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

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

#include <asm/uaccess.h>
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#include <linux/atomic.h>
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#include <linux/mutex.h>
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#include <linux/workqueue.h>
#include <linux/cgroup.h>
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/*
 * 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 {
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	CS_ONLINE,
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	CS_CPU_EXCLUSIVE,
	CS_MEM_EXCLUSIVE,
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	CS_MEM_HARDWALL,
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	CS_MEMORY_MIGRATE,
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	CS_SCHED_LOAD_BALANCE,
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	CS_SPREAD_PAGE,
	CS_SPREAD_SLAB,
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} cpuset_flagbits_t;

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

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

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

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

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

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

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

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

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

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/**
 * cpuset_for_each_child - traverse online children of a cpuset
 * @child_cs: loop cursor pointing to the current child
 * @pos_cgrp: used for iteration
 * @parent_cs: target cpuset to walk children of
 *
 * Walk @child_cs through the online children of @parent_cs.  Must be used
 * with RCU read locked.
 */
#define cpuset_for_each_child(child_cs, pos_cgrp, parent_cs)		\
	cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup)	\
		if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp)))))

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/*
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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
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 * found any online mems, return node_states[N_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_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,
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					node_states[N_MEMORY]))
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		cs = cs->parent;
	if (cs)
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		nodes_and(*pmask, cs->mems_allowed,
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					node_states[N_MEMORY]);
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	else
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		*pmask = node_states[N_MEMORY];
	BUG_ON(!nodes_intersects(*pmask, node_states[N_MEMORY]));
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}

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/*
 * update task's spread flag if cpuset's page/slab spread flag is set
 *
 * 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;
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	int ret;

	rcu_read_lock();
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	/* Each of our child cpusets must be a subset of us */
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	ret = -EBUSY;
	cpuset_for_each_child(c, cont, cur)
		if (!is_cpuset_subset(c, trial))
			goto out;
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	/* Remaining checks don't apply to root cpuset */
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	ret = 0;
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	if (cur == &top_cpuset)
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		goto out;
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	par = cur->parent;

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	/* We must be a subset of our parent cpuset */
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	ret = -EACCES;
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	if (!is_cpuset_subset(trial, par))
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		goto out;
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	/*
	 * If either I or some sibling (!= me) is exclusive, we can't
	 * overlap
	 */
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	ret = -EINVAL;
	cpuset_for_each_child(c, cont, par) {
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		if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
		    c != cur &&
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		    cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
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			goto out;
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		if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
		    c != cur &&
		    nodes_intersects(trial->mems_allowed, c->mems_allowed))
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			goto out;
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	}

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	/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
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	ret = -ENOSPC;
	if (cgroup_task_count(cur->css.cgroup) &&
	    (cpumask_empty(trial->cpus_allowed) ||
	     nodes_empty(trial->mems_allowed)))
		goto out;
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	ret = 0;
out:
	rcu_read_unlock();
	return ret;
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}

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

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

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static void
update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *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);

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		rcu_read_lock();
		cpuset_for_each_child(child, cont, cp)
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			list_add_tail(&child->stack_list, &q);
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		rcu_read_unlock();
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	}
}

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/*
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 * generate_sched_domains()
 *
 * This function builds a partial partition of the systems CPUs
 * A 'partial partition' is a set of non-overlapping subsets whose
 * union is a subset of that set.
 * 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().
 */
585
static int generate_sched_domains(cpumask_var_t **domains,
586
			struct sched_domain_attr **attributes)
P
Paul Jackson 已提交
587
{
588
	LIST_HEAD(q);		/* queue of cpusets to be scanned */
P
Paul Jackson 已提交
589 590 591 592
	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 */
593
	cpumask_var_t *doms;	/* resulting partition; i.e. sched domains */
594
	struct sched_domain_attr *dattr;  /* attributes for custom domains */
595
	int ndoms = 0;		/* number of sched domains in result */
596
	int nslot;		/* next empty doms[] struct cpumask slot */
P
Paul Jackson 已提交
597 598

	doms = NULL;
599
	dattr = NULL;
600
	csa = NULL;
P
Paul Jackson 已提交
601 602 603

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
604 605
		ndoms = 1;
		doms = alloc_sched_domains(ndoms);
P
Paul Jackson 已提交
606
		if (!doms)
607 608
			goto done;

609 610 611
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
612
			update_domain_attr_tree(dattr, &top_cpuset);
613
		}
614
		cpumask_copy(doms[0], top_cpuset.cpus_allowed);
615 616

		goto done;
P
Paul Jackson 已提交
617 618 619 620 621 622 623
	}

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

624 625
	list_add(&top_cpuset.stack_list, &q);
	while (!list_empty(&q)) {
P
Paul Jackson 已提交
626 627
		struct cgroup *cont;
		struct cpuset *child;   /* scans child cpusets of cp */
628

629 630 631
		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

632
		if (cpumask_empty(cp->cpus_allowed))
633 634
			continue;

635 636 637 638 639 640 641
		/*
		 * 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
642
			csa[csn++] = cp;
643 644
			continue;
		}
645

646 647
		rcu_read_lock();
		cpuset_for_each_child(child, cont, cp)
648
			list_add_tail(&child->stack_list, &q);
649
		rcu_read_unlock();
P
Paul Jackson 已提交
650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678
  	}

	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;
			}
		}
	}

679 680 681 682
	/*
	 * Now we know how many domains to create.
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
	 */
683
	doms = alloc_sched_domains(ndoms);
684
	if (!doms)
685 686 687 688 689 690
		goto done;

	/*
	 * The rest of the code, including the scheduler, can deal with
	 * dattr==NULL case. No need to abort if alloc fails.
	 */
691
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
P
Paul Jackson 已提交
692 693 694

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
695
		struct cpumask *dp;
P
Paul Jackson 已提交
696 697
		int apn = a->pn;

698 699 700 701 702
		if (apn < 0) {
			/* Skip completed partitions */
			continue;
		}

703
		dp = doms[nslot];
704 705 706 707 708 709 710 711 712 713

		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
714
			}
715 716
			continue;
		}
P
Paul Jackson 已提交
717

718
		cpumask_clear(dp);
719 720 721 722 723 724
		if (dattr)
			*(dattr + nslot) = SD_ATTR_INIT;
		for (j = i; j < csn; j++) {
			struct cpuset *b = csa[j];

			if (apn == b->pn) {
725
				cpumask_or(dp, dp, b->cpus_allowed);
726 727 728 729 730
				if (dattr)
					update_domain_attr_tree(dattr + nslot, b);

				/* Done with this partition */
				b->pn = -1;
P
Paul Jackson 已提交
731 732
			}
		}
733
		nslot++;
P
Paul Jackson 已提交
734 735 736
	}
	BUG_ON(nslot != ndoms);

737 738 739
done:
	kfree(csa);

740 741 742 743 744 745 746
	/*
	 * Fallback to the default domain if kmalloc() failed.
	 * See comments in partition_sched_domains().
	 */
	if (doms == NULL)
		ndoms = 1;

747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764
	*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;
765
	cpumask_var_t *doms;
766 767
	int ndoms;

768
	get_online_cpus();
769 770 771 772 773 774 775 776 777

	/* 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);

778
	put_online_cpus();
779
}
780 781 782 783 784
#else /* !CONFIG_SMP */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
}

785
static int generate_sched_domains(cpumask_var_t **domains,
786 787 788 789 790 791
			struct sched_domain_attr **attributes)
{
	*domains = NULL;
	return 1;
}
#endif /* CONFIG_SMP */
P
Paul Jackson 已提交
792

793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815
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)
{
816
	queue_work(cpuset_wq, &rebuild_sched_domains_work);
817 818 819 820 821 822 823 824 825 826 827 828 829 830
}

/*
 * 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
831 832
}

C
Cliff Wickman 已提交
833 834 835 836 837
/**
 * 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
 *
838
 * Call with cgroup_mutex held.  May take callback_mutex during call.
C
Cliff Wickman 已提交
839 840 841
 * 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).
842
 */
843 844
static int cpuset_test_cpumask(struct task_struct *tsk,
			       struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
845
{
846
	return !cpumask_equal(&tsk->cpus_allowed,
C
Cliff Wickman 已提交
847 848
			(cgroup_cs(scan->cg))->cpus_allowed);
}
849

C
Cliff Wickman 已提交
850 851 852 853 854 855 856 857 858 859 860
/**
 * 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.
 */
861 862
static void cpuset_change_cpumask(struct task_struct *tsk,
				  struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
863
{
864
	set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
C
Cliff Wickman 已提交
865 866
}

867 868 869
/**
 * 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
870
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
871 872 873 874 875 876
 *
 * Called with cgroup_mutex held
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 *
877 878
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
879
 */
880
static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
881 882 883 884 885 886
{
	struct cgroup_scanner scan;

	scan.cg = cs->css.cgroup;
	scan.test_task = cpuset_test_cpumask;
	scan.process_task = cpuset_change_cpumask;
887 888
	scan.heap = heap;
	cgroup_scan_tasks(&scan);
889 890
}

C
Cliff Wickman 已提交
891 892 893 894 895
/**
 * 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
 */
896 897
static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
			  const char *buf)
L
Linus Torvalds 已提交
898
{
899
	struct ptr_heap heap;
C
Cliff Wickman 已提交
900 901
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
902

903
	/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
904 905 906
	if (cs == &top_cpuset)
		return -EACCES;

907
	/*
908
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
909 910 911
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
912
	 */
913
	if (!*buf) {
914
		cpumask_clear(trialcs->cpus_allowed);
915
	} else {
916
		retval = cpulist_parse(buf, trialcs->cpus_allowed);
917 918
		if (retval < 0)
			return retval;
919

920
		if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
921
			return -EINVAL;
922
	}
923
	retval = validate_change(cs, trialcs);
924 925
	if (retval < 0)
		return retval;
P
Paul Jackson 已提交
926

P
Paul Menage 已提交
927
	/* Nothing to do if the cpus didn't change */
928
	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
P
Paul Menage 已提交
929
		return 0;
C
Cliff Wickman 已提交
930

931 932 933 934
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval)
		return retval;

935
	is_load_balanced = is_sched_load_balance(trialcs);
P
Paul Jackson 已提交
936

937
	mutex_lock(&callback_mutex);
938
	cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
939
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
940

P
Paul Menage 已提交
941 942
	/*
	 * Scan tasks in the cpuset, and update the cpumasks of any
C
Cliff Wickman 已提交
943
	 * that need an update.
P
Paul Menage 已提交
944
	 */
945 946 947
	update_tasks_cpumask(cs, &heap);

	heap_free(&heap);
C
Cliff Wickman 已提交
948

P
Paul Menage 已提交
949
	if (is_load_balanced)
950
		async_rebuild_sched_domains();
951
	return 0;
L
Linus Torvalds 已提交
952 953
}

954 955 956 957 958 959 960 961
/*
 * 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.
 *
962
 *    Call holding cgroup_mutex, so current's cpuset won't change
963
 *    during this call, as manage_mutex holds off any cpuset_attach()
964 965
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
966
 *    our task's cpuset.
967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982
 *
 *    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);

983
	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
984 985
}

986
/*
987 988 989 990 991 992 993 994 995 996 997
 * 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)
{
998
	bool need_loop;
999

1000 1001 1002 1003 1004 1005 1006 1007 1008 1009
	/*
	 * 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);
1010 1011 1012 1013 1014 1015 1016 1017
	/*
	 * 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);
1018

1019 1020
	if (need_loop)
		write_seqcount_begin(&tsk->mems_allowed_seq);
1021

1022 1023
	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
1024 1025

	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1026
	tsk->mems_allowed = *newmems;
1027 1028 1029 1030

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

1031
	task_unlock(tsk);
1032 1033 1034 1035 1036 1037
}

/*
 * 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.
1038 1039 1040 1041 1042 1043 1044 1045
 */
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;
1046
	static nodemask_t newmems;	/* protected by cgroup_mutex */
1047 1048

	cs = cgroup_cs(scan->cg);
1049
	guarantee_online_mems(cs, &newmems);
1050

1051
	cpuset_change_task_nodemask(p, &newmems);
1052

1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
	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);
}

1065 1066
static void *cpuset_being_rebound;

1067 1068 1069 1070
/**
 * 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
1071
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1072 1073
 *
 * Called with cgroup_mutex held
1074 1075
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
1076
 */
1077 1078
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
				 struct ptr_heap *heap)
L
Linus Torvalds 已提交
1079
{
1080
	struct cgroup_scanner scan;
1081

1082
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
1083

1084 1085 1086
	scan.cg = cs->css.cgroup;
	scan.test_task = NULL;
	scan.process_task = cpuset_change_nodemask;
1087
	scan.heap = heap;
1088
	scan.data = (nodemask_t *)oldmem;
1089 1090

	/*
1091 1092 1093 1094 1095 1096
	 * 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.
1097
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1098
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1099
	 */
1100
	cgroup_scan_tasks(&scan);
1101

1102
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1103
	cpuset_being_rebound = NULL;
L
Linus Torvalds 已提交
1104 1105
}

1106 1107 1108
/*
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
1109 1110 1111 1112
 * 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.
1113 1114 1115 1116 1117 1118
 *
 * 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.
 */
1119 1120
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
			   const char *buf)
1121
{
1122
	NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
1123
	int retval;
1124
	struct ptr_heap heap;
1125

1126 1127 1128
	if (!oldmem)
		return -ENOMEM;

1129
	/*
1130
	 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1131 1132
	 * it's read-only
	 */
1133 1134 1135 1136
	if (cs == &top_cpuset) {
		retval = -EACCES;
		goto done;
	}
1137 1138 1139 1140 1141 1142 1143 1144

	/*
	 * 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) {
1145
		nodes_clear(trialcs->mems_allowed);
1146
	} else {
1147
		retval = nodelist_parse(buf, trialcs->mems_allowed);
1148 1149 1150
		if (retval < 0)
			goto done;

1151
		if (!nodes_subset(trialcs->mems_allowed,
1152
				node_states[N_MEMORY])) {
1153 1154 1155
			retval =  -EINVAL;
			goto done;
		}
1156
	}
1157 1158
	*oldmem = cs->mems_allowed;
	if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
1159 1160 1161
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
1162
	retval = validate_change(cs, trialcs);
1163 1164 1165
	if (retval < 0)
		goto done;

1166 1167 1168 1169
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval < 0)
		goto done;

1170
	mutex_lock(&callback_mutex);
1171
	cs->mems_allowed = trialcs->mems_allowed;
1172 1173
	mutex_unlock(&callback_mutex);

1174
	update_tasks_nodemask(cs, oldmem, &heap);
1175 1176

	heap_free(&heap);
1177
done:
1178
	NODEMASK_FREE(oldmem);
1179 1180 1181
	return retval;
}

1182 1183 1184 1185 1186
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1187
static int update_relax_domain_level(struct cpuset *cs, s64 val)
1188
{
1189
#ifdef CONFIG_SMP
1190
	if (val < -1 || val >= sched_domain_level_max)
1191
		return -EINVAL;
1192
#endif
1193 1194 1195

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
1196 1197
		if (!cpumask_empty(cs->cpus_allowed) &&
		    is_sched_load_balance(cs))
1198
			async_rebuild_sched_domains();
1199 1200 1201 1202 1203
	}

	return 0;
}

1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243
/*
 * 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
1244 1245
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
1246 1247 1248
 * bit:		the bit to update (see cpuset_flagbits_t)
 * cs:		the cpuset to update
 * turning_on: 	whether the flag is being set or cleared
1249
 *
1250
 * Call with cgroup_mutex held.
L
Linus Torvalds 已提交
1251 1252
 */

1253 1254
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1255
{
1256
	struct cpuset *trialcs;
R
Rakib Mullick 已提交
1257
	int balance_flag_changed;
1258 1259 1260
	int spread_flag_changed;
	struct ptr_heap heap;
	int err;
L
Linus Torvalds 已提交
1261

1262 1263 1264 1265
	trialcs = alloc_trial_cpuset(cs);
	if (!trialcs)
		return -ENOMEM;

L
Linus Torvalds 已提交
1266
	if (turning_on)
1267
		set_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1268
	else
1269
		clear_bit(bit, &trialcs->flags);
L
Linus Torvalds 已提交
1270

1271
	err = validate_change(cs, trialcs);
1272
	if (err < 0)
1273
		goto out;
P
Paul Jackson 已提交
1274

1275 1276 1277 1278
	err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (err < 0)
		goto out;

P
Paul Jackson 已提交
1279
	balance_flag_changed = (is_sched_load_balance(cs) !=
1280
				is_sched_load_balance(trialcs));
P
Paul Jackson 已提交
1281

1282 1283 1284
	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
			|| (is_spread_page(cs) != is_spread_page(trialcs)));

1285
	mutex_lock(&callback_mutex);
1286
	cs->flags = trialcs->flags;
1287
	mutex_unlock(&callback_mutex);
1288

1289
	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1290
		async_rebuild_sched_domains();
P
Paul Jackson 已提交
1291

1292 1293 1294
	if (spread_flag_changed)
		update_tasks_flags(cs, &heap);
	heap_free(&heap);
1295 1296 1297
out:
	free_trial_cpuset(trialcs);
	return err;
L
Linus Torvalds 已提交
1298 1299
}

1300
/*
A
Adrian Bunk 已提交
1301
 * Frequency meter - How fast is some event occurring?
1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397
 *
 * 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;
}

1398
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1399
static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1400
{
1401
	struct cpuset *cs = cgroup_cs(cgrp);
1402 1403
	struct task_struct *task;
	int ret;
L
Linus Torvalds 已提交
1404

1405
	if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
L
Linus Torvalds 已提交
1406
		return -ENOSPC;
1407

1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422
	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;
	}
1423

1424
	return 0;
1425
}
L
Linus Torvalds 已提交
1426

1427 1428 1429 1430 1431 1432 1433
/*
 * Protected by cgroup_mutex.  cpus_attach is used only by cpuset_attach()
 * but we can't allocate it dynamically there.  Define it global and
 * allocate from cpuset_init().
 */
static cpumask_var_t cpus_attach;

1434
static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1435
{
1436 1437 1438
	/* static bufs protected by cgroup_mutex */
	static nodemask_t cpuset_attach_nodemask_from;
	static nodemask_t cpuset_attach_nodemask_to;
1439
	struct mm_struct *mm;
1440 1441
	struct task_struct *task;
	struct task_struct *leader = cgroup_taskset_first(tset);
1442 1443 1444
	struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *oldcs = cgroup_cs(oldcgrp);
1445

1446 1447 1448 1449 1450 1451 1452 1453
	/* prepare for attach */
	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);

1454 1455 1456 1457 1458 1459 1460 1461 1462 1463
	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);
	}
1464

1465 1466 1467 1468 1469 1470
	/*
	 * 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;
1471
	mm = get_task_mm(leader);
1472
	if (mm) {
1473
		mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1474
		if (is_memory_migrate(cs))
1475 1476
			cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
					  &cpuset_attach_nodemask_to);
1477 1478
		mmput(mm);
	}
L
Linus Torvalds 已提交
1479 1480 1481 1482 1483
}

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

typedef enum {
1484
	FILE_MEMORY_MIGRATE,
L
Linus Torvalds 已提交
1485 1486 1487 1488
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
1489
	FILE_MEM_HARDWALL,
P
Paul Jackson 已提交
1490
	FILE_SCHED_LOAD_BALANCE,
1491
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1492 1493
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1494 1495
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
L
Linus Torvalds 已提交
1496 1497
} cpuset_filetype_t;

1498 1499 1500 1501 1502 1503
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;

1504
	if (!cgroup_lock_live_group(cgrp))
1505 1506 1507
		return -ENODEV;

	switch (type) {
L
Linus Torvalds 已提交
1508
	case FILE_CPU_EXCLUSIVE:
1509
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1510 1511
		break;
	case FILE_MEM_EXCLUSIVE:
1512
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1513
		break;
1514 1515 1516
	case FILE_MEM_HARDWALL:
		retval = update_flag(CS_MEM_HARDWALL, cs, val);
		break;
P
Paul Jackson 已提交
1517
	case FILE_SCHED_LOAD_BALANCE:
1518
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1519
		break;
1520
	case FILE_MEMORY_MIGRATE:
1521
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1522
		break;
1523
	case FILE_MEMORY_PRESSURE_ENABLED:
1524
		cpuset_memory_pressure_enabled = !!val;
1525 1526 1527 1528
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1529
	case FILE_SPREAD_PAGE:
1530
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1531 1532
		break;
	case FILE_SPREAD_SLAB:
1533
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1534
		break;
L
Linus Torvalds 已提交
1535 1536
	default:
		retval = -EINVAL;
1537
		break;
L
Linus Torvalds 已提交
1538
	}
1539
	cgroup_unlock();
L
Linus Torvalds 已提交
1540 1541 1542
	return retval;
}

1543 1544 1545 1546 1547 1548
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;

1549
	if (!cgroup_lock_live_group(cgrp))
1550
		return -ENODEV;
1551

1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, val);
		break;
	default:
		retval = -EINVAL;
		break;
	}
	cgroup_unlock();
	return retval;
}

1564 1565 1566 1567 1568 1569 1570
/*
 * 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;
1571 1572
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *trialcs;
1573 1574 1575 1576

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

1577
	trialcs = alloc_trial_cpuset(cs);
1578 1579 1580 1581
	if (!trialcs) {
		retval = -ENOMEM;
		goto out;
	}
1582

1583 1584
	switch (cft->private) {
	case FILE_CPULIST:
1585
		retval = update_cpumask(cs, trialcs, buf);
1586 1587
		break;
	case FILE_MEMLIST:
1588
		retval = update_nodemask(cs, trialcs, buf);
1589 1590 1591 1592 1593
		break;
	default:
		retval = -EINVAL;
		break;
	}
1594 1595

	free_trial_cpuset(trialcs);
1596
out:
1597 1598 1599 1600
	cgroup_unlock();
	return retval;
}

L
Linus Torvalds 已提交
1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
/*
 * 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.
 */

1613
static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1614
{
1615
	size_t count;
L
Linus Torvalds 已提交
1616

1617
	mutex_lock(&callback_mutex);
1618
	count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1619
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1620

1621
	return count;
L
Linus Torvalds 已提交
1622 1623
}

1624
static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
L
Linus Torvalds 已提交
1625
{
1626
	size_t count;
L
Linus Torvalds 已提交
1627

1628
	mutex_lock(&callback_mutex);
1629
	count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
1630
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1631

1632
	return count;
L
Linus Torvalds 已提交
1633 1634
}

1635 1636 1637 1638 1639
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
1640
{
1641
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1642 1643 1644 1645 1646
	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

1647
	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
L
Linus Torvalds 已提交
1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664
		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
1665
	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
L
Linus Torvalds 已提交
1666 1667 1668 1669 1670
out:
	free_page((unsigned long)page);
	return retval;
}

1671 1672 1673 1674 1675 1676 1677 1678 1679
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);
1680 1681
	case FILE_MEM_HARDWALL:
		return is_mem_hardwall(cs);
1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696
	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();
	}
1697 1698 1699

	/* Unreachable but makes gcc happy */
	return 0;
1700
}
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1702 1703 1704 1705 1706 1707 1708 1709 1710 1711
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();
	}
1712 1713 1714

	/* Unrechable but makes gcc happy */
	return 0;
1715 1716
}

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

1722 1723 1724 1725
static struct cftype files[] = {
	{
		.name = "cpus",
		.read = cpuset_common_file_read,
1726 1727
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * NR_CPUS),
1728 1729 1730 1731 1732 1733
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
		.read = cpuset_common_file_read,
1734 1735
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * MAX_NUMNODES),
1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
		.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,
	},

1753 1754 1755 1756 1757 1758 1759
	{
		.name = "mem_hardwall",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_HARDWALL,
	},

1760 1761 1762 1763 1764 1765 1766 1767 1768
	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
1769 1770
		.read_s64 = cpuset_read_s64,
		.write_s64 = cpuset_write_s64,
1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785
		.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
	},

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

	{
		.name = "memory_pressure",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE,
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		.mode = S_IRUGO,
1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801
	},

	{
		.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,
	},
1802

1803 1804 1805 1806 1807 1808 1809
	{
		.name = "memory_pressure_enabled",
		.flags = CFTYPE_ONLY_ON_ROOT,
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE_ENABLED,
	},
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1811 1812
	{ }	/* terminate */
};
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/*
1815
 *	cpuset_css_alloc - allocate a cpuset css
1816
 *	cont:	control group that the new cpuset will be part of
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1817 1818
 */

1819
static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
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{
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	struct cpuset *cs;
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T
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1823
	if (!cont->parent)
1824
		return &top_cpuset.css;
1825

T
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1826
	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
L
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1827
	if (!cs)
1828
		return ERR_PTR(-ENOMEM);
1829 1830 1831 1832
	if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
		kfree(cs);
		return ERR_PTR(-ENOMEM);
	}
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1834
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1835
	cpumask_clear(cs->cpus_allowed);
1836
	nodes_clear(cs->mems_allowed);
1837
	fmeter_init(&cs->fmeter);
1838
	cs->relax_domain_level = -1;
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1839 1840 1841 1842 1843 1844 1845 1846 1847
	cs->parent = cgroup_cs(cont->parent);

	return &cs->css;
}

static int cpuset_css_online(struct cgroup *cgrp)
{
	struct cpuset *cs = cgroup_cs(cgrp);
	struct cpuset *parent = cs->parent;
1848 1849
	struct cpuset *tmp_cs;
	struct cgroup *pos_cg;
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1850 1851 1852 1853

	if (!parent)
		return 0;

T
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1854
	set_bit(CS_ONLINE, &cs->flags);
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1855 1856 1857 1858
	if (is_spread_page(parent))
		set_bit(CS_SPREAD_PAGE, &cs->flags);
	if (is_spread_slab(parent))
		set_bit(CS_SPREAD_SLAB, &cs->flags);
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1860
	number_of_cpusets++;
1861

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1862 1863
	if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags))
		return 0;
1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877

	/*
	 * 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.
	 */
1878 1879 1880 1881
	rcu_read_lock();
	cpuset_for_each_child(tmp_cs, pos_cg, parent) {
		if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
			rcu_read_unlock();
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1882
			return 0;
1883
		}
1884
	}
1885
	rcu_read_unlock();
1886 1887 1888 1889 1890

	mutex_lock(&callback_mutex);
	cs->mems_allowed = parent->mems_allowed;
	cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
	mutex_unlock(&callback_mutex);
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1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905

	return 0;
}

static void cpuset_css_offline(struct cgroup *cgrp)
{
	struct cpuset *cs = cgroup_cs(cgrp);

	/* css_offline is called w/o cgroup_mutex, grab it */
	cgroup_lock();

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

	number_of_cpusets--;
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	clear_bit(CS_ONLINE, &cs->flags);
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1907 1908

	cgroup_unlock();
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}

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1911 1912 1913
/*
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
1914
 * will call async_rebuild_sched_domains().
P
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1915 1916
 */

1917
static void cpuset_css_free(struct cgroup *cont)
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1918
{
1919
	struct cpuset *cs = cgroup_cs(cont);
L
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1920

1921
	free_cpumask_var(cs->cpus_allowed);
1922
	kfree(cs);
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1923 1924
}

1925 1926
struct cgroup_subsys cpuset_subsys = {
	.name = "cpuset",
1927
	.css_alloc = cpuset_css_alloc,
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1928 1929
	.css_online = cpuset_css_online,
	.css_offline = cpuset_css_offline,
1930
	.css_free = cpuset_css_free,
1931 1932 1933
	.can_attach = cpuset_can_attach,
	.attach = cpuset_attach,
	.subsys_id = cpuset_subsys_id,
1934
	.base_cftypes = files,
1935 1936 1937
	.early_init = 1,
};

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1938 1939 1940 1941 1942 1943 1944 1945
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1946
	int err = 0;
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1947

1948 1949 1950
	if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
		BUG();

1951
	cpumask_setall(top_cpuset.cpus_allowed);
1952
	nodes_setall(top_cpuset.mems_allowed);
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1953

1954
	fmeter_init(&top_cpuset.fmeter);
P
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1955
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1956
	top_cpuset.relax_domain_level = -1;
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1957 1958 1959

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1960 1961
		return err;

1962 1963 1964
	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
		BUG();

1965
	number_of_cpusets = 1;
1966
	return 0;
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}

1969 1970 1971 1972 1973 1974 1975 1976
/**
 * 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.
 */
1977 1978
static void cpuset_do_move_task(struct task_struct *tsk,
				struct cgroup_scanner *scan)
1979
{
1980
	struct cgroup *new_cgroup = scan->data;
1981

1982
	cgroup_attach_task(new_cgroup, tsk);
1983 1984 1985 1986 1987 1988 1989
}

/**
 * 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
 *
1990 1991
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1992 1993 1994 1995 1996 1997
 *
 * 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)
{
1998
	struct cgroup_scanner scan;
1999

2000 2001 2002 2003 2004
	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;
2005

2006
	if (cgroup_scan_tasks(&scan))
2007 2008 2009 2010
		printk(KERN_ERR "move_member_tasks_to_cpuset: "
				"cgroup_scan_tasks failed\n");
}

2011
/*
2012
 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2013 2014
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
2015 2016
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
2017
 *
2018 2019
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
2020
 */
2021 2022 2023 2024 2025 2026 2027 2028 2029
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
	parent = cs->parent;
2030
	while (cpumask_empty(parent->cpus_allowed) ||
2031
			nodes_empty(parent->mems_allowed))
2032 2033 2034 2035 2036
		parent = parent->parent;

	move_member_tasks_to_cpuset(cs, parent);
}

2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053
/*
 * 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);
2054 2055
	rcu_read_lock();
	cpuset_for_each_child(child, cont, cp)
2056
		list_add_tail(&child->stack_list, queue);
2057
	rcu_read_unlock();
2058 2059 2060 2061 2062

	return cp;
}


2063
/*
2064 2065 2066 2067
 * 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.
2068
 *
2069
 * Called with cgroup_mutex held.  We take callback_mutex to modify
2070 2071 2072 2073 2074 2075
 * 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.
 *
2076
 * In the case of memory hot-unplug, it will remove nodes from N_MEMORY
2077
 * if all present pages from a node are offlined.
2078
 */
2079 2080
static void
scan_cpusets_upon_hotplug(struct cpuset *root, enum hotplug_event event)
2081
{
2082
	LIST_HEAD(queue);
2083
	struct cpuset *cp;		/* scans cpusets being updated */
2084
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2085

2086 2087
	list_add_tail((struct list_head *)&root->stack_list, &queue);

2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108
	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;
2109

2110 2111
	case CPUSET_MEM_OFFLINE:
		while ((cp = cpuset_next(&queue)) != NULL) {
2112

2113 2114
			/* Continue past cpusets with all mems online */
			if (nodes_subset(cp->mems_allowed,
2115
					node_states[N_MEMORY]))
2116
				continue;
2117

2118 2119 2120 2121 2122
			oldmems = cp->mems_allowed;

			/* Remove offline mems from this cpuset. */
			mutex_lock(&callback_mutex);
			nodes_and(cp->mems_allowed, cp->mems_allowed,
2123
						node_states[N_MEMORY]);
2124
			mutex_unlock(&callback_mutex);
2125

2126 2127 2128 2129 2130
			/* 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);
2131
		}
2132 2133 2134
	}
}

2135 2136 2137 2138 2139 2140
/*
 * 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.
 *
2141 2142 2143
 * The only exception to this is suspend/resume, where we don't
 * modify cpusets at all.
 *
2144
 * This routine ensures that top_cpuset.cpus_allowed tracks
2145
 * cpu_active_mask on each CPU hotplug (cpuhp) event.
2146 2147 2148
 *
 * Called within get_online_cpus().  Needs to call cgroup_lock()
 * before calling generate_sched_domains().
2149 2150 2151
 *
 * @cpu_online: Indicates whether this is a CPU online event (true) or
 * a CPU offline event (false).
2152
 */
2153
void cpuset_update_active_cpus(bool cpu_online)
2154
{
2155
	struct sched_domain_attr *attr;
2156
	cpumask_var_t *doms;
2157 2158 2159
	int ndoms;

	cgroup_lock();
2160
	mutex_lock(&callback_mutex);
2161
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2162
	mutex_unlock(&callback_mutex);
2163 2164 2165 2166

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

2167 2168 2169 2170 2171
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);
2172 2173
}

2174
#ifdef CONFIG_MEMORY_HOTPLUG
2175
/*
2176 2177
 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
 * Call this routine anytime after node_states[N_MEMORY] changes.
2178
 * See cpuset_update_active_cpus() for CPU hotplug handling.
2179
 */
2180 2181
static int cpuset_track_online_nodes(struct notifier_block *self,
				unsigned long action, void *arg)
2182
{
2183
	static nodemask_t oldmems;	/* protected by cgroup_mutex */
2184

2185
	cgroup_lock();
2186 2187
	switch (action) {
	case MEM_ONLINE:
2188
		oldmems = top_cpuset.mems_allowed;
2189
		mutex_lock(&callback_mutex);
2190
		top_cpuset.mems_allowed = node_states[N_MEMORY];
2191
		mutex_unlock(&callback_mutex);
2192
		update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
2193 2194 2195 2196
		break;
	case MEM_OFFLINE:
		/*
		 * needn't update top_cpuset.mems_allowed explicitly because
2197
		 * scan_cpusets_upon_hotplug() will update it.
2198
		 */
2199
		scan_cpusets_upon_hotplug(&top_cpuset, CPUSET_MEM_OFFLINE);
2200 2201 2202 2203
		break;
	default:
		break;
	}
2204
	cgroup_unlock();
2205

2206
	return NOTIFY_OK;
2207 2208 2209
}
#endif

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2210 2211 2212 2213 2214 2215 2216 2217
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
 **/

void __init cpuset_init_smp(void)
{
2218
	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2219
	top_cpuset.mems_allowed = node_states[N_MEMORY];
2220

2221
	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2222 2223 2224

	cpuset_wq = create_singlethread_workqueue("cpuset");
	BUG_ON(!cpuset_wq);
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2225 2226 2227 2228 2229
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2230
 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
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2231
 *
2232
 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
L
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2233
 * attached to the specified @tsk.  Guaranteed to return some non-empty
2234
 * subset of cpu_online_mask, even if this means going outside the
L
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2235 2236 2237
 * tasks cpuset.
 **/

2238
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
L
Linus Torvalds 已提交
2239
{
2240
	mutex_lock(&callback_mutex);
2241
	task_lock(tsk);
2242
	guarantee_online_cpus(task_cs(tsk), pmask);
2243
	task_unlock(tsk);
2244
	mutex_unlock(&callback_mutex);
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2245 2246
}

2247
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2248 2249 2250 2251 2252 2253
{
	const struct cpuset *cs;

	rcu_read_lock();
	cs = task_cs(tsk);
	if (cs)
2254
		do_set_cpus_allowed(tsk, cs->cpus_allowed);
2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269
	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.
2270 2271 2272
	 *
	 * select_fallback_rq() will fix things ups and set cpu_possible_mask
	 * if required.
2273 2274 2275
	 */
}

L
Linus Torvalds 已提交
2276 2277
void cpuset_init_current_mems_allowed(void)
{
2278
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
2279 2280
}

2281 2282 2283 2284 2285 2286
/**
 * 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
2287
 * subset of node_states[N_MEMORY], even if this means going outside the
2288 2289 2290 2291 2292 2293 2294
 * tasks cpuset.
 **/

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

2295
	mutex_lock(&callback_mutex);
2296
	task_lock(tsk);
2297
	guarantee_online_mems(task_cs(tsk), &mask);
2298
	task_unlock(tsk);
2299
	mutex_unlock(&callback_mutex);
2300 2301 2302 2303

	return mask;
}

2304
/**
2305 2306
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
2307
 *
2308
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
2309
 */
2310
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
2311
{
2312
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
2313 2314
}

2315
/*
2316 2317 2318 2319
 * 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.
2320
 */
2321
static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2322
{
2323
	while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2324 2325 2326 2327
		cs = cs->parent;
	return cs;
}

2328
/**
2329 2330
 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2331
 * @gfp_mask: memory allocation flags
2332
 *
2333 2334 2335 2336 2337 2338
 * 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.
2339 2340
 * Otherwise, no.
 *
2341 2342 2343
 * 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.
2344
 *
2345 2346
 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
 * cpusets, and never sleeps.
2347 2348 2349 2350 2351 2352 2353
 *
 * 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'.
 *
2354
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2355 2356
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2357
 * GFP_KERNEL allocations are not so marked, so can escape to the
2358
 * nearest enclosing hardwalled ancestor cpuset.
2359
 *
2360 2361 2362 2363 2364 2365 2366
 * 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.
2367
 *
2368
 * The first call here from mm/page_alloc:get_page_from_freelist()
2369 2370 2371
 * 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).
2372 2373 2374 2375 2376 2377
 *
 * 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:
2378 2379
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2380
 *	TIF_MEMDIE   - any node ok
2381
 *	GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2382
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2383 2384
 *
 * Rule:
2385
 *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2386 2387
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2388
 */
2389
int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2390
{
2391
	const struct cpuset *cs;	/* current cpuset ancestors */
2392
	int allowed;			/* is allocation in zone z allowed? */
2393

2394
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2395
		return 1;
2396
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2397 2398
	if (node_isset(node, current->mems_allowed))
		return 1;
2399 2400 2401 2402 2403 2404
	/*
	 * 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;
2405 2406 2407
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2408 2409 2410
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2411
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2412
	mutex_lock(&callback_mutex);
2413 2414

	task_lock(current);
2415
	cs = nearest_hardwall_ancestor(task_cs(current));
2416 2417
	task_unlock(current);

2418
	allowed = node_isset(node, cs->mems_allowed);
2419
	mutex_unlock(&callback_mutex);
2420
	return allowed;
L
Linus Torvalds 已提交
2421 2422
}

2423
/*
2424 2425
 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
 * @node: is this an allowed node?
2426 2427
 * @gfp_mask: memory allocation flags
 *
2428 2429 2430 2431 2432
 * 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.
2433 2434 2435 2436 2437 2438 2439
 *
 * 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'.
 *
2440 2441
 * Unlike the cpuset_node_allowed_softwall() variant, above,
 * this variant requires that the node be in the current task's
2442 2443 2444 2445
 * 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.
 */
2446
int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2447 2448 2449 2450 2451
{
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2452 2453 2454 2455 2456 2457
	/*
	 * 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;
2458 2459 2460
	return 0;
}

2461
/**
2462 2463
 * 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
2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487
 *
 * 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().
 */

2488
static int cpuset_spread_node(int *rotor)
2489 2490 2491
{
	int node;

2492
	node = next_node(*rotor, current->mems_allowed);
2493 2494
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
2495
	*rotor = node;
2496 2497
	return node;
}
2498 2499 2500

int cpuset_mem_spread_node(void)
{
2501 2502 2503 2504
	if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
		current->cpuset_mem_spread_rotor =
			node_random(&current->mems_allowed);

2505 2506 2507 2508 2509
	return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
}

int cpuset_slab_spread_node(void)
{
2510 2511 2512 2513
	if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
		current->cpuset_slab_spread_rotor =
			node_random(&current->mems_allowed);

2514 2515 2516
	return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
}

2517 2518
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2519
/**
2520 2521 2522 2523 2524 2525 2526 2527
 * 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.
2528 2529
 **/

2530 2531
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2532
{
2533
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2534 2535
}

2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558
/**
 * 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);
}

2559 2560 2561 2562 2563 2564
/*
 * 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.
 */

2565
int cpuset_memory_pressure_enabled __read_mostly;
2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587

/**
 * 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);
2588
	fmeter_markevent(&task_cs(current)->fmeter);
2589 2590 2591
	task_unlock(current);
}

2592
#ifdef CONFIG_PROC_PID_CPUSET
L
Linus Torvalds 已提交
2593 2594 2595 2596
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2597 2598
 *  - 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,
2599
 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2600
 *    anyway.
L
Linus Torvalds 已提交
2601
 */
P
Paul Jackson 已提交
2602
static int proc_cpuset_show(struct seq_file *m, void *unused_v)
L
Linus Torvalds 已提交
2603
{
2604
	struct pid *pid;
L
Linus Torvalds 已提交
2605 2606
	struct task_struct *tsk;
	char *buf;
2607
	struct cgroup_subsys_state *css;
2608
	int retval;
L
Linus Torvalds 已提交
2609

2610
	retval = -ENOMEM;
L
Linus Torvalds 已提交
2611 2612
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2613 2614 2615
		goto out;

	retval = -ESRCH;
2616 2617
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2618 2619
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2620

2621
	retval = -EINVAL;
2622 2623 2624
	cgroup_lock();
	css = task_subsys_state(tsk, cpuset_subsys_id);
	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
L
Linus Torvalds 已提交
2625
	if (retval < 0)
2626
		goto out_unlock;
L
Linus Torvalds 已提交
2627 2628
	seq_puts(m, buf);
	seq_putc(m, '\n');
2629
out_unlock:
2630
	cgroup_unlock();
2631 2632
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2633
	kfree(buf);
2634
out:
L
Linus Torvalds 已提交
2635 2636 2637 2638 2639
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2640 2641
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
L
Linus Torvalds 已提交
2642 2643
}

2644
const struct file_operations proc_cpuset_operations = {
L
Linus Torvalds 已提交
2645 2646 2647 2648 2649
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
2650
#endif /* CONFIG_PROC_PID_CPUSET */
L
Linus Torvalds 已提交
2651

2652
/* Display task mems_allowed in /proc/<pid>/status file. */
2653 2654 2655
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
	seq_printf(m, "Mems_allowed:\t");
2656
	seq_nodemask(m, &task->mems_allowed);
2657
	seq_printf(m, "\n");
2658
	seq_printf(m, "Mems_allowed_list:\t");
2659
	seq_nodemask_list(m, &task->mems_allowed);
2660
	seq_printf(m, "\n");
L
Linus Torvalds 已提交
2661
}