cpuset.c 52.9 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
/*
 *  kernel/cpuset.c
 *
 *  Processor and Memory placement constraints for sets of tasks.
 *
 *  Copyright (C) 2003 BULL SA.
 *  Copyright (C) 2004 Silicon Graphics, Inc.
 *
 *  Portions derived from Patrick Mochel's sysfs code.
 *  sysfs is Copyright (c) 2001-3 Patrick Mochel
 *  Portions Copyright (c) 2004 Silicon Graphics, Inc.
 *
 *  2003-10-10 Written by Simon Derr <simon.derr@bull.net>
 *  2003-10-22 Updates by Stephen Hemminger.
 *  2004 May-July Rework by Paul Jackson <pj@sgi.com>
 *
 *  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/config.h>
#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>
35
#include <linux/mempolicy.h>
Linus Torvalds's avatar
Linus Torvalds committed
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
#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>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/smp_lock.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>
#include <asm/semaphore.h>

#define CPUSET_SUPER_MAGIC 		0x27e0eb

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 */

64
65
66
	/*
	 * Count is atomic so can incr (fork) or decr (exit) without a lock.
	 */
Linus Torvalds's avatar
Linus Torvalds committed
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
	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.
	 */
	 int mems_generation;
};

/* bits in struct cpuset flags field */
typedef enum {
	CS_CPU_EXCLUSIVE,
	CS_MEM_EXCLUSIVE,
	CS_REMOVED,
	CS_NOTIFY_ON_RELEASE
} cpuset_flagbits_t;

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

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

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

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

/*
 * Increment this atomic integer everytime any cpuset changes its
 * 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.
 */
static atomic_t cpuset_mems_generation = ATOMIC_INIT(1);

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),
	.parent = NULL,
	.dentry = NULL,
	.mems_generation = 0,
};

static struct vfsmount *cpuset_mount;
static struct super_block *cpuset_sb = NULL;

/*
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
 * We have two global cpuset semaphores below.  They can nest.
 * It is ok to first take manage_sem, then nest callback_sem.  We also
 * require taking task_lock() when dereferencing a tasks cpuset pointer.
 * See "The task_lock() exception", at the end of this comment.
 *
 * A task must hold both semaphores to modify cpusets.  If a task
 * holds manage_sem, then it blocks others wanting that semaphore,
 * ensuring that it is the only task able to also acquire callback_sem
 * and be able to modify cpusets.  It can perform various checks on
 * the cpuset structure first, knowing nothing will change.  It can
 * also allocate memory while just holding manage_sem.  While it is
 * performing these checks, various callback routines can briefly
 * acquire callback_sem to query cpusets.  Once it is ready to make
 * the changes, it takes callback_sem, blocking everyone else.
 *
 * Calls to the kernel memory allocator can not be made while holding
 * callback_sem, as that would risk double tripping on callback_sem
 * from one of the callbacks into the cpuset code from within
 * __alloc_pages().
 *
 * If a task is only holding callback_sem, then it has read-only
 * 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.
 * So in general, code holding manage_sem or callback_sem can't rely
 * on the count field not changing.  However, if the count goes to
 * zero, then only attach_task(), which holds both semaphores, can
 * 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).
 * So code holding manage_sem or callback_sem can safely assume that
 * if the count is zero, it will stay zero.  Similarly, if a task
 * holds manage_sem or callback_sem on a cpuset with zero count, it
 * knows that the cpuset won't be removed, as cpuset_rmdir() needs
 * both of those semaphores.
 *
 * A possible optimization to improve parallelism would be to make
 * callback_sem a R/W semaphore (rwsem), allowing the callback routines
 * to proceed in parallel, with read access, until the holder of
 * manage_sem needed to take this rwsem for exclusive write access
 * and modify some cpusets.
 *
 * The cpuset_common_file_write handler for operations that modify
 * the cpuset hierarchy holds manage_sem across the entire operation,
 * single threading all such cpuset modifications across the system.
 *
 * The cpuset_common_file_read() handlers only hold callback_sem across
 * 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
 * (usually) take either semaphore.  These are the two most performance
 * critical pieces of code here.  The exception occurs on cpuset_exit(),
 * when a task in a notify_on_release cpuset exits.  Then manage_sem
206
 * is taken, and if the cpuset count is zero, a usermode call made
Linus Torvalds's avatar
Linus Torvalds committed
207
208
209
 * to /sbin/cpuset_release_agent with the name of the cpuset (path
 * relative to the root of cpuset file system) as the argument.
 *
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
 * 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
 * least one task in the system (init, pid == 1), therefore, top_cpuset
 * 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
 * so using both semaphores, however there are several performance
 * critical places that need to reference task->cpuset without the
 * expense of grabbing a system global semaphore.  Therefore except as
 * 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.
Linus Torvalds's avatar
Linus Torvalds committed
230
231
 */

232
233
static DECLARE_MUTEX(manage_sem);
static DECLARE_MUTEX(callback_sem);
234

Linus Torvalds's avatar
Linus Torvalds committed
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/*
 * 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_blksize = PAGE_CACHE_SIZE;
		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)
{
282
	struct dentry *d = lookup_one_len(name, parent, strlen(name));
Linus Torvalds's avatar
Linus Torvalds committed
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
	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) {
		struct dentry *d = list_entry(node, struct dentry, d_child);
		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;
	}
	list_del_init(&dentry->d_child);
	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) */
		inode->i_nlink++;
	} else {
		return -ENOMEM;
	}

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

static struct super_block *cpuset_get_sb(struct file_system_type *fs_type,
					int flags, const char *unused_dev_name,
					void *data)
{
	return get_sb_single(fs_type, flags, data, cpuset_fill_super);
}

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:
 *	- the cpuset to use in file->f_dentry->d_parent->d_fsdata
 *	- the 'cftype' of the file is file->f_dentry->d_fsdata
 */

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;
}

/*
408
 * Call with manage_sem held.  Writes path of cpuset into buf.
Linus Torvalds's avatar
Linus Torvalds committed
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
 * 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.
 *
452
453
454
455
456
457
458
459
 * 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.
 *
460
461
462
463
464
 * When we had only one cpuset semaphore, we had to call this
 * without holding it, to avoid deadlock when call_usermodehelper()
 * allocated memory.  With two locks, we could now call this while
 * holding manage_sem, but we still don't, so as to minimize
 * the time manage_sem is held.
Linus Torvalds's avatar
Linus Torvalds committed
465
466
 */

467
static void cpuset_release_agent(const char *pathbuf)
Linus Torvalds's avatar
Linus Torvalds committed
468
469
470
471
{
	char *argv[3], *envp[3];
	int i;

472
473
474
	if (!pathbuf)
		return;

Linus Torvalds's avatar
Linus Torvalds committed
475
476
	i = 0;
	argv[i++] = "/sbin/cpuset_release_agent";
477
	argv[i++] = (char *)pathbuf;
Linus Torvalds's avatar
Linus Torvalds committed
478
479
480
481
482
483
484
485
	argv[i] = NULL;

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

486
487
	call_usermodehelper(argv[0], argv, envp, 0);
	kfree(pathbuf);
Linus Torvalds's avatar
Linus Torvalds committed
488
489
490
491
492
493
}

/*
 * 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
494
495
 * 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
496
497
 * cpuset_release_agent() with it later on, once manage_sem is dropped.
 * Call here with manage_sem held.
498
499
500
501
502
 *
 * 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
503
504
 * calling check_for_release() with manage_sem held and the address
 * of the pathbuf pointer, then dropping manage_sem, then calling
505
 * cpuset_release_agent() with pathbuf, as set by check_for_release().
Linus Torvalds's avatar
Linus Torvalds committed
506
507
 */

508
static void check_for_release(struct cpuset *cs, char **ppathbuf)
Linus Torvalds's avatar
Linus Torvalds committed
509
510
511
512
513
514
515
516
517
{
	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)
518
519
520
			kfree(buf);
		else
			*ppathbuf = buf;
Linus Torvalds's avatar
Linus Torvalds committed
521
522
523
524
525
526
527
528
529
530
531
532
533
534
	}
}

/*
 * 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.
 *
535
 * Call with callback_sem held.
Linus Torvalds's avatar
Linus Torvalds committed
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
 */

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.
 *
559
 * Call with callback_sem held.
Linus Torvalds's avatar
Linus Torvalds committed
560
561
562
563
564
565
566
567
568
569
570
571
572
573
 */

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));
}

/*
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
 * Refresh current tasks mems_allowed and mems_generation from current
 * tasks cpuset.
 *
 * Call without callback_sem or task_lock() held.  May be called with
 * or without manage_sem held.  Will acquire task_lock() and might
 * acquire callback_sem during call.
 *
 * The task_lock() is required to dereference current->cpuset safely.
 * Without it, we could pick up the pointer value of current->cpuset
 * in one instruction, and then attach_task could give us a different
 * cpuset, and then the cpuset we had could be removed and freed,
 * and then on our next instruction, we could dereference a no longer
 * valid cpuset pointer to get its mems_generation field.
 *
 * 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.
Linus Torvalds's avatar
Linus Torvalds committed
592
593
594
595
 */

static void refresh_mems(void)
{
596
597
598
599
600
	int my_cpusets_mem_gen;

	task_lock(current);
	my_cpusets_mem_gen = current->cpuset->mems_generation;
	task_unlock(current);
Linus Torvalds's avatar
Linus Torvalds committed
601

602
603
	if (current->cpuset_mems_generation != my_cpusets_mem_gen) {
		struct cpuset *cs;
604
		nodemask_t oldmem = current->mems_allowed;
605
606
607
608

		down(&callback_sem);
		task_lock(current);
		cs = current->cpuset;
Linus Torvalds's avatar
Linus Torvalds committed
609
610
		guarantee_online_mems(cs, &current->mems_allowed);
		current->cpuset_mems_generation = cs->mems_generation;
611
612
		task_unlock(current);
		up(&callback_sem);
613
614
		if (!nodes_equal(oldmem, current->mems_allowed))
			numa_policy_rebind(&oldmem, &current->mems_allowed);
Linus Torvalds's avatar
Linus Torvalds committed
615
616
617
618
619
620
621
622
	}
}

/*
 * 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
623
 * are only set if the other's are set.  Call holding manage_sem.
Linus Torvalds's avatar
Linus Torvalds committed
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
 */

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
641
 * manage_sem held.
Linus Torvalds's avatar
Linus Torvalds committed
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
 *
 * '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 */
	if ((par = cur->parent) == NULL)
		return 0;

	/* 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;
}

687
688
689
690
691
692
693
694
/*
 * 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
 *
695
 * Call with manage_sem held.  May nest a call to the
696
697
 * lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
 */
698

699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
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);
	}
	if (is_removed(cur) || !is_cpu_exclusive(cur)) {
		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();
}

740
741
742
743
/*
 * Call with manage_sem held.  May take callback_sem during call.
 */

Linus Torvalds's avatar
Linus Torvalds committed
744
745
746
static int update_cpumask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
747
	int retval, cpus_unchanged;
Linus Torvalds's avatar
Linus Torvalds committed
748
749
750
751
752
753
754
755
756

	trialcs = *cs;
	retval = cpulist_parse(buf, trialcs.cpus_allowed);
	if (retval < 0)
		return retval;
	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
	if (cpus_empty(trialcs.cpus_allowed))
		return -ENOSPC;
	retval = validate_change(cs, &trialcs);
757
758
759
	if (retval < 0)
		return retval;
	cpus_unchanged = cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed);
760
	down(&callback_sem);
761
	cs->cpus_allowed = trialcs.cpus_allowed;
762
	up(&callback_sem);
763
764
765
	if (is_cpu_exclusive(cs) && !cpus_unchanged)
		update_cpu_domains(cs);
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
766
767
}

768
769
770
771
/*
 * Call with manage_sem held.  May take callback_sem during call.
 */

Linus Torvalds's avatar
Linus Torvalds committed
772
773
774
775
776
777
778
779
780
781
782
783
784
785
static int update_nodemask(struct cpuset *cs, char *buf)
{
	struct cpuset trialcs;
	int retval;

	trialcs = *cs;
	retval = nodelist_parse(buf, trialcs.mems_allowed);
	if (retval < 0)
		return retval;
	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
	if (nodes_empty(trialcs.mems_allowed))
		return -ENOSPC;
	retval = validate_change(cs, &trialcs);
	if (retval == 0) {
786
		down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
787
788
789
		cs->mems_allowed = trialcs.mems_allowed;
		atomic_inc(&cpuset_mems_generation);
		cs->mems_generation = atomic_read(&cpuset_mems_generation);
790
		up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
791
792
793
794
795
796
797
798
799
800
	}
	return retval;
}

/*
 * 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,
 *						CS_NOTIFY_ON_RELEASE)
 * cs:	the cpuset to update
 * buf:	the buffer where we read the 0 or 1
801
802
 *
 * Call with manage_sem held.
Linus Torvalds's avatar
Linus Torvalds committed
803
804
805
806
807
808
 */

static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
{
	int turning_on;
	struct cpuset trialcs;
809
	int err, cpu_exclusive_changed;
Linus Torvalds's avatar
Linus Torvalds committed
810
811
812
813
814
815
816
817
818
819

	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);
820
821
822
823
	if (err < 0)
		return err;
	cpu_exclusive_changed =
		(is_cpu_exclusive(cs) != is_cpu_exclusive(&trialcs));
824
	down(&callback_sem);
825
826
827
828
	if (turning_on)
		set_bit(bit, &cs->flags);
	else
		clear_bit(bit, &cs->flags);
829
	up(&callback_sem);
830
831
832
833

	if (cpu_exclusive_changed)
                update_cpu_domains(cs);
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
834
835
}

836
837
838
839
840
841
842
843
844
/*
 * 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.
 *
 * Call holding manage_sem.  May take callback_sem and task_lock of
 * the task 'pid' during call.
 */

845
static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
Linus Torvalds's avatar
Linus Torvalds committed
846
847
848
849
850
851
{
	pid_t pid;
	struct task_struct *tsk;
	struct cpuset *oldcs;
	cpumask_t cpus;

852
	if (sscanf(pidbuf, "%d", &pid) != 1)
Linus Torvalds's avatar
Linus Torvalds committed
853
854
855
856
857
858
859
860
		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);
861
		if (!tsk || tsk->flags & PF_EXITING) {
Linus Torvalds's avatar
Linus Torvalds committed
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
			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);
	}

879
880
	down(&callback_sem);

Linus Torvalds's avatar
Linus Torvalds committed
881
882
883
884
	task_lock(tsk);
	oldcs = tsk->cpuset;
	if (!oldcs) {
		task_unlock(tsk);
885
		up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
886
887
888
889
890
891
892
893
894
895
		put_task_struct(tsk);
		return -ESRCH;
	}
	atomic_inc(&cs->count);
	tsk->cpuset = cs;
	task_unlock(tsk);

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

896
	up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
897
898
	put_task_struct(tsk);
	if (atomic_dec_and_test(&oldcs->count))
899
		check_for_release(oldcs, ppathbuf);
Linus Torvalds's avatar
Linus Torvalds committed
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
	return 0;
}

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

typedef enum {
	FILE_ROOT,
	FILE_DIR,
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
	FILE_NOTIFY_ON_RELEASE,
	FILE_TASKLIST,
} cpuset_filetype_t;

static ssize_t cpuset_common_file_write(struct file *file, const char __user *userbuf,
					size_t nbytes, loff_t *unused_ppos)
{
	struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
	struct cftype *cft = __d_cft(file->f_dentry);
	cpuset_filetype_t type = cft->private;
	char *buffer;
923
	char *pathbuf = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
	int retval = 0;

	/* Crude upper limit on largest legitimate cpulist user might write. */
	if (nbytes > 100 + 6 * NR_CPUS)
		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 */

940
	down(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963

	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;
	case FILE_TASKLIST:
964
		retval = attach_task(cs, buffer, &pathbuf);
Linus Torvalds's avatar
Linus Torvalds committed
965
966
967
968
969
970
971
972
973
		break;
	default:
		retval = -EINVAL;
		goto out2;
	}

	if (retval == 0)
		retval = nbytes;
out2:
974
	up(&manage_sem);
975
	cpuset_release_agent(pathbuf);
Linus Torvalds's avatar
Linus Torvalds committed
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
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;
	struct cftype *cft = __d_cft(file->f_dentry);
	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;

1014
	down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1015
	mask = cs->cpus_allowed;
1016
	up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1017
1018
1019
1020
1021
1022
1023
1024

	return cpulist_scnprintf(page, PAGE_SIZE, mask);
}

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

1025
	down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1026
	mask = cs->mems_allowed;
1027
	up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068

	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)
{
	struct cftype *cft = __d_cft(file->f_dentry);
	struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
	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;
	default:
		retval = -EINVAL;
		goto out;
	}
	*s++ = '\n';

Al Viro's avatar
Al Viro committed
1069
	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
Linus Torvalds's avatar
Linus Torvalds committed
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
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;
	struct cftype *cft = __d_cft(file->f_dentry);
	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;

	cft = __d_cft(file->f_dentry);
	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)
{
	struct cftype *cft = __d_cft(file->f_dentry);
	if (cft->release)
		return cft->release(inode, file);
	return 0;
}

Paul Jackson's avatar
Paul Jackson committed
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
/*
 * 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);
}

Linus Torvalds's avatar
Linus Torvalds committed
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
static struct file_operations cpuset_file_operations = {
	.read = cpuset_file_read,
	.write = cpuset_file_write,
	.llseek = generic_file_llseek,
	.open = cpuset_file_open,
	.release = cpuset_file_release,
};

static struct inode_operations cpuset_dir_inode_operations = {
	.lookup = simple_lookup,
	.mkdir = cpuset_mkdir,
	.rmdir = cpuset_rmdir,
Paul Jackson's avatar
Paul Jackson committed
1147
	.rename = cpuset_rename,
Linus Torvalds's avatar
Linus Torvalds committed
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
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
};

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) */
		inode->i_nlink++;
	} 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.
 *	cs: 	the cpuset we create the directory for.
 *		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;
		parent->d_inode->i_nlink++;
		cs->dentry = dentry;
	}
	dput(dentry);

	return error;
}

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

	down(&dir->d_inode->i_sem);
	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);
	up(&dir->d_inode->i_sem);
	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'.
1251
1252
1253
 * 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.
Linus Torvalds's avatar
Linus Torvalds committed
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
 */
static inline int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs)
{
	int n = 0;
	struct task_struct *g, *p;

	read_lock(&tasklist_lock);

	do_each_thread(g, p) {
		if (p->cpuset == cs) {
			pidarray[n++] = p->pid;
			if (unlikely(n == npids))
				goto array_full;
		}
	} 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;
}

1295
1296
1297
1298
1299
1300
/*
 * Handle an open on 'tasks' file.  Prepare a buffer listing the
 * process id's of tasks currently attached to the cpuset being opened.
 *
 * Does not require any specific cpuset semaphores, and does not take any.
 */
Linus Torvalds's avatar
Linus Torvalds committed
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
static int cpuset_tasks_open(struct inode *unused, struct file *file)
{
	struct cpuset *cs = __d_cs(file->f_dentry->d_parent);
	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;

	if (*ppos + nbytes > ctr->bufsz)
		nbytes = ctr->bufsz - *ppos;
	if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
		return -EFAULT;
	*ppos += nbytes;
	return nbytes;
}

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,
};

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;
	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
 *
 *	Must be called with the semaphore on the parent inode held
 */

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;

1448
	down(&manage_sem);
1449
	refresh_mems();
Linus Torvalds's avatar
Linus Torvalds committed
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
	cs->flags = 0;
	if (notify_on_release(parent))
		set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
	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);
	atomic_inc(&cpuset_mems_generation);
	cs->mems_generation = atomic_read(&cpuset_mems_generation);

	cs->parent = parent;

1463
	down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1464
	list_add(&cs->sibling, &cs->parent->children);
1465
	up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1466
1467
1468
1469
1470
1471

	err = cpuset_create_dir(cs, name, mode);
	if (err < 0)
		goto err;

	/*
1472
	 * Release manage_sem before cpuset_populate_dir() because it
Linus Torvalds's avatar
Linus Torvalds committed
1473
1474
1475
	 * will down() this new directory's i_sem and if we race with
	 * another mkdir, we might deadlock.
	 */
1476
	up(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1477
1478
1479
1480
1481
1482

	err = cpuset_populate_dir(cs->dentry);
	/* If err < 0, we have a half-filled directory - oh well ;) */
	return 0;
err:
	list_del(&cs->sibling);
1483
	up(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
	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;

	/* the vfs holds inode->i_sem already */
	return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR);
}

static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
{
	struct cpuset *cs = dentry->d_fsdata;
	struct dentry *d;
	struct cpuset *parent;
1501
	char *pathbuf = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
1502
1503
1504

	/* the vfs holds both inode->i_sem already */

1505
	down(&manage_sem);
1506
	refresh_mems();
Linus Torvalds's avatar
Linus Torvalds committed
1507
	if (atomic_read(&cs->count) > 0) {
1508
		up(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1509
1510
1511
		return -EBUSY;
	}
	if (!list_empty(&cs->children)) {
1512
		up(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1513
1514
1515
		return -EBUSY;
	}
	parent = cs->parent;
1516
	down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1517
	set_bit(CS_REMOVED, &cs->flags);
1518
1519
	if (is_cpu_exclusive(cs))
		update_cpu_domains(cs);
Linus Torvalds's avatar
Linus Torvalds committed
1520
	list_del(&cs->sibling);	/* delete my sibling from parent->children */
1521
	spin_lock(&cs->dentry->d_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1522
1523
1524
1525
1526
	d = dget(cs->dentry);
	cs->dentry = NULL;
	spin_unlock(&d->d_lock);
	cpuset_d_remove_dir(d);
	dput(d);
1527
1528
1529
1530
	up(&callback_sem);
	if (list_empty(&parent->children))
		check_for_release(parent, &pathbuf);
	up(&manage_sem);
1531
	cpuset_release_agent(pathbuf);
Linus Torvalds's avatar
Linus Torvalds committed
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
	return 0;
}

/**
 * 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;

	atomic_inc(&cpuset_mems_generation);
	top_cpuset.mems_generation = atomic_read(&cpuset_mems_generation);

	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;
	root->d_inode->i_nlink++;
	top_cpuset.dentry = root;
	root->d_inode->i_op = &cpuset_dir_inode_operations;
	err = cpuset_populate_dir(root);
out:
	return err;
}

/**
 * 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;
}

/**
 * cpuset_fork - attach newly forked task to its parents cpuset.
1588
 * @tsk: pointer to task_struct of forking parent process.
Linus Torvalds's avatar
Linus Torvalds committed
1589
 *
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
 * 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.
Linus Torvalds's avatar
Linus Torvalds committed
1602
1603
 **/

1604
void cpuset_fork(struct task_struct *child)
Linus Torvalds's avatar
Linus Torvalds committed
1605
{
1606
1607
1608
1609
	task_lock(current);
	child->cpuset = current->cpuset;
	atomic_inc(&child->cpuset->count);
	task_unlock(current);
Linus Torvalds's avatar
Linus Torvalds committed
1610
1611
1612
1613
1614
1615
1616
1617
}

/**
 * cpuset_exit - detach cpuset from exiting task
 * @tsk: pointer to task_struct of exiting process
 *
 * Description: Detach cpuset from @tsk and release it.
 *
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
 * Note that cpusets marked notify_on_release force every task in
 * them to take the global manage_sem semaphore when exiting.
 * 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
 * goes to zero, except inside a critical section guarded by manage_sem
 * or callback_sem.   Otherwise a zero cpuset use count is a license to
 * any other task to nuke the cpuset immediately, via cpuset_rmdir().
 *
 * This routine has to take manage_sem, not callback_sem, because
 * it is holding that semaphore while calling check_for_release(),
 * which calls kmalloc(), so can't be called holding callback__sem().
 *
 * We don't need to task_lock() this reference to tsk->cpuset,
 * because tsk is already marked PF_EXITING, so attach_task() won't
 * mess with it.
Linus Torvalds's avatar
Linus Torvalds committed
1636
1637
1638
1639
1640
1641
 **/

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

1642
1643
	BUG_ON(!(tsk->flags & PF_EXITING));

Linus Torvalds's avatar
Linus Torvalds committed
1644
1645
1646
	cs = tsk->cpuset;
	tsk->cpuset = NULL;

1647
	if (notify_on_release(cs)) {
1648
1649
		char *pathbuf = NULL;

1650
		down(&manage_sem);
1651
		if (atomic_dec_and_test(&cs->count))
1652
			check_for_release(cs, &pathbuf);
1653
		up(&manage_sem);
1654
		cpuset_release_agent(pathbuf);
1655
1656
	} else {
		atomic_dec(&cs->count);
Linus Torvalds's avatar
Linus Torvalds committed
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
	}
}

/**
 * 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.
 **/

1670
cpumask_t cpuset_cpus_allowed(const struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
1671
1672
1673
{
	cpumask_t mask;

1674
	down(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1675
1676
1677
	task_lock((struct task_struct *)tsk);
	guarantee_online_cpus(tsk->cpuset, &mask);
	task_unlock((struct task_struct *)tsk);
1678
	up(&callback_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1679
1680
1681
1682
1683
1684
1685
1686
1687

	return mask;
}

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

1688
1689
1690
/**
 * cpuset_update_current_mems_allowed - update mems parameters to new values
 *
Linus Torvalds's avatar
Linus Torvalds committed
1691
1692
1693
 * If the current tasks cpusets mems_allowed changed behind our backs,
 * update current->mems_allowed and mems_generation to the new value.
 * Do not call this routine if in_interrupt().
1694
1695
1696
1697
1698
 *
 * Call without callback_sem or task_lock() held.  May be called
 * with or without manage_sem held.  Unless exiting, it will acquire
 * task_lock().  Also might acquire callback_sem during call to
 * refresh_mems().
Linus Torvalds's avatar
Linus Torvalds committed
1699
1700
1701
1702
 */

void cpuset_update_current_mems_allowed(void)
{
1703
1704
	struct cpuset *cs;
	int need_to_refresh = 0;
Linus Torvalds's avatar
Linus Torvalds committed
1705

1706
1707
	task_lock(current);
	cs = current->cpuset;
Linus Torvalds's avatar
Linus Torvalds committed
1708
	if (!cs)
1709
1710
1711
1712
1713
1714
		goto done;
	if (current->cpuset_mems_generation != cs->mems_generation)
		need_to_refresh = 1;
done:
	task_unlock(current);
	if (need_to_refresh)
Linus Torvalds's avatar
Linus Torvalds committed
1715
1716
1717
		refresh_mems();
}

1718
1719
1720
1721
/**
 * cpuset_restrict_to_mems_allowed - limit nodes to current mems_allowed
 * @nodes: pointer to a node bitmap that is and-ed with mems_allowed
 */
Linus Torvalds's avatar
Linus Torvalds committed
1722
1723
1724
1725
1726
1727
void cpuset_restrict_to_mems_allowed(unsigned long *nodes)
{
	bitmap_and(nodes, nodes, nodes_addr(current->mems_allowed),
							MAX_NUMNODES);
}

1728
1729
1730
1731
/**
 * cpuset_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed
 * @zl: the zonelist to be checked
 *
Linus Torvalds's avatar
Linus Torvalds committed
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
 * 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++) {
		int nid = zl->zones[i]->zone_pgdat->node_id;

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

1747
1748
/*
 * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
1749
 * ancestor to the specified cpuset.  Call holding callback_sem.
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
 * 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;
}

1760
/**
1761
1762
1763
 * cpuset_zone_allowed - Can we allocate memory on zone z's memory node?
 * @z: is this zone on an allowed node?
 * @gfp_mask: memory allocation flags (we use __GFP_HARDWALL)
1764
 *
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
 * If we're in interrupt, yes, we can always allocate.  If zone
 * 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.
 * Otherwise, no.
 *
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
 * and do not allow allocations outside the current tasks cpuset.
 * GFP_KERNEL allocations are not so marked, so can escape to the
 * nearest mem_exclusive ancestor cpuset.
 *
1776
 * Scanning up parent cpusets requires callback_sem.  The __alloc_pages()
1777
1778
1779
1780
 * 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
1781
 * short of memory, might require taking the callback_sem semaphore.
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
 *
 * The first loop over the zonelist in mm/page_alloc.c:__alloc_pages()
 * calls here with __GFP_HARDWALL always set in gfp_mask, enforcing
 * hardwall cpusets - no allocation on a node outside the cpuset is
 * allowed (unless in interrupt, of course).
 *
 * The second loop doesn't even call here for GFP_ATOMIC requests
 * (if the __alloc_pages() local variable 'wait' is set).  That check
 * and the checks below have the combined affect in the second loop of
 * the __alloc_pages() routine that:
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
 *	GFP_KERNEL   - any node in enclosing mem_exclusive cpuset ok
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
 **/

1798
int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
1799
{
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
	int node;			/* node that zone z is on */
	const struct cpuset *cs;	/* current cpuset ancestors */
	int allowed = 1;		/* is allocation in zone z allowed? */

	if (in_interrupt())
		return 1;
	node = z->zone_pgdat->node_id;
	if (node_isset(node, current->mems_allowed))
		return 1;
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

1812
1813
1814
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

1815
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
1816
1817
1818
1819
1820
1821
	down(&callback_sem);

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

1822
	allowed = node_isset(node, cs->mems_allowed);
1823
	up(&callback_sem);
1824
	return allowed;
Linus Torvalds's avatar
Linus Torvalds committed
1825
1826
}

1827
1828
1829
1830
1831
1832
1833
1834
1835
/**
 * 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.
 *
1836
 * Acquires callback_sem - not suitable for calling from a fast path.
1837
1838
1839
1840
1841
1842
1843
 **/

int cpuset_excl_nodes_overlap(const struct task_struct *p)
{
	const struct cpuset *cs1, *cs2;	/* my and p's cpuset ancestors */
	int overlap = 0;		/* do cpusets overlap? */

1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
	down(&callback_sem);

	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);

1862
1863
	overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed);
done:
1864
	up(&callback_sem);
1865
1866
1867
1868

	return overlap;
}

Linus Torvalds's avatar
Linus Torvalds committed
1869
1870
1871
1872
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
1873
1874
1875
1876
 *  - 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,
 *    and we take manage_sem, keeping attach_task() from changing it
 *    anyway.
Linus Torvalds's avatar
Linus Torvalds committed
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
 */

static int proc_cpuset_show(struct seq_file *m, void *v)
{
	struct cpuset *cs;
	struct task_struct *tsk;
	char *buf;
	int retval = 0;

	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	tsk = m->private;
1891
	down(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
	cs = tsk->cpuset;
	if (!cs) {
		retval = -EINVAL;
		goto out;
	}

	retval = cpuset_path(cs, buf, PAGE_SIZE);
	if (retval < 0)
		goto out;
	seq_puts(m, buf);
	seq_putc(m, '\n');
out:
1904
	up(&manage_sem);
Linus Torvalds's avatar
Linus Torvalds committed
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
	kfree(buf);
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
	struct task_struct *tsk = PROC_I(inode)->task;
	return single_open(file, proc_cpuset_show, tsk);
}

struct file_operations proc_cpuset_operations = {
	.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;
}