628
	seq_nodemask_list(m, &task->mems_allowed);
2629
	seq_printf(m, "\n");
L
Linus Torvalds 已提交
2630
}