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1/*
2 * kernel/cpuset.c
3 *
4 * Processor and Memory placement constraints for sets of tasks.
5 *
6 * Copyright (C) 2003 BULL SA.
7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8 * Copyright (C) 2006 Google, Inc
9 *
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
12 *
13 * 2003-10-10 Written by Simon Derr.
14 * 2003-10-22 Updates by Stephen Hemminger.
15 * 2004 May-July Rework by Paul Jackson.
16 * 2006 Rework by Paul Menage to use generic cgroups
17 * 2008 Rework of the scheduler domains and CPU hotplug handling
18 * by Max Krasnyansky
19 *
20 * This file is subject to the terms and conditions of the GNU General Public
21 * License. See the file COPYING in the main directory of the Linux
22 * distribution for more details.
23 */
24
25#include <linux/cpu.h>
26#include <linux/cpumask.h>
27#include <linux/cpuset.h>
28#include <linux/err.h>
29#include <linux/errno.h>
30#include <linux/file.h>
31#include <linux/fs.h>
32#include <linux/init.h>
33#include <linux/interrupt.h>
34#include <linux/kernel.h>
35#include <linux/kmod.h>
36#include <linux/list.h>
37#include <linux/mempolicy.h>
38#include <linux/mm.h>
39#include <linux/memory.h>
40#include <linux/export.h>
41#include <linux/mount.h>
42#include <linux/namei.h>
43#include <linux/pagemap.h>
44#include <linux/proc_fs.h>
45#include <linux/rcupdate.h>
46#include <linux/sched.h>
47#include <linux/seq_file.h>
48#include <linux/security.h>
49#include <linux/slab.h>
50#include <linux/spinlock.h>
51#include <linux/stat.h>
52#include <linux/string.h>
53#include <linux/time.h>
54#include <linux/backing-dev.h>
55#include <linux/sort.h>
56
57#include <asm/uaccess.h>
58#include <linux/atomic.h>
59#include <linux/mutex.h>
60#include <linux/workqueue.h>
61#include <linux/cgroup.h>
62
63/*
64 * Workqueue for cpuset related tasks.
65 *
66 * Using kevent workqueue may cause deadlock when memory_migrate
67 * is set. So we create a separate workqueue thread for cpuset.
68 */
69static struct workqueue_struct *cpuset_wq;
70
71/*
72 * Tracks how many cpusets are currently defined in system.
73 * When there is only one cpuset (the root cpuset) we can
74 * short circuit some hooks.
75 */
76int number_of_cpusets __read_mostly;
77
78/* Forward declare cgroup structures */
79struct cgroup_subsys cpuset_subsys;
80struct cpuset;
81
82/* See "Frequency meter" comments, below. */
83
84struct fmeter {
85 int cnt; /* unprocessed events count */
86 int val; /* most recent output value */
87 time_t time; /* clock (secs) when val computed */
88 spinlock_t lock; /* guards read or write of above */
89};
90
91struct cpuset {
92 struct cgroup_subsys_state css;
93
94 unsigned long flags; /* "unsigned long" so bitops work */
95 cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
96 nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
97
98 struct cpuset *parent; /* my parent */
99
100 struct fmeter fmeter; /* memory_pressure filter */
101
102 /* partition number for rebuild_sched_domains() */
103 int pn;
104
105 /* for custom sched domain */
106 int relax_domain_level;
107
108 /* used for walking a cpuset hierarchy */
109 struct list_head stack_list;
110};
111
112/* Retrieve the cpuset for a cgroup */
113static inline struct cpuset *cgroup_cs(struct cgroup *cont)
114{
115 return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
116 struct cpuset, css);
117}
118
119/* Retrieve the cpuset for a task */
120static inline struct cpuset *task_cs(struct task_struct *task)
121{
122 return container_of(task_subsys_state(task, cpuset_subsys_id),
123 struct cpuset, css);
124}
125
126#ifdef CONFIG_NUMA
127static inline bool task_has_mempolicy(struct task_struct *task)
128{
129 return task->mempolicy;
130}
131#else
132static inline bool task_has_mempolicy(struct task_struct *task)
133{
134 return false;
135}
136#endif
137
138
139/* bits in struct cpuset flags field */
140typedef enum {
141 CS_CPU_EXCLUSIVE,
142 CS_MEM_EXCLUSIVE,
143 CS_MEM_HARDWALL,
144 CS_MEMORY_MIGRATE,
145 CS_SCHED_LOAD_BALANCE,
146 CS_SPREAD_PAGE,
147 CS_SPREAD_SLAB,
148} cpuset_flagbits_t;
149
150/* convenient tests for these bits */
151static inline int is_cpu_exclusive(const struct cpuset *cs)
152{
153 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
154}
155
156static inline int is_mem_exclusive(const struct cpuset *cs)
157{
158 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
159}
160
161static inline int is_mem_hardwall(const struct cpuset *cs)
162{
163 return test_bit(CS_MEM_HARDWALL, &cs->flags);
164}
165
166static inline int is_sched_load_balance(const struct cpuset *cs)
167{
168 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
169}
170
171static inline int is_memory_migrate(const struct cpuset *cs)
172{
173 return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
174}
175
176static inline int is_spread_page(const struct cpuset *cs)
177{
178 return test_bit(CS_SPREAD_PAGE, &cs->flags);
179}
180
181static inline int is_spread_slab(const struct cpuset *cs)
182{
183 return test_bit(CS_SPREAD_SLAB, &cs->flags);
184}
185
186static struct cpuset top_cpuset = {
187 .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
188};
189
190/*
191 * There are two global mutexes guarding cpuset structures. The first
192 * is the main control groups cgroup_mutex, accessed via
193 * cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific
194 * callback_mutex, below. They can nest. It is ok to first take
195 * cgroup_mutex, then nest callback_mutex. We also require taking
196 * task_lock() when dereferencing a task's cpuset pointer. See "The
197 * task_lock() exception", at the end of this comment.
198 *
199 * A task must hold both mutexes to modify cpusets. If a task
200 * holds cgroup_mutex, then it blocks others wanting that mutex,
201 * ensuring that it is the only task able to also acquire callback_mutex
202 * and be able to modify cpusets. It can perform various checks on
203 * the cpuset structure first, knowing nothing will change. It can
204 * also allocate memory while just holding cgroup_mutex. While it is
205 * performing these checks, various callback routines can briefly
206 * acquire callback_mutex to query cpusets. Once it is ready to make
207 * the changes, it takes callback_mutex, blocking everyone else.
208 *
209 * Calls to the kernel memory allocator can not be made while holding
210 * callback_mutex, as that would risk double tripping on callback_mutex
211 * from one of the callbacks into the cpuset code from within
212 * __alloc_pages().
213 *
214 * If a task is only holding callback_mutex, then it has read-only
215 * access to cpusets.
216 *
217 * Now, the task_struct fields mems_allowed and mempolicy may be changed
218 * by other task, we use alloc_lock in the task_struct fields to protect
219 * them.
220 *
221 * The cpuset_common_file_read() handlers only hold callback_mutex across
222 * small pieces of code, such as when reading out possibly multi-word
223 * cpumasks and nodemasks.
224 *
225 * Accessing a task's cpuset should be done in accordance with the
226 * guidelines for accessing subsystem state in kernel/cgroup.c
227 */
228
229static DEFINE_MUTEX(callback_mutex);
230
231/*
232 * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
233 * buffers. They are statically allocated to prevent using excess stack
234 * when calling cpuset_print_task_mems_allowed().
235 */
236#define CPUSET_NAME_LEN (128)
237#define CPUSET_NODELIST_LEN (256)
238static char cpuset_name[CPUSET_NAME_LEN];
239static char cpuset_nodelist[CPUSET_NODELIST_LEN];
240static DEFINE_SPINLOCK(cpuset_buffer_lock);
241
242/*
243 * This is ugly, but preserves the userspace API for existing cpuset
244 * users. If someone tries to mount the "cpuset" filesystem, we
245 * silently switch it to mount "cgroup" instead
246 */
247static struct dentry *cpuset_mount(struct file_system_type *fs_type,
248 int flags, const char *unused_dev_name, void *data)
249{
250 struct file_system_type *cgroup_fs = get_fs_type("cgroup");
251 struct dentry *ret = ERR_PTR(-ENODEV);
252 if (cgroup_fs) {
253 char mountopts[] =
254 "cpuset,noprefix,"
255 "release_agent=/sbin/cpuset_release_agent";
256 ret = cgroup_fs->mount(cgroup_fs, flags,
257 unused_dev_name, mountopts);
258 put_filesystem(cgroup_fs);
259 }
260 return ret;
261}
262
263static struct file_system_type cpuset_fs_type = {
264 .name = "cpuset",
265 .mount = cpuset_mount,
266};
267
268/*
269 * Return in pmask the portion of a cpusets's cpus_allowed that
270 * are online. If none are online, walk up the cpuset hierarchy
271 * until we find one that does have some online cpus. If we get
272 * all the way to the top and still haven't found any online cpus,
273 * return cpu_online_mask. Or if passed a NULL cs from an exit'ing
274 * task, return cpu_online_mask.
275 *
276 * One way or another, we guarantee to return some non-empty subset
277 * of cpu_online_mask.
278 *
279 * Call with callback_mutex held.
280 */
281
282static void guarantee_online_cpus(const struct cpuset *cs,
283 struct cpumask *pmask)
284{
285 while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
286 cs = cs->parent;
287 if (cs)
288 cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
289 else
290 cpumask_copy(pmask, cpu_online_mask);
291 BUG_ON(!cpumask_intersects(pmask, cpu_online_mask));
292}
293
294/*
295 * Return in *pmask the portion of a cpusets's mems_allowed that
296 * are online, with memory. If none are online with memory, walk
297 * up the cpuset hierarchy until we find one that does have some
298 * online mems. If we get all the way to the top and still haven't
299 * found any online mems, return node_states[N_HIGH_MEMORY].
300 *
301 * One way or another, we guarantee to return some non-empty subset
302 * of node_states[N_HIGH_MEMORY].
303 *
304 * Call with callback_mutex held.
305 */
306
307static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
308{
309 while (cs && !nodes_intersects(cs->mems_allowed,
310 node_states[N_HIGH_MEMORY]))
311 cs = cs->parent;
312 if (cs)
313 nodes_and(*pmask, cs->mems_allowed,
314 node_states[N_HIGH_MEMORY]);
315 else
316 *pmask = node_states[N_HIGH_MEMORY];
317 BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
318}
319
320/*
321 * update task's spread flag if cpuset's page/slab spread flag is set
322 *
323 * Called with callback_mutex/cgroup_mutex held
324 */
325static void cpuset_update_task_spread_flag(struct cpuset *cs,
326 struct task_struct *tsk)
327{
328 if (is_spread_page(cs))
329 tsk->flags |= PF_SPREAD_PAGE;
330 else
331 tsk->flags &= ~PF_SPREAD_PAGE;
332 if (is_spread_slab(cs))
333 tsk->flags |= PF_SPREAD_SLAB;
334 else
335 tsk->flags &= ~PF_SPREAD_SLAB;
336}
337
338/*
339 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
340 *
341 * One cpuset is a subset of another if all its allowed CPUs and
342 * Memory Nodes are a subset of the other, and its exclusive flags
343 * are only set if the other's are set. Call holding cgroup_mutex.
344 */
345
346static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
347{
348 return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
349 nodes_subset(p->mems_allowed, q->mems_allowed) &&
350 is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
351 is_mem_exclusive(p) <= is_mem_exclusive(q);
352}
353
354/**
355 * alloc_trial_cpuset - allocate a trial cpuset
356 * @cs: the cpuset that the trial cpuset duplicates
357 */
358static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
359{
360 struct cpuset *trial;
361
362 trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
363 if (!trial)
364 return NULL;
365
366 if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
367 kfree(trial);
368 return NULL;
369 }
370 cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
371
372 return trial;
373}
374
375/**
376 * free_trial_cpuset - free the trial cpuset
377 * @trial: the trial cpuset to be freed
378 */
379static void free_trial_cpuset(struct cpuset *trial)
380{
381 free_cpumask_var(trial->cpus_allowed);
382 kfree(trial);
383}
384
385/*
386 * validate_change() - Used to validate that any proposed cpuset change
387 * follows the structural rules for cpusets.
388 *
389 * If we replaced the flag and mask values of the current cpuset
390 * (cur) with those values in the trial cpuset (trial), would
391 * our various subset and exclusive rules still be valid? Presumes
392 * cgroup_mutex held.
393 *
394 * 'cur' is the address of an actual, in-use cpuset. Operations
395 * such as list traversal that depend on the actual address of the
396 * cpuset in the list must use cur below, not trial.
397 *
398 * 'trial' is the address of bulk structure copy of cur, with
399 * perhaps one or more of the fields cpus_allowed, mems_allowed,
400 * or flags changed to new, trial values.
401 *
402 * Return 0 if valid, -errno if not.
403 */
404
405static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
406{
407 struct cgroup *cont;
408 struct cpuset *c, *par;
409
410 /* Each of our child cpusets must be a subset of us */
411 list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
412 if (!is_cpuset_subset(cgroup_cs(cont), trial))
413 return -EBUSY;
414 }
415
416 /* Remaining checks don't apply to root cpuset */
417 if (cur == &top_cpuset)
418 return 0;
419
420 par = cur->parent;
421
422 /* We must be a subset of our parent cpuset */
423 if (!is_cpuset_subset(trial, par))
424 return -EACCES;
425
426 /*
427 * If either I or some sibling (!= me) is exclusive, we can't
428 * overlap
429 */
430 list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
431 c = cgroup_cs(cont);
432 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
433 c != cur &&
434 cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
435 return -EINVAL;
436 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
437 c != cur &&
438 nodes_intersects(trial->mems_allowed, c->mems_allowed))
439 return -EINVAL;
440 }
441
442 /* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
443 if (cgroup_task_count(cur->css.cgroup)) {
444 if (cpumask_empty(trial->cpus_allowed) ||
445 nodes_empty(trial->mems_allowed)) {
446 return -ENOSPC;
447 }
448 }
449
450 return 0;
451}
452
453#ifdef CONFIG_SMP
454/*
455 * Helper routine for generate_sched_domains().
456 * Do cpusets a, b have overlapping cpus_allowed masks?
457 */
458static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
459{
460 return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
461}
462
463static void
464update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
465{
466 if (dattr->relax_domain_level < c->relax_domain_level)
467 dattr->relax_domain_level = c->relax_domain_level;
468 return;
469}
470
471static void
472update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
473{
474 LIST_HEAD(q);
475
476 list_add(&c->stack_list, &q);
477 while (!list_empty(&q)) {
478 struct cpuset *cp;
479 struct cgroup *cont;
480 struct cpuset *child;
481
482 cp = list_first_entry(&q, struct cpuset, stack_list);
483 list_del(q.next);
484
485 if (cpumask_empty(cp->cpus_allowed))
486 continue;
487
488 if (is_sched_load_balance(cp))
489 update_domain_attr(dattr, cp);
490
491 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
492 child = cgroup_cs(cont);
493 list_add_tail(&child->stack_list, &q);
494 }
495 }
496}
497
498/*
499 * generate_sched_domains()
500 *
501 * This function builds a partial partition of the systems CPUs
502 * A 'partial partition' is a set of non-overlapping subsets whose
503 * union is a subset of that set.
504 * The output of this function needs to be passed to kernel/sched.c
505 * partition_sched_domains() routine, which will rebuild the scheduler's
506 * load balancing domains (sched domains) as specified by that partial
507 * partition.
508 *
509 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
510 * for a background explanation of this.
511 *
512 * Does not return errors, on the theory that the callers of this
513 * routine would rather not worry about failures to rebuild sched
514 * domains when operating in the severe memory shortage situations
515 * that could cause allocation failures below.
516 *
517 * Must be called with cgroup_lock held.
518 *
519 * The three key local variables below are:
520 * q - a linked-list queue of cpuset pointers, used to implement a
521 * top-down scan of all cpusets. This scan loads a pointer
522 * to each cpuset marked is_sched_load_balance into the
523 * array 'csa'. For our purposes, rebuilding the schedulers
524 * sched domains, we can ignore !is_sched_load_balance cpusets.
525 * csa - (for CpuSet Array) Array of pointers to all the cpusets
526 * that need to be load balanced, for convenient iterative
527 * access by the subsequent code that finds the best partition,
528 * i.e the set of domains (subsets) of CPUs such that the
529 * cpus_allowed of every cpuset marked is_sched_load_balance
530 * is a subset of one of these domains, while there are as
531 * many such domains as possible, each as small as possible.
532 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
533 * the kernel/sched.c routine partition_sched_domains() in a
534 * convenient format, that can be easily compared to the prior
535 * value to determine what partition elements (sched domains)
536 * were changed (added or removed.)
537 *
538 * Finding the best partition (set of domains):
539 * The triple nested loops below over i, j, k scan over the
540 * load balanced cpusets (using the array of cpuset pointers in
541 * csa[]) looking for pairs of cpusets that have overlapping
542 * cpus_allowed, but which don't have the same 'pn' partition
543 * number and gives them in the same partition number. It keeps
544 * looping on the 'restart' label until it can no longer find
545 * any such pairs.
546 *
547 * The union of the cpus_allowed masks from the set of
548 * all cpusets having the same 'pn' value then form the one
549 * element of the partition (one sched domain) to be passed to
550 * partition_sched_domains().
551 */
552static int generate_sched_domains(cpumask_var_t **domains,
553 struct sched_domain_attr **attributes)
554{
555 LIST_HEAD(q); /* queue of cpusets to be scanned */
556 struct cpuset *cp; /* scans q */
557 struct cpuset **csa; /* array of all cpuset ptrs */
558 int csn; /* how many cpuset ptrs in csa so far */
559 int i, j, k; /* indices for partition finding loops */
560 cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
561 struct sched_domain_attr *dattr; /* attributes for custom domains */
562 int ndoms = 0; /* number of sched domains in result */
563 int nslot; /* next empty doms[] struct cpumask slot */
564
565 doms = NULL;
566 dattr = NULL;
567 csa = NULL;
568
569 /* Special case for the 99% of systems with one, full, sched domain */
570 if (is_sched_load_balance(&top_cpuset)) {
571 ndoms = 1;
572 doms = alloc_sched_domains(ndoms);
573 if (!doms)
574 goto done;
575
576 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
577 if (dattr) {
578 *dattr = SD_ATTR_INIT;
579 update_domain_attr_tree(dattr, &top_cpuset);
580 }
581 cpumask_copy(doms[0], top_cpuset.cpus_allowed);
582
583 goto done;
584 }
585
586 csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
587 if (!csa)
588 goto done;
589 csn = 0;
590
591 list_add(&top_cpuset.stack_list, &q);
592 while (!list_empty(&q)) {
593 struct cgroup *cont;
594 struct cpuset *child; /* scans child cpusets of cp */
595
596 cp = list_first_entry(&q, struct cpuset, stack_list);
597 list_del(q.next);
598
599 if (cpumask_empty(cp->cpus_allowed))
600 continue;
601
602 /*
603 * All child cpusets contain a subset of the parent's cpus, so
604 * just skip them, and then we call update_domain_attr_tree()
605 * to calc relax_domain_level of the corresponding sched
606 * domain.
607 */
608 if (is_sched_load_balance(cp)) {
609 csa[csn++] = cp;
610 continue;
611 }
612
613 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
614 child = cgroup_cs(cont);
615 list_add_tail(&child->stack_list, &q);
616 }
617 }
618
619 for (i = 0; i < csn; i++)
620 csa[i]->pn = i;
621 ndoms = csn;
622
623restart:
624 /* Find the best partition (set of sched domains) */
625 for (i = 0; i < csn; i++) {
626 struct cpuset *a = csa[i];
627 int apn = a->pn;
628
629 for (j = 0; j < csn; j++) {
630 struct cpuset *b = csa[j];
631 int bpn = b->pn;
632
633 if (apn != bpn && cpusets_overlap(a, b)) {
634 for (k = 0; k < csn; k++) {
635 struct cpuset *c = csa[k];
636
637 if (c->pn == bpn)
638 c->pn = apn;
639 }
640 ndoms--; /* one less element */
641 goto restart;
642 }
643 }
644 }
645
646 /*
647 * Now we know how many domains to create.
648 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
649 */
650 doms = alloc_sched_domains(ndoms);
651 if (!doms)
652 goto done;
653
654 /*
655 * The rest of the code, including the scheduler, can deal with
656 * dattr==NULL case. No need to abort if alloc fails.
657 */
658 dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
659
660 for (nslot = 0, i = 0; i < csn; i++) {
661 struct cpuset *a = csa[i];
662 struct cpumask *dp;
663 int apn = a->pn;
664
665 if (apn < 0) {
666 /* Skip completed partitions */
667 continue;
668 }
669
670 dp = doms[nslot];
671
672 if (nslot == ndoms) {
673 static int warnings = 10;
674 if (warnings) {
675 printk(KERN_WARNING
676 "rebuild_sched_domains confused:"
677 " nslot %d, ndoms %d, csn %d, i %d,"
678 " apn %d\n",
679 nslot, ndoms, csn, i, apn);
680 warnings--;
681 }
682 continue;
683 }
684
685 cpumask_clear(dp);
686 if (dattr)
687 *(dattr + nslot) = SD_ATTR_INIT;
688 for (j = i; j < csn; j++) {
689 struct cpuset *b = csa[j];
690
691 if (apn == b->pn) {
692 cpumask_or(dp, dp, b->cpus_allowed);
693 if (dattr)
694 update_domain_attr_tree(dattr + nslot, b);
695
696 /* Done with this partition */
697 b->pn = -1;
698 }
699 }
700 nslot++;
701 }
702 BUG_ON(nslot != ndoms);
703
704done:
705 kfree(csa);
706
707 /*
708 * Fallback to the default domain if kmalloc() failed.
709 * See comments in partition_sched_domains().
710 */
711 if (doms == NULL)
712 ndoms = 1;
713
714 *domains = doms;
715 *attributes = dattr;
716 return ndoms;
717}
718
719/*
720 * Rebuild scheduler domains.
721 *
722 * Call with neither cgroup_mutex held nor within get_online_cpus().
723 * Takes both cgroup_mutex and get_online_cpus().
724 *
725 * Cannot be directly called from cpuset code handling changes
726 * to the cpuset pseudo-filesystem, because it cannot be called
727 * from code that already holds cgroup_mutex.
728 */
729static void do_rebuild_sched_domains(struct work_struct *unused)
730{
731 struct sched_domain_attr *attr;
732 cpumask_var_t *doms;
733 int ndoms;
734
735 get_online_cpus();
736
737 /* Generate domain masks and attrs */
738 cgroup_lock();
739 ndoms = generate_sched_domains(&doms, &attr);
740 cgroup_unlock();
741
742 /* Have scheduler rebuild the domains */
743 partition_sched_domains(ndoms, doms, attr);
744
745 put_online_cpus();
746}
747#else /* !CONFIG_SMP */
748static void do_rebuild_sched_domains(struct work_struct *unused)
749{
750}
751
752static int generate_sched_domains(cpumask_var_t **domains,
753 struct sched_domain_attr **attributes)
754{
755 *domains = NULL;
756 return 1;
757}
758#endif /* CONFIG_SMP */
759
760static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
761
762/*
763 * Rebuild scheduler domains, asynchronously via workqueue.
764 *
765 * If the flag 'sched_load_balance' of any cpuset with non-empty
766 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
767 * which has that flag enabled, or if any cpuset with a non-empty
768 * 'cpus' is removed, then call this routine to rebuild the
769 * scheduler's dynamic sched domains.
770 *
771 * The rebuild_sched_domains() and partition_sched_domains()
772 * routines must nest cgroup_lock() inside get_online_cpus(),
773 * but such cpuset changes as these must nest that locking the
774 * other way, holding cgroup_lock() for much of the code.
775 *
776 * So in order to avoid an ABBA deadlock, the cpuset code handling
777 * these user changes delegates the actual sched domain rebuilding
778 * to a separate workqueue thread, which ends up processing the
779 * above do_rebuild_sched_domains() function.
780 */
781static void async_rebuild_sched_domains(void)
782{
783 queue_work(cpuset_wq, &rebuild_sched_domains_work);
784}
785
786/*
787 * Accomplishes the same scheduler domain rebuild as the above
788 * async_rebuild_sched_domains(), however it directly calls the
789 * rebuild routine synchronously rather than calling it via an
790 * asynchronous work thread.
791 *
792 * This can only be called from code that is not holding
793 * cgroup_mutex (not nested in a cgroup_lock() call.)
794 */
795void rebuild_sched_domains(void)
796{
797 do_rebuild_sched_domains(NULL);
798}
799
800/**
801 * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
802 * @tsk: task to test
803 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
804 *
805 * Call with cgroup_mutex held. May take callback_mutex during call.
806 * Called for each task in a cgroup by cgroup_scan_tasks().
807 * Return nonzero if this tasks's cpus_allowed mask should be changed (in other
808 * words, if its mask is not equal to its cpuset's mask).
809 */
810static int cpuset_test_cpumask(struct task_struct *tsk,
811 struct cgroup_scanner *scan)
812{
813 return !cpumask_equal(&tsk->cpus_allowed,
814 (cgroup_cs(scan->cg))->cpus_allowed);
815}
816
817/**
818 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
819 * @tsk: task to test
820 * @scan: struct cgroup_scanner containing the cgroup of the task
821 *
822 * Called by cgroup_scan_tasks() for each task in a cgroup whose
823 * cpus_allowed mask needs to be changed.
824 *
825 * We don't need to re-check for the cgroup/cpuset membership, since we're
826 * holding cgroup_lock() at this point.
827 */
828static void cpuset_change_cpumask(struct task_struct *tsk,
829 struct cgroup_scanner *scan)
830{
831 set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
832}
833
834/**
835 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
836 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
837 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
838 *
839 * Called with cgroup_mutex held
840 *
841 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
842 * calling callback functions for each.
843 *
844 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
845 * if @heap != NULL.
846 */
847static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
848{
849 struct cgroup_scanner scan;
850
851 scan.cg = cs->css.cgroup;
852 scan.test_task = cpuset_test_cpumask;
853 scan.process_task = cpuset_change_cpumask;
854 scan.heap = heap;
855 cgroup_scan_tasks(&scan);
856}
857
858/**
859 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
860 * @cs: the cpuset to consider
861 * @buf: buffer of cpu numbers written to this cpuset
862 */
863static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
864 const char *buf)
865{
866 struct ptr_heap heap;
867 int retval;
868 int is_load_balanced;
869
870 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
871 if (cs == &top_cpuset)
872 return -EACCES;
873
874 /*
875 * An empty cpus_allowed is ok only if the cpuset has no tasks.
876 * Since cpulist_parse() fails on an empty mask, we special case
877 * that parsing. The validate_change() call ensures that cpusets
878 * with tasks have cpus.
879 */
880 if (!*buf) {
881 cpumask_clear(trialcs->cpus_allowed);
882 } else {
883 retval = cpulist_parse(buf, trialcs->cpus_allowed);
884 if (retval < 0)
885 return retval;
886
887 if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
888 return -EINVAL;
889 }
890 retval = validate_change(cs, trialcs);
891 if (retval < 0)
892 return retval;
893
894 /* Nothing to do if the cpus didn't change */
895 if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
896 return 0;
897
898 retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
899 if (retval)
900 return retval;
901
902 is_load_balanced = is_sched_load_balance(trialcs);
903
904 mutex_lock(&callback_mutex);
905 cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
906 mutex_unlock(&callback_mutex);
907
908 /*
909 * Scan tasks in the cpuset, and update the cpumasks of any
910 * that need an update.
911 */
912 update_tasks_cpumask(cs, &heap);
913
914 heap_free(&heap);
915
916 if (is_load_balanced)
917 async_rebuild_sched_domains();
918 return 0;
919}
920
921/*
922 * cpuset_migrate_mm
923 *
924 * Migrate memory region from one set of nodes to another.
925 *
926 * Temporarilly set tasks mems_allowed to target nodes of migration,
927 * so that the migration code can allocate pages on these nodes.
928 *
929 * Call holding cgroup_mutex, so current's cpuset won't change
930 * during this call, as manage_mutex holds off any cpuset_attach()
931 * calls. Therefore we don't need to take task_lock around the
932 * call to guarantee_online_mems(), as we know no one is changing
933 * our task's cpuset.
934 *
935 * While the mm_struct we are migrating is typically from some
936 * other task, the task_struct mems_allowed that we are hacking
937 * is for our current task, which must allocate new pages for that
938 * migrating memory region.
939 */
940
941static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
942 const nodemask_t *to)
943{
944 struct task_struct *tsk = current;
945
946 tsk->mems_allowed = *to;
947
948 do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
949
950 guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
951}
952
953/*
954 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
955 * @tsk: the task to change
956 * @newmems: new nodes that the task will be set
957 *
958 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
959 * we structure updates as setting all new allowed nodes, then clearing newly
960 * disallowed ones.
961 */
962static void cpuset_change_task_nodemask(struct task_struct *tsk,
963 nodemask_t *newmems)
964{
965 bool need_loop;
966
967 /*
968 * Allow tasks that have access to memory reserves because they have
969 * been OOM killed to get memory anywhere.
970 */
971 if (unlikely(test_thread_flag(TIF_MEMDIE)))
972 return;
973 if (current->flags & PF_EXITING) /* Let dying task have memory */
974 return;
975
976 task_lock(tsk);
977 /*
978 * Determine if a loop is necessary if another thread is doing
979 * get_mems_allowed(). If at least one node remains unchanged and
980 * tsk does not have a mempolicy, then an empty nodemask will not be
981 * possible when mems_allowed is larger than a word.
982 */
983 need_loop = task_has_mempolicy(tsk) ||
984 !nodes_intersects(*newmems, tsk->mems_allowed);
985
986 if (need_loop)
987 write_seqcount_begin(&tsk->mems_allowed_seq);
988
989 nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
990 mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
991
992 mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
993 tsk->mems_allowed = *newmems;
994
995 if (need_loop)
996 write_seqcount_end(&tsk->mems_allowed_seq);
997
998 task_unlock(tsk);
999}
1000
1001/*
1002 * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
1003 * of it to cpuset's new mems_allowed, and migrate pages to new nodes if
1004 * memory_migrate flag is set. Called with cgroup_mutex held.
1005 */
1006static void cpuset_change_nodemask(struct task_struct *p,
1007 struct cgroup_scanner *scan)
1008{
1009 struct mm_struct *mm;
1010 struct cpuset *cs;
1011 int migrate;
1012 const nodemask_t *oldmem = scan->data;
1013 static nodemask_t newmems; /* protected by cgroup_mutex */
1014
1015 cs = cgroup_cs(scan->cg);
1016 guarantee_online_mems(cs, &newmems);
1017
1018 cpuset_change_task_nodemask(p, &newmems);
1019
1020 mm = get_task_mm(p);
1021 if (!mm)
1022 return;
1023
1024 migrate = is_memory_migrate(cs);
1025
1026 mpol_rebind_mm(mm, &cs->mems_allowed);
1027 if (migrate)
1028 cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
1029 mmput(mm);
1030}
1031
1032static void *cpuset_being_rebound;
1033
1034/**
1035 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1036 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1037 * @oldmem: old mems_allowed of cpuset cs
1038 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1039 *
1040 * Called with cgroup_mutex held
1041 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1042 * if @heap != NULL.
1043 */
1044static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
1045 struct ptr_heap *heap)
1046{
1047 struct cgroup_scanner scan;
1048
1049 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1050
1051 scan.cg = cs->css.cgroup;
1052 scan.test_task = NULL;
1053 scan.process_task = cpuset_change_nodemask;
1054 scan.heap = heap;
1055 scan.data = (nodemask_t *)oldmem;
1056
1057 /*
1058 * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1059 * take while holding tasklist_lock. Forks can happen - the
1060 * mpol_dup() cpuset_being_rebound check will catch such forks,
1061 * and rebind their vma mempolicies too. Because we still hold
1062 * the global cgroup_mutex, we know that no other rebind effort
1063 * will be contending for the global variable cpuset_being_rebound.
1064 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1065 * is idempotent. Also migrate pages in each mm to new nodes.
1066 */
1067 cgroup_scan_tasks(&scan);
1068
1069 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1070 cpuset_being_rebound = NULL;
1071}
1072
1073/*
1074 * Handle user request to change the 'mems' memory placement
1075 * of a cpuset. Needs to validate the request, update the
1076 * cpusets mems_allowed, and for each task in the cpuset,
1077 * update mems_allowed and rebind task's mempolicy and any vma
1078 * mempolicies and if the cpuset is marked 'memory_migrate',
1079 * migrate the tasks pages to the new memory.
1080 *
1081 * Call with cgroup_mutex held. May take callback_mutex during call.
1082 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1083 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1084 * their mempolicies to the cpusets new mems_allowed.
1085 */
1086static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1087 const char *buf)
1088{
1089 NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
1090 int retval;
1091 struct ptr_heap heap;
1092
1093 if (!oldmem)
1094 return -ENOMEM;
1095
1096 /*
1097 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
1098 * it's read-only
1099 */
1100 if (cs == &top_cpuset) {
1101 retval = -EACCES;
1102 goto done;
1103 }
1104
1105 /*
1106 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1107 * Since nodelist_parse() fails on an empty mask, we special case
1108 * that parsing. The validate_change() call ensures that cpusets
1109 * with tasks have memory.
1110 */
1111 if (!*buf) {
1112 nodes_clear(trialcs->mems_allowed);
1113 } else {
1114 retval = nodelist_parse(buf, trialcs->mems_allowed);
1115 if (retval < 0)
1116 goto done;
1117
1118 if (!nodes_subset(trialcs->mems_allowed,
1119 node_states[N_HIGH_MEMORY])) {
1120 retval = -EINVAL;
1121 goto done;
1122 }
1123 }
1124 *oldmem = cs->mems_allowed;
1125 if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
1126 retval = 0; /* Too easy - nothing to do */
1127 goto done;
1128 }
1129 retval = validate_change(cs, trialcs);
1130 if (retval < 0)
1131 goto done;
1132
1133 retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
1134 if (retval < 0)
1135 goto done;
1136
1137 mutex_lock(&callback_mutex);
1138 cs->mems_allowed = trialcs->mems_allowed;
1139 mutex_unlock(&callback_mutex);
1140
1141 update_tasks_nodemask(cs, oldmem, &heap);
1142
1143 heap_free(&heap);
1144done:
1145 NODEMASK_FREE(oldmem);
1146 return retval;
1147}
1148
1149int current_cpuset_is_being_rebound(void)
1150{
1151 return task_cs(current) == cpuset_being_rebound;
1152}
1153
1154static int update_relax_domain_level(struct cpuset *cs, s64 val)
1155{
1156#ifdef CONFIG_SMP
1157 if (val < -1 || val >= sched_domain_level_max)
1158 return -EINVAL;
1159#endif
1160
1161 if (val != cs->relax_domain_level) {
1162 cs->relax_domain_level = val;
1163 if (!cpumask_empty(cs->cpus_allowed) &&
1164 is_sched_load_balance(cs))
1165 async_rebuild_sched_domains();
1166 }
1167
1168 return 0;
1169}
1170
1171/*
1172 * cpuset_change_flag - make a task's spread flags the same as its cpuset's
1173 * @tsk: task to be updated
1174 * @scan: struct cgroup_scanner containing the cgroup of the task
1175 *
1176 * Called by cgroup_scan_tasks() for each task in a cgroup.
1177 *
1178 * We don't need to re-check for the cgroup/cpuset membership, since we're
1179 * holding cgroup_lock() at this point.
1180 */
1181static void cpuset_change_flag(struct task_struct *tsk,
1182 struct cgroup_scanner *scan)
1183{
1184 cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk);
1185}
1186
1187/*
1188 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1189 * @cs: the cpuset in which each task's spread flags needs to be changed
1190 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1191 *
1192 * Called with cgroup_mutex held
1193 *
1194 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1195 * calling callback functions for each.
1196 *
1197 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1198 * if @heap != NULL.
1199 */
1200static void update_tasks_flags(struct cpuset *cs, struct ptr_heap *heap)
1201{
1202 struct cgroup_scanner scan;
1203
1204 scan.cg = cs->css.cgroup;
1205 scan.test_task = NULL;
1206 scan.process_task = cpuset_change_flag;
1207 scan.heap = heap;
1208 cgroup_scan_tasks(&scan);
1209}
1210
1211/*
1212 * update_flag - read a 0 or a 1 in a file and update associated flag
1213 * bit: the bit to update (see cpuset_flagbits_t)
1214 * cs: the cpuset to update
1215 * turning_on: whether the flag is being set or cleared
1216 *
1217 * Call with cgroup_mutex held.
1218 */
1219
1220static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1221 int turning_on)
1222{
1223 struct cpuset *trialcs;
1224 int balance_flag_changed;
1225 int spread_flag_changed;
1226 struct ptr_heap heap;
1227 int err;
1228
1229 trialcs = alloc_trial_cpuset(cs);
1230 if (!trialcs)
1231 return -ENOMEM;
1232
1233 if (turning_on)
1234 set_bit(bit, &trialcs->flags);
1235 else
1236 clear_bit(bit, &trialcs->flags);
1237
1238 err = validate_change(cs, trialcs);
1239 if (err < 0)
1240 goto out;
1241
1242 err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
1243 if (err < 0)
1244 goto out;
1245
1246 balance_flag_changed = (is_sched_load_balance(cs) !=
1247 is_sched_load_balance(trialcs));
1248
1249 spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1250 || (is_spread_page(cs) != is_spread_page(trialcs)));
1251
1252 mutex_lock(&callback_mutex);
1253 cs->flags = trialcs->flags;
1254 mutex_unlock(&callback_mutex);
1255
1256 if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1257 async_rebuild_sched_domains();
1258
1259 if (spread_flag_changed)
1260 update_tasks_flags(cs, &heap);
1261 heap_free(&heap);
1262out:
1263 free_trial_cpuset(trialcs);
1264 return err;
1265}
1266
1267/*
1268 * Frequency meter - How fast is some event occurring?
1269 *
1270 * These routines manage a digitally filtered, constant time based,
1271 * event frequency meter. There are four routines:
1272 * fmeter_init() - initialize a frequency meter.
1273 * fmeter_markevent() - called each time the event happens.
1274 * fmeter_getrate() - returns the recent rate of such events.
1275 * fmeter_update() - internal routine used to update fmeter.
1276 *
1277 * A common data structure is passed to each of these routines,
1278 * which is used to keep track of the state required to manage the
1279 * frequency meter and its digital filter.
1280 *
1281 * The filter works on the number of events marked per unit time.
1282 * The filter is single-pole low-pass recursive (IIR). The time unit
1283 * is 1 second. Arithmetic is done using 32-bit integers scaled to
1284 * simulate 3 decimal digits of precision (multiplied by 1000).
1285 *
1286 * With an FM_COEF of 933, and a time base of 1 second, the filter
1287 * has a half-life of 10 seconds, meaning that if the events quit
1288 * happening, then the rate returned from the fmeter_getrate()
1289 * will be cut in half each 10 seconds, until it converges to zero.
1290 *
1291 * It is not worth doing a real infinitely recursive filter. If more
1292 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1293 * just compute FM_MAXTICKS ticks worth, by which point the level
1294 * will be stable.
1295 *
1296 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1297 * arithmetic overflow in the fmeter_update() routine.
1298 *
1299 * Given the simple 32 bit integer arithmetic used, this meter works
1300 * best for reporting rates between one per millisecond (msec) and
1301 * one per 32 (approx) seconds. At constant rates faster than one
1302 * per msec it maxes out at values just under 1,000,000. At constant
1303 * rates between one per msec, and one per second it will stabilize
1304 * to a value N*1000, where N is the rate of events per second.
1305 * At constant rates between one per second and one per 32 seconds,
1306 * it will be choppy, moving up on the seconds that have an event,
1307 * and then decaying until the next event. At rates slower than
1308 * about one in 32 seconds, it decays all the way back to zero between
1309 * each event.
1310 */
1311
1312#define FM_COEF 933 /* coefficient for half-life of 10 secs */
1313#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1314#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1315#define FM_SCALE 1000 /* faux fixed point scale */
1316
1317/* Initialize a frequency meter */
1318static void fmeter_init(struct fmeter *fmp)
1319{
1320 fmp->cnt = 0;
1321 fmp->val = 0;
1322 fmp->time = 0;
1323 spin_lock_init(&fmp->lock);
1324}
1325
1326/* Internal meter update - process cnt events and update value */
1327static void fmeter_update(struct fmeter *fmp)
1328{
1329 time_t now = get_seconds();
1330 time_t ticks = now - fmp->time;
1331
1332 if (ticks == 0)
1333 return;
1334
1335 ticks = min(FM_MAXTICKS, ticks);
1336 while (ticks-- > 0)
1337 fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1338 fmp->time = now;
1339
1340 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1341 fmp->cnt = 0;
1342}
1343
1344/* Process any previous ticks, then bump cnt by one (times scale). */
1345static void fmeter_markevent(struct fmeter *fmp)
1346{
1347 spin_lock(&fmp->lock);
1348 fmeter_update(fmp);
1349 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1350 spin_unlock(&fmp->lock);
1351}
1352
1353/* Process any previous ticks, then return current value. */
1354static int fmeter_getrate(struct fmeter *fmp)
1355{
1356 int val;
1357
1358 spin_lock(&fmp->lock);
1359 fmeter_update(fmp);
1360 val = fmp->val;
1361 spin_unlock(&fmp->lock);
1362 return val;
1363}
1364
1365/*
1366 * Protected by cgroup_lock. The nodemasks must be stored globally because
1367 * dynamically allocating them is not allowed in can_attach, and they must
1368 * persist until attach.
1369 */
1370static cpumask_var_t cpus_attach;
1371static nodemask_t cpuset_attach_nodemask_from;
1372static nodemask_t cpuset_attach_nodemask_to;
1373
1374/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1375static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1376{
1377 struct cpuset *cs = cgroup_cs(cgrp);
1378 struct task_struct *task;
1379 int ret;
1380
1381 if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
1382 return -ENOSPC;
1383
1384 cgroup_taskset_for_each(task, cgrp, tset) {
1385 /*
1386 * Kthreads bound to specific cpus cannot be moved to a new
1387 * cpuset; we cannot change their cpu affinity and
1388 * isolating such threads by their set of allowed nodes is
1389 * unnecessary. Thus, cpusets are not applicable for such
1390 * threads. This prevents checking for success of
1391 * set_cpus_allowed_ptr() on all attached tasks before
1392 * cpus_allowed may be changed.
1393 */
1394 if (task->flags & PF_THREAD_BOUND)
1395 return -EINVAL;
1396 if ((ret = security_task_setscheduler(task)))
1397 return ret;
1398 }
1399
1400 /* prepare for attach */
1401 if (cs == &top_cpuset)
1402 cpumask_copy(cpus_attach, cpu_possible_mask);
1403 else
1404 guarantee_online_cpus(cs, cpus_attach);
1405
1406 guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
1407
1408 return 0;
1409}
1410
1411static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
1412{
1413 struct mm_struct *mm;
1414 struct task_struct *task;
1415 struct task_struct *leader = cgroup_taskset_first(tset);
1416 struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
1417 struct cpuset *cs = cgroup_cs(cgrp);
1418 struct cpuset *oldcs = cgroup_cs(oldcgrp);
1419
1420 cgroup_taskset_for_each(task, cgrp, tset) {
1421 /*
1422 * can_attach beforehand should guarantee that this doesn't
1423 * fail. TODO: have a better way to handle failure here
1424 */
1425 WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
1426
1427 cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
1428 cpuset_update_task_spread_flag(cs, task);
1429 }
1430
1431 /*
1432 * Change mm, possibly for multiple threads in a threadgroup. This is
1433 * expensive and may sleep.
1434 */
1435 cpuset_attach_nodemask_from = oldcs->mems_allowed;
1436 cpuset_attach_nodemask_to = cs->mems_allowed;
1437 mm = get_task_mm(leader);
1438 if (mm) {
1439 mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1440 if (is_memory_migrate(cs))
1441 cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
1442 &cpuset_attach_nodemask_to);
1443 mmput(mm);
1444 }
1445}
1446
1447/* The various types of files and directories in a cpuset file system */
1448
1449typedef enum {
1450 FILE_MEMORY_MIGRATE,
1451 FILE_CPULIST,
1452 FILE_MEMLIST,
1453 FILE_CPU_EXCLUSIVE,
1454 FILE_MEM_EXCLUSIVE,
1455 FILE_MEM_HARDWALL,
1456 FILE_SCHED_LOAD_BALANCE,
1457 FILE_SCHED_RELAX_DOMAIN_LEVEL,
1458 FILE_MEMORY_PRESSURE_ENABLED,
1459 FILE_MEMORY_PRESSURE,
1460 FILE_SPREAD_PAGE,
1461 FILE_SPREAD_SLAB,
1462} cpuset_filetype_t;
1463
1464static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1465{
1466 int retval = 0;
1467 struct cpuset *cs = cgroup_cs(cgrp);
1468 cpuset_filetype_t type = cft->private;
1469
1470 if (!cgroup_lock_live_group(cgrp))
1471 return -ENODEV;
1472
1473 switch (type) {
1474 case FILE_CPU_EXCLUSIVE:
1475 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1476 break;
1477 case FILE_MEM_EXCLUSIVE:
1478 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1479 break;
1480 case FILE_MEM_HARDWALL:
1481 retval = update_flag(CS_MEM_HARDWALL, cs, val);
1482 break;
1483 case FILE_SCHED_LOAD_BALANCE:
1484 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1485 break;
1486 case FILE_MEMORY_MIGRATE:
1487 retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1488 break;
1489 case FILE_MEMORY_PRESSURE_ENABLED:
1490 cpuset_memory_pressure_enabled = !!val;
1491 break;
1492 case FILE_MEMORY_PRESSURE:
1493 retval = -EACCES;
1494 break;
1495 case FILE_SPREAD_PAGE:
1496 retval = update_flag(CS_SPREAD_PAGE, cs, val);
1497 break;
1498 case FILE_SPREAD_SLAB:
1499 retval = update_flag(CS_SPREAD_SLAB, cs, val);
1500 break;
1501 default:
1502 retval = -EINVAL;
1503 break;
1504 }
1505 cgroup_unlock();
1506 return retval;
1507}
1508
1509static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
1510{
1511 int retval = 0;
1512 struct cpuset *cs = cgroup_cs(cgrp);
1513 cpuset_filetype_t type = cft->private;
1514
1515 if (!cgroup_lock_live_group(cgrp))
1516 return -ENODEV;
1517
1518 switch (type) {
1519 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1520 retval = update_relax_domain_level(cs, val);
1521 break;
1522 default:
1523 retval = -EINVAL;
1524 break;
1525 }
1526 cgroup_unlock();
1527 return retval;
1528}
1529
1530/*
1531 * Common handling for a write to a "cpus" or "mems" file.
1532 */
1533static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
1534 const char *buf)
1535{
1536 int retval = 0;
1537 struct cpuset *cs = cgroup_cs(cgrp);
1538 struct cpuset *trialcs;
1539
1540 if (!cgroup_lock_live_group(cgrp))
1541 return -ENODEV;
1542
1543 trialcs = alloc_trial_cpuset(cs);
1544 if (!trialcs) {
1545 retval = -ENOMEM;
1546 goto out;
1547 }
1548
1549 switch (cft->private) {
1550 case FILE_CPULIST:
1551 retval = update_cpumask(cs, trialcs, buf);
1552 break;
1553 case FILE_MEMLIST:
1554 retval = update_nodemask(cs, trialcs, buf);
1555 break;
1556 default:
1557 retval = -EINVAL;
1558 break;
1559 }
1560
1561 free_trial_cpuset(trialcs);
1562out:
1563 cgroup_unlock();
1564 return retval;
1565}
1566
1567/*
1568 * These ascii lists should be read in a single call, by using a user
1569 * buffer large enough to hold the entire map. If read in smaller
1570 * chunks, there is no guarantee of atomicity. Since the display format
1571 * used, list of ranges of sequential numbers, is variable length,
1572 * and since these maps can change value dynamically, one could read
1573 * gibberish by doing partial reads while a list was changing.
1574 * A single large read to a buffer that crosses a page boundary is
1575 * ok, because the result being copied to user land is not recomputed
1576 * across a page fault.
1577 */
1578
1579static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
1580{
1581 size_t count;
1582
1583 mutex_lock(&callback_mutex);
1584 count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1585 mutex_unlock(&callback_mutex);
1586
1587 return count;
1588}
1589
1590static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
1591{
1592 size_t count;
1593
1594 mutex_lock(&callback_mutex);
1595 count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
1596 mutex_unlock(&callback_mutex);
1597
1598 return count;
1599}
1600
1601static ssize_t cpuset_common_file_read(struct cgroup *cont,
1602 struct cftype *cft,
1603 struct file *file,
1604 char __user *buf,
1605 size_t nbytes, loff_t *ppos)
1606{
1607 struct cpuset *cs = cgroup_cs(cont);
1608 cpuset_filetype_t type = cft->private;
1609 char *page;
1610 ssize_t retval = 0;
1611 char *s;
1612
1613 if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
1614 return -ENOMEM;
1615
1616 s = page;
1617
1618 switch (type) {
1619 case FILE_CPULIST:
1620 s += cpuset_sprintf_cpulist(s, cs);
1621 break;
1622 case FILE_MEMLIST:
1623 s += cpuset_sprintf_memlist(s, cs);
1624 break;
1625 default:
1626 retval = -EINVAL;
1627 goto out;
1628 }
1629 *s++ = '\n';
1630
1631 retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
1632out:
1633 free_page((unsigned long)page);
1634 return retval;
1635}
1636
1637static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
1638{
1639 struct cpuset *cs = cgroup_cs(cont);
1640 cpuset_filetype_t type = cft->private;
1641 switch (type) {
1642 case FILE_CPU_EXCLUSIVE:
1643 return is_cpu_exclusive(cs);
1644 case FILE_MEM_EXCLUSIVE:
1645 return is_mem_exclusive(cs);
1646 case FILE_MEM_HARDWALL:
1647 return is_mem_hardwall(cs);
1648 case FILE_SCHED_LOAD_BALANCE:
1649 return is_sched_load_balance(cs);
1650 case FILE_MEMORY_MIGRATE:
1651 return is_memory_migrate(cs);
1652 case FILE_MEMORY_PRESSURE_ENABLED:
1653 return cpuset_memory_pressure_enabled;
1654 case FILE_MEMORY_PRESSURE:
1655 return fmeter_getrate(&cs->fmeter);
1656 case FILE_SPREAD_PAGE:
1657 return is_spread_page(cs);
1658 case FILE_SPREAD_SLAB:
1659 return is_spread_slab(cs);
1660 default:
1661 BUG();
1662 }
1663
1664 /* Unreachable but makes gcc happy */
1665 return 0;
1666}
1667
1668static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
1669{
1670 struct cpuset *cs = cgroup_cs(cont);
1671 cpuset_filetype_t type = cft->private;
1672 switch (type) {
1673 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1674 return cs->relax_domain_level;
1675 default:
1676 BUG();
1677 }
1678
1679 /* Unrechable but makes gcc happy */
1680 return 0;
1681}
1682
1683
1684/*
1685 * for the common functions, 'private' gives the type of file
1686 */
1687
1688static struct cftype files[] = {
1689 {
1690 .name = "cpus",
1691 .read = cpuset_common_file_read,
1692 .write_string = cpuset_write_resmask,
1693 .max_write_len = (100U + 6 * NR_CPUS),
1694 .private = FILE_CPULIST,
1695 },
1696
1697 {
1698 .name = "mems",
1699 .read = cpuset_common_file_read,
1700 .write_string = cpuset_write_resmask,
1701 .max_write_len = (100U + 6 * MAX_NUMNODES),
1702 .private = FILE_MEMLIST,
1703 },
1704
1705 {
1706 .name = "cpu_exclusive",
1707 .read_u64 = cpuset_read_u64,
1708 .write_u64 = cpuset_write_u64,
1709 .private = FILE_CPU_EXCLUSIVE,
1710 },
1711
1712 {
1713 .name = "mem_exclusive",
1714 .read_u64 = cpuset_read_u64,
1715 .write_u64 = cpuset_write_u64,
1716 .private = FILE_MEM_EXCLUSIVE,
1717 },
1718
1719 {
1720 .name = "mem_hardwall",
1721 .read_u64 = cpuset_read_u64,
1722 .write_u64 = cpuset_write_u64,
1723 .private = FILE_MEM_HARDWALL,
1724 },
1725
1726 {
1727 .name = "sched_load_balance",
1728 .read_u64 = cpuset_read_u64,
1729 .write_u64 = cpuset_write_u64,
1730 .private = FILE_SCHED_LOAD_BALANCE,
1731 },
1732
1733 {
1734 .name = "sched_relax_domain_level",
1735 .read_s64 = cpuset_read_s64,
1736 .write_s64 = cpuset_write_s64,
1737 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1738 },
1739
1740 {
1741 .name = "memory_migrate",
1742 .read_u64 = cpuset_read_u64,
1743 .write_u64 = cpuset_write_u64,
1744 .private = FILE_MEMORY_MIGRATE,
1745 },
1746
1747 {
1748 .name = "memory_pressure",
1749 .read_u64 = cpuset_read_u64,
1750 .write_u64 = cpuset_write_u64,
1751 .private = FILE_MEMORY_PRESSURE,
1752 .mode = S_IRUGO,
1753 },
1754
1755 {
1756 .name = "memory_spread_page",
1757 .read_u64 = cpuset_read_u64,
1758 .write_u64 = cpuset_write_u64,
1759 .private = FILE_SPREAD_PAGE,
1760 },
1761
1762 {
1763 .name = "memory_spread_slab",
1764 .read_u64 = cpuset_read_u64,
1765 .write_u64 = cpuset_write_u64,
1766 .private = FILE_SPREAD_SLAB,
1767 },
1768
1769 {
1770 .name = "memory_pressure_enabled",
1771 .flags = CFTYPE_ONLY_ON_ROOT,
1772 .read_u64 = cpuset_read_u64,
1773 .write_u64 = cpuset_write_u64,
1774 .private = FILE_MEMORY_PRESSURE_ENABLED,
1775 },
1776
1777 { } /* terminate */
1778};
1779
1780/*
1781 * post_clone() is called during cgroup_create() when the
1782 * clone_children mount argument was specified. The cgroup
1783 * can not yet have any tasks.
1784 *
1785 * Currently we refuse to set up the cgroup - thereby
1786 * refusing the task to be entered, and as a result refusing
1787 * the sys_unshare() or clone() which initiated it - if any
1788 * sibling cpusets have exclusive cpus or mem.
1789 *
1790 * If this becomes a problem for some users who wish to
1791 * allow that scenario, then cpuset_post_clone() could be
1792 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1793 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
1794 * held.
1795 */
1796static void cpuset_post_clone(struct cgroup *cgroup)
1797{
1798 struct cgroup *parent, *child;
1799 struct cpuset *cs, *parent_cs;
1800
1801 parent = cgroup->parent;
1802 list_for_each_entry(child, &parent->children, sibling) {
1803 cs = cgroup_cs(child);
1804 if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
1805 return;
1806 }
1807 cs = cgroup_cs(cgroup);
1808 parent_cs = cgroup_cs(parent);
1809
1810 mutex_lock(&callback_mutex);
1811 cs->mems_allowed = parent_cs->mems_allowed;
1812 cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
1813 mutex_unlock(&callback_mutex);
1814 return;
1815}
1816
1817/*
1818 * cpuset_create - create a cpuset
1819 * cont: control group that the new cpuset will be part of
1820 */
1821
1822static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
1823{
1824 struct cpuset *cs;
1825 struct cpuset *parent;
1826
1827 if (!cont->parent) {
1828 return &top_cpuset.css;
1829 }
1830 parent = cgroup_cs(cont->parent);
1831 cs = kmalloc(sizeof(*cs), GFP_KERNEL);
1832 if (!cs)
1833 return ERR_PTR(-ENOMEM);
1834 if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
1835 kfree(cs);
1836 return ERR_PTR(-ENOMEM);
1837 }
1838
1839 cs->flags = 0;
1840 if (is_spread_page(parent))
1841 set_bit(CS_SPREAD_PAGE, &cs->flags);
1842 if (is_spread_slab(parent))
1843 set_bit(CS_SPREAD_SLAB, &cs->flags);
1844 set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1845 cpumask_clear(cs->cpus_allowed);
1846 nodes_clear(cs->mems_allowed);
1847 fmeter_init(&cs->fmeter);
1848 cs->relax_domain_level = -1;
1849
1850 cs->parent = parent;
1851 number_of_cpusets++;
1852 return &cs->css ;
1853}
1854
1855/*
1856 * If the cpuset being removed has its flag 'sched_load_balance'
1857 * enabled, then simulate turning sched_load_balance off, which
1858 * will call async_rebuild_sched_domains().
1859 */
1860
1861static void cpuset_destroy(struct cgroup *cont)
1862{
1863 struct cpuset *cs = cgroup_cs(cont);
1864
1865 if (is_sched_load_balance(cs))
1866 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1867
1868 number_of_cpusets--;
1869 free_cpumask_var(cs->cpus_allowed);
1870 kfree(cs);
1871}
1872
1873struct cgroup_subsys cpuset_subsys = {
1874 .name = "cpuset",
1875 .create = cpuset_create,
1876 .destroy = cpuset_destroy,
1877 .can_attach = cpuset_can_attach,
1878 .attach = cpuset_attach,
1879 .post_clone = cpuset_post_clone,
1880 .subsys_id = cpuset_subsys_id,
1881 .base_cftypes = files,
1882 .early_init = 1,
1883};
1884
1885/**
1886 * cpuset_init - initialize cpusets at system boot
1887 *
1888 * Description: Initialize top_cpuset and the cpuset internal file system,
1889 **/
1890
1891int __init cpuset_init(void)
1892{
1893 int err = 0;
1894
1895 if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
1896 BUG();
1897
1898 cpumask_setall(top_cpuset.cpus_allowed);
1899 nodes_setall(top_cpuset.mems_allowed);
1900
1901 fmeter_init(&top_cpuset.fmeter);
1902 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1903 top_cpuset.relax_domain_level = -1;
1904
1905 err = register_filesystem(&cpuset_fs_type);
1906 if (err < 0)
1907 return err;
1908
1909 if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
1910 BUG();
1911
1912 number_of_cpusets = 1;
1913 return 0;
1914}
1915
1916/**
1917 * cpuset_do_move_task - move a given task to another cpuset
1918 * @tsk: pointer to task_struct the task to move
1919 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
1920 *
1921 * Called by cgroup_scan_tasks() for each task in a cgroup.
1922 * Return nonzero to stop the walk through the tasks.
1923 */
1924static void cpuset_do_move_task(struct task_struct *tsk,
1925 struct cgroup_scanner *scan)
1926{
1927 struct cgroup *new_cgroup = scan->data;
1928
1929 cgroup_attach_task(new_cgroup, tsk);
1930}
1931
1932/**
1933 * move_member_tasks_to_cpuset - move tasks from one cpuset to another
1934 * @from: cpuset in which the tasks currently reside
1935 * @to: cpuset to which the tasks will be moved
1936 *
1937 * Called with cgroup_mutex held
1938 * callback_mutex must not be held, as cpuset_attach() will take it.
1939 *
1940 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1941 * calling callback functions for each.
1942 */
1943static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
1944{
1945 struct cgroup_scanner scan;
1946
1947 scan.cg = from->css.cgroup;
1948 scan.test_task = NULL; /* select all tasks in cgroup */
1949 scan.process_task = cpuset_do_move_task;
1950 scan.heap = NULL;
1951 scan.data = to->css.cgroup;
1952
1953 if (cgroup_scan_tasks(&scan))
1954 printk(KERN_ERR "move_member_tasks_to_cpuset: "
1955 "cgroup_scan_tasks failed\n");
1956}
1957
1958/*
1959 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1960 * or memory nodes, we need to walk over the cpuset hierarchy,
1961 * removing that CPU or node from all cpusets. If this removes the
1962 * last CPU or node from a cpuset, then move the tasks in the empty
1963 * cpuset to its next-highest non-empty parent.
1964 *
1965 * Called with cgroup_mutex held
1966 * callback_mutex must not be held, as cpuset_attach() will take it.
1967 */
1968static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
1969{
1970 struct cpuset *parent;
1971
1972 /*
1973 * The cgroup's css_sets list is in use if there are tasks
1974 * in the cpuset; the list is empty if there are none;
1975 * the cs->css.refcnt seems always 0.
1976 */
1977 if (list_empty(&cs->css.cgroup->css_sets))
1978 return;
1979
1980 /*
1981 * Find its next-highest non-empty parent, (top cpuset
1982 * has online cpus, so can't be empty).
1983 */
1984 parent = cs->parent;
1985 while (cpumask_empty(parent->cpus_allowed) ||
1986 nodes_empty(parent->mems_allowed))
1987 parent = parent->parent;
1988
1989 move_member_tasks_to_cpuset(cs, parent);
1990}
1991
1992/*
1993 * Walk the specified cpuset subtree and look for empty cpusets.
1994 * The tasks of such cpuset must be moved to a parent cpuset.
1995 *
1996 * Called with cgroup_mutex held. We take callback_mutex to modify
1997 * cpus_allowed and mems_allowed.
1998 *
1999 * This walk processes the tree from top to bottom, completing one layer
2000 * before dropping down to the next. It always processes a node before
2001 * any of its children.
2002 *
2003 * For now, since we lack memory hot unplug, we'll never see a cpuset
2004 * that has tasks along with an empty 'mems'. But if we did see such
2005 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
2006 */
2007static void scan_for_empty_cpusets(struct cpuset *root)
2008{
2009 LIST_HEAD(queue);
2010 struct cpuset *cp; /* scans cpusets being updated */
2011 struct cpuset *child; /* scans child cpusets of cp */
2012 struct cgroup *cont;
2013 static nodemask_t oldmems; /* protected by cgroup_mutex */
2014
2015 list_add_tail((struct list_head *)&root->stack_list, &queue);
2016
2017 while (!list_empty(&queue)) {
2018 cp = list_first_entry(&queue, struct cpuset, stack_list);
2019 list_del(queue.next);
2020 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
2021 child = cgroup_cs(cont);
2022 list_add_tail(&child->stack_list, &queue);
2023 }
2024
2025 /* Continue past cpusets with all cpus, mems online */
2026 if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&
2027 nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
2028 continue;
2029
2030 oldmems = cp->mems_allowed;
2031
2032 /* Remove offline cpus and mems from this cpuset. */
2033 mutex_lock(&callback_mutex);
2034 cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
2035 cpu_active_mask);
2036 nodes_and(cp->mems_allowed, cp->mems_allowed,
2037 node_states[N_HIGH_MEMORY]);
2038 mutex_unlock(&callback_mutex);
2039
2040 /* Move tasks from the empty cpuset to a parent */
2041 if (cpumask_empty(cp->cpus_allowed) ||
2042 nodes_empty(cp->mems_allowed))
2043 remove_tasks_in_empty_cpuset(cp);
2044 else {
2045 update_tasks_cpumask(cp, NULL);
2046 update_tasks_nodemask(cp, &oldmems, NULL);
2047 }
2048 }
2049}
2050
2051/*
2052 * The top_cpuset tracks what CPUs and Memory Nodes are online,
2053 * period. This is necessary in order to make cpusets transparent
2054 * (of no affect) on systems that are actively using CPU hotplug
2055 * but making no active use of cpusets.
2056 *
2057 * This routine ensures that top_cpuset.cpus_allowed tracks
2058 * cpu_active_mask on each CPU hotplug (cpuhp) event.
2059 *
2060 * Called within get_online_cpus(). Needs to call cgroup_lock()
2061 * before calling generate_sched_domains().
2062 */
2063void cpuset_update_active_cpus(void)
2064{
2065 struct sched_domain_attr *attr;
2066 cpumask_var_t *doms;
2067 int ndoms;
2068
2069 cgroup_lock();
2070 mutex_lock(&callback_mutex);
2071 cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2072 mutex_unlock(&callback_mutex);
2073 scan_for_empty_cpusets(&top_cpuset);
2074 ndoms = generate_sched_domains(&doms, &attr);
2075 cgroup_unlock();
2076
2077 /* Have scheduler rebuild the domains */
2078 partition_sched_domains(ndoms, doms, attr);
2079}
2080
2081#ifdef CONFIG_MEMORY_HOTPLUG
2082/*
2083 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2084 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
2085 * See also the previous routine cpuset_track_online_cpus().
2086 */
2087static int cpuset_track_online_nodes(struct notifier_block *self,
2088 unsigned long action, void *arg)
2089{
2090 static nodemask_t oldmems; /* protected by cgroup_mutex */
2091
2092 cgroup_lock();
2093 switch (action) {
2094 case MEM_ONLINE:
2095 oldmems = top_cpuset.mems_allowed;
2096 mutex_lock(&callback_mutex);
2097 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2098 mutex_unlock(&callback_mutex);
2099 update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
2100 break;
2101 case MEM_OFFLINE:
2102 /*
2103 * needn't update top_cpuset.mems_allowed explicitly because
2104 * scan_for_empty_cpusets() will update it.
2105 */
2106 scan_for_empty_cpusets(&top_cpuset);
2107 break;
2108 default:
2109 break;
2110 }
2111 cgroup_unlock();
2112
2113 return NOTIFY_OK;
2114}
2115#endif
2116
2117/**
2118 * cpuset_init_smp - initialize cpus_allowed
2119 *
2120 * Description: Finish top cpuset after cpu, node maps are initialized
2121 **/
2122
2123void __init cpuset_init_smp(void)
2124{
2125 cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2126 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2127
2128 hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2129
2130 cpuset_wq = create_singlethread_workqueue("cpuset");
2131 BUG_ON(!cpuset_wq);
2132}
2133
2134/**
2135 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2136 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2137 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2138 *
2139 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2140 * attached to the specified @tsk. Guaranteed to return some non-empty
2141 * subset of cpu_online_mask, even if this means going outside the
2142 * tasks cpuset.
2143 **/
2144
2145void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
2146{
2147 mutex_lock(&callback_mutex);
2148 task_lock(tsk);
2149 guarantee_online_cpus(task_cs(tsk), pmask);
2150 task_unlock(tsk);
2151 mutex_unlock(&callback_mutex);
2152}
2153
2154void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2155{
2156 const struct cpuset *cs;
2157
2158 rcu_read_lock();
2159 cs = task_cs(tsk);
2160 if (cs)
2161 do_set_cpus_allowed(tsk, cs->cpus_allowed);
2162 rcu_read_unlock();
2163
2164 /*
2165 * We own tsk->cpus_allowed, nobody can change it under us.
2166 *
2167 * But we used cs && cs->cpus_allowed lockless and thus can
2168 * race with cgroup_attach_task() or update_cpumask() and get
2169 * the wrong tsk->cpus_allowed. However, both cases imply the
2170 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2171 * which takes task_rq_lock().
2172 *
2173 * If we are called after it dropped the lock we must see all
2174 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2175 * set any mask even if it is not right from task_cs() pov,
2176 * the pending set_cpus_allowed_ptr() will fix things.
2177 *
2178 * select_fallback_rq() will fix things ups and set cpu_possible_mask
2179 * if required.
2180 */
2181}
2182
2183void cpuset_init_current_mems_allowed(void)
2184{
2185 nodes_setall(current->mems_allowed);
2186}
2187
2188/**
2189 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2190 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2191 *
2192 * Description: Returns the nodemask_t mems_allowed of the cpuset
2193 * attached to the specified @tsk. Guaranteed to return some non-empty
2194 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2195 * tasks cpuset.
2196 **/
2197
2198nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2199{
2200 nodemask_t mask;
2201
2202 mutex_lock(&callback_mutex);
2203 task_lock(tsk);
2204 guarantee_online_mems(task_cs(tsk), &mask);
2205 task_unlock(tsk);
2206 mutex_unlock(&callback_mutex);
2207
2208 return mask;
2209}
2210
2211/**
2212 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2213 * @nodemask: the nodemask to be checked
2214 *
2215 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2216 */
2217int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2218{
2219 return nodes_intersects(*nodemask, current->mems_allowed);
2220}
2221
2222/*
2223 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2224 * mem_hardwall ancestor to the specified cpuset. Call holding
2225 * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
2226 * (an unusual configuration), then returns the root cpuset.
2227 */
2228static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2229{
2230 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2231 cs = cs->parent;
2232 return cs;
2233}
2234
2235/**
2236 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
2237 * @node: is this an allowed node?
2238 * @gfp_mask: memory allocation flags
2239 *
2240 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2241 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2242 * yes. If it's not a __GFP_HARDWALL request and this node is in the nearest
2243 * hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been
2244 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2245 * flag, yes.
2246 * Otherwise, no.
2247 *
2248 * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
2249 * cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall()
2250 * might sleep, and might allow a node from an enclosing cpuset.
2251 *
2252 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
2253 * cpusets, and never sleeps.
2254 *
2255 * The __GFP_THISNODE placement logic is really handled elsewhere,
2256 * by forcibly using a zonelist starting at a specified node, and by
2257 * (in get_page_from_freelist()) refusing to consider the zones for
2258 * any node on the zonelist except the first. By the time any such
2259 * calls get to this routine, we should just shut up and say 'yes'.
2260 *
2261 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2262 * and do not allow allocations outside the current tasks cpuset
2263 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2264 * GFP_KERNEL allocations are not so marked, so can escape to the
2265 * nearest enclosing hardwalled ancestor cpuset.
2266 *
2267 * Scanning up parent cpusets requires callback_mutex. The
2268 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2269 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2270 * current tasks mems_allowed came up empty on the first pass over
2271 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
2272 * cpuset are short of memory, might require taking the callback_mutex
2273 * mutex.
2274 *
2275 * The first call here from mm/page_alloc:get_page_from_freelist()
2276 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2277 * so no allocation on a node outside the cpuset is allowed (unless
2278 * in interrupt, of course).
2279 *
2280 * The second pass through get_page_from_freelist() doesn't even call
2281 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2282 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2283 * in alloc_flags. That logic and the checks below have the combined
2284 * affect that:
2285 * in_interrupt - any node ok (current task context irrelevant)
2286 * GFP_ATOMIC - any node ok
2287 * TIF_MEMDIE - any node ok
2288 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
2289 * GFP_USER - only nodes in current tasks mems allowed ok.
2290 *
2291 * Rule:
2292 * Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2293 * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2294 * the code that might scan up ancestor cpusets and sleep.
2295 */
2296int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
2297{
2298 const struct cpuset *cs; /* current cpuset ancestors */
2299 int allowed; /* is allocation in zone z allowed? */
2300
2301 if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2302 return 1;
2303 might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2304 if (node_isset(node, current->mems_allowed))
2305 return 1;
2306 /*
2307 * Allow tasks that have access to memory reserves because they have
2308 * been OOM killed to get memory anywhere.
2309 */
2310 if (unlikely(test_thread_flag(TIF_MEMDIE)))
2311 return 1;
2312 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
2313 return 0;
2314
2315 if (current->flags & PF_EXITING) /* Let dying task have memory */
2316 return 1;
2317
2318 /* Not hardwall and node outside mems_allowed: scan up cpusets */
2319 mutex_lock(&callback_mutex);
2320
2321 task_lock(current);
2322 cs = nearest_hardwall_ancestor(task_cs(current));
2323 task_unlock(current);
2324
2325 allowed = node_isset(node, cs->mems_allowed);
2326 mutex_unlock(&callback_mutex);
2327 return allowed;
2328}
2329
2330/*
2331 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
2332 * @node: is this an allowed node?
2333 * @gfp_mask: memory allocation flags
2334 *
2335 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2336 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2337 * yes. If the task has been OOM killed and has access to memory reserves as
2338 * specified by the TIF_MEMDIE flag, yes.
2339 * Otherwise, no.
2340 *
2341 * The __GFP_THISNODE placement logic is really handled elsewhere,
2342 * by forcibly using a zonelist starting at a specified node, and by
2343 * (in get_page_from_freelist()) refusing to consider the zones for
2344 * any node on the zonelist except the first. By the time any such
2345 * calls get to this routine, we should just shut up and say 'yes'.
2346 *
2347 * Unlike the cpuset_node_allowed_softwall() variant, above,
2348 * this variant requires that the node be in the current task's
2349 * mems_allowed or that we're in interrupt. It does not scan up the
2350 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2351 * It never sleeps.
2352 */
2353int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2354{
2355 if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2356 return 1;
2357 if (node_isset(node, current->mems_allowed))
2358 return 1;
2359 /*
2360 * Allow tasks that have access to memory reserves because they have
2361 * been OOM killed to get memory anywhere.
2362 */
2363 if (unlikely(test_thread_flag(TIF_MEMDIE)))
2364 return 1;
2365 return 0;
2366}
2367
2368/**
2369 * cpuset_unlock - release lock on cpuset changes
2370 *
2371 * Undo the lock taken in a previous cpuset_lock() call.
2372 */
2373
2374void cpuset_unlock(void)
2375{
2376 mutex_unlock(&callback_mutex);
2377}
2378
2379/**
2380 * cpuset_mem_spread_node() - On which node to begin search for a file page
2381 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2382 *
2383 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2384 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2385 * and if the memory allocation used cpuset_mem_spread_node()
2386 * to determine on which node to start looking, as it will for
2387 * certain page cache or slab cache pages such as used for file
2388 * system buffers and inode caches, then instead of starting on the
2389 * local node to look for a free page, rather spread the starting
2390 * node around the tasks mems_allowed nodes.
2391 *
2392 * We don't have to worry about the returned node being offline
2393 * because "it can't happen", and even if it did, it would be ok.
2394 *
2395 * The routines calling guarantee_online_mems() are careful to
2396 * only set nodes in task->mems_allowed that are online. So it
2397 * should not be possible for the following code to return an
2398 * offline node. But if it did, that would be ok, as this routine
2399 * is not returning the node where the allocation must be, only
2400 * the node where the search should start. The zonelist passed to
2401 * __alloc_pages() will include all nodes. If the slab allocator
2402 * is passed an offline node, it will fall back to the local node.
2403 * See kmem_cache_alloc_node().
2404 */
2405
2406static int cpuset_spread_node(int *rotor)
2407{
2408 int node;
2409
2410 node = next_node(*rotor, current->mems_allowed);
2411 if (node == MAX_NUMNODES)
2412 node = first_node(current->mems_allowed);
2413 *rotor = node;
2414 return node;
2415}
2416
2417int cpuset_mem_spread_node(void)
2418{
2419 if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
2420 current->cpuset_mem_spread_rotor =
2421 node_random(¤t->mems_allowed);
2422
2423 return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
2424}
2425
2426int cpuset_slab_spread_node(void)
2427{
2428 if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
2429 current->cpuset_slab_spread_rotor =
2430 node_random(¤t->mems_allowed);
2431
2432 return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
2433}
2434
2435EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2436
2437/**
2438 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2439 * @tsk1: pointer to task_struct of some task.
2440 * @tsk2: pointer to task_struct of some other task.
2441 *
2442 * Description: Return true if @tsk1's mems_allowed intersects the
2443 * mems_allowed of @tsk2. Used by the OOM killer to determine if
2444 * one of the task's memory usage might impact the memory available
2445 * to the other.
2446 **/
2447
2448int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2449 const struct task_struct *tsk2)
2450{
2451 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2452}
2453
2454/**
2455 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2456 * @task: pointer to task_struct of some task.
2457 *
2458 * Description: Prints @task's name, cpuset name, and cached copy of its
2459 * mems_allowed to the kernel log. Must hold task_lock(task) to allow
2460 * dereferencing task_cs(task).
2461 */
2462void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2463{
2464 struct dentry *dentry;
2465
2466 dentry = task_cs(tsk)->css.cgroup->dentry;
2467 spin_lock(&cpuset_buffer_lock);
2468 snprintf(cpuset_name, CPUSET_NAME_LEN,
2469 dentry ? (const char *)dentry->d_name.name : "/");
2470 nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2471 tsk->mems_allowed);
2472 printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
2473 tsk->comm, cpuset_name, cpuset_nodelist);
2474 spin_unlock(&cpuset_buffer_lock);
2475}
2476
2477/*
2478 * Collection of memory_pressure is suppressed unless
2479 * this flag is enabled by writing "1" to the special
2480 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2481 */
2482
2483int cpuset_memory_pressure_enabled __read_mostly;
2484
2485/**
2486 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2487 *
2488 * Keep a running average of the rate of synchronous (direct)
2489 * page reclaim efforts initiated by tasks in each cpuset.
2490 *
2491 * This represents the rate at which some task in the cpuset
2492 * ran low on memory on all nodes it was allowed to use, and
2493 * had to enter the kernels page reclaim code in an effort to
2494 * create more free memory by tossing clean pages or swapping
2495 * or writing dirty pages.
2496 *
2497 * Display to user space in the per-cpuset read-only file
2498 * "memory_pressure". Value displayed is an integer
2499 * representing the recent rate of entry into the synchronous
2500 * (direct) page reclaim by any task attached to the cpuset.
2501 **/
2502
2503void __cpuset_memory_pressure_bump(void)
2504{
2505 task_lock(current);
2506 fmeter_markevent(&task_cs(current)->fmeter);
2507 task_unlock(current);
2508}
2509
2510#ifdef CONFIG_PROC_PID_CPUSET
2511/*
2512 * proc_cpuset_show()
2513 * - Print tasks cpuset path into seq_file.
2514 * - Used for /proc/<pid>/cpuset.
2515 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2516 * doesn't really matter if tsk->cpuset changes after we read it,
2517 * and we take cgroup_mutex, keeping cpuset_attach() from changing it
2518 * anyway.
2519 */
2520static int proc_cpuset_show(struct seq_file *m, void *unused_v)
2521{
2522 struct pid *pid;
2523 struct task_struct *tsk;
2524 char *buf;
2525 struct cgroup_subsys_state *css;
2526 int retval;
2527
2528 retval = -ENOMEM;
2529 buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
2530 if (!buf)
2531 goto out;
2532
2533 retval = -ESRCH;
2534 pid = m->private;
2535 tsk = get_pid_task(pid, PIDTYPE_PID);
2536 if (!tsk)
2537 goto out_free;
2538
2539 retval = -EINVAL;
2540 cgroup_lock();
2541 css = task_subsys_state(tsk, cpuset_subsys_id);
2542 retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
2543 if (retval < 0)
2544 goto out_unlock;
2545 seq_puts(m, buf);
2546 seq_putc(m, '\n');
2547out_unlock:
2548 cgroup_unlock();
2549 put_task_struct(tsk);
2550out_free:
2551 kfree(buf);
2552out:
2553 return retval;
2554}
2555
2556static int cpuset_open(struct inode *inode, struct file *file)
2557{
2558 struct pid *pid = PROC_I(inode)->pid;
2559 return single_open(file, proc_cpuset_show, pid);
2560}
2561
2562const struct file_operations proc_cpuset_operations = {
2563 .open = cpuset_open,
2564 .read = seq_read,
2565 .llseek = seq_lseek,
2566 .release = single_release,
2567};
2568#endif /* CONFIG_PROC_PID_CPUSET */
2569
2570/* Display task mems_allowed in /proc/<pid>/status file. */
2571void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2572{
2573 seq_printf(m, "Mems_allowed:\t");
2574 seq_nodemask(m, &task->mems_allowed);
2575 seq_printf(m, "\n");
2576 seq_printf(m, "Mems_allowed_list:\t");
2577 seq_nodemask_list(m, &task->mems_allowed);
2578 seq_printf(m, "\n");
2579}