cpuset.c 67.9 KB
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/*
 *  kernel/cpuset.c
 *
 *  Processor and Memory placement constraints for sets of tasks.
 *
 *  Copyright (C) 2003 BULL SA.
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 *  Copyright (C) 2004-2007 Silicon Graphics, Inc.
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 *  Copyright (C) 2006 Google, Inc
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 *
 *  Portions derived from Patrick Mochel's sysfs code.
 *  sysfs is Copyright (c) 2001-3 Patrick Mochel
 *
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 *  2003-10-10 Written by Simon Derr.
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 *  2003-10-22 Updates by Stephen Hemminger.
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 *  2004 May-July Rework by Paul Jackson.
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 *  2006 Rework by Paul Menage to use generic cgroups
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 *
 *  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>
#include <linux/module.h>
#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>
#include <asm/atomic.h>
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#include <linux/mutex.h>
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#include <linux/kfifo.h>
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#include <linux/workqueue.h>
#include <linux/cgroup.h>
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/*
 * Tracks how many cpusets are currently defined in system.
 * When there is only one cpuset (the root cpuset) we can
 * short circuit some hooks.
 */
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int number_of_cpusets __read_mostly;
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/* 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 */
	cpumask_t cpus_allowed;		/* CPUs allowed to tasks in cpuset */
	nodemask_t mems_allowed;	/* Memory Nodes allowed to tasks */

	struct cpuset *parent;		/* my parent */

	/*
	 * Copy of global cpuset_mems_generation as of the most
	 * recent time this cpuset changed its mems_allowed.
	 */
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	int mems_generation;

	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 heirarchy */
	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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struct cpuset_hotplug_scanner {
	struct cgroup_scanner scan;
	struct cgroup *to;
};
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/* bits in struct cpuset flags field */
typedef enum {
	CS_CPU_EXCLUSIVE,
	CS_MEM_EXCLUSIVE,
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	CS_MEMORY_MIGRATE,
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	CS_SCHED_LOAD_BALANCE,
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	CS_SPREAD_PAGE,
	CS_SPREAD_SLAB,
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} cpuset_flagbits_t;

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

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

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static inline int is_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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/*
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 * Increment this integer everytime any cpuset changes its
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 * mems_allowed value.  Users of cpusets can track this generation
 * number, and avoid having to lock and reload mems_allowed unless
 * the cpuset they're using changes generation.
 *
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 * A single, global generation is needed because cpuset_attach_task() could
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 * reattach a task to a different cpuset, which must not have its
 * generation numbers aliased with those of that tasks previous cpuset.
 *
 * Generations are needed for mems_allowed because one task cannot
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 * modify another's memory placement.  So we must enable every task,
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 * on every visit to __alloc_pages(), to efficiently check whether
 * its current->cpuset->mems_allowed has changed, requiring an update
 * of its current->mems_allowed.
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 *
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 * Since writes to cpuset_mems_generation are guarded by the cgroup lock
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 * there is no need to mark it atomic.
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 */
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static int cpuset_mems_generation;
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static struct cpuset top_cpuset = {
	.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
	.cpus_allowed = CPU_MASK_ALL,
	.mems_allowed = NODE_MASK_ALL,
};

/*
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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.
 *
 * The task_struct fields mems_allowed and mems_generation may only
 * be accessed in the context of that task, so require no locks.
 *
 * The cpuset_common_file_write handler for operations that modify
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 * the cpuset hierarchy holds cgroup_mutex across the entire operation,
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 * single threading all such cpuset modifications across the system.
 *
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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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/* This is ugly, but preserves the userspace API for existing cpuset
 * users. If someone tries to mount the "cpuset" filesystem, we
 * silently switch it to mount "cgroup" instead */
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static int cpuset_get_sb(struct file_system_type *fs_type,
			 int flags, const char *unused_dev_name,
			 void *data, struct vfsmount *mnt)
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{
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	struct file_system_type *cgroup_fs = get_fs_type("cgroup");
	int ret = -ENODEV;
	if (cgroup_fs) {
		char mountopts[] =
			"cpuset,noprefix,"
			"release_agent=/sbin/cpuset_release_agent";
		ret = cgroup_fs->get_sb(cgroup_fs, flags,
					   unused_dev_name, mountopts, mnt);
		put_filesystem(cgroup_fs);
	}
	return ret;
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}

static struct file_system_type cpuset_fs_type = {
	.name = "cpuset",
	.get_sb = cpuset_get_sb,
};

/*
 * Return in *pmask the portion of a cpusets's cpus_allowed that
 * are online.  If none are online, walk up the cpuset hierarchy
 * until we find one that does have some online cpus.  If we get
 * all the way to the top and still haven't found any online cpus,
 * return cpu_online_map.  Or if passed a NULL cs from an exit'ing
 * task, return cpu_online_map.
 *
 * One way or another, we guarantee to return some non-empty subset
 * of cpu_online_map.
 *
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 * Call with callback_mutex held.
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 */

static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask)
{
	while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map))
		cs = cs->parent;
	if (cs)
		cpus_and(*pmask, cs->cpus_allowed, cpu_online_map);
	else
		*pmask = cpu_online_map;
	BUG_ON(!cpus_intersects(*pmask, cpu_online_map));
}

/*
 * Return in *pmask the portion of a cpusets's mems_allowed that
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 * are online, with memory.  If none are online with memory, walk
 * up the cpuset hierarchy until we find one that does have some
 * online mems.  If we get all the way to the top and still haven't
 * found any online mems, return node_states[N_HIGH_MEMORY].
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of node_states[N_HIGH_MEMORY].
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 *
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 * Call with callback_mutex held.
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 */

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

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/**
 * cpuset_update_task_memory_state - update task memory placement
 *
 * If the current tasks cpusets mems_allowed changed behind our
 * backs, update current->mems_allowed, mems_generation and task NUMA
 * mempolicy to the new value.
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 *
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 * Task mempolicy is updated by rebinding it relative to the
 * current->cpuset if a task has its memory placement changed.
 * Do not call this routine if in_interrupt().
 *
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 * Call without callback_mutex or task_lock() held.  May be
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 * called with or without cgroup_mutex held.  Thanks in part to
 * 'the_top_cpuset_hack', the task's cpuset pointer will never
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 * be NULL.  This routine also might acquire callback_mutex during
 * call.
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 *
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 * Reading current->cpuset->mems_generation doesn't need task_lock
 * to guard the current->cpuset derefence, because it is guarded
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 * from concurrent freeing of current->cpuset using RCU.
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 *
 * The rcu_dereference() is technically probably not needed,
 * as I don't actually mind if I see a new cpuset pointer but
 * an old value of mems_generation.  However this really only
 * matters on alpha systems using cpusets heavily.  If I dropped
 * that rcu_dereference(), it would save them a memory barrier.
 * For all other arch's, rcu_dereference is a no-op anyway, and for
 * alpha systems not using cpusets, another planned optimization,
 * avoiding the rcu critical section for tasks in the root cpuset
 * which is statically allocated, so can't vanish, will make this
 * irrelevant.  Better to use RCU as intended, than to engage in
 * some cute trick to save a memory barrier that is impossible to
 * test, for alpha systems using cpusets heavily, which might not
 * even exist.
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 *
 * This routine is needed to update the per-task mems_allowed data,
 * within the tasks context, when it is trying to allocate memory
 * (in various mm/mempolicy.c routines) and notices that some other
 * task has been modifying its cpuset.
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 */

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void cpuset_update_task_memory_state(void)
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{
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	int my_cpusets_mem_gen;
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	struct task_struct *tsk = current;
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	struct cpuset *cs;
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	if (task_cs(tsk) == &top_cpuset) {
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		/* Don't need rcu for top_cpuset.  It's never freed. */
		my_cpusets_mem_gen = top_cpuset.mems_generation;
	} else {
		rcu_read_lock();
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		my_cpusets_mem_gen = task_cs(current)->mems_generation;
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		rcu_read_unlock();
	}
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	if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
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		mutex_lock(&callback_mutex);
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		task_lock(tsk);
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		cs = task_cs(tsk); /* Maybe changed when task not locked */
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		guarantee_online_mems(cs, &tsk->mems_allowed);
		tsk->cpuset_mems_generation = cs->mems_generation;
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		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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		task_unlock(tsk);
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		mutex_unlock(&callback_mutex);
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		mpol_rebind_task(tsk, &tsk->mems_allowed);
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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)
{
	return	cpus_subset(p->cpus_allowed, q->cpus_allowed) &&
		nodes_subset(p->mems_allowed, q->mems_allowed) &&
		is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
		is_mem_exclusive(p) <= is_mem_exclusive(q);
}

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

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

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

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

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	par = cur->parent;

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

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

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

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	return 0;
}

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/*
 * Helper routine for rebuild_sched_domains().
 * Do cpusets a, b have overlapping cpus_allowed masks?
 */

static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
{
	return cpus_intersects(a->cpus_allowed, b->cpus_allowed);
}

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

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/*
 * rebuild_sched_domains()
 *
 * 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.
 *
 * This routine builds a partial partition of the systems CPUs
 * (the set of non-overlappping cpumask_t's in the array 'part'
 * below), and passes that partial partition to the kernel/sched.c
 * partition_sched_domains() routine, which will rebuild the
 * schedulers load balancing domains (sched domains) as specified
 * by that partial partition.  A 'partial partition' is a set of
 * non-overlapping subsets whose union is a subset of that set.
 *
 * See "What is sched_load_balance" in Documentation/cpusets.txt
 * 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.
 *
 * Call with cgroup_mutex held.  May take callback_mutex during
 * call due to the kfifo_alloc() and kmalloc() calls.  May nest
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 * a call to the get_online_cpus()/put_online_cpus() pair.
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 * Must not be called holding callback_mutex, because we must not
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 * call get_online_cpus() while holding callback_mutex.  Elsewhere
 * the kernel nests callback_mutex inside get_online_cpus() calls.
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 * So the reverse nesting would risk an ABBA deadlock.
 *
 * The three key local variables below are:
 *    q  - a kfifo queue of cpuset pointers, used to implement a
 *	   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().
 */

static void rebuild_sched_domains(void)
{
	struct kfifo *q;	/* queue of cpusets to be scanned */
	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 */
	cpumask_t *doms;	/* resulting partition; i.e. sched domains */
569
	struct sched_domain_attr *dattr;  /* attributes for custom domains */
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570 571 572 573 574 575
	int ndoms;		/* number of sched domains in result */
	int nslot;		/* next empty doms[] cpumask_t slot */

	q = NULL;
	csa = NULL;
	doms = NULL;
576
	dattr = NULL;
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577 578 579 580 581 582 583

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
		ndoms = 1;
		doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
		if (!doms)
			goto rebuild;
584 585 586 587 588
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
			update_domain_attr(dattr, &top_cpuset);
		}
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589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644
		*doms = top_cpuset.cpus_allowed;
		goto rebuild;
	}

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

	cp = &top_cpuset;
	__kfifo_put(q, (void *)&cp, sizeof(cp));
	while (__kfifo_get(q, (void *)&cp, sizeof(cp))) {
		struct cgroup *cont;
		struct cpuset *child;   /* scans child cpusets of cp */
		if (is_sched_load_balance(cp))
			csa[csn++] = cp;
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			__kfifo_put(q, (void *)&child, sizeof(cp));
		}
  	}

	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;
			}
		}
	}

	/* Convert <csn, csa> to <ndoms, doms> */
	doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
	if (!doms)
		goto rebuild;
645
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
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646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
		int apn = a->pn;

		if (apn >= 0) {
			cpumask_t *dp = doms + nslot;

			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--;
				}
				continue;
			}

			cpus_clear(*dp);
668 669
			if (dattr)
				*(dattr + nslot) = SD_ATTR_INIT;
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670 671 672 673 674 675
			for (j = i; j < csn; j++) {
				struct cpuset *b = csa[j];

				if (apn == b->pn) {
					cpus_or(*dp, *dp, b->cpus_allowed);
					b->pn = -1;
676
					update_domain_attr(dattr, b);
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677 678 679 680 681 682 683 684 685
				}
			}
			nslot++;
		}
	}
	BUG_ON(nslot != ndoms);

rebuild:
	/* Have scheduler rebuild sched domains */
686
	get_online_cpus();
687
	partition_sched_domains(ndoms, doms, dattr);
688
	put_online_cpus();
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Paul Jackson 已提交
689 690 691 692 693 694

done:
	if (q && !IS_ERR(q))
		kfifo_free(q);
	kfree(csa);
	/* Don't kfree(doms) -- partition_sched_domains() does that. */
695
	/* Don't kfree(dattr) -- partition_sched_domains() does that. */
P
Paul Jackson 已提交
696 697
}

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698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727
static inline int started_after_time(struct task_struct *t1,
				     struct timespec *time,
				     struct task_struct *t2)
{
	int start_diff = timespec_compare(&t1->start_time, time);
	if (start_diff > 0) {
		return 1;
	} else if (start_diff < 0) {
		return 0;
	} else {
		/*
		 * Arbitrarily, if two processes started at the same
		 * time, we'll say that the lower pointer value
		 * started first. Note that t2 may have exited by now
		 * so this may not be a valid pointer any longer, but
		 * that's fine - it still serves to distinguish
		 * between two tasks started (effectively)
		 * simultaneously.
		 */
		return t1 > t2;
	}
}

static inline int started_after(void *p1, void *p2)
{
	struct task_struct *t1 = p1;
	struct task_struct *t2 = p2;
	return started_after_time(t1, &t2->start_time, t2);
}

C
Cliff Wickman 已提交
728 729 730 731 732
/**
 * 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
 *
733
 * Call with cgroup_mutex held.  May take callback_mutex during call.
C
Cliff Wickman 已提交
734 735 736
 * 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).
737
 */
738 739
static int cpuset_test_cpumask(struct task_struct *tsk,
			       struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
740 741 742 743
{
	return !cpus_equal(tsk->cpus_allowed,
			(cgroup_cs(scan->cg))->cpus_allowed);
}
744

C
Cliff Wickman 已提交
745 746 747 748 749 750 751 752 753 754 755
/**
 * 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.
 */
756 757
static void cpuset_change_cpumask(struct task_struct *tsk,
				  struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
758
{
759
	set_cpus_allowed_ptr(tsk, &((cgroup_cs(scan->cg))->cpus_allowed));
C
Cliff Wickman 已提交
760 761 762 763 764 765 766
}

/**
 * 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
 */
L
Linus Torvalds 已提交
767 768 769
static int update_cpumask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
C
Cliff Wickman 已提交
770
	struct cgroup_scanner scan;
P
Paul Menage 已提交
771
	struct ptr_heap heap;
C
Cliff Wickman 已提交
772 773
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
774

775 776 777 778
	/* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
	if (cs == &top_cpuset)
		return -EACCES;

L
Linus Torvalds 已提交
779
	trialcs = *cs;
780 781

	/*
782
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
783 784 785
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
786
	 */
787 788
	buf = strstrip(buf);
	if (!*buf) {
789 790 791 792 793 794
		cpus_clear(trialcs.cpus_allowed);
	} else {
		retval = cpulist_parse(buf, trialcs.cpus_allowed);
		if (retval < 0)
			return retval;
	}
L
Linus Torvalds 已提交
795 796
	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
	retval = validate_change(cs, &trialcs);
797 798
	if (retval < 0)
		return retval;
P
Paul Jackson 已提交
799

P
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800 801 802
	/* Nothing to do if the cpus didn't change */
	if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
		return 0;
C
Cliff Wickman 已提交
803

P
Paul Menage 已提交
804 805 806 807
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after);
	if (retval)
		return retval;

P
Paul Jackson 已提交
808 809
	is_load_balanced = is_sched_load_balance(&trialcs);

810
	mutex_lock(&callback_mutex);
811
	cs->cpus_allowed = trialcs.cpus_allowed;
812
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
813

P
Paul Menage 已提交
814 815
	/*
	 * Scan tasks in the cpuset, and update the cpumasks of any
C
Cliff Wickman 已提交
816
	 * that need an update.
P
Paul Menage 已提交
817
	 */
C
Cliff Wickman 已提交
818 819 820 821 822
	scan.cg = cs->css.cgroup;
	scan.test_task = cpuset_test_cpumask;
	scan.process_task = cpuset_change_cpumask;
	scan.heap = &heap;
	cgroup_scan_tasks(&scan);
P
Paul Menage 已提交
823
	heap_free(&heap);
C
Cliff Wickman 已提交
824

P
Paul Menage 已提交
825
	if (is_load_balanced)
P
Paul Jackson 已提交
826
		rebuild_sched_domains();
827
	return 0;
L
Linus Torvalds 已提交
828 829
}

830 831 832 833 834 835 836 837
/*
 * 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.
 *
838
 *    Call holding cgroup_mutex, so current's cpuset won't change
839
 *    during this call, as manage_mutex holds off any cpuset_attach()
840 841
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
842
 *    our task's cpuset.
843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874
 *
 *    Hold callback_mutex around the two modifications of our tasks
 *    mems_allowed to synchronize with cpuset_mems_allowed().
 *
 *    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.
 *
 *    We call cpuset_update_task_memory_state() before hacking
 *    our tasks mems_allowed, so that we are assured of being in
 *    sync with our tasks cpuset, and in particular, callbacks to
 *    cpuset_update_task_memory_state() from nested page allocations
 *    won't see any mismatch of our cpuset and task mems_generation
 *    values, so won't overwrite our hacked tasks mems_allowed
 *    nodemask.
 */

static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
							const nodemask_t *to)
{
	struct task_struct *tsk = current;

	cpuset_update_task_memory_state();

	mutex_lock(&callback_mutex);
	tsk->mems_allowed = *to;
	mutex_unlock(&callback_mutex);

	do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);

	mutex_lock(&callback_mutex);
875
	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
876 877 878
	mutex_unlock(&callback_mutex);
}

879
/*
880 881 882
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
 * cpusets mems_allowed and mems_generation, and for each
883 884 885
 * task in the cpuset, rebind any vma mempolicies and if
 * the cpuset is marked 'memory_migrate', migrate the tasks
 * pages to the new memory.
886
 *
887
 * Call with cgroup_mutex held.  May take callback_mutex during call.
888 889 890
 * 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.
891 892
 */

893 894
static void *cpuset_being_rebound;

L
Linus Torvalds 已提交
895 896 897
static int update_nodemask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
898
	nodemask_t oldmem;
899
	struct task_struct *p;
900 901
	struct mm_struct **mmarray;
	int i, n, ntasks;
902
	int migrate;
903
	int fudge;
L
Linus Torvalds 已提交
904
	int retval;
905
	struct cgroup_iter it;
L
Linus Torvalds 已提交
906

907 908 909 910
	/*
	 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
	 * it's read-only
	 */
911 912 913
	if (cs == &top_cpuset)
		return -EACCES;

L
Linus Torvalds 已提交
914
	trialcs = *cs;
915 916

	/*
917 918 919 920
	 * 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.
921
	 */
922 923
	buf = strstrip(buf);
	if (!*buf) {
924 925 926 927 928 929
		nodes_clear(trialcs.mems_allowed);
	} else {
		retval = nodelist_parse(buf, trialcs.mems_allowed);
		if (retval < 0)
			goto done;
	}
930 931
	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed,
						node_states[N_HIGH_MEMORY]);
932 933 934 935 936
	oldmem = cs->mems_allowed;
	if (nodes_equal(oldmem, trialcs.mems_allowed)) {
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
937 938 939 940
	retval = validate_change(cs, &trialcs);
	if (retval < 0)
		goto done;

941
	mutex_lock(&callback_mutex);
942
	cs->mems_allowed = trialcs.mems_allowed;
943
	cs->mems_generation = cpuset_mems_generation++;
944
	mutex_unlock(&callback_mutex);
945

946
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
947 948 949 950 951 952 953 954 955 956 957 958 959

	fudge = 10;				/* spare mmarray[] slots */
	fudge += cpus_weight(cs->cpus_allowed);	/* imagine one fork-bomb/cpu */
	retval = -ENOMEM;

	/*
	 * Allocate mmarray[] to hold mm reference for each task
	 * in cpuset cs.  Can't kmalloc GFP_KERNEL while holding
	 * tasklist_lock.  We could use GFP_ATOMIC, but with a
	 * few more lines of code, we can retry until we get a big
	 * enough mmarray[] w/o using GFP_ATOMIC.
	 */
	while (1) {
960
		ntasks = cgroup_task_count(cs->css.cgroup);  /* guess */
961 962 963 964
		ntasks += fudge;
		mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
		if (!mmarray)
			goto done;
965
		read_lock(&tasklist_lock);		/* block fork */
966
		if (cgroup_task_count(cs->css.cgroup) <= ntasks)
967
			break;				/* got enough */
968
		read_unlock(&tasklist_lock);		/* try again */
969 970 971 972 973 974
		kfree(mmarray);
	}

	n = 0;

	/* Load up mmarray[] with mm reference for each task in cpuset. */
975 976
	cgroup_iter_start(cs->css.cgroup, &it);
	while ((p = cgroup_iter_next(cs->css.cgroup, &it))) {
977 978 979 980 981
		struct mm_struct *mm;

		if (n >= ntasks) {
			printk(KERN_WARNING
				"Cpuset mempolicy rebind incomplete.\n");
982
			break;
983 984 985 986 987
		}
		mm = get_task_mm(p);
		if (!mm)
			continue;
		mmarray[n++] = mm;
988 989
	}
	cgroup_iter_end(cs->css.cgroup, &it);
990
	read_unlock(&tasklist_lock);
991 992 993 994 995 996

	/*
	 * Now that we've dropped the tasklist spinlock, we can
	 * rebind the vma mempolicies of each mm in mmarray[] to their
	 * new cpuset, and release that mm.  The mpol_rebind_mm()
	 * call takes mmap_sem, which we couldn't take while holding
997
	 * tasklist_lock.  Forks can happen again now - the mpol_dup()
998 999
	 * cpuset_being_rebound check will catch such forks, and rebind
	 * their vma mempolicies too.  Because we still hold the global
1000
	 * cgroup_mutex, we know that no other rebind effort will
1001 1002
	 * be contending for the global variable cpuset_being_rebound.
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1003
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1004
	 */
1005
	migrate = is_memory_migrate(cs);
1006 1007 1008 1009
	for (i = 0; i < n; i++) {
		struct mm_struct *mm = mmarray[i];

		mpol_rebind_mm(mm, &cs->mems_allowed);
1010 1011
		if (migrate)
			cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
1012 1013 1014
		mmput(mm);
	}

1015
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1016
	kfree(mmarray);
1017
	cpuset_being_rebound = NULL;
1018
	retval = 0;
1019
done:
L
Linus Torvalds 已提交
1020 1021 1022
	return retval;
}

1023 1024 1025 1026 1027
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042
static int update_relax_domain_level(struct cpuset *cs, char *buf)
{
	int val = simple_strtol(buf, NULL, 10);

	if (val < 0)
		val = -1;

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
		rebuild_sched_domains();
	}

	return 0;
}

L
Linus Torvalds 已提交
1043 1044 1045
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
 * bit:	the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE,
P
Paul Jackson 已提交
1046
 *				CS_SCHED_LOAD_BALANCE,
1047 1048
 *				CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE,
 *				CS_SPREAD_PAGE, CS_SPREAD_SLAB)
L
Linus Torvalds 已提交
1049 1050
 * cs:	the cpuset to update
 * buf:	the buffer where we read the 0 or 1
1051
 *
1052
 * Call with cgroup_mutex held.
L
Linus Torvalds 已提交
1053 1054
 */

1055 1056
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1057 1058
{
	struct cpuset trialcs;
1059
	int err;
P
Paul Jackson 已提交
1060
	int cpus_nonempty, balance_flag_changed;
L
Linus Torvalds 已提交
1061 1062 1063 1064 1065 1066 1067 1068

	trialcs = *cs;
	if (turning_on)
		set_bit(bit, &trialcs.flags);
	else
		clear_bit(bit, &trialcs.flags);

	err = validate_change(cs, &trialcs);
1069 1070
	if (err < 0)
		return err;
P
Paul Jackson 已提交
1071 1072 1073 1074 1075

	cpus_nonempty = !cpus_empty(trialcs.cpus_allowed);
	balance_flag_changed = (is_sched_load_balance(cs) !=
		 			is_sched_load_balance(&trialcs));

1076
	mutex_lock(&callback_mutex);
1077
	cs->flags = trialcs.flags;
1078
	mutex_unlock(&callback_mutex);
1079

P
Paul Jackson 已提交
1080 1081 1082
	if (cpus_nonempty && balance_flag_changed)
		rebuild_sched_domains();

1083
	return 0;
L
Linus Torvalds 已提交
1084 1085
}

1086
/*
A
Adrian Bunk 已提交
1087
 * Frequency meter - How fast is some event occurring?
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
 *
 * 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;
}

1184
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1185 1186
static int cpuset_can_attach(struct cgroup_subsys *ss,
			     struct cgroup *cont, struct task_struct *tsk)
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{
1188
	struct cpuset *cs = cgroup_cs(cont);
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1189 1190 1191 1192

	if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
		return -ENOSPC;

1193 1194
	return security_task_setscheduler(tsk, 0, NULL);
}
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1195

1196 1197 1198 1199 1200 1201 1202 1203 1204
static void cpuset_attach(struct cgroup_subsys *ss,
			  struct cgroup *cont, struct cgroup *oldcont,
			  struct task_struct *tsk)
{
	cpumask_t cpus;
	nodemask_t from, to;
	struct mm_struct *mm;
	struct cpuset *cs = cgroup_cs(cont);
	struct cpuset *oldcs = cgroup_cs(oldcont);
1205

1206
	mutex_lock(&callback_mutex);
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	guarantee_online_cpus(cs, &cpus);
1208
	set_cpus_allowed_ptr(tsk, &cpus);
1209
	mutex_unlock(&callback_mutex);
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1211 1212
	from = oldcs->mems_allowed;
	to = cs->mems_allowed;
1213 1214 1215
	mm = get_task_mm(tsk);
	if (mm) {
		mpol_rebind_mm(mm, &to);
1216
		if (is_memory_migrate(cs))
1217
			cpuset_migrate_mm(mm, &from, &to);
1218 1219 1220
		mmput(mm);
	}

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}

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

typedef enum {
1226
	FILE_MEMORY_MIGRATE,
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	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
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1231
	FILE_SCHED_LOAD_BALANCE,
1232
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1233 1234
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1235 1236
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
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1237 1238
} cpuset_filetype_t;

1239 1240 1241
static ssize_t cpuset_common_file_write(struct cgroup *cont,
					struct cftype *cft,
					struct file *file,
1242
					const char __user *userbuf,
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					size_t nbytes, loff_t *unused_ppos)
{
1245
	struct cpuset *cs = cgroup_cs(cont);
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	cpuset_filetype_t type = cft->private;
	char *buffer;
	int retval = 0;

	/* Crude upper limit on largest legitimate cpulist user might write. */
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	if (nbytes > 100U + 6 * max(NR_CPUS, MAX_NUMNODES))
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		return -E2BIG;

	/* +1 for nul-terminator */
1255 1256
	buffer = kmalloc(nbytes + 1, GFP_KERNEL);
	if (!buffer)
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		return -ENOMEM;

	if (copy_from_user(buffer, userbuf, nbytes)) {
		retval = -EFAULT;
		goto out1;
	}
	buffer[nbytes] = 0;	/* nul-terminate */

1265
	cgroup_lock();
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1266

1267
	if (cgroup_is_removed(cont)) {
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		retval = -ENODEV;
		goto out2;
	}

	switch (type) {
	case FILE_CPULIST:
		retval = update_cpumask(cs, buffer);
		break;
	case FILE_MEMLIST:
		retval = update_nodemask(cs, buffer);
		break;
1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, buffer);
		break;
	default:
		retval = -EINVAL;
		goto out2;
	}

	if (retval == 0)
		retval = nbytes;
out2:
	cgroup_unlock();
out1:
	kfree(buffer);
	return retval;
}

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;

	cgroup_lock();

	if (cgroup_is_removed(cgrp)) {
		cgroup_unlock();
		return -ENODEV;
	}

	switch (type) {
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	case FILE_CPU_EXCLUSIVE:
1311
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
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		break;
	case FILE_MEM_EXCLUSIVE:
1314
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
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		break;
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	case FILE_SCHED_LOAD_BALANCE:
1317
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1318
		break;
1319
	case FILE_MEMORY_MIGRATE:
1320
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1321
		break;
1322
	case FILE_MEMORY_PRESSURE_ENABLED:
1323
		cpuset_memory_pressure_enabled = !!val;
1324 1325 1326 1327
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1328
	case FILE_SPREAD_PAGE:
1329
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1330
		cs->mems_generation = cpuset_mems_generation++;
1331 1332
		break;
	case FILE_SPREAD_SLAB:
1333
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1334
		cs->mems_generation = cpuset_mems_generation++;
1335
		break;
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	default:
		retval = -EINVAL;
1338
		break;
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	}
1340
	cgroup_unlock();
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	return retval;
}

/*
 * 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.
 */

static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
{
	cpumask_t mask;

1360
	mutex_lock(&callback_mutex);
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	mask = cs->cpus_allowed;
1362
	mutex_unlock(&callback_mutex);
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	return cpulist_scnprintf(page, PAGE_SIZE, mask);
}

static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
{
	nodemask_t mask;

1371
	mutex_lock(&callback_mutex);
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	mask = cs->mems_allowed;
1373
	mutex_unlock(&callback_mutex);
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	return nodelist_scnprintf(page, PAGE_SIZE, mask);
}

1378 1379 1380 1381 1382
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)
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{
1384
	struct cpuset *cs = cgroup_cs(cont);
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	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

1390
	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
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		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;
1402 1403 1404
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		s += sprintf(s, "%d", cs->relax_domain_level);
		break;
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	default:
		retval = -EINVAL;
		goto out;
	}
	*s++ = '\n';

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	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
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out:
	free_page((unsigned long)page);
	return retval;
}

1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441
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);
	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();
	}
}
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/*
 * for the common functions, 'private' gives the type of file
 */

1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517
static struct cftype files[] = {
	{
		.name = "cpus",
		.read = cpuset_common_file_read,
		.write = cpuset_common_file_write,
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
		.read = cpuset_common_file_read,
		.write = cpuset_common_file_write,
		.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,
	},

	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.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,
	},

	{
		.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,
	},
1518 1519
};

1520 1521
static struct cftype cft_memory_pressure_enabled = {
	.name = "memory_pressure_enabled",
1522 1523
	.read_u64 = cpuset_read_u64,
	.write_u64 = cpuset_write_u64,
1524 1525 1526
	.private = FILE_MEMORY_PRESSURE_ENABLED,
};

1527
static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
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{
	int err;

1531 1532
	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
	if (err)
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1533
		return err;
1534
	/* memory_pressure_enabled is in root cpuset only */
1535
	if (!cont->parent)
1536
		err = cgroup_add_file(cont, ss,
1537 1538
				      &cft_memory_pressure_enabled);
	return err;
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1539 1540
}

1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554
/*
 * post_clone() is called at the end of cgroup_clone().
 * 'cgroup' was just created automatically as a result of
 * a cgroup_clone(), and the current task is about to
 * be moved into 'cgroup'.
 *
 * Currently we refuse to set up the cgroup - thereby
 * refusing the task to be entered, and as a result refusing
 * the sys_unshare() or clone() which initiated it - if any
 * sibling cpusets have exclusive cpus or mem.
 *
 * If this becomes a problem for some users who wish to
 * allow that scenario, then cpuset_post_clone() could be
 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1555 1556
 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
 * held.
1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577
 */
static void cpuset_post_clone(struct cgroup_subsys *ss,
			      struct cgroup *cgroup)
{
	struct cgroup *parent, *child;
	struct cpuset *cs, *parent_cs;

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

	cs->mems_allowed = parent_cs->mems_allowed;
	cs->cpus_allowed = parent_cs->cpus_allowed;
	return;
}

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/*
 *	cpuset_create - create a cpuset
1580 1581
 *	ss:	cpuset cgroup subsystem
 *	cont:	control group that the new cpuset will be part of
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 */

1584 1585 1586
static struct cgroup_subsys_state *cpuset_create(
	struct cgroup_subsys *ss,
	struct cgroup *cont)
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1587 1588
{
	struct cpuset *cs;
1589
	struct cpuset *parent;
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1590

1591 1592 1593 1594 1595 1596
	if (!cont->parent) {
		/* This is early initialization for the top cgroup */
		top_cpuset.mems_generation = cpuset_mems_generation++;
		return &top_cpuset.css;
	}
	parent = cgroup_cs(cont->parent);
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1597 1598
	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
	if (!cs)
1599
		return ERR_PTR(-ENOMEM);
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1600

1601
	cpuset_update_task_memory_state();
L
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1602
	cs->flags = 0;
1603 1604 1605 1606
	if (is_spread_page(parent))
		set_bit(CS_SPREAD_PAGE, &cs->flags);
	if (is_spread_slab(parent))
		set_bit(CS_SPREAD_SLAB, &cs->flags);
P
Paul Jackson 已提交
1607
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1608 1609
	cpus_clear(cs->cpus_allowed);
	nodes_clear(cs->mems_allowed);
1610
	cs->mems_generation = cpuset_mems_generation++;
1611
	fmeter_init(&cs->fmeter);
1612
	cs->relax_domain_level = -1;
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1613 1614

	cs->parent = parent;
1615
	number_of_cpusets++;
1616
	return &cs->css ;
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1617 1618
}

P
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1619 1620 1621 1622 1623
/*
 * Locking note on the strange update_flag() call below:
 *
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
1624
 * will call rebuild_sched_domains().  The get_online_cpus()
P
Paul Jackson 已提交
1625 1626
 * call in rebuild_sched_domains() must not be made while holding
 * callback_mutex.  Elsewhere the kernel nests callback_mutex inside
1627
 * get_online_cpus() calls.  So the reverse nesting would risk an
P
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1628 1629 1630
 * ABBA deadlock.
 */

1631
static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
L
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1632
{
1633
	struct cpuset *cs = cgroup_cs(cont);
L
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1634

1635
	cpuset_update_task_memory_state();
P
Paul Jackson 已提交
1636 1637

	if (is_sched_load_balance(cs))
1638
		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
P
Paul Jackson 已提交
1639

1640
	number_of_cpusets--;
1641
	kfree(cs);
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1642 1643
}

1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655
struct cgroup_subsys cpuset_subsys = {
	.name = "cpuset",
	.create = cpuset_create,
	.destroy  = cpuset_destroy,
	.can_attach = cpuset_can_attach,
	.attach = cpuset_attach,
	.populate = cpuset_populate,
	.post_clone = cpuset_post_clone,
	.subsys_id = cpuset_subsys_id,
	.early_init = 1,
};

1656 1657 1658 1659 1660 1661 1662 1663
/*
 * cpuset_init_early - just enough so that the calls to
 * cpuset_update_task_memory_state() in early init code
 * are harmless.
 */

int __init cpuset_init_early(void)
{
1664
	top_cpuset.mems_generation = cpuset_mems_generation++;
1665 1666 1667
	return 0;
}

1668

L
Linus Torvalds 已提交
1669 1670 1671 1672 1673 1674 1675 1676
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1677
	int err = 0;
L
Linus Torvalds 已提交
1678

1679 1680
	cpus_setall(top_cpuset.cpus_allowed);
	nodes_setall(top_cpuset.mems_allowed);
L
Linus Torvalds 已提交
1681

1682
	fmeter_init(&top_cpuset.fmeter);
1683
	top_cpuset.mems_generation = cpuset_mems_generation++;
P
Paul Jackson 已提交
1684
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1685
	top_cpuset.relax_domain_level = -1;
L
Linus Torvalds 已提交
1686 1687 1688

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1689 1690
		return err;

1691
	number_of_cpusets = 1;
1692
	return 0;
L
Linus Torvalds 已提交
1693 1694
}

1695 1696 1697 1698 1699 1700 1701 1702
/**
 * 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.
 */
1703 1704
static void cpuset_do_move_task(struct task_struct *tsk,
				struct cgroup_scanner *scan)
1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716
{
	struct cpuset_hotplug_scanner *chsp;

	chsp = container_of(scan, struct cpuset_hotplug_scanner, scan);
	cgroup_attach_task(chsp->to, tsk);
}

/**
 * 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
 *
1717 1718
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737
 *
 * 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)
{
	struct cpuset_hotplug_scanner scan;

	scan.scan.cg = from->css.cgroup;
	scan.scan.test_task = NULL; /* select all tasks in cgroup */
	scan.scan.process_task = cpuset_do_move_task;
	scan.scan.heap = NULL;
	scan.to = to->css.cgroup;

	if (cgroup_scan_tasks((struct cgroup_scanner *)&scan))
		printk(KERN_ERR "move_member_tasks_to_cpuset: "
				"cgroup_scan_tasks failed\n");
}

1738 1739 1740 1741
/*
 * If common_cpu_mem_hotplug_unplug(), below, unplugs any CPUs
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
1742 1743
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
1744
 *
1745 1746
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1747
 */
1748 1749 1750 1751
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

1752 1753 1754 1755 1756
	/*
	 * The cgroup's css_sets list is in use if there are tasks
	 * in the cpuset; the list is empty if there are none;
	 * the cs->css.refcnt seems always 0.
	 */
1757 1758
	if (list_empty(&cs->css.cgroup->css_sets))
		return;
1759

1760 1761 1762 1763 1764
	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
	parent = cs->parent;
1765 1766
	while (cpus_empty(parent->cpus_allowed) ||
			nodes_empty(parent->mems_allowed))
1767 1768 1769 1770 1771 1772 1773 1774 1775
		parent = parent->parent;

	move_member_tasks_to_cpuset(cs, parent);
}

/*
 * Walk the specified cpuset subtree and look for empty cpusets.
 * The tasks of such cpuset must be moved to a parent cpuset.
 *
1776
 * Called with cgroup_mutex held.  We take callback_mutex to modify
1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787
 * cpus_allowed and mems_allowed.
 *
 * This walk processes the tree from top to bottom, completing one layer
 * before dropping down to the next.  It always processes a node before
 * any of its children.
 *
 * For now, since we lack memory hot unplug, we'll never see a cpuset
 * that has tasks along with an empty 'mems'.  But if we did see such
 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
 */
static void scan_for_empty_cpusets(const struct cpuset *root)
1788
{
1789 1790 1791
	struct cpuset *cp;	/* scans cpusets being updated */
	struct cpuset *child;	/* scans child cpusets of cp */
	struct list_head queue;
1792
	struct cgroup *cont;
1793

1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805
	INIT_LIST_HEAD(&queue);

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

	while (!list_empty(&queue)) {
		cp = container_of(queue.next, struct cpuset, stack_list);
		list_del(queue.next);
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			list_add_tail(&child->stack_list, &queue);
		}
		cont = cp->css.cgroup;
1806 1807 1808 1809 1810 1811

		/* Continue past cpusets with all cpus, mems online */
		if (cpus_subset(cp->cpus_allowed, cpu_online_map) &&
		    nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
			continue;

1812
		/* Remove offline cpus and mems from this cpuset. */
1813
		mutex_lock(&callback_mutex);
1814 1815 1816
		cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map);
		nodes_and(cp->mems_allowed, cp->mems_allowed,
						node_states[N_HIGH_MEMORY]);
1817 1818 1819
		mutex_unlock(&callback_mutex);

		/* Move tasks from the empty cpuset to a parent */
1820
		if (cpus_empty(cp->cpus_allowed) ||
1821
		     nodes_empty(cp->mems_allowed))
1822
			remove_tasks_in_empty_cpuset(cp);
1823 1824 1825 1826 1827
	}
}

/*
 * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track
1828
 * cpu_online_map and node_states[N_HIGH_MEMORY].  Force the top cpuset to
1829
 * track what's online after any CPU or memory node hotplug or unplug event.
1830 1831 1832 1833 1834 1835 1836 1837 1838
 *
 * Since there are two callers of this routine, one for CPU hotplug
 * events and one for memory node hotplug events, we could have coded
 * two separate routines here.  We code it as a single common routine
 * in order to minimize text size.
 */

static void common_cpu_mem_hotplug_unplug(void)
{
1839
	cgroup_lock();
1840 1841

	top_cpuset.cpus_allowed = cpu_online_map;
1842
	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
1843
	scan_for_empty_cpusets(&top_cpuset);
1844

1845
	cgroup_unlock();
1846 1847
}

1848 1849 1850 1851 1852 1853
/*
 * 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.
 *
1854 1855
 * This routine ensures that top_cpuset.cpus_allowed tracks
 * cpu_online_map on each CPU hotplug (cpuhp) event.
1856 1857
 */

P
Paul Jackson 已提交
1858 1859
static int cpuset_handle_cpuhp(struct notifier_block *unused_nb,
				unsigned long phase, void *unused_cpu)
1860
{
1861 1862 1863
	if (phase == CPU_DYING || phase == CPU_DYING_FROZEN)
		return NOTIFY_DONE;

1864
	common_cpu_mem_hotplug_unplug();
1865 1866 1867
	return 0;
}

1868
#ifdef CONFIG_MEMORY_HOTPLUG
1869
/*
1870 1871 1872
 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
 * Call this routine anytime after you change
 * node_states[N_HIGH_MEMORY].
1873 1874 1875
 * See also the previous routine cpuset_handle_cpuhp().
 */

A
Al Viro 已提交
1876
void cpuset_track_online_nodes(void)
1877
{
1878
	common_cpu_mem_hotplug_unplug();
1879 1880 1881
}
#endif

L
Linus Torvalds 已提交
1882 1883 1884 1885 1886 1887 1888 1889 1890
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
 **/

void __init cpuset_init_smp(void)
{
	top_cpuset.cpus_allowed = cpu_online_map;
1891
	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
1892 1893

	hotcpu_notifier(cpuset_handle_cpuhp, 0);
L
Linus Torvalds 已提交
1894 1895 1896
}

/**
1897

L
Linus Torvalds 已提交
1898 1899
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
1900
 * @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
L
Linus Torvalds 已提交
1901 1902 1903 1904 1905 1906 1907
 *
 * Description: Returns the cpumask_t cpus_allowed of the cpuset
 * attached to the specified @tsk.  Guaranteed to return some non-empty
 * subset of cpu_online_map, even if this means going outside the
 * tasks cpuset.
 **/

1908
void cpuset_cpus_allowed(struct task_struct *tsk, cpumask_t *pmask)
L
Linus Torvalds 已提交
1909
{
1910
	mutex_lock(&callback_mutex);
1911
	cpuset_cpus_allowed_locked(tsk, pmask);
1912 1913 1914 1915 1916
	mutex_unlock(&callback_mutex);
}

/**
 * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset.
1917
 * Must be called with callback_mutex held.
1918
 **/
1919
void cpuset_cpus_allowed_locked(struct task_struct *tsk, cpumask_t *pmask)
1920
{
1921
	task_lock(tsk);
1922
	guarantee_online_cpus(task_cs(tsk), pmask);
1923
	task_unlock(tsk);
L
Linus Torvalds 已提交
1924 1925 1926 1927
}

void cpuset_init_current_mems_allowed(void)
{
1928
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
1929 1930
}

1931 1932 1933 1934 1935 1936
/**
 * 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
1937
 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
1938 1939 1940 1941 1942 1943 1944
 * tasks cpuset.
 **/

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

1945
	mutex_lock(&callback_mutex);
1946
	task_lock(tsk);
1947
	guarantee_online_mems(task_cs(tsk), &mask);
1948
	task_unlock(tsk);
1949
	mutex_unlock(&callback_mutex);
1950 1951 1952 1953

	return mask;
}

1954
/**
1955 1956
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
1957
 *
1958
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
1959
 */
1960
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
1961
{
1962
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
1963 1964
}

1965 1966
/*
 * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
1967
 * ancestor to the specified cpuset.  Call holding callback_mutex.
1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
 * If no ancestor is mem_exclusive (an unusual configuration), then
 * returns the root cpuset.
 */
static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs)
{
	while (!is_mem_exclusive(cs) && cs->parent)
		cs = cs->parent;
	return cs;
}

1978
/**
1979
 * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node?
1980
 * @z: is this zone on an allowed node?
1981
 * @gfp_mask: memory allocation flags
1982
 *
1983 1984
 * If we're in interrupt, yes, we can always allocate.  If
 * __GFP_THISNODE is set, yes, we can always allocate.  If zone
1985 1986 1987
 * z's node is in our tasks mems_allowed, yes.  If it's not a
 * __GFP_HARDWALL request and this zone's nodes is in the nearest
 * mem_exclusive cpuset ancestor to this tasks cpuset, yes.
1988 1989
 * If the task has been OOM killed and has access to memory reserves
 * as specified by the TIF_MEMDIE flag, yes.
1990 1991
 * Otherwise, no.
 *
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
 * If __GFP_HARDWALL is set, cpuset_zone_allowed_softwall()
 * reduces to cpuset_zone_allowed_hardwall().  Otherwise,
 * cpuset_zone_allowed_softwall() might sleep, and might allow a zone
 * from an enclosing cpuset.
 *
 * cpuset_zone_allowed_hardwall() only handles the simpler case of
 * hardwall cpusets, and never sleeps.
 *
 * 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'.
 *
2006
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2007 2008
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2009
 * GFP_KERNEL allocations are not so marked, so can escape to the
2010
 * nearest enclosing mem_exclusive ancestor cpuset.
2011
 *
2012 2013 2014 2015 2016 2017 2018
 * 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.
2019
 *
2020
 * The first call here from mm/page_alloc:get_page_from_freelist()
2021 2022 2023
 * 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).
2024 2025 2026 2027 2028 2029
 *
 * 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:
2030 2031
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2032
 *	TIF_MEMDIE   - any node ok
2033 2034
 *	GFP_KERNEL   - any node in enclosing mem_exclusive cpuset ok
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2035 2036
 *
 * Rule:
2037
 *    Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you
2038 2039
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2040
 */
2041

2042
int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2043
{
2044 2045
	int node;			/* node that zone z is on */
	const struct cpuset *cs;	/* current cpuset ancestors */
2046
	int allowed;			/* is allocation in zone z allowed? */
2047

2048
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2049
		return 1;
2050
	node = zone_to_nid(z);
2051
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2052 2053
	if (node_isset(node, current->mems_allowed))
		return 1;
2054 2055 2056 2057 2058 2059
	/*
	 * 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;
2060 2061 2062
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2063 2064 2065
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2066
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2067
	mutex_lock(&callback_mutex);
2068 2069

	task_lock(current);
2070
	cs = nearest_exclusive_ancestor(task_cs(current));
2071 2072
	task_unlock(current);

2073
	allowed = node_isset(node, cs->mems_allowed);
2074
	mutex_unlock(&callback_mutex);
2075
	return allowed;
L
Linus Torvalds 已提交
2076 2077
}

2078 2079 2080 2081 2082 2083 2084
/*
 * cpuset_zone_allowed_hardwall - Can we allocate on zone z's memory node?
 * @z: is this zone on an allowed node?
 * @gfp_mask: memory allocation flags
 *
 * If we're in interrupt, yes, we can always allocate.
 * If __GFP_THISNODE is set, yes, we can always allocate.  If zone
2085 2086 2087
 * z's node is in our tasks 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.
2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110
 *
 * 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'.
 *
 * Unlike the cpuset_zone_allowed_softwall() variant, above,
 * this variant requires that the zone be in the current tasks
 * 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.
 */

int __cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
{
	int node;			/* node that zone z is on */

	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	node = zone_to_nid(z);
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2111 2112 2113 2114 2115 2116
	/*
	 * 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;
2117 2118 2119
	return 0;
}

P
Paul Jackson 已提交
2120 2121 2122
/**
 * cpuset_lock - lock out any changes to cpuset structures
 *
2123
 * The out of memory (oom) code needs to mutex_lock cpusets
P
Paul Jackson 已提交
2124
 * from being changed while it scans the tasklist looking for a
2125
 * task in an overlapping cpuset.  Expose callback_mutex via this
P
Paul Jackson 已提交
2126 2127
 * cpuset_lock() routine, so the oom code can lock it, before
 * locking the task list.  The tasklist_lock is a spinlock, so
2128
 * must be taken inside callback_mutex.
P
Paul Jackson 已提交
2129 2130 2131 2132
 */

void cpuset_lock(void)
{
2133
	mutex_lock(&callback_mutex);
P
Paul Jackson 已提交
2134 2135 2136 2137 2138 2139 2140 2141 2142 2143
}

/**
 * cpuset_unlock - release lock on cpuset changes
 *
 * Undo the lock taken in a previous cpuset_lock() call.
 */

void cpuset_unlock(void)
{
2144
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
2145 2146
}

2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184
/**
 * cpuset_mem_spread_node() - On which node to begin search for a page
 *
 * 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().
 */

int cpuset_mem_spread_node(void)
{
	int node;

	node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
	current->cpuset_mem_spread_rotor = node;
	return node;
}
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2185
/**
2186 2187 2188 2189 2190 2191 2192 2193
 * 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.
2194 2195
 **/

2196 2197
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2198
{
2199
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2200 2201
}

2202 2203 2204 2205 2206 2207
/*
 * 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.
 */

2208
int cpuset_memory_pressure_enabled __read_mostly;
2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230

/**
 * 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);
2231
	fmeter_markevent(&task_cs(current)->fmeter);
2232 2233 2234
	task_unlock(current);
}

2235
#ifdef CONFIG_PROC_PID_CPUSET
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2236 2237 2238 2239
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2240 2241
 *  - 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,
2242
 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2243
 *    anyway.
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2244
 */
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2245
static int proc_cpuset_show(struct seq_file *m, void *unused_v)
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2246
{
2247
	struct pid *pid;
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2248 2249
	struct task_struct *tsk;
	char *buf;
2250
	struct cgroup_subsys_state *css;
2251
	int retval;
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2252

2253
	retval = -ENOMEM;
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2254 2255
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2256 2257 2258
		goto out;

	retval = -ESRCH;
2259 2260
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2261 2262
	if (!tsk)
		goto out_free;
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2263

2264
	retval = -EINVAL;
2265 2266 2267
	cgroup_lock();
	css = task_subsys_state(tsk, cpuset_subsys_id);
	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
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2268
	if (retval < 0)
2269
		goto out_unlock;
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2270 2271
	seq_puts(m, buf);
	seq_putc(m, '\n');
2272
out_unlock:
2273
	cgroup_unlock();
2274 2275
	put_task_struct(tsk);
out_free:
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2276
	kfree(buf);
2277
out:
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2278 2279 2280 2281 2282
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2283 2284
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
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2285 2286
}

2287
const struct file_operations proc_cpuset_operations = {
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2288 2289 2290 2291 2292
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
2293
#endif /* CONFIG_PROC_PID_CPUSET */
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2294 2295

/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
2296 2297 2298 2299 2300 2301
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
	seq_printf(m, "Cpus_allowed:\t");
	m->count += cpumask_scnprintf(m->buf + m->count, m->size - m->count,
					task->cpus_allowed);
	seq_printf(m, "\n");
2302 2303 2304 2305
	seq_printf(m, "Cpus_allowed_list:\t");
	m->count += cpulist_scnprintf(m->buf + m->count, m->size - m->count,
					task->cpus_allowed);
	seq_printf(m, "\n");
2306 2307 2308 2309
	seq_printf(m, "Mems_allowed:\t");
	m->count += nodemask_scnprintf(m->buf + m->count, m->size - m->count,
					task->mems_allowed);
	seq_printf(m, "\n");
2310 2311 2312 2313
	seq_printf(m, "Mems_allowed_list:\t");
	m->count += nodelist_scnprintf(m->buf + m->count, m->size - m->count,
					task->mems_allowed);
	seq_printf(m, "\n");
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2314
}