cpuset.c 79.0 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) 2004-2006 Silicon Graphics, 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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 *
 *  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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#define CPUSET_SUPER_MAGIC		0x27e0eb
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/*
 * Tracks how many cpusets are currently defined in system.
 * When there is only one cpuset (the root cpuset) we can
 * short circuit some hooks.
 */
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int number_of_cpusets __read_mostly;
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/* See "Frequency meter" comments, below. */

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

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struct cpuset {
	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 */

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	/*
	 * Count is atomic so can incr (fork) or decr (exit) without a lock.
	 */
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	atomic_t count;			/* count tasks using this cpuset */

	/*
	 * We link our 'sibling' struct into our parents 'children'.
	 * Our children link their 'sibling' into our 'children'.
	 */
	struct list_head sibling;	/* my parents children */
	struct list_head children;	/* my children */

	struct cpuset *parent;		/* my parent */
	struct dentry *dentry;		/* cpuset fs entry */

	/*
	 * 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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};

/* 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_REMOVED,
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	CS_NOTIFY_ON_RELEASE,
	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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}

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

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

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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.
 *
 * A single, global generation is needed because attach_task() could
 * 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
 * modify anothers memory placement.  So we must enable every task,
 * 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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 *
 * Since cpuset_mems_generation is guarded by manage_mutex,
 * 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,
	.count = ATOMIC_INIT(0),
	.sibling = LIST_HEAD_INIT(top_cpuset.sibling),
	.children = LIST_HEAD_INIT(top_cpuset.children),
};

static struct vfsmount *cpuset_mount;
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static struct super_block *cpuset_sb;
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/*
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 * We have two global cpuset mutexes below.  They can nest.
 * It is ok to first take manage_mutex, then nest callback_mutex.  We also
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 * require taking task_lock() when dereferencing a tasks cpuset pointer.
 * See "The task_lock() exception", at the end of this comment.
 *
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 * A task must hold both mutexes to modify cpusets.  If a task
 * holds manage_mutex, then it blocks others wanting that mutex,
 * 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 manage_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.
 *
 * Any task can increment and decrement the count field without lock.
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 * So in general, code holding manage_mutex or callback_mutex can't rely
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 * on the count field not changing.  However, if the count goes to
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 * zero, then only attach_task(), which holds both mutexes, can
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 * increment it again.  Because a count of zero means that no tasks
 * are currently attached, therefore there is no way a task attached
 * to that cpuset can fork (the other way to increment the count).
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 * So code holding manage_mutex or callback_mutex can safely assume that
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 * if the count is zero, it will stay zero.  Similarly, if a task
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 * holds manage_mutex or callback_mutex on a cpuset with zero count, it
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 * knows that the cpuset won't be removed, as cpuset_rmdir() needs
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 * both of those mutexes.
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 *
 * The cpuset_common_file_write handler for operations that modify
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 * the cpuset hierarchy holds manage_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.
 *
 * The fork and exit callbacks cpuset_fork() and cpuset_exit(), don't
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 * (usually) take either mutex.  These are the two most performance
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 * critical pieces of code here.  The exception occurs on cpuset_exit(),
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 * when a task in a notify_on_release cpuset exits.  Then manage_mutex
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 * is taken, and if the cpuset count is zero, a usermode call made
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 * to /sbin/cpuset_release_agent with the name of the cpuset (path
 * relative to the root of cpuset file system) as the argument.
 *
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 * A cpuset can only be deleted if both its 'count' of using tasks
 * is zero, and its list of 'children' cpusets is empty.  Since all
 * tasks in the system use _some_ cpuset, and since there is always at
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 * least one task in the system (init), therefore, top_cpuset
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 * always has either children cpusets and/or using tasks.  So we don't
 * need a special hack to ensure that top_cpuset cannot be deleted.
 *
 * The above "Tale of Two Semaphores" would be complete, but for:
 *
 *	The task_lock() exception
 *
 * The need for this exception arises from the action of attach_task(),
 * which overwrites one tasks cpuset pointer with another.  It does
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 * so using both mutexes, however there are several performance
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 * critical places that need to reference task->cpuset without the
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 * expense of grabbing a system global mutex.  Therefore except as
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 * noted below, when dereferencing or, as in attach_task(), modifying
 * a tasks cpuset pointer we use task_lock(), which acts on a spinlock
 * (task->alloc_lock) already in the task_struct routinely used for
 * such matters.
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 *
 * P.S.  One more locking exception.  RCU is used to guard the
 * update of a tasks cpuset pointer by attach_task() and the
 * access of task->cpuset->mems_generation via that pointer in
 * the routine cpuset_update_task_memory_state().
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 */

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static DEFINE_MUTEX(manage_mutex);
static DEFINE_MUTEX(callback_mutex);
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/*
 * A couple of forward declarations required, due to cyclic reference loop:
 *  cpuset_mkdir -> cpuset_create -> cpuset_populate_dir -> cpuset_add_file
 *  -> cpuset_create_file -> cpuset_dir_inode_operations -> cpuset_mkdir.
 */

static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode);
static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry);

static struct backing_dev_info cpuset_backing_dev_info = {
	.ra_pages = 0,		/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};

static struct inode *cpuset_new_inode(mode_t mode)
{
	struct inode *inode = new_inode(cpuset_sb);

	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = current->fsuid;
		inode->i_gid = current->fsgid;
		inode->i_blocks = 0;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		inode->i_mapping->backing_dev_info = &cpuset_backing_dev_info;
	}
	return inode;
}

static void cpuset_diput(struct dentry *dentry, struct inode *inode)
{
	/* is dentry a directory ? if so, kfree() associated cpuset */
	if (S_ISDIR(inode->i_mode)) {
		struct cpuset *cs = dentry->d_fsdata;
		BUG_ON(!(is_removed(cs)));
		kfree(cs);
	}
	iput(inode);
}

static struct dentry_operations cpuset_dops = {
	.d_iput = cpuset_diput,
};

static struct dentry *cpuset_get_dentry(struct dentry *parent, const char *name)
{
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	struct dentry *d = lookup_one_len(name, parent, strlen(name));
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	if (!IS_ERR(d))
		d->d_op = &cpuset_dops;
	return d;
}

static void remove_dir(struct dentry *d)
{
	struct dentry *parent = dget(d->d_parent);

	d_delete(d);
	simple_rmdir(parent->d_inode, d);
	dput(parent);
}

/*
 * NOTE : the dentry must have been dget()'ed
 */
static void cpuset_d_remove_dir(struct dentry *dentry)
{
	struct list_head *node;

	spin_lock(&dcache_lock);
	node = dentry->d_subdirs.next;
	while (node != &dentry->d_subdirs) {
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		struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
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		list_del_init(node);
		if (d->d_inode) {
			d = dget_locked(d);
			spin_unlock(&dcache_lock);
			d_delete(d);
			simple_unlink(dentry->d_inode, d);
			dput(d);
			spin_lock(&dcache_lock);
		}
		node = dentry->d_subdirs.next;
	}
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	list_del_init(&dentry->d_u.d_child);
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	spin_unlock(&dcache_lock);
	remove_dir(dentry);
}

static struct super_operations cpuset_ops = {
	.statfs = simple_statfs,
	.drop_inode = generic_delete_inode,
};

static int cpuset_fill_super(struct super_block *sb, void *unused_data,
							int unused_silent)
{
	struct inode *inode;
	struct dentry *root;

	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = CPUSET_SUPER_MAGIC;
	sb->s_op = &cpuset_ops;
	cpuset_sb = sb;

	inode = cpuset_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR);
	if (inode) {
		inode->i_op = &simple_dir_inode_operations;
		inode->i_fop = &simple_dir_operations;
		/* directories start off with i_nlink == 2 (for "." entry) */
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		inc_nlink(inode);
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	} else {
		return -ENOMEM;
	}

	root = d_alloc_root(inode);
	if (!root) {
		iput(inode);
		return -ENOMEM;
	}
	sb->s_root = root;
	return 0;
}

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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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	return get_sb_single(fs_type, flags, data, cpuset_fill_super, mnt);
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}

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

/* struct cftype:
 *
 * The files in the cpuset filesystem mostly have a very simple read/write
 * handling, some common function will take care of it. Nevertheless some cases
 * (read tasks) are special and therefore I define this structure for every
 * kind of file.
 *
 *
 * When reading/writing to a file:
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 *	- the cpuset to use in file->f_path.dentry->d_parent->d_fsdata
 *	- the 'cftype' of the file is file->f_path.dentry->d_fsdata
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 */

struct cftype {
	char *name;
	int private;
	int (*open) (struct inode *inode, struct file *file);
	ssize_t (*read) (struct file *file, char __user *buf, size_t nbytes,
							loff_t *ppos);
	int (*write) (struct file *file, const char __user *buf, size_t nbytes,
							loff_t *ppos);
	int (*release) (struct inode *inode, struct file *file);
};

static inline struct cpuset *__d_cs(struct dentry *dentry)
{
	return dentry->d_fsdata;
}

static inline struct cftype *__d_cft(struct dentry *dentry)
{
	return dentry->d_fsdata;
}

/*
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 * Call with manage_mutex held.  Writes path of cpuset into buf.
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 * Returns 0 on success, -errno on error.
 */

static int cpuset_path(const struct cpuset *cs, char *buf, int buflen)
{
	char *start;

	start = buf + buflen;

	*--start = '\0';
	for (;;) {
		int len = cs->dentry->d_name.len;
		if ((start -= len) < buf)
			return -ENAMETOOLONG;
		memcpy(start, cs->dentry->d_name.name, len);
		cs = cs->parent;
		if (!cs)
			break;
		if (!cs->parent)
			continue;
		if (--start < buf)
			return -ENAMETOOLONG;
		*start = '/';
	}
	memmove(buf, start, buf + buflen - start);
	return 0;
}

/*
 * Notify userspace when a cpuset is released, by running
 * /sbin/cpuset_release_agent with the name of the cpuset (path
 * relative to the root of cpuset file system) as the argument.
 *
 * Most likely, this user command will try to rmdir this cpuset.
 *
 * This races with the possibility that some other task will be
 * attached to this cpuset before it is removed, or that some other
 * user task will 'mkdir' a child cpuset of this cpuset.  That's ok.
 * The presumed 'rmdir' will fail quietly if this cpuset is no longer
 * unused, and this cpuset will be reprieved from its death sentence,
 * to continue to serve a useful existence.  Next time it's released,
 * we will get notified again, if it still has 'notify_on_release' set.
 *
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 * The final arg to call_usermodehelper() is 0, which means don't
 * wait.  The separate /sbin/cpuset_release_agent task is forked by
 * call_usermodehelper(), then control in this thread returns here,
 * without waiting for the release agent task.  We don't bother to
 * wait because the caller of this routine has no use for the exit
 * status of the /sbin/cpuset_release_agent task, so no sense holding
 * our caller up for that.
 *
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 * When we had only one cpuset mutex, we had to call this
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 * without holding it, to avoid deadlock when call_usermodehelper()
 * allocated memory.  With two locks, we could now call this while
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 * holding manage_mutex, but we still don't, so as to minimize
 * the time manage_mutex is held.
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 */

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static void cpuset_release_agent(const char *pathbuf)
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{
	char *argv[3], *envp[3];
	int i;

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	if (!pathbuf)
		return;

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	i = 0;
	argv[i++] = "/sbin/cpuset_release_agent";
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	argv[i++] = (char *)pathbuf;
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	argv[i] = NULL;

	i = 0;
	/* minimal command environment */
	envp[i++] = "HOME=/";
	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
	envp[i] = NULL;

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	call_usermodehelper(argv[0], argv, envp, 0);
	kfree(pathbuf);
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}

/*
 * Either cs->count of using tasks transitioned to zero, or the
 * cs->children list of child cpusets just became empty.  If this
 * cs is notify_on_release() and now both the user count is zero and
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 * the list of children is empty, prepare cpuset path in a kmalloc'd
 * buffer, to be returned via ppathbuf, so that the caller can invoke
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 * cpuset_release_agent() with it later on, once manage_mutex is dropped.
 * Call here with manage_mutex held.
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 *
 * This check_for_release() routine is responsible for kmalloc'ing
 * pathbuf.  The above cpuset_release_agent() is responsible for
 * kfree'ing pathbuf.  The caller of these routines is responsible
 * for providing a pathbuf pointer, initialized to NULL, then
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 * calling check_for_release() with manage_mutex held and the address
 * of the pathbuf pointer, then dropping manage_mutex, then calling
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 * cpuset_release_agent() with pathbuf, as set by check_for_release().
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 */

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static void check_for_release(struct cpuset *cs, char **ppathbuf)
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{
	if (notify_on_release(cs) && atomic_read(&cs->count) == 0 &&
	    list_empty(&cs->children)) {
		char *buf;

		buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
		if (!buf)
			return;
		if (cpuset_path(cs, buf, PAGE_SIZE) < 0)
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			kfree(buf);
		else
			*ppathbuf = buf;
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	}
}

/*
 * 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
 * are online.  If none are online, 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_online_map.
 *
 * One way or another, we guarantee to return some non-empty subset
 * of node_online_map.
 *
592
 * Call with callback_mutex held.
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 */

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

606 607 608 609 610 611
/**
 * 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.
612
 *
613 614 615 616
 * 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().
 *
617 618 619 620
 * Call without callback_mutex or task_lock() held.  May be
 * called with or without manage_mutex held.  Thanks in part to
 * 'the_top_cpuset_hack', the tasks cpuset pointer will never
 * be NULL.  This routine also might acquire callback_mutex and
621
 * current->mm->mmap_sem during call.
622
 *
623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640
 * Reading current->cpuset->mems_generation doesn't need task_lock
 * to guard the current->cpuset derefence, because it is guarded
 * from concurrent freeing of current->cpuset by attach_task(),
 * using RCU.
 *
 * 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.
641 642 643 644 645
 *
 * 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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 */

648
void cpuset_update_task_memory_state(void)
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{
650
	int my_cpusets_mem_gen;
651
	struct task_struct *tsk = current;
652
	struct cpuset *cs;
653

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	if (tsk->cpuset == &top_cpuset) {
		/* Don't need rcu for top_cpuset.  It's never freed. */
		my_cpusets_mem_gen = top_cpuset.mems_generation;
	} else {
		rcu_read_lock();
		cs = rcu_dereference(tsk->cpuset);
		my_cpusets_mem_gen = cs->mems_generation;
		rcu_read_unlock();
	}
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664
	if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
665
		mutex_lock(&callback_mutex);
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		task_lock(tsk);
		cs = tsk->cpuset;	/* Maybe changed when task not locked */
		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;
678
		task_unlock(tsk);
679
		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
689
 * are only set if the other's are set.  Call holding manage_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
707
 * manage_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)
{
	struct cpuset *c, *par;

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

	/* Remaining checks don't apply to root cpuset */
731
	if (cur == &top_cpuset)
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		return 0;

734 735
	par = cur->parent;

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

	/* If either I or some sibling (!= me) is exclusive, we can't overlap */
	list_for_each_entry(c, &par->children, sibling) {
		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;
	}

	return 0;
}

755 756 757 758 759 760 761 762
/*
 * For a given cpuset cur, partition the system as follows
 * a. All cpus in the parent cpuset's cpus_allowed that are not part of any
 *    exclusive child cpusets
 * b. All cpus in the current cpuset's cpus_allowed that are not part of any
 *    exclusive child cpusets
 * Build these two partitions by calling partition_sched_domains
 *
763
 * Call with manage_mutex held.  May nest a call to the
764
 * lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
765 766
 * Must not be called holding callback_mutex, because we must
 * not call lock_cpu_hotplug() while holding callback_mutex.
767
 */
768

769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785
static void update_cpu_domains(struct cpuset *cur)
{
	struct cpuset *c, *par = cur->parent;
	cpumask_t pspan, cspan;

	if (par == NULL || cpus_empty(cur->cpus_allowed))
		return;

	/*
	 * Get all cpus from parent's cpus_allowed not part of exclusive
	 * children
	 */
	pspan = par->cpus_allowed;
	list_for_each_entry(c, &par->children, sibling) {
		if (is_cpu_exclusive(c))
			cpus_andnot(pspan, pspan, c->cpus_allowed);
	}
786
	if (!is_cpu_exclusive(cur)) {
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809
		cpus_or(pspan, pspan, cur->cpus_allowed);
		if (cpus_equal(pspan, cur->cpus_allowed))
			return;
		cspan = CPU_MASK_NONE;
	} else {
		if (cpus_empty(pspan))
			return;
		cspan = cur->cpus_allowed;
		/*
		 * Get all cpus from current cpuset's cpus_allowed not part
		 * of exclusive children
		 */
		list_for_each_entry(c, &cur->children, sibling) {
			if (is_cpu_exclusive(c))
				cpus_andnot(cspan, cspan, c->cpus_allowed);
		}
	}

	lock_cpu_hotplug();
	partition_sched_domains(&pspan, &cspan);
	unlock_cpu_hotplug();
}

810
/*
811
 * Call with manage_mutex held.  May take callback_mutex during call.
812 813
 */

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static int update_cpumask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
817
	int retval, cpus_unchanged;
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819 820 821 822
	/* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
	if (cs == &top_cpuset)
		return -EACCES;

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	trialcs = *cs;
824 825 826 827 828 829 830 831 832 833 834 835 836

	/*
	 * We allow a cpuset's cpus_allowed to be empty; if it has attached
	 * tasks, we'll catch it later when we validate the change and return
	 * -ENOSPC.
	 */
	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
		cpus_clear(trialcs.cpus_allowed);
	} else {
		retval = cpulist_parse(buf, trialcs.cpus_allowed);
		if (retval < 0)
			return retval;
	}
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	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
838 839
	/* cpus_allowed cannot be empty for a cpuset with attached tasks. */
	if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed))
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		return -ENOSPC;
	retval = validate_change(cs, &trialcs);
842 843 844
	if (retval < 0)
		return retval;
	cpus_unchanged = cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed);
845
	mutex_lock(&callback_mutex);
846
	cs->cpus_allowed = trialcs.cpus_allowed;
847
	mutex_unlock(&callback_mutex);
848 849 850
	if (is_cpu_exclusive(cs) && !cpus_unchanged)
		update_cpu_domains(cs);
	return 0;
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}

853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901
/*
 * 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.
 *
 *    Call holding manage_mutex, so our current->cpuset won't change
 *    during this call, as manage_mutex holds off any attach_task()
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
 *    our tasks cpuset.
 *
 *    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);
	guarantee_online_mems(tsk->cpuset, &tsk->mems_allowed);
	mutex_unlock(&callback_mutex);
}

902
/*
903 904 905
 * 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
906 907 908
 * task in the cpuset, rebind any vma mempolicies and if
 * the cpuset is marked 'memory_migrate', migrate the tasks
 * pages to the new memory.
909
 *
910
 * Call with manage_mutex held.  May take callback_mutex during call.
911 912 913
 * 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.
914 915
 */

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static int update_nodemask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
919
	nodemask_t oldmem;
920 921 922
	struct task_struct *g, *p;
	struct mm_struct **mmarray;
	int i, n, ntasks;
923
	int migrate;
924
	int fudge;
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	int retval;

927 928 929 930
	/* top_cpuset.mems_allowed tracks node_online_map; it's read-only */
	if (cs == &top_cpuset)
		return -EACCES;

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	trialcs = *cs;
932 933 934 935 936 937 938 939 940 941 942 943 944

	/*
	 * We allow a cpuset's mems_allowed to be empty; if it has attached
	 * tasks, we'll catch it later when we validate the change and return
	 * -ENOSPC.
	 */
	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
		nodes_clear(trialcs.mems_allowed);
	} else {
		retval = nodelist_parse(buf, trialcs.mems_allowed);
		if (retval < 0)
			goto done;
	}
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	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
946 947 948 949 950
	oldmem = cs->mems_allowed;
	if (nodes_equal(oldmem, trialcs.mems_allowed)) {
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
951 952
	/* mems_allowed cannot be empty for a cpuset with attached tasks. */
	if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) {
953 954
		retval = -ENOSPC;
		goto done;
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	}
956 957 958 959
	retval = validate_change(cs, &trialcs);
	if (retval < 0)
		goto done;

960
	mutex_lock(&callback_mutex);
961
	cs->mems_allowed = trialcs.mems_allowed;
962
	cs->mems_generation = cpuset_mems_generation++;
963
	mutex_unlock(&callback_mutex);
964

965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018
	set_cpuset_being_rebound(cs);		/* causes mpol_copy() rebind */

	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) {
		ntasks = atomic_read(&cs->count);	/* guess */
		ntasks += fudge;
		mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
		if (!mmarray)
			goto done;
		write_lock_irq(&tasklist_lock);		/* block fork */
		if (atomic_read(&cs->count) <= ntasks)
			break;				/* got enough */
		write_unlock_irq(&tasklist_lock);	/* try again */
		kfree(mmarray);
	}

	n = 0;

	/* Load up mmarray[] with mm reference for each task in cpuset. */
	do_each_thread(g, p) {
		struct mm_struct *mm;

		if (n >= ntasks) {
			printk(KERN_WARNING
				"Cpuset mempolicy rebind incomplete.\n");
			continue;
		}
		if (p->cpuset != cs)
			continue;
		mm = get_task_mm(p);
		if (!mm)
			continue;
		mmarray[n++] = mm;
	} while_each_thread(g, p);
	write_unlock_irq(&tasklist_lock);

	/*
	 * 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
	 * tasklist_lock.  Forks can happen again now - the mpol_copy()
	 * cpuset_being_rebound check will catch such forks, and rebind
	 * their vma mempolicies too.  Because we still hold the global
1019
	 * cpuset manage_mutex, we know that no other rebind effort will
1020 1021
	 * be contending for the global variable cpuset_being_rebound.
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1022
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1023
	 */
1024
	migrate = is_memory_migrate(cs);
1025 1026 1027 1028
	for (i = 0; i < n; i++) {
		struct mm_struct *mm = mmarray[i];

		mpol_rebind_mm(mm, &cs->mems_allowed);
1029 1030
		if (migrate)
			cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
1031 1032 1033 1034 1035 1036 1037
		mmput(mm);
	}

	/* We're done rebinding vma's to this cpusets new mems_allowed. */
	kfree(mmarray);
	set_cpuset_being_rebound(NULL);
	retval = 0;
1038
done:
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	return retval;
}

1042
/*
1043
 * Call with manage_mutex held.
1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054
 */

static int update_memory_pressure_enabled(struct cpuset *cs, char *buf)
{
	if (simple_strtoul(buf, NULL, 10) != 0)
		cpuset_memory_pressure_enabled = 1;
	else
		cpuset_memory_pressure_enabled = 0;
	return 0;
}

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/*
 * 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,
1058 1059
 *				CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE,
 *				CS_SPREAD_PAGE, CS_SPREAD_SLAB)
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 * cs:	the cpuset to update
 * buf:	the buffer where we read the 0 or 1
1062
 *
1063
 * Call with manage_mutex held.
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 */

static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
{
	int turning_on;
	struct cpuset trialcs;
1070
	int err, cpu_exclusive_changed;
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	turning_on = (simple_strtoul(buf, NULL, 10) != 0);

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

	err = validate_change(cs, &trialcs);
1081 1082 1083 1084
	if (err < 0)
		return err;
	cpu_exclusive_changed =
		(is_cpu_exclusive(cs) != is_cpu_exclusive(&trialcs));
1085
	mutex_lock(&callback_mutex);
1086
	cs->flags = trialcs.flags;
1087
	mutex_unlock(&callback_mutex);
1088 1089 1090 1091

	if (cpu_exclusive_changed)
                update_cpu_domains(cs);
	return 0;
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}

1094
/*
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Adrian Bunk 已提交
1095
 * Frequency meter - How fast is some event occurring?
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 1184 1185 1186 1187 1188 1189 1190 1191
 *
 * 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;
}

1192 1193 1194 1195 1196
/*
 * Attack task specified by pid in 'pidbuf' to cpuset 'cs', possibly
 * writing the path of the old cpuset in 'ppathbuf' if it needs to be
 * notified on release.
 *
1197
 * Call holding manage_mutex.  May take callback_mutex and task_lock of
1198 1199 1200
 * the task 'pid' during call.
 */

1201
static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
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{
	pid_t pid;
	struct task_struct *tsk;
	struct cpuset *oldcs;
	cpumask_t cpus;
1207
	nodemask_t from, to;
1208
	struct mm_struct *mm;
1209
	int retval;
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1211
	if (sscanf(pidbuf, "%d", &pid) != 1)
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		return -EIO;
	if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
		return -ENOSPC;

	if (pid) {
		read_lock(&tasklist_lock);

		tsk = find_task_by_pid(pid);
1220
		if (!tsk || tsk->flags & PF_EXITING) {
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			read_unlock(&tasklist_lock);
			return -ESRCH;
		}

		get_task_struct(tsk);
		read_unlock(&tasklist_lock);

		if ((current->euid) && (current->euid != tsk->uid)
		    && (current->euid != tsk->suid)) {
			put_task_struct(tsk);
			return -EACCES;
		}
	} else {
		tsk = current;
		get_task_struct(tsk);
	}

1238 1239 1240 1241 1242 1243
	retval = security_task_setscheduler(tsk, 0, NULL);
	if (retval) {
		put_task_struct(tsk);
		return retval;
	}

1244
	mutex_lock(&callback_mutex);
1245

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	task_lock(tsk);
	oldcs = tsk->cpuset;
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	/*
	 * After getting 'oldcs' cpuset ptr, be sure still not exiting.
	 * If 'oldcs' might be the top_cpuset due to the_top_cpuset_hack
	 * then fail this attach_task(), to avoid breaking top_cpuset.count.
	 */
	if (tsk->flags & PF_EXITING) {
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		task_unlock(tsk);
1255
		mutex_unlock(&callback_mutex);
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		put_task_struct(tsk);
		return -ESRCH;
	}
	atomic_inc(&cs->count);
1260
	rcu_assign_pointer(tsk->cpuset, cs);
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	task_unlock(tsk);

	guarantee_online_cpus(cs, &cpus);
	set_cpus_allowed(tsk, cpus);

1266 1267 1268
	from = oldcs->mems_allowed;
	to = cs->mems_allowed;

1269
	mutex_unlock(&callback_mutex);
1270 1271 1272 1273

	mm = get_task_mm(tsk);
	if (mm) {
		mpol_rebind_mm(mm, &to);
1274
		if (is_memory_migrate(cs))
1275
			cpuset_migrate_mm(mm, &from, &to);
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		mmput(mm);
	}

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	put_task_struct(tsk);
1280
	synchronize_rcu();
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	if (atomic_dec_and_test(&oldcs->count))
1282
		check_for_release(oldcs, ppathbuf);
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	return 0;
}

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

typedef enum {
	FILE_ROOT,
	FILE_DIR,
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	FILE_MEMORY_MIGRATE,
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	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
	FILE_NOTIFY_ON_RELEASE,
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	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
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	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
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	FILE_TASKLIST,
} cpuset_filetype_t;

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static ssize_t cpuset_common_file_write(struct file *file,
					const char __user *userbuf,
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					size_t nbytes, loff_t *unused_ppos)
{
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	struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent);
	struct cftype *cft = __d_cft(file->f_path.dentry);
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	cpuset_filetype_t type = cft->private;
	char *buffer;
1312
	char *pathbuf = NULL;
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	int retval = 0;

	/* Crude upper limit on largest legitimate cpulist user might write. */
1316
	if (nbytes > 100 + 6 * max(NR_CPUS, MAX_NUMNODES))
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		return -E2BIG;

	/* +1 for nul-terminator */
	if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
		return -ENOMEM;

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

1329
	mutex_lock(&manage_mutex);
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	if (is_removed(cs)) {
		retval = -ENODEV;
		goto out2;
	}

	switch (type) {
	case FILE_CPULIST:
		retval = update_cpumask(cs, buffer);
		break;
	case FILE_MEMLIST:
		retval = update_nodemask(cs, buffer);
		break;
	case FILE_CPU_EXCLUSIVE:
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, buffer);
		break;
	case FILE_MEM_EXCLUSIVE:
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, buffer);
		break;
	case FILE_NOTIFY_ON_RELEASE:
		retval = update_flag(CS_NOTIFY_ON_RELEASE, cs, buffer);
		break;
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	case FILE_MEMORY_MIGRATE:
		retval = update_flag(CS_MEMORY_MIGRATE, cs, buffer);
		break;
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	case FILE_MEMORY_PRESSURE_ENABLED:
		retval = update_memory_pressure_enabled(cs, buffer);
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
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	case FILE_SPREAD_PAGE:
		retval = update_flag(CS_SPREAD_PAGE, cs, buffer);
1363
		cs->mems_generation = cpuset_mems_generation++;
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		break;
	case FILE_SPREAD_SLAB:
		retval = update_flag(CS_SPREAD_SLAB, cs, buffer);
1367
		cs->mems_generation = cpuset_mems_generation++;
1368
		break;
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	case FILE_TASKLIST:
1370
		retval = attach_task(cs, buffer, &pathbuf);
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		break;
	default:
		retval = -EINVAL;
		goto out2;
	}

	if (retval == 0)
		retval = nbytes;
out2:
1380
	mutex_unlock(&manage_mutex);
1381
	cpuset_release_agent(pathbuf);
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out1:
	kfree(buffer);
	return retval;
}

static ssize_t cpuset_file_write(struct file *file, const char __user *buf,
						size_t nbytes, loff_t *ppos)
{
	ssize_t retval = 0;
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	struct cftype *cft = __d_cft(file->f_path.dentry);
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	if (!cft)
		return -ENODEV;

	/* special function ? */
	if (cft->write)
		retval = cft->write(file, buf, nbytes, ppos);
	else
		retval = cpuset_common_file_write(file, buf, nbytes, ppos);

	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;

1420
	mutex_lock(&callback_mutex);
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	mask = cs->cpus_allowed;
1422
	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;

1431
	mutex_lock(&callback_mutex);
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	mask = cs->mems_allowed;
1433
	mutex_unlock(&callback_mutex);
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	return nodelist_scnprintf(page, PAGE_SIZE, mask);
}

static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
				size_t nbytes, loff_t *ppos)
{
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	struct cftype *cft = __d_cft(file->f_path.dentry);
	struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent);
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	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

	if (!(page = (char *)__get_free_page(GFP_KERNEL)))
		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;
	case FILE_CPU_EXCLUSIVE:
		*s++ = is_cpu_exclusive(cs) ? '1' : '0';
		break;
	case FILE_MEM_EXCLUSIVE:
		*s++ = is_mem_exclusive(cs) ? '1' : '0';
		break;
	case FILE_NOTIFY_ON_RELEASE:
		*s++ = notify_on_release(cs) ? '1' : '0';
		break;
1469 1470 1471
	case FILE_MEMORY_MIGRATE:
		*s++ = is_memory_migrate(cs) ? '1' : '0';
		break;
1472 1473 1474 1475 1476 1477
	case FILE_MEMORY_PRESSURE_ENABLED:
		*s++ = cpuset_memory_pressure_enabled ? '1' : '0';
		break;
	case FILE_MEMORY_PRESSURE:
		s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter));
		break;
1478 1479 1480 1481 1482 1483
	case FILE_SPREAD_PAGE:
		*s++ = is_spread_page(cs) ? '1' : '0';
		break;
	case FILE_SPREAD_SLAB:
		*s++ = is_spread_slab(cs) ? '1' : '0';
		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;
}

static ssize_t cpuset_file_read(struct file *file, char __user *buf, size_t nbytes,
								loff_t *ppos)
{
	ssize_t retval = 0;
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	struct cftype *cft = __d_cft(file->f_path.dentry);
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	if (!cft)
		return -ENODEV;

	/* special function ? */
	if (cft->read)
		retval = cft->read(file, buf, nbytes, ppos);
	else
		retval = cpuset_common_file_read(file, buf, nbytes, ppos);

	return retval;
}

static int cpuset_file_open(struct inode *inode, struct file *file)
{
	int err;
	struct cftype *cft;

	err = generic_file_open(inode, file);
	if (err)
		return err;

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	cft = __d_cft(file->f_path.dentry);
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	if (!cft)
		return -ENODEV;
	if (cft->open)
		err = cft->open(inode, file);
	else
		err = 0;

	return err;
}

static int cpuset_file_release(struct inode *inode, struct file *file)
{
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	struct cftype *cft = __d_cft(file->f_path.dentry);
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	if (cft->release)
		return cft->release(inode, file);
	return 0;
}

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/*
 * cpuset_rename - Only allow simple rename of directories in place.
 */
static int cpuset_rename(struct inode *old_dir, struct dentry *old_dentry,
                  struct inode *new_dir, struct dentry *new_dentry)
{
	if (!S_ISDIR(old_dentry->d_inode->i_mode))
		return -ENOTDIR;
	if (new_dentry->d_inode)
		return -EEXIST;
	if (old_dir != new_dir)
		return -EIO;
	return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
}

1556
static const struct file_operations cpuset_file_operations = {
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	.read = cpuset_file_read,
	.write = cpuset_file_write,
	.llseek = generic_file_llseek,
	.open = cpuset_file_open,
	.release = cpuset_file_release,
};

1564
static const struct inode_operations cpuset_dir_inode_operations = {
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	.lookup = simple_lookup,
	.mkdir = cpuset_mkdir,
	.rmdir = cpuset_rmdir,
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	.rename = cpuset_rename,
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};

static int cpuset_create_file(struct dentry *dentry, int mode)
{
	struct inode *inode;

	if (!dentry)
		return -ENOENT;
	if (dentry->d_inode)
		return -EEXIST;

	inode = cpuset_new_inode(mode);
	if (!inode)
		return -ENOMEM;

	if (S_ISDIR(mode)) {
		inode->i_op = &cpuset_dir_inode_operations;
		inode->i_fop = &simple_dir_operations;

		/* start off with i_nlink == 2 (for "." entry) */
1589
		inc_nlink(inode);
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	} else if (S_ISREG(mode)) {
		inode->i_size = 0;
		inode->i_fop = &cpuset_file_operations;
	}

	d_instantiate(dentry, inode);
	dget(dentry);	/* Extra count - pin the dentry in core */
	return 0;
}

/*
 *	cpuset_create_dir - create a directory for an object.
1602
 *	cs:	the cpuset we create the directory for.
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 *		It must have a valid ->parent field
 *		And we are going to fill its ->dentry field.
 *	name:	The name to give to the cpuset directory. Will be copied.
 *	mode:	mode to set on new directory.
 */

static int cpuset_create_dir(struct cpuset *cs, const char *name, int mode)
{
	struct dentry *dentry = NULL;
	struct dentry *parent;
	int error = 0;

	parent = cs->parent->dentry;
	dentry = cpuset_get_dentry(parent, name);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	error = cpuset_create_file(dentry, S_IFDIR | mode);
	if (!error) {
		dentry->d_fsdata = cs;
1622
		inc_nlink(parent->d_inode);
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		cs->dentry = dentry;
	}
	dput(dentry);

	return error;
}

static int cpuset_add_file(struct dentry *dir, const struct cftype *cft)
{
	struct dentry *dentry;
	int error;

1635
	mutex_lock(&dir->d_inode->i_mutex);
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	dentry = cpuset_get_dentry(dir, cft->name);
	if (!IS_ERR(dentry)) {
		error = cpuset_create_file(dentry, 0644 | S_IFREG);
		if (!error)
			dentry->d_fsdata = (void *)cft;
		dput(dentry);
	} else
		error = PTR_ERR(dentry);
1644
	mutex_unlock(&dir->d_inode->i_mutex);
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	return error;
}

/*
 * Stuff for reading the 'tasks' file.
 *
 * Reading this file can return large amounts of data if a cpuset has
 * *lots* of attached tasks. So it may need several calls to read(),
 * but we cannot guarantee that the information we produce is correct
 * unless we produce it entirely atomically.
 *
 * Upon tasks file open(), a struct ctr_struct is allocated, that
 * will have a pointer to an array (also allocated here).  The struct
 * ctr_struct * is stored in file->private_data.  Its resources will
 * be freed by release() when the file is closed.  The array is used
 * to sprintf the PIDs and then used by read().
 */

/* cpusets_tasks_read array */

struct ctr_struct {
	char *buf;
	int bufsz;
};

/*
 * Load into 'pidarray' up to 'npids' of the tasks using cpuset 'cs'.
1672 1673 1674
 * Return actual number of pids loaded.  No need to task_lock(p)
 * when reading out p->cpuset, as we don't really care if it changes
 * on the next cycle, and we are not going to try to dereference it.
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 */
1676
static int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs)
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{
	int n = 0;
	struct task_struct *g, *p;

	read_lock(&tasklist_lock);

	do_each_thread(g, p) {
		if (p->cpuset == cs) {
			if (unlikely(n == npids))
				goto array_full;
1687
			pidarray[n++] = p->pid;
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1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715
		}
	} while_each_thread(g, p);

array_full:
	read_unlock(&tasklist_lock);
	return n;
}

static int cmppid(const void *a, const void *b)
{
	return *(pid_t *)a - *(pid_t *)b;
}

/*
 * Convert array 'a' of 'npids' pid_t's to a string of newline separated
 * decimal pids in 'buf'.  Don't write more than 'sz' chars, but return
 * count 'cnt' of how many chars would be written if buf were large enough.
 */
static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids)
{
	int cnt = 0;
	int i;

	for (i = 0; i < npids; i++)
		cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]);
	return cnt;
}

1716 1717 1718 1719
/*
 * Handle an open on 'tasks' file.  Prepare a buffer listing the
 * process id's of tasks currently attached to the cpuset being opened.
 *
1720
 * Does not require any specific cpuset mutexes, and does not take any.
1721
 */
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static int cpuset_tasks_open(struct inode *unused, struct file *file)
{
J
Josef Sipek 已提交
1724
	struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent);
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1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774
	struct ctr_struct *ctr;
	pid_t *pidarray;
	int npids;
	char c;

	if (!(file->f_mode & FMODE_READ))
		return 0;

	ctr = kmalloc(sizeof(*ctr), GFP_KERNEL);
	if (!ctr)
		goto err0;

	/*
	 * If cpuset gets more users after we read count, we won't have
	 * enough space - tough.  This race is indistinguishable to the
	 * caller from the case that the additional cpuset users didn't
	 * show up until sometime later on.
	 */
	npids = atomic_read(&cs->count);
	pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
	if (!pidarray)
		goto err1;

	npids = pid_array_load(pidarray, npids, cs);
	sort(pidarray, npids, sizeof(pid_t), cmppid, NULL);

	/* Call pid_array_to_buf() twice, first just to get bufsz */
	ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1;
	ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL);
	if (!ctr->buf)
		goto err2;
	ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids);

	kfree(pidarray);
	file->private_data = ctr;
	return 0;

err2:
	kfree(pidarray);
err1:
	kfree(ctr);
err0:
	return -ENOMEM;
}

static ssize_t cpuset_tasks_read(struct file *file, char __user *buf,
						size_t nbytes, loff_t *ppos)
{
	struct ctr_struct *ctr = file->private_data;

1775
	return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz);
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}

static int cpuset_tasks_release(struct inode *unused_inode, struct file *file)
{
	struct ctr_struct *ctr;

	if (file->f_mode & FMODE_READ) {
		ctr = file->private_data;
		kfree(ctr->buf);
		kfree(ctr);
	}
	return 0;
}

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

static struct cftype cft_tasks = {
	.name = "tasks",
	.open = cpuset_tasks_open,
	.read = cpuset_tasks_read,
	.release = cpuset_tasks_release,
	.private = FILE_TASKLIST,
};

static struct cftype cft_cpus = {
	.name = "cpus",
	.private = FILE_CPULIST,
};

static struct cftype cft_mems = {
	.name = "mems",
	.private = FILE_MEMLIST,
};

static struct cftype cft_cpu_exclusive = {
	.name = "cpu_exclusive",
	.private = FILE_CPU_EXCLUSIVE,
};

static struct cftype cft_mem_exclusive = {
	.name = "mem_exclusive",
	.private = FILE_MEM_EXCLUSIVE,
};

static struct cftype cft_notify_on_release = {
	.name = "notify_on_release",
	.private = FILE_NOTIFY_ON_RELEASE,
};

1827 1828 1829 1830 1831
static struct cftype cft_memory_migrate = {
	.name = "memory_migrate",
	.private = FILE_MEMORY_MIGRATE,
};

1832 1833 1834 1835 1836 1837 1838 1839 1840 1841
static struct cftype cft_memory_pressure_enabled = {
	.name = "memory_pressure_enabled",
	.private = FILE_MEMORY_PRESSURE_ENABLED,
};

static struct cftype cft_memory_pressure = {
	.name = "memory_pressure",
	.private = FILE_MEMORY_PRESSURE,
};

1842 1843 1844 1845 1846 1847 1848 1849 1850 1851
static struct cftype cft_spread_page = {
	.name = "memory_spread_page",
	.private = FILE_SPREAD_PAGE,
};

static struct cftype cft_spread_slab = {
	.name = "memory_spread_slab",
	.private = FILE_SPREAD_SLAB,
};

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static int cpuset_populate_dir(struct dentry *cs_dentry)
{
	int err;

	if ((err = cpuset_add_file(cs_dentry, &cft_cpus)) < 0)
		return err;
	if ((err = cpuset_add_file(cs_dentry, &cft_mems)) < 0)
		return err;
	if ((err = cpuset_add_file(cs_dentry, &cft_cpu_exclusive)) < 0)
		return err;
	if ((err = cpuset_add_file(cs_dentry, &cft_mem_exclusive)) < 0)
		return err;
	if ((err = cpuset_add_file(cs_dentry, &cft_notify_on_release)) < 0)
		return err;
1866 1867
	if ((err = cpuset_add_file(cs_dentry, &cft_memory_migrate)) < 0)
		return err;
1868 1869
	if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0)
		return err;
1870 1871 1872 1873
	if ((err = cpuset_add_file(cs_dentry, &cft_spread_page)) < 0)
		return err;
	if ((err = cpuset_add_file(cs_dentry, &cft_spread_slab)) < 0)
		return err;
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	if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0)
		return err;
	return 0;
}

/*
 *	cpuset_create - create a cpuset
 *	parent:	cpuset that will be parent of the new cpuset.
 *	name:		name of the new cpuset. Will be strcpy'ed.
 *	mode:		mode to set on new inode
 *
1885
 *	Must be called with the mutex on the parent inode held
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 */

static long cpuset_create(struct cpuset *parent, const char *name, int mode)
{
	struct cpuset *cs;
	int err;

	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
	if (!cs)
		return -ENOMEM;

1897
	mutex_lock(&manage_mutex);
1898
	cpuset_update_task_memory_state();
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Linus Torvalds 已提交
1899 1900 1901
	cs->flags = 0;
	if (notify_on_release(parent))
		set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
1902 1903 1904 1905
	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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Linus Torvalds 已提交
1906 1907 1908 1909 1910
	cs->cpus_allowed = CPU_MASK_NONE;
	cs->mems_allowed = NODE_MASK_NONE;
	atomic_set(&cs->count, 0);
	INIT_LIST_HEAD(&cs->sibling);
	INIT_LIST_HEAD(&cs->children);
1911
	cs->mems_generation = cpuset_mems_generation++;
1912
	fmeter_init(&cs->fmeter);
L
Linus Torvalds 已提交
1913 1914 1915

	cs->parent = parent;

1916
	mutex_lock(&callback_mutex);
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1917
	list_add(&cs->sibling, &cs->parent->children);
1918
	number_of_cpusets++;
1919
	mutex_unlock(&callback_mutex);
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	err = cpuset_create_dir(cs, name, mode);
	if (err < 0)
		goto err;

	/*
1926
	 * Release manage_mutex before cpuset_populate_dir() because it
1927
	 * will down() this new directory's i_mutex and if we race with
L
Linus Torvalds 已提交
1928 1929
	 * another mkdir, we might deadlock.
	 */
1930
	mutex_unlock(&manage_mutex);
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1931 1932 1933 1934 1935 1936

	err = cpuset_populate_dir(cs->dentry);
	/* If err < 0, we have a half-filled directory - oh well ;) */
	return 0;
err:
	list_del(&cs->sibling);
1937
	mutex_unlock(&manage_mutex);
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Linus Torvalds 已提交
1938 1939 1940 1941 1942 1943 1944 1945
	kfree(cs);
	return err;
}

static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	struct cpuset *c_parent = dentry->d_parent->d_fsdata;

1946
	/* the vfs holds inode->i_mutex already */
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Linus Torvalds 已提交
1947 1948 1949
	return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR);
}

1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960
/*
 * Locking note on the strange update_flag() call below:
 *
 * If the cpuset being removed is marked cpu_exclusive, then simulate
 * turning cpu_exclusive off, which will call update_cpu_domains().
 * The lock_cpu_hotplug() call in update_cpu_domains() must not be
 * made while holding callback_mutex.  Elsewhere the kernel nests
 * callback_mutex inside lock_cpu_hotplug() calls.  So the reverse
 * nesting would risk an ABBA deadlock.
 */

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1961 1962 1963 1964 1965
static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
{
	struct cpuset *cs = dentry->d_fsdata;
	struct dentry *d;
	struct cpuset *parent;
1966
	char *pathbuf = NULL;
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1967

1968
	/* the vfs holds both inode->i_mutex already */
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1969

1970
	mutex_lock(&manage_mutex);
1971
	cpuset_update_task_memory_state();
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1972
	if (atomic_read(&cs->count) > 0) {
1973
		mutex_unlock(&manage_mutex);
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		return -EBUSY;
	}
	if (!list_empty(&cs->children)) {
1977
		mutex_unlock(&manage_mutex);
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		return -EBUSY;
	}
1980 1981 1982 1983 1984 1985 1986
	if (is_cpu_exclusive(cs)) {
		int retval = update_flag(CS_CPU_EXCLUSIVE, cs, "0");
		if (retval < 0) {
			mutex_unlock(&manage_mutex);
			return retval;
		}
	}
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	parent = cs->parent;
1988
	mutex_lock(&callback_mutex);
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	set_bit(CS_REMOVED, &cs->flags);
	list_del(&cs->sibling);	/* delete my sibling from parent->children */
1991
	spin_lock(&cs->dentry->d_lock);
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	d = dget(cs->dentry);
	cs->dentry = NULL;
	spin_unlock(&d->d_lock);
	cpuset_d_remove_dir(d);
	dput(d);
1997
	number_of_cpusets--;
1998
	mutex_unlock(&callback_mutex);
1999 2000
	if (list_empty(&parent->children))
		check_for_release(parent, &pathbuf);
2001
	mutex_unlock(&manage_mutex);
2002
	cpuset_release_agent(pathbuf);
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	return 0;
}

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
/*
 * 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)
{
	struct task_struct *tsk = current;

	tsk->cpuset = &top_cpuset;
2017
	tsk->cpuset->mems_generation = cpuset_mems_generation++;
2018 2019 2020
	return 0;
}

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/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
	struct dentry *root;
	int err;

	top_cpuset.cpus_allowed = CPU_MASK_ALL;
	top_cpuset.mems_allowed = NODE_MASK_ALL;

2035
	fmeter_init(&top_cpuset.fmeter);
2036
	top_cpuset.mems_generation = cpuset_mems_generation++;
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	init_task.cpuset = &top_cpuset;

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
		goto out;
	cpuset_mount = kern_mount(&cpuset_fs_type);
	if (IS_ERR(cpuset_mount)) {
		printk(KERN_ERR "cpuset: could not mount!\n");
		err = PTR_ERR(cpuset_mount);
		cpuset_mount = NULL;
		goto out;
	}
	root = cpuset_mount->mnt_sb->s_root;
	root->d_fsdata = &top_cpuset;
2052
	inc_nlink(root->d_inode);
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Linus Torvalds 已提交
2053 2054
	top_cpuset.dentry = root;
	root->d_inode->i_op = &cpuset_dir_inode_operations;
2055
	number_of_cpusets = 1;
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Linus Torvalds 已提交
2056
	err = cpuset_populate_dir(root);
2057 2058 2059
	/* memory_pressure_enabled is in root cpuset only */
	if (err == 0)
		err = cpuset_add_file(root, &cft_memory_pressure_enabled);
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out:
	return err;
}

2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127
/*
 * 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
 * last CPU or node from a cpuset, then the guarantee_online_cpus()
 * or guarantee_online_mems() code will use that emptied cpusets
 * parent online CPUs or nodes.  Cpusets that were already empty of
 * CPUs or nodes are left empty.
 *
 * This routine is intentionally inefficient in a couple of regards.
 * It will check all cpusets in a subtree even if the top cpuset of
 * the subtree has no offline CPUs or nodes.  It checks both CPUs and
 * nodes, even though the caller could have been coded to know that
 * only one of CPUs or nodes needed to be checked on a given call.
 * This was done to minimize text size rather than cpu cycles.
 *
 * Call with both manage_mutex and callback_mutex held.
 *
 * Recursive, on depth of cpuset subtree.
 */

static void guarantee_online_cpus_mems_in_subtree(const struct cpuset *cur)
{
	struct cpuset *c;

	/* Each of our child cpusets mems must be online */
	list_for_each_entry(c, &cur->children, sibling) {
		guarantee_online_cpus_mems_in_subtree(c);
		if (!cpus_empty(c->cpus_allowed))
			guarantee_online_cpus(c, &c->cpus_allowed);
		if (!nodes_empty(c->mems_allowed))
			guarantee_online_mems(c, &c->mems_allowed);
	}
}

/*
 * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track
 * cpu_online_map and node_online_map.  Force the top cpuset to track
 * whats online after any CPU or memory node hotplug or unplug event.
 *
 * To ensure that we don't remove a CPU or node from the top cpuset
 * that is currently in use by a child cpuset (which would violate
 * the rule that cpusets must be subsets of their parent), we first
 * call the recursive routine guarantee_online_cpus_mems_in_subtree().
 *
 * 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)
{
	mutex_lock(&manage_mutex);
	mutex_lock(&callback_mutex);

	guarantee_online_cpus_mems_in_subtree(&top_cpuset);
	top_cpuset.cpus_allowed = cpu_online_map;
	top_cpuset.mems_allowed = node_online_map;

	mutex_unlock(&callback_mutex);
	mutex_unlock(&manage_mutex);
}

2128 2129 2130 2131 2132 2133
/*
 * 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.
 *
2134 2135
 * This routine ensures that top_cpuset.cpus_allowed tracks
 * cpu_online_map on each CPU hotplug (cpuhp) event.
2136 2137 2138 2139 2140
 */

static int cpuset_handle_cpuhp(struct notifier_block *nb,
				unsigned long phase, void *cpu)
{
2141
	common_cpu_mem_hotplug_unplug();
2142 2143 2144
	return 0;
}

2145
#ifdef CONFIG_MEMORY_HOTPLUG
2146 2147 2148 2149 2150 2151
/*
 * Keep top_cpuset.mems_allowed tracking node_online_map.
 * Call this routine anytime after you change node_online_map.
 * See also the previous routine cpuset_handle_cpuhp().
 */

A
Al Viro 已提交
2152
void cpuset_track_online_nodes(void)
2153
{
2154
	common_cpu_mem_hotplug_unplug();
2155 2156 2157
}
#endif

L
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2158 2159 2160 2161 2162 2163 2164 2165 2166 2167
/**
 * 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;
	top_cpuset.mems_allowed = node_online_map;
2168 2169

	hotcpu_notifier(cpuset_handle_cpuhp, 0);
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2170 2171 2172 2173
}

/**
 * cpuset_fork - attach newly forked task to its parents cpuset.
2174
 * @tsk: pointer to task_struct of forking parent process.
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2175
 *
2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187
 * Description: A task inherits its parent's cpuset at fork().
 *
 * A pointer to the shared cpuset was automatically copied in fork.c
 * by dup_task_struct().  However, we ignore that copy, since it was
 * not made under the protection of task_lock(), so might no longer be
 * a valid cpuset pointer.  attach_task() might have already changed
 * current->cpuset, allowing the previously referenced cpuset to
 * be removed and freed.  Instead, we task_lock(current) and copy
 * its present value of current->cpuset for our freshly forked child.
 *
 * At the point that cpuset_fork() is called, 'current' is the parent
 * task, and the passed argument 'child' points to the child task.
L
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 **/

2190
void cpuset_fork(struct task_struct *child)
L
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2191
{
2192 2193 2194 2195
	task_lock(current);
	child->cpuset = current->cpuset;
	atomic_inc(&child->cpuset->count);
	task_unlock(current);
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}

/**
 * cpuset_exit - detach cpuset from exiting task
 * @tsk: pointer to task_struct of exiting process
 *
 * Description: Detach cpuset from @tsk and release it.
 *
2204
 * Note that cpusets marked notify_on_release force every task in
2205
 * them to take the global manage_mutex mutex when exiting.
2206 2207 2208 2209 2210
 * This could impact scaling on very large systems.  Be reluctant to
 * use notify_on_release cpusets where very high task exit scaling
 * is required on large systems.
 *
 * Don't even think about derefencing 'cs' after the cpuset use count
2211 2212
 * goes to zero, except inside a critical section guarded by manage_mutex
 * or callback_mutex.   Otherwise a zero cpuset use count is a license to
2213 2214
 * any other task to nuke the cpuset immediately, via cpuset_rmdir().
 *
2215 2216 2217
 * This routine has to take manage_mutex, not callback_mutex, because
 * it is holding that mutex while calling check_for_release(),
 * which calls kmalloc(), so can't be called holding callback_mutex().
2218
 *
2219
 * the_top_cpuset_hack:
2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250
 *
 *    Set the exiting tasks cpuset to the root cpuset (top_cpuset).
 *
 *    Don't leave a task unable to allocate memory, as that is an
 *    accident waiting to happen should someone add a callout in
 *    do_exit() after the cpuset_exit() call that might allocate.
 *    If a task tries to allocate memory with an invalid cpuset,
 *    it will oops in cpuset_update_task_memory_state().
 *
 *    We call cpuset_exit() while the task is still competent to
 *    handle notify_on_release(), then leave the task attached to
 *    the root cpuset (top_cpuset) for the remainder of its exit.
 *
 *    To do this properly, we would increment the reference count on
 *    top_cpuset, and near the very end of the kernel/exit.c do_exit()
 *    code we would add a second cpuset function call, to drop that
 *    reference.  This would just create an unnecessary hot spot on
 *    the top_cpuset reference count, to no avail.
 *
 *    Normally, holding a reference to a cpuset without bumping its
 *    count is unsafe.   The cpuset could go away, or someone could
 *    attach us to a different cpuset, decrementing the count on
 *    the first cpuset that we never incremented.  But in this case,
 *    top_cpuset isn't going away, and either task has PF_EXITING set,
 *    which wards off any attach_task() attempts, or task is a failed
 *    fork, never visible to attach_task.
 *
 *    Another way to do this would be to set the cpuset pointer
 *    to NULL here, and check in cpuset_update_task_memory_state()
 *    for a NULL pointer.  This hack avoids that NULL check, for no
 *    cost (other than this way too long comment ;).
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2251 2252 2253 2254 2255 2256
 **/

void cpuset_exit(struct task_struct *tsk)
{
	struct cpuset *cs;

2257
	task_lock(current);
L
Linus Torvalds 已提交
2258
	cs = tsk->cpuset;
2259
	tsk->cpuset = &top_cpuset;	/* the_top_cpuset_hack - see above */
2260
	task_unlock(current);
L
Linus Torvalds 已提交
2261

2262
	if (notify_on_release(cs)) {
2263 2264
		char *pathbuf = NULL;

2265
		mutex_lock(&manage_mutex);
2266
		if (atomic_dec_and_test(&cs->count))
2267
			check_for_release(cs, &pathbuf);
2268
		mutex_unlock(&manage_mutex);
2269
		cpuset_release_agent(pathbuf);
2270 2271
	} else {
		atomic_dec(&cs->count);
L
Linus Torvalds 已提交
2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284
	}
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
 *
 * 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.
 **/

2285
cpumask_t cpuset_cpus_allowed(struct task_struct *tsk)
L
Linus Torvalds 已提交
2286 2287 2288
{
	cpumask_t mask;

2289
	mutex_lock(&callback_mutex);
2290
	task_lock(tsk);
L
Linus Torvalds 已提交
2291
	guarantee_online_cpus(tsk->cpuset, &mask);
2292
	task_unlock(tsk);
2293
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
2294 2295 2296 2297 2298 2299 2300 2301 2302

	return mask;
}

void cpuset_init_current_mems_allowed(void)
{
	current->mems_allowed = NODE_MASK_ALL;
}

2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316
/**
 * 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
 * subset of node_online_map, even if this means going outside the
 * tasks cpuset.
 **/

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

2317
	mutex_lock(&callback_mutex);
2318 2319 2320
	task_lock(tsk);
	guarantee_online_mems(tsk->cpuset, &mask);
	task_unlock(tsk);
2321
	mutex_unlock(&callback_mutex);
2322 2323 2324 2325

	return mask;
}

2326 2327 2328 2329
/**
 * cpuset_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed
 * @zl: the zonelist to be checked
 *
L
Linus Torvalds 已提交
2330 2331 2332 2333 2334 2335 2336
 * Are any of the nodes on zonelist zl allowed in current->mems_allowed?
 */
int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)
{
	int i;

	for (i = 0; zl->zones[i]; i++) {
2337
		int nid = zone_to_nid(zl->zones[i]);
L
Linus Torvalds 已提交
2338 2339 2340 2341 2342 2343 2344

		if (node_isset(nid, current->mems_allowed))
			return 1;
	}
	return 0;
}

2345 2346
/*
 * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
2347
 * ancestor to the specified cpuset.  Call holding callback_mutex.
2348 2349 2350 2351 2352 2353 2354 2355 2356 2357
 * 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;
}

2358
/**
2359
 * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node?
2360
 * @z: is this zone on an allowed node?
2361
 * @gfp_mask: memory allocation flags
2362
 *
2363 2364
 * If we're in interrupt, yes, we can always allocate.  If
 * __GFP_THISNODE is set, yes, we can always allocate.  If zone
2365 2366 2367
 * 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.
2368 2369
 * If the task has been OOM killed and has access to memory reserves
 * as specified by the TIF_MEMDIE flag, yes.
2370 2371
 * Otherwise, no.
 *
2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
 * 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'.
 *
2386
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2387 2388
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2389
 * GFP_KERNEL allocations are not so marked, so can escape to the
2390
 * nearest enclosing mem_exclusive ancestor cpuset.
2391
 *
2392 2393 2394 2395 2396 2397 2398
 * 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.
2399
 *
2400
 * The first call here from mm/page_alloc:get_page_from_freelist()
2401 2402 2403
 * 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).
2404 2405 2406 2407 2408 2409
 *
 * 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:
2410 2411
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2412
 *	TIF_MEMDIE   - any node ok
2413 2414
 *	GFP_KERNEL   - any node in enclosing mem_exclusive cpuset ok
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2415 2416
 *
 * Rule:
2417
 *    Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you
2418 2419
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2420
 */
2421

2422
int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2423
{
2424 2425
	int node;			/* node that zone z is on */
	const struct cpuset *cs;	/* current cpuset ancestors */
2426
	int allowed;			/* is allocation in zone z allowed? */
2427

2428
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2429
		return 1;
2430
	node = zone_to_nid(z);
2431
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2432 2433
	if (node_isset(node, current->mems_allowed))
		return 1;
2434 2435 2436 2437 2438 2439
	/*
	 * 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;
2440 2441 2442
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2443 2444 2445
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2446
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2447
	mutex_lock(&callback_mutex);
2448 2449 2450 2451 2452

	task_lock(current);
	cs = nearest_exclusive_ancestor(current->cpuset);
	task_unlock(current);

2453
	allowed = node_isset(node, cs->mems_allowed);
2454
	mutex_unlock(&callback_mutex);
2455
	return allowed;
L
Linus Torvalds 已提交
2456 2457
}

2458 2459 2460 2461 2462 2463 2464
/*
 * 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
2465 2466 2467
 * 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.
2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490
 *
 * 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;
2491 2492 2493 2494 2495 2496
        /*
         * 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;
2497 2498 2499
	return 0;
}

P
Paul Jackson 已提交
2500 2501 2502
/**
 * cpuset_lock - lock out any changes to cpuset structures
 *
2503
 * The out of memory (oom) code needs to mutex_lock cpusets
P
Paul Jackson 已提交
2504
 * from being changed while it scans the tasklist looking for a
2505
 * task in an overlapping cpuset.  Expose callback_mutex via this
P
Paul Jackson 已提交
2506 2507
 * cpuset_lock() routine, so the oom code can lock it, before
 * locking the task list.  The tasklist_lock is a spinlock, so
2508
 * must be taken inside callback_mutex.
P
Paul Jackson 已提交
2509 2510 2511 2512
 */

void cpuset_lock(void)
{
2513
	mutex_lock(&callback_mutex);
P
Paul Jackson 已提交
2514 2515 2516 2517 2518 2519 2520 2521 2522 2523
}

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

void cpuset_unlock(void)
{
2524
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
2525 2526
}

2527 2528 2529 2530 2531 2532 2533 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 2559 2560 2561 2562 2563 2564
/**
 * 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);

2565 2566 2567 2568 2569 2570 2571 2572 2573
/**
 * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors?
 * @p: pointer to task_struct of some other task.
 *
 * Description: Return true if the nearest mem_exclusive ancestor
 * cpusets of tasks @p and current overlap.  Used by oom killer to
 * determine if task @p's memory usage might impact the memory
 * available to the current task.
 *
2574
 * Call while holding callback_mutex.
2575 2576 2577 2578 2579
 **/

int cpuset_excl_nodes_overlap(const struct task_struct *p)
{
	const struct cpuset *cs1, *cs2;	/* my and p's cpuset ancestors */
N
Nick Piggin 已提交
2580
	int overlap = 1;		/* do cpusets overlap? */
2581

2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597
	task_lock(current);
	if (current->flags & PF_EXITING) {
		task_unlock(current);
		goto done;
	}
	cs1 = nearest_exclusive_ancestor(current->cpuset);
	task_unlock(current);

	task_lock((struct task_struct *)p);
	if (p->flags & PF_EXITING) {
		task_unlock((struct task_struct *)p);
		goto done;
	}
	cs2 = nearest_exclusive_ancestor(p->cpuset);
	task_unlock((struct task_struct *)p);

2598 2599 2600 2601 2602
	overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed);
done:
	return overlap;
}

2603 2604 2605 2606 2607 2608
/*
 * 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.
 */

2609
int cpuset_memory_pressure_enabled __read_mostly;
2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638

/**
 * 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)
{
	struct cpuset *cs;

	task_lock(current);
	cs = current->cpuset;
	fmeter_markevent(&cs->fmeter);
	task_unlock(current);
}

L
Linus Torvalds 已提交
2639 2640 2641 2642
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2643 2644
 *  - 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,
2645
 *    and we take manage_mutex, keeping attach_task() from changing it
2646 2647 2648
 *    anyway.  No need to check that tsk->cpuset != NULL, thanks to
 *    the_top_cpuset_hack in cpuset_exit(), which sets an exiting tasks
 *    cpuset to top_cpuset.
L
Linus Torvalds 已提交
2649 2650 2651
 */
static int proc_cpuset_show(struct seq_file *m, void *v)
{
2652
	struct pid *pid;
L
Linus Torvalds 已提交
2653 2654
	struct task_struct *tsk;
	char *buf;
2655
	int retval;
L
Linus Torvalds 已提交
2656

2657
	retval = -ENOMEM;
L
Linus Torvalds 已提交
2658 2659
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2660 2661 2662
		goto out;

	retval = -ESRCH;
2663 2664
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2665 2666
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2667

2668
	retval = -EINVAL;
2669
	mutex_lock(&manage_mutex);
2670

2671
	retval = cpuset_path(tsk->cpuset, buf, PAGE_SIZE);
L
Linus Torvalds 已提交
2672
	if (retval < 0)
2673
		goto out_unlock;
L
Linus Torvalds 已提交
2674 2675
	seq_puts(m, buf);
	seq_putc(m, '\n');
2676
out_unlock:
2677
	mutex_unlock(&manage_mutex);
2678 2679
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2680
	kfree(buf);
2681
out:
L
Linus Torvalds 已提交
2682 2683 2684 2685 2686
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2687 2688
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
L
Linus Torvalds 已提交
2689 2690
}

2691
const struct file_operations proc_cpuset_operations = {
L
Linus Torvalds 已提交
2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
char *cpuset_task_status_allowed(struct task_struct *task, char *buffer)
{
	buffer += sprintf(buffer, "Cpus_allowed:\t");
	buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed);
	buffer += sprintf(buffer, "\n");
	buffer += sprintf(buffer, "Mems_allowed:\t");
	buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed);
	buffer += sprintf(buffer, "\n");
	return buffer;
}