cpuset.c 73.9 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;

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/* the type of hotplug event */
enum hotplug_event {
	CPUSET_CPU_OFFLINE,
	CPUSET_MEM_OFFLINE,
};

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/* 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,
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 * return cpu_online_mask.  Or if passed a NULL cs from an exit'ing
 * task, return cpu_online_mask.
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of cpu_online_mask.
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 *
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 * Call with callback_mutex held.
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 */

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static void guarantee_online_cpus(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 */
566
	cpumask_var_t *doms;	/* resulting partition; i.e. sched domains */
567
	struct sched_domain_attr *dattr;  /* attributes for custom domains */
568
	int ndoms = 0;		/* number of sched domains in result */
569
	int nslot;		/* next empty doms[] struct cpumask slot */
P
Paul Jackson 已提交
570 571

	doms = NULL;
572
	dattr = NULL;
573
	csa = NULL;
P
Paul Jackson 已提交
574 575 576

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
577 578
		ndoms = 1;
		doms = alloc_sched_domains(ndoms);
P
Paul Jackson 已提交
579
		if (!doms)
580 581
			goto done;

582 583 584
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
585
			update_domain_attr_tree(dattr, &top_cpuset);
586
		}
587
		cpumask_copy(doms[0], top_cpuset.cpus_allowed);
588 589

		goto done;
P
Paul Jackson 已提交
590 591 592 593 594 595 596
	}

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

597 598
	list_add(&top_cpuset.stack_list, &q);
	while (!list_empty(&q)) {
P
Paul Jackson 已提交
599 600
		struct cgroup *cont;
		struct cpuset *child;   /* scans child cpusets of cp */
601

602 603 604
		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

605
		if (cpumask_empty(cp->cpus_allowed))
606 607
			continue;

608 609 610 611 612 613 614
		/*
		 * 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
615
			csa[csn++] = cp;
616 617
			continue;
		}
618

P
Paul Jackson 已提交
619 620
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
621
			list_add_tail(&child->stack_list, &q);
P
Paul Jackson 已提交
622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651
		}
  	}

	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;
			}
		}
	}

652 653 654 655
	/*
	 * Now we know how many domains to create.
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
	 */
656
	doms = alloc_sched_domains(ndoms);
657
	if (!doms)
658 659 660 661 662 663
		goto done;

	/*
	 * The rest of the code, including the scheduler, can deal with
	 * dattr==NULL case. No need to abort if alloc fails.
	 */
664
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
P
Paul Jackson 已提交
665 666 667

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
668
		struct cpumask *dp;
P
Paul Jackson 已提交
669 670
		int apn = a->pn;

671 672 673 674 675
		if (apn < 0) {
			/* Skip completed partitions */
			continue;
		}

676
		dp = doms[nslot];
677 678 679 680 681 682 683 684 685 686

		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
687
			}
688 689
			continue;
		}
P
Paul Jackson 已提交
690

691
		cpumask_clear(dp);
692 693 694 695 696 697
		if (dattr)
			*(dattr + nslot) = SD_ATTR_INIT;
		for (j = i; j < csn; j++) {
			struct cpuset *b = csa[j];

			if (apn == b->pn) {
698
				cpumask_or(dp, dp, b->cpus_allowed);
699 700 701 702 703
				if (dattr)
					update_domain_attr_tree(dattr + nslot, b);

				/* Done with this partition */
				b->pn = -1;
P
Paul Jackson 已提交
704 705
			}
		}
706
		nslot++;
P
Paul Jackson 已提交
707 708 709
	}
	BUG_ON(nslot != ndoms);

710 711 712
done:
	kfree(csa);

713 714 715 716 717 718 719
	/*
	 * Fallback to the default domain if kmalloc() failed.
	 * See comments in partition_sched_domains().
	 */
	if (doms == NULL)
		ndoms = 1;

720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737
	*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;
738
	cpumask_var_t *doms;
739 740
	int ndoms;

741
	get_online_cpus();
742 743 744 745 746 747 748 749 750

	/* 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);

751
	put_online_cpus();
752
}
753 754 755 756 757
#else /* !CONFIG_SMP */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
}

758
static int generate_sched_domains(cpumask_var_t **domains,
759 760 761 762 763 764
			struct sched_domain_attr **attributes)
{
	*domains = NULL;
	return 1;
}
#endif /* CONFIG_SMP */
P
Paul Jackson 已提交
765

766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788
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)
{
789
	queue_work(cpuset_wq, &rebuild_sched_domains_work);
790 791 792 793 794 795 796 797 798 799 800 801 802 803
}

/*
 * 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
804 805
}

C
Cliff Wickman 已提交
806 807 808 809 810
/**
 * 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
 *
811
 * Call with cgroup_mutex held.  May take callback_mutex during call.
C
Cliff Wickman 已提交
812 813 814
 * 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).
815
 */
816 817
static int cpuset_test_cpumask(struct task_struct *tsk,
			       struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
818
{
819
	return !cpumask_equal(&tsk->cpus_allowed,
C
Cliff Wickman 已提交
820 821
			(cgroup_cs(scan->cg))->cpus_allowed);
}
822

C
Cliff Wickman 已提交
823 824 825 826 827 828 829 830 831 832 833
/**
 * 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.
 */
834 835
static void cpuset_change_cpumask(struct task_struct *tsk,
				  struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
836
{
837
	set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
C
Cliff Wickman 已提交
838 839
}

840 841 842
/**
 * 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
843
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
844 845 846 847 848 849
 *
 * Called with cgroup_mutex held
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 *
850 851
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
852
 */
853
static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
854 855 856 857 858 859
{
	struct cgroup_scanner scan;

	scan.cg = cs->css.cgroup;
	scan.test_task = cpuset_test_cpumask;
	scan.process_task = cpuset_change_cpumask;
860 861
	scan.heap = heap;
	cgroup_scan_tasks(&scan);
862 863
}

C
Cliff Wickman 已提交
864 865 866 867 868
/**
 * 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
 */
869 870
static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
			  const char *buf)
L
Linus Torvalds 已提交
871
{
872
	struct ptr_heap heap;
C
Cliff Wickman 已提交
873 874
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
875

876
	/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
877 878 879
	if (cs == &top_cpuset)
		return -EACCES;

880
	/*
881
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
882 883 884
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
885
	 */
886
	if (!*buf) {
887
		cpumask_clear(trialcs->cpus_allowed);
888
	} else {
889
		retval = cpulist_parse(buf, trialcs->cpus_allowed);
890 891
		if (retval < 0)
			return retval;
892

893
		if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
894
			return -EINVAL;
895
	}
896
	retval = validate_change(cs, trialcs);
897 898
	if (retval < 0)
		return retval;
P
Paul Jackson 已提交
899

P
Paul Menage 已提交
900
	/* Nothing to do if the cpus didn't change */
901
	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
P
Paul Menage 已提交
902
		return 0;
C
Cliff Wickman 已提交
903

904 905 906 907
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval)
		return retval;

908
	is_load_balanced = is_sched_load_balance(trialcs);
P
Paul Jackson 已提交
909

910
	mutex_lock(&callback_mutex);
911
	cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
912
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
913

P
Paul Menage 已提交
914 915
	/*
	 * Scan tasks in the cpuset, and update the cpumasks of any
C
Cliff Wickman 已提交
916
	 * that need an update.
P
Paul Menage 已提交
917
	 */
918 919 920
	update_tasks_cpumask(cs, &heap);

	heap_free(&heap);
C
Cliff Wickman 已提交
921

P
Paul Menage 已提交
922
	if (is_load_balanced)
923
		async_rebuild_sched_domains();
924
	return 0;
L
Linus Torvalds 已提交
925 926
}

927 928 929 930 931 932 933 934
/*
 * 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.
 *
935
 *    Call holding cgroup_mutex, so current's cpuset won't change
936
 *    during this call, as manage_mutex holds off any cpuset_attach()
937 938
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
939
 *    our task's cpuset.
940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
 *
 *    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);

956
	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
957 958
}

959
/*
960 961 962 963 964 965 966 967 968 969 970
 * 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)
{
971
	bool need_loop;
972

973 974 975 976 977 978 979 980 981 982
	/*
	 * 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);
983 984 985 986 987 988 989 990
	/*
	 * 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);
991

992 993
	if (need_loop)
		write_seqcount_begin(&tsk->mems_allowed_seq);
994

995 996
	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
997 998

	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
999
	tsk->mems_allowed = *newmems;
1000 1001 1002 1003

	if (need_loop)
		write_seqcount_end(&tsk->mems_allowed_seq);

1004
	task_unlock(tsk);
1005 1006 1007 1008 1009 1010
}

/*
 * 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.
1011 1012 1013 1014 1015 1016 1017 1018
 */
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;
1019
	static nodemask_t newmems;	/* protected by cgroup_mutex */
1020 1021

	cs = cgroup_cs(scan->cg);
1022
	guarantee_online_mems(cs, &newmems);
1023

1024
	cpuset_change_task_nodemask(p, &newmems);
1025

1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
	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);
}

1038 1039
static void *cpuset_being_rebound;

1040 1041 1042 1043
/**
 * 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
1044
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1045 1046
 *
 * Called with cgroup_mutex held
1047 1048
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
1049
 */
1050 1051
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
				 struct ptr_heap *heap)
L
Linus Torvalds 已提交
1052
{
1053
	struct cgroup_scanner scan;
1054

1055
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
1056

1057 1058 1059
	scan.cg = cs->css.cgroup;
	scan.test_task = NULL;
	scan.process_task = cpuset_change_nodemask;
1060
	scan.heap = heap;
1061
	scan.data = (nodemask_t *)oldmem;
1062 1063

	/*
1064 1065 1066 1067 1068 1069
	 * 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.
1070
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1071
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1072
	 */
1073
	cgroup_scan_tasks(&scan);
1074

1075
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1076
	cpuset_being_rebound = NULL;
L
Linus Torvalds 已提交
1077 1078
}

1079 1080 1081
/*
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
1082 1083 1084 1085
 * 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.
1086 1087 1088 1089 1090 1091
 *
 * 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.
 */
1092 1093
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
			   const char *buf)
1094
{
1095
	NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
1096
	int retval;
1097
	struct ptr_heap heap;
1098

1099 1100 1101
	if (!oldmem)
		return -ENOMEM;

1102 1103 1104 1105
	/*
	 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
	 * it's read-only
	 */
1106 1107 1108 1109
	if (cs == &top_cpuset) {
		retval = -EACCES;
		goto done;
	}
1110 1111 1112 1113 1114 1115 1116 1117

	/*
	 * 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) {
1118
		nodes_clear(trialcs->mems_allowed);
1119
	} else {
1120
		retval = nodelist_parse(buf, trialcs->mems_allowed);
1121 1122 1123
		if (retval < 0)
			goto done;

1124
		if (!nodes_subset(trialcs->mems_allowed,
1125 1126 1127 1128
				node_states[N_HIGH_MEMORY])) {
			retval =  -EINVAL;
			goto done;
		}
1129
	}
1130 1131
	*oldmem = cs->mems_allowed;
	if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
1132 1133 1134
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
1135
	retval = validate_change(cs, trialcs);
1136 1137 1138
	if (retval < 0)
		goto done;

1139 1140 1141 1142
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval < 0)
		goto done;

1143
	mutex_lock(&callback_mutex);
1144
	cs->mems_allowed = trialcs->mems_allowed;
1145 1146
	mutex_unlock(&callback_mutex);

1147
	update_tasks_nodemask(cs, oldmem, &heap);
1148 1149

	heap_free(&heap);
1150
done:
1151
	NODEMASK_FREE(oldmem);
1152 1153 1154
	return retval;
}

1155 1156 1157 1158 1159
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1160
static int update_relax_domain_level(struct cpuset *cs, s64 val)
1161
{
1162
#ifdef CONFIG_SMP
1163
	if (val < -1 || val >= sched_domain_level_max)
1164
		return -EINVAL;
1165
#endif
1166 1167 1168

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
1169 1170
		if (!cpumask_empty(cs->cpus_allowed) &&
		    is_sched_load_balance(cs))
1171
			async_rebuild_sched_domains();
1172 1173 1174 1175 1176
	}

	return 0;
}

1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216
/*
 * 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
1217 1218
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
1219 1220 1221
 * bit:		the bit to update (see cpuset_flagbits_t)
 * cs:		the cpuset to update
 * turning_on: 	whether the flag is being set or cleared
1222
 *
1223
 * Call with cgroup_mutex held.
L
Linus Torvalds 已提交
1224 1225
 */

1226 1227
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1228
{
1229
	struct cpuset *trialcs;
R
Rakib Mullick 已提交
1230
	int balance_flag_changed;
1231 1232 1233
	int spread_flag_changed;
	struct ptr_heap heap;
	int err;
L
Linus Torvalds 已提交
1234

1235 1236 1237 1238
	trialcs = alloc_trial_cpuset(cs);
	if (!trialcs)
		return -ENOMEM;

L
Linus Torvalds 已提交
1239
	if (turning_on)
1240
		set_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1241
	else
1242
		clear_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1243

1244
	err = validate_change(cs, trialcs);
1245
	if (err < 0)
1246
		goto out;
P
Paul Jackson 已提交
1247

1248 1249 1250 1251
	err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (err < 0)
		goto out;

P
Paul Jackson 已提交
1252
	balance_flag_changed = (is_sched_load_balance(cs) !=
1253
				is_sched_load_balance(trialcs));
P
Paul Jackson 已提交
1254

1255 1256 1257
	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
			|| (is_spread_page(cs) != is_spread_page(trialcs)));

1258
	mutex_lock(&callback_mutex);
1259
	cs->flags = trialcs->flags;
1260
	mutex_unlock(&callback_mutex);
1261

1262
	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1263
		async_rebuild_sched_domains();
P
Paul Jackson 已提交
1264

1265 1266 1267
	if (spread_flag_changed)
		update_tasks_flags(cs, &heap);
	heap_free(&heap);
1268 1269 1270
out:
	free_trial_cpuset(trialcs);
	return err;
L
Linus Torvalds 已提交
1271 1272
}

1273
/*
A
Adrian Bunk 已提交
1274
 * Frequency meter - How fast is some event occurring?
1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370
 *
 * 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;
}

1371 1372
/*
 * Protected by cgroup_lock. The nodemasks must be stored globally because
1373 1374
 * dynamically allocating them is not allowed in can_attach, and they must
 * persist until attach.
1375 1376 1377 1378 1379
 */
static cpumask_var_t cpus_attach;
static nodemask_t cpuset_attach_nodemask_from;
static nodemask_t cpuset_attach_nodemask_to;

1380
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1381
static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1382
{
1383
	struct cpuset *cs = cgroup_cs(cgrp);
1384 1385
	struct task_struct *task;
	int ret;
L
Linus Torvalds 已提交
1386

1387
	if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
L
Linus Torvalds 已提交
1388
		return -ENOSPC;
1389

1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
	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;
	}
1405

1406
	/* prepare for attach */
1407 1408 1409 1410 1411 1412 1413
	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);

1414
	return 0;
1415
}
L
Linus Torvalds 已提交
1416

1417
static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1418 1419
{
	struct mm_struct *mm;
1420 1421
	struct task_struct *task;
	struct task_struct *leader = cgroup_taskset_first(tset);
1422 1423 1424
	struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *oldcs = cgroup_cs(oldcgrp);
1425

1426 1427 1428 1429 1430 1431 1432 1433 1434 1435
	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);
	}
1436

1437 1438 1439 1440 1441 1442
	/*
	 * 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;
1443
	mm = get_task_mm(leader);
1444
	if (mm) {
1445
		mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1446
		if (is_memory_migrate(cs))
1447 1448
			cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
					  &cpuset_attach_nodemask_to);
1449 1450
		mmput(mm);
	}
L
Linus Torvalds 已提交
1451 1452 1453 1454 1455
}

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

typedef enum {
1456
	FILE_MEMORY_MIGRATE,
L
Linus Torvalds 已提交
1457 1458 1459 1460
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
1461
	FILE_MEM_HARDWALL,
P
Paul Jackson 已提交
1462
	FILE_SCHED_LOAD_BALANCE,
1463
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1464 1465
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1466 1467
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
L
Linus Torvalds 已提交
1468 1469
} cpuset_filetype_t;

1470 1471 1472 1473 1474 1475
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;

1476
	if (!cgroup_lock_live_group(cgrp))
1477 1478 1479
		return -ENODEV;

	switch (type) {
L
Linus Torvalds 已提交
1480
	case FILE_CPU_EXCLUSIVE:
1481
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1482 1483
		break;
	case FILE_MEM_EXCLUSIVE:
1484
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1485
		break;
1486 1487 1488
	case FILE_MEM_HARDWALL:
		retval = update_flag(CS_MEM_HARDWALL, cs, val);
		break;
P
Paul Jackson 已提交
1489
	case FILE_SCHED_LOAD_BALANCE:
1490
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1491
		break;
1492
	case FILE_MEMORY_MIGRATE:
1493
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1494
		break;
1495
	case FILE_MEMORY_PRESSURE_ENABLED:
1496
		cpuset_memory_pressure_enabled = !!val;
1497 1498 1499 1500
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1501
	case FILE_SPREAD_PAGE:
1502
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1503 1504
		break;
	case FILE_SPREAD_SLAB:
1505
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1506
		break;
L
Linus Torvalds 已提交
1507 1508
	default:
		retval = -EINVAL;
1509
		break;
L
Linus Torvalds 已提交
1510
	}
1511
	cgroup_unlock();
L
Linus Torvalds 已提交
1512 1513 1514
	return retval;
}

1515 1516 1517 1518 1519 1520
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;

1521
	if (!cgroup_lock_live_group(cgrp))
1522
		return -ENODEV;
1523

1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, val);
		break;
	default:
		retval = -EINVAL;
		break;
	}
	cgroup_unlock();
	return retval;
}

1536 1537 1538 1539 1540 1541 1542
/*
 * 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;
1543 1544
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *trialcs;
1545 1546 1547 1548

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

1549
	trialcs = alloc_trial_cpuset(cs);
1550 1551 1552 1553
	if (!trialcs) {
		retval = -ENOMEM;
		goto out;
	}
1554

1555 1556
	switch (cft->private) {
	case FILE_CPULIST:
1557
		retval = update_cpumask(cs, trialcs, buf);
1558 1559
		break;
	case FILE_MEMLIST:
1560
		retval = update_nodemask(cs, trialcs, buf);
1561 1562 1563 1564 1565
		break;
	default:
		retval = -EINVAL;
		break;
	}
1566 1567

	free_trial_cpuset(trialcs);
1568
out:
1569 1570 1571 1572
	cgroup_unlock();
	return retval;
}

L
Linus Torvalds 已提交
1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584
/*
 * 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.
 */

1585
static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1586
{
1587
	size_t count;
L
Linus Torvalds 已提交
1588

1589
	mutex_lock(&callback_mutex);
1590
	count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1591
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1592

1593
	return count;
L
Linus Torvalds 已提交
1594 1595
}

1596
static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1597
{
1598
	size_t count;
L
Linus Torvalds 已提交
1599

1600
	mutex_lock(&callback_mutex);
1601
	count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
1602
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1603

1604
	return count;
L
Linus Torvalds 已提交
1605 1606
}

1607 1608 1609 1610 1611
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
1612
{
1613
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1614 1615 1616 1617 1618
	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

1619
	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
L
Linus Torvalds 已提交
1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636
		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
1637
	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
L
Linus Torvalds 已提交
1638 1639 1640 1641 1642
out:
	free_page((unsigned long)page);
	return retval;
}

1643 1644 1645 1646 1647 1648 1649 1650 1651
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);
1652 1653
	case FILE_MEM_HARDWALL:
		return is_mem_hardwall(cs);
1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668
	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();
	}
1669 1670 1671

	/* Unreachable but makes gcc happy */
	return 0;
1672
}
L
Linus Torvalds 已提交
1673

1674 1675 1676 1677 1678 1679 1680 1681 1682 1683
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();
	}
1684 1685 1686

	/* Unrechable but makes gcc happy */
	return 0;
1687 1688
}

L
Linus Torvalds 已提交
1689 1690 1691 1692 1693

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

1694 1695 1696 1697
static struct cftype files[] = {
	{
		.name = "cpus",
		.read = cpuset_common_file_read,
1698 1699
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * NR_CPUS),
1700 1701 1702 1703 1704 1705
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
		.read = cpuset_common_file_read,
1706 1707
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * MAX_NUMNODES),
1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724
		.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,
	},

1725 1726 1727 1728 1729 1730 1731
	{
		.name = "mem_hardwall",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_HARDWALL,
	},

1732 1733 1734 1735 1736 1737 1738 1739 1740
	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
1741 1742
		.read_s64 = cpuset_read_s64,
		.write_s64 = cpuset_write_s64,
1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757
		.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
	},

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

	{
		.name = "memory_pressure",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE,
L
Li Zefan 已提交
1758
		.mode = S_IRUGO,
1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773
	},

	{
		.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,
	},
1774

1775 1776 1777 1778 1779 1780 1781
	{
		.name = "memory_pressure_enabled",
		.flags = CFTYPE_ONLY_ON_ROOT,
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE_ENABLED,
	},
L
Linus Torvalds 已提交
1782

1783 1784
	{ }	/* terminate */
};
L
Linus Torvalds 已提交
1785 1786

/*
1787
 *	cpuset_css_alloc - allocate a cpuset css
1788
 *	cont:	control group that the new cpuset will be part of
L
Linus Torvalds 已提交
1789 1790
 */

1791
static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
L
Linus Torvalds 已提交
1792
{
1793 1794 1795
	struct cgroup *parent_cg = cont->parent;
	struct cgroup *tmp_cg;
	struct cpuset *parent, *cs;
L
Linus Torvalds 已提交
1796

1797
	if (!parent_cg)
1798
		return &top_cpuset.css;
1799 1800
	parent = cgroup_cs(parent_cg);

L
Linus Torvalds 已提交
1801 1802
	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
	if (!cs)
1803
		return ERR_PTR(-ENOMEM);
1804 1805 1806 1807
	if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
		kfree(cs);
		return ERR_PTR(-ENOMEM);
	}
L
Linus Torvalds 已提交
1808 1809

	cs->flags = 0;
1810 1811 1812 1813
	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
1814
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1815
	cpumask_clear(cs->cpus_allowed);
1816
	nodes_clear(cs->mems_allowed);
1817
	fmeter_init(&cs->fmeter);
1818
	cs->relax_domain_level = -1;
L
Linus Torvalds 已提交
1819 1820

	cs->parent = parent;
1821
	number_of_cpusets++;
1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851

	if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cont->flags))
		goto skip_clone;

	/*
	 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
	 * set.  This flag handling is implemented in cgroup core for
	 * histrical reasons - the flag may be specified during mount.
	 *
	 * Currently, if any sibling cpusets have exclusive cpus or mem, we
	 * refuse to clone the configuration - thereby refusing the task to
	 * be entered, and as a result refusing the sys_unshare() or
	 * clone() which initiated it.  If this becomes a problem for some
	 * users who wish to allow that scenario, then this could be
	 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
	 * (and likewise for mems) to the new cgroup.
	 */
	list_for_each_entry(tmp_cg, &parent_cg->children, sibling) {
		struct cpuset *tmp_cs = cgroup_cs(tmp_cg);

		if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs))
			goto skip_clone;
	}

	mutex_lock(&callback_mutex);
	cs->mems_allowed = parent->mems_allowed;
	cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
	mutex_unlock(&callback_mutex);
skip_clone:
	return &cs->css;
L
Linus Torvalds 已提交
1852 1853
}

P
Paul Jackson 已提交
1854 1855 1856
/*
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
1857
 * will call async_rebuild_sched_domains().
P
Paul Jackson 已提交
1858 1859
 */

1860
static void cpuset_css_free(struct cgroup *cont)
L
Linus Torvalds 已提交
1861
{
1862
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1863

P
Paul Jackson 已提交
1864
	if (is_sched_load_balance(cs))
1865
		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
P
Paul Jackson 已提交
1866

1867
	number_of_cpusets--;
1868
	free_cpumask_var(cs->cpus_allowed);
1869
	kfree(cs);
L
Linus Torvalds 已提交
1870 1871
}

1872 1873
struct cgroup_subsys cpuset_subsys = {
	.name = "cpuset",
1874 1875
	.css_alloc = cpuset_css_alloc,
	.css_free = cpuset_css_free,
1876 1877 1878
	.can_attach = cpuset_can_attach,
	.attach = cpuset_attach,
	.subsys_id = cpuset_subsys_id,
1879
	.base_cftypes = files,
1880 1881 1882
	.early_init = 1,
};

L
Linus Torvalds 已提交
1883 1884 1885 1886 1887 1888 1889 1890
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1891
	int err = 0;
L
Linus Torvalds 已提交
1892

1893 1894 1895
	if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
		BUG();

1896
	cpumask_setall(top_cpuset.cpus_allowed);
1897
	nodes_setall(top_cpuset.mems_allowed);
L
Linus Torvalds 已提交
1898

1899
	fmeter_init(&top_cpuset.fmeter);
P
Paul Jackson 已提交
1900
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1901
	top_cpuset.relax_domain_level = -1;
L
Linus Torvalds 已提交
1902 1903 1904

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1905 1906
		return err;

1907 1908 1909
	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
		BUG();

1910
	number_of_cpusets = 1;
1911
	return 0;
L
Linus Torvalds 已提交
1912 1913
}

1914 1915 1916 1917 1918 1919 1920 1921
/**
 * 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.
 */
1922 1923
static void cpuset_do_move_task(struct task_struct *tsk,
				struct cgroup_scanner *scan)
1924
{
1925
	struct cgroup *new_cgroup = scan->data;
1926

1927
	cgroup_attach_task(new_cgroup, tsk);
1928 1929 1930 1931 1932 1933 1934
}

/**
 * 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
 *
1935 1936
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1937 1938 1939 1940 1941 1942
 *
 * 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)
{
1943
	struct cgroup_scanner scan;
1944

1945 1946 1947 1948 1949
	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;
1950

1951
	if (cgroup_scan_tasks(&scan))
1952 1953 1954 1955
		printk(KERN_ERR "move_member_tasks_to_cpuset: "
				"cgroup_scan_tasks failed\n");
}

1956
/*
1957
 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1958 1959
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
1960 1961
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
1962
 *
1963 1964
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1965
 */
1966 1967 1968 1969
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

1970 1971 1972 1973 1974
	/*
	 * 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.
	 */
1975 1976
	if (list_empty(&cs->css.cgroup->css_sets))
		return;
1977

1978 1979 1980 1981 1982
	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
	parent = cs->parent;
1983
	while (cpumask_empty(parent->cpus_allowed) ||
1984
			nodes_empty(parent->mems_allowed))
1985 1986 1987 1988 1989
		parent = parent->parent;

	move_member_tasks_to_cpuset(cs, parent);
}

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
/*
 * Helper function to traverse cpusets.
 * It can be used to walk the cpuset tree from top to bottom, completing
 * one layer before dropping down to the next (thus always processing a
 * node before any of its children).
 */
static struct cpuset *cpuset_next(struct list_head *queue)
{
	struct cpuset *cp;
	struct cpuset *child;	/* scans child cpusets of cp */
	struct cgroup *cont;

	if (list_empty(queue))
		return NULL;

	cp = list_first_entry(queue, struct cpuset, stack_list);
	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);
	}

	return cp;
}


2016
/*
2017 2018 2019 2020
 * Walk the specified cpuset subtree upon a hotplug operation (CPU/Memory
 * online/offline) and update the cpusets accordingly.
 * For regular CPU/Mem hotplug, look for empty cpusets; the tasks of such
 * cpuset must be moved to a parent cpuset.
2021
 *
2022
 * Called with cgroup_mutex held.  We take callback_mutex to modify
2023 2024 2025 2026 2027 2028
 * 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.
 *
2029 2030
 * In the case of memory hot-unplug, it will remove nodes from N_HIGH_MEMORY
 * if all present pages from a node are offlined.
2031
 */
2032 2033
static void
scan_cpusets_upon_hotplug(struct cpuset *root, enum hotplug_event event)
2034
{
2035
	LIST_HEAD(queue);
2036
	struct cpuset *cp;		/* scans cpusets being updated */
2037
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2038

2039 2040
	list_add_tail((struct list_head *)&root->stack_list, &queue);

2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061
	switch (event) {
	case CPUSET_CPU_OFFLINE:
		while ((cp = cpuset_next(&queue)) != NULL) {

			/* Continue past cpusets with all cpus online */
			if (cpumask_subset(cp->cpus_allowed, cpu_active_mask))
				continue;

			/* Remove offline cpus from this cpuset. */
			mutex_lock(&callback_mutex);
			cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
							cpu_active_mask);
			mutex_unlock(&callback_mutex);

			/* Move tasks from the empty cpuset to a parent */
			if (cpumask_empty(cp->cpus_allowed))
				remove_tasks_in_empty_cpuset(cp);
			else
				update_tasks_cpumask(cp, NULL);
		}
		break;
2062

2063 2064
	case CPUSET_MEM_OFFLINE:
		while ((cp = cpuset_next(&queue)) != NULL) {
2065

2066 2067 2068 2069
			/* Continue past cpusets with all mems online */
			if (nodes_subset(cp->mems_allowed,
					node_states[N_HIGH_MEMORY]))
				continue;
2070

2071 2072 2073 2074 2075
			oldmems = cp->mems_allowed;

			/* Remove offline mems from this cpuset. */
			mutex_lock(&callback_mutex);
			nodes_and(cp->mems_allowed, cp->mems_allowed,
2076
						node_states[N_HIGH_MEMORY]);
2077
			mutex_unlock(&callback_mutex);
2078

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

2088 2089 2090 2091 2092 2093
/*
 * 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.
 *
2094 2095 2096
 * The only exception to this is suspend/resume, where we don't
 * modify cpusets at all.
 *
2097
 * This routine ensures that top_cpuset.cpus_allowed tracks
2098
 * cpu_active_mask on each CPU hotplug (cpuhp) event.
2099 2100 2101
 *
 * Called within get_online_cpus().  Needs to call cgroup_lock()
 * before calling generate_sched_domains().
2102 2103 2104
 *
 * @cpu_online: Indicates whether this is a CPU online event (true) or
 * a CPU offline event (false).
2105
 */
2106
void cpuset_update_active_cpus(bool cpu_online)
2107
{
2108
	struct sched_domain_attr *attr;
2109
	cpumask_var_t *doms;
2110 2111 2112
	int ndoms;

	cgroup_lock();
2113
	mutex_lock(&callback_mutex);
2114
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2115
	mutex_unlock(&callback_mutex);
2116 2117 2118 2119

	if (!cpu_online)
		scan_cpusets_upon_hotplug(&top_cpuset, CPUSET_CPU_OFFLINE);

2120 2121 2122 2123 2124
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);
2125 2126
}

2127
#ifdef CONFIG_MEMORY_HOTPLUG
2128
/*
2129
 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2130
 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
2131
 * See cpuset_update_active_cpus() for CPU hotplug handling.
2132
 */
2133 2134
static int cpuset_track_online_nodes(struct notifier_block *self,
				unsigned long action, void *arg)
2135
{
2136
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2137

2138
	cgroup_lock();
2139 2140
	switch (action) {
	case MEM_ONLINE:
2141
		oldmems = top_cpuset.mems_allowed;
2142
		mutex_lock(&callback_mutex);
2143
		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2144
		mutex_unlock(&callback_mutex);
2145
		update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
2146 2147 2148 2149
		break;
	case MEM_OFFLINE:
		/*
		 * needn't update top_cpuset.mems_allowed explicitly because
2150
		 * scan_cpusets_upon_hotplug() will update it.
2151
		 */
2152
		scan_cpusets_upon_hotplug(&top_cpuset, CPUSET_MEM_OFFLINE);
2153 2154 2155 2156
		break;
	default:
		break;
	}
2157
	cgroup_unlock();
2158

2159
	return NOTIFY_OK;
2160 2161 2162
}
#endif

L
Linus Torvalds 已提交
2163 2164 2165 2166 2167 2168 2169 2170
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
 **/

void __init cpuset_init_smp(void)
{
2171
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2172
	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2173

2174
	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2175 2176 2177

	cpuset_wq = create_singlethread_workqueue("cpuset");
	BUG_ON(!cpuset_wq);
L
Linus Torvalds 已提交
2178 2179 2180 2181 2182
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2183
 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
L
Linus Torvalds 已提交
2184
 *
2185
 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
L
Linus Torvalds 已提交
2186
 * attached to the specified @tsk.  Guaranteed to return some non-empty
2187
 * subset of cpu_online_mask, even if this means going outside the
L
Linus Torvalds 已提交
2188 2189 2190
 * tasks cpuset.
 **/

2191
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
L
Linus Torvalds 已提交
2192
{
2193
	mutex_lock(&callback_mutex);
2194
	task_lock(tsk);
2195
	guarantee_online_cpus(task_cs(tsk), pmask);
2196
	task_unlock(tsk);
2197
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
2198 2199
}

2200
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2201 2202 2203 2204 2205 2206
{
	const struct cpuset *cs;

	rcu_read_lock();
	cs = task_cs(tsk);
	if (cs)
2207
		do_set_cpus_allowed(tsk, cs->cpus_allowed);
2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222
	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.
2223 2224 2225
	 *
	 * select_fallback_rq() will fix things ups and set cpu_possible_mask
	 * if required.
2226 2227 2228
	 */
}

L
Linus Torvalds 已提交
2229 2230
void cpuset_init_current_mems_allowed(void)
{
2231
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
2232 2233
}

2234 2235 2236 2237 2238 2239
/**
 * 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
2240
 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2241 2242 2243 2244 2245 2246 2247
 * tasks cpuset.
 **/

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

2248
	mutex_lock(&callback_mutex);
2249
	task_lock(tsk);
2250
	guarantee_online_mems(task_cs(tsk), &mask);
2251
	task_unlock(tsk);
2252
	mutex_unlock(&callback_mutex);
2253 2254 2255 2256

	return mask;
}

2257
/**
2258 2259
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
2260
 *
2261
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
2262
 */
2263
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
2264
{
2265
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
2266 2267
}

2268
/*
2269 2270 2271 2272
 * 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.
2273
 */
2274
static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2275
{
2276
	while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2277 2278 2279 2280
		cs = cs->parent;
	return cs;
}

2281
/**
2282 2283
 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2284
 * @gfp_mask: memory allocation flags
2285
 *
2286 2287 2288 2289 2290 2291
 * 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.
2292 2293
 * Otherwise, no.
 *
2294 2295 2296
 * 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.
2297
 *
2298 2299
 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
 * cpusets, and never sleeps.
2300 2301 2302 2303 2304 2305 2306
 *
 * 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'.
 *
2307
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2308 2309
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2310
 * GFP_KERNEL allocations are not so marked, so can escape to the
2311
 * nearest enclosing hardwalled ancestor cpuset.
2312
 *
2313 2314 2315 2316 2317 2318 2319
 * 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.
2320
 *
2321
 * The first call here from mm/page_alloc:get_page_from_freelist()
2322 2323 2324
 * 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).
2325 2326 2327 2328 2329 2330
 *
 * 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:
2331 2332
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2333
 *	TIF_MEMDIE   - any node ok
2334
 *	GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2335
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2336 2337
 *
 * Rule:
2338
 *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2339 2340
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2341
 */
2342
int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2343
{
2344
	const struct cpuset *cs;	/* current cpuset ancestors */
2345
	int allowed;			/* is allocation in zone z allowed? */
2346

2347
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2348
		return 1;
2349
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2350 2351
	if (node_isset(node, current->mems_allowed))
		return 1;
2352 2353 2354 2355 2356 2357
	/*
	 * 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;
2358 2359 2360
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2361 2362 2363
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2364
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2365
	mutex_lock(&callback_mutex);
2366 2367

	task_lock(current);
2368
	cs = nearest_hardwall_ancestor(task_cs(current));
2369 2370
	task_unlock(current);

2371
	allowed = node_isset(node, cs->mems_allowed);
2372
	mutex_unlock(&callback_mutex);
2373
	return allowed;
L
Linus Torvalds 已提交
2374 2375
}

2376
/*
2377 2378
 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2379 2380
 * @gfp_mask: memory allocation flags
 *
2381 2382 2383 2384 2385
 * 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.
2386 2387 2388 2389 2390 2391 2392
 *
 * 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'.
 *
2393 2394
 * Unlike the cpuset_node_allowed_softwall() variant, above,
 * this variant requires that the node be in the current task's
2395 2396 2397 2398
 * 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.
 */
2399
int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2400 2401 2402 2403 2404
{
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2405 2406 2407 2408 2409 2410
	/*
	 * 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;
2411 2412 2413
	return 0;
}

P
Paul Jackson 已提交
2414 2415 2416 2417 2418 2419 2420 2421
/**
 * cpuset_unlock - release lock on cpuset changes
 *
 * Undo the lock taken in a previous cpuset_lock() call.
 */

void cpuset_unlock(void)
{
2422
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
2423 2424
}

2425
/**
2426 2427
 * 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
2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451
 *
 * 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().
 */

2452
static int cpuset_spread_node(int *rotor)
2453 2454 2455
{
	int node;

2456
	node = next_node(*rotor, current->mems_allowed);
2457 2458
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
2459
	*rotor = node;
2460 2461
	return node;
}
2462 2463 2464

int cpuset_mem_spread_node(void)
{
2465 2466 2467 2468
	if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
		current->cpuset_mem_spread_rotor =
			node_random(&current->mems_allowed);

2469 2470 2471 2472 2473
	return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
}

int cpuset_slab_spread_node(void)
{
2474 2475 2476 2477
	if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
		current->cpuset_slab_spread_rotor =
			node_random(&current->mems_allowed);

2478 2479 2480
	return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
}

2481 2482
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2483
/**
2484 2485 2486 2487 2488 2489 2490 2491
 * 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.
2492 2493
 **/

2494 2495
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2496
{
2497
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2498 2499
}

2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522
/**
 * 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);
}

2523 2524 2525 2526 2527 2528
/*
 * 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.
 */

2529
int cpuset_memory_pressure_enabled __read_mostly;
2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551

/**
 * 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);
2552
	fmeter_markevent(&task_cs(current)->fmeter);
2553 2554 2555
	task_unlock(current);
}

2556
#ifdef CONFIG_PROC_PID_CPUSET
L
Linus Torvalds 已提交
2557 2558 2559 2560
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2561 2562
 *  - 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,
2563
 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2564
 *    anyway.
L
Linus Torvalds 已提交
2565
 */
P
Paul Jackson 已提交
2566
static int proc_cpuset_show(struct seq_file *m, void *unused_v)
L
Linus Torvalds 已提交
2567
{
2568
	struct pid *pid;
L
Linus Torvalds 已提交
2569 2570
	struct task_struct *tsk;
	char *buf;
2571
	struct cgroup_subsys_state *css;
2572
	int retval;
L
Linus Torvalds 已提交
2573

2574
	retval = -ENOMEM;
L
Linus Torvalds 已提交
2575 2576
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2577 2578 2579
		goto out;

	retval = -ESRCH;
2580 2581
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2582 2583
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2584

2585
	retval = -EINVAL;
2586 2587 2588
	cgroup_lock();
	css = task_subsys_state(tsk, cpuset_subsys_id);
	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
L
Linus Torvalds 已提交
2589
	if (retval < 0)
2590
		goto out_unlock;
L
Linus Torvalds 已提交
2591 2592
	seq_puts(m, buf);
	seq_putc(m, '\n');
2593
out_unlock:
2594
	cgroup_unlock();
2595 2596
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2597
	kfree(buf);
2598
out:
L
Linus Torvalds 已提交
2599 2600 2601 2602 2603
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2604 2605
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
L
Linus Torvalds 已提交
2606 2607
}

2608
const struct file_operations proc_cpuset_operations = {
L
Linus Torvalds 已提交
2609 2610 2611 2612 2613
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
2614
#endif /* CONFIG_PROC_PID_CPUSET */
L
Linus Torvalds 已提交
2615

2616
/* Display task mems_allowed in /proc/<pid>/status file. */
2617 2618 2619
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
	seq_printf(m, "Mems_allowed:\t");
2620
	seq_nodemask(m, &task->mems_allowed);
2621
	seq_printf(m, "\n");
2622
	seq_printf(m, "Mems_allowed_list:\t");
2623
	seq_nodemask_list(m, &task->mems_allowed);
2624
	seq_printf(m, "\n");
L
Linus Torvalds 已提交
2625
}