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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/kthread.h>
37#include <linux/list.h>
38#include <linux/mempolicy.h>
39#include <linux/mm.h>
40#include <linux/memory.h>
41#include <linux/export.h>
42#include <linux/mount.h>
43#include <linux/fs_context.h>
44#include <linux/namei.h>
45#include <linux/pagemap.h>
46#include <linux/proc_fs.h>
47#include <linux/rcupdate.h>
48#include <linux/sched.h>
49#include <linux/sched/deadline.h>
50#include <linux/sched/mm.h>
51#include <linux/sched/task.h>
52#include <linux/seq_file.h>
53#include <linux/security.h>
54#include <linux/slab.h>
55#include <linux/spinlock.h>
56#include <linux/stat.h>
57#include <linux/string.h>
58#include <linux/time.h>
59#include <linux/time64.h>
60#include <linux/backing-dev.h>
61#include <linux/sort.h>
62#include <linux/oom.h>
63#include <linux/sched/isolation.h>
64#include <linux/uaccess.h>
65#include <linux/atomic.h>
66#include <linux/mutex.h>
67#include <linux/cgroup.h>
68#include <linux/wait.h>
69
70DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key);
71DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
72
73/*
74 * There could be abnormal cpuset configurations for cpu or memory
75 * node binding, add this key to provide a quick low-cost judgment
76 * of the situation.
77 */
78DEFINE_STATIC_KEY_FALSE(cpusets_insane_config_key);
79
80/* See "Frequency meter" comments, below. */
81
82struct fmeter {
83 int cnt; /* unprocessed events count */
84 int val; /* most recent output value */
85 time64_t time; /* clock (secs) when val computed */
86 spinlock_t lock; /* guards read or write of above */
87};
88
89/*
90 * Invalid partition error code
91 */
92enum prs_errcode {
93 PERR_NONE = 0,
94 PERR_INVCPUS,
95 PERR_INVPARENT,
96 PERR_NOTPART,
97 PERR_NOTEXCL,
98 PERR_NOCPUS,
99 PERR_HOTPLUG,
100 PERR_CPUSEMPTY,
101};
102
103static const char * const perr_strings[] = {
104 [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus",
105 [PERR_INVPARENT] = "Parent is an invalid partition root",
106 [PERR_NOTPART] = "Parent is not a partition root",
107 [PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive",
108 [PERR_NOCPUS] = "Parent unable to distribute cpu downstream",
109 [PERR_HOTPLUG] = "No cpu available due to hotplug",
110 [PERR_CPUSEMPTY] = "cpuset.cpus is empty",
111};
112
113struct cpuset {
114 struct cgroup_subsys_state css;
115
116 unsigned long flags; /* "unsigned long" so bitops work */
117
118 /*
119 * On default hierarchy:
120 *
121 * The user-configured masks can only be changed by writing to
122 * cpuset.cpus and cpuset.mems, and won't be limited by the
123 * parent masks.
124 *
125 * The effective masks is the real masks that apply to the tasks
126 * in the cpuset. They may be changed if the configured masks are
127 * changed or hotplug happens.
128 *
129 * effective_mask == configured_mask & parent's effective_mask,
130 * and if it ends up empty, it will inherit the parent's mask.
131 *
132 *
133 * On legacy hierarchy:
134 *
135 * The user-configured masks are always the same with effective masks.
136 */
137
138 /* user-configured CPUs and Memory Nodes allow to tasks */
139 cpumask_var_t cpus_allowed;
140 nodemask_t mems_allowed;
141
142 /* effective CPUs and Memory Nodes allow to tasks */
143 cpumask_var_t effective_cpus;
144 nodemask_t effective_mems;
145
146 /*
147 * CPUs allocated to child sub-partitions (default hierarchy only)
148 * - CPUs granted by the parent = effective_cpus U subparts_cpus
149 * - effective_cpus and subparts_cpus are mutually exclusive.
150 *
151 * effective_cpus contains only onlined CPUs, but subparts_cpus
152 * may have offlined ones.
153 */
154 cpumask_var_t subparts_cpus;
155
156 /*
157 * This is old Memory Nodes tasks took on.
158 *
159 * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
160 * - A new cpuset's old_mems_allowed is initialized when some
161 * task is moved into it.
162 * - old_mems_allowed is used in cpuset_migrate_mm() when we change
163 * cpuset.mems_allowed and have tasks' nodemask updated, and
164 * then old_mems_allowed is updated to mems_allowed.
165 */
166 nodemask_t old_mems_allowed;
167
168 struct fmeter fmeter; /* memory_pressure filter */
169
170 /*
171 * Tasks are being attached to this cpuset. Used to prevent
172 * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
173 */
174 int attach_in_progress;
175
176 /* partition number for rebuild_sched_domains() */
177 int pn;
178
179 /* for custom sched domain */
180 int relax_domain_level;
181
182 /* number of CPUs in subparts_cpus */
183 int nr_subparts_cpus;
184
185 /* partition root state */
186 int partition_root_state;
187
188 /*
189 * Default hierarchy only:
190 * use_parent_ecpus - set if using parent's effective_cpus
191 * child_ecpus_count - # of children with use_parent_ecpus set
192 */
193 int use_parent_ecpus;
194 int child_ecpus_count;
195
196 /* Invalid partition error code, not lock protected */
197 enum prs_errcode prs_err;
198
199 /* Handle for cpuset.cpus.partition */
200 struct cgroup_file partition_file;
201};
202
203/*
204 * Partition root states:
205 *
206 * 0 - member (not a partition root)
207 * 1 - partition root
208 * 2 - partition root without load balancing (isolated)
209 * -1 - invalid partition root
210 * -2 - invalid isolated partition root
211 */
212#define PRS_MEMBER 0
213#define PRS_ROOT 1
214#define PRS_ISOLATED 2
215#define PRS_INVALID_ROOT -1
216#define PRS_INVALID_ISOLATED -2
217
218static inline bool is_prs_invalid(int prs_state)
219{
220 return prs_state < 0;
221}
222
223/*
224 * Temporary cpumasks for working with partitions that are passed among
225 * functions to avoid memory allocation in inner functions.
226 */
227struct tmpmasks {
228 cpumask_var_t addmask, delmask; /* For partition root */
229 cpumask_var_t new_cpus; /* For update_cpumasks_hier() */
230};
231
232static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
233{
234 return css ? container_of(css, struct cpuset, css) : NULL;
235}
236
237/* Retrieve the cpuset for a task */
238static inline struct cpuset *task_cs(struct task_struct *task)
239{
240 return css_cs(task_css(task, cpuset_cgrp_id));
241}
242
243static inline struct cpuset *parent_cs(struct cpuset *cs)
244{
245 return css_cs(cs->css.parent);
246}
247
248/* bits in struct cpuset flags field */
249typedef enum {
250 CS_ONLINE,
251 CS_CPU_EXCLUSIVE,
252 CS_MEM_EXCLUSIVE,
253 CS_MEM_HARDWALL,
254 CS_MEMORY_MIGRATE,
255 CS_SCHED_LOAD_BALANCE,
256 CS_SPREAD_PAGE,
257 CS_SPREAD_SLAB,
258} cpuset_flagbits_t;
259
260/* convenient tests for these bits */
261static inline bool is_cpuset_online(struct cpuset *cs)
262{
263 return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);
264}
265
266static inline int is_cpu_exclusive(const struct cpuset *cs)
267{
268 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
269}
270
271static inline int is_mem_exclusive(const struct cpuset *cs)
272{
273 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
274}
275
276static inline int is_mem_hardwall(const struct cpuset *cs)
277{
278 return test_bit(CS_MEM_HARDWALL, &cs->flags);
279}
280
281static inline int is_sched_load_balance(const struct cpuset *cs)
282{
283 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
284}
285
286static inline int is_memory_migrate(const struct cpuset *cs)
287{
288 return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
289}
290
291static inline int is_spread_page(const struct cpuset *cs)
292{
293 return test_bit(CS_SPREAD_PAGE, &cs->flags);
294}
295
296static inline int is_spread_slab(const struct cpuset *cs)
297{
298 return test_bit(CS_SPREAD_SLAB, &cs->flags);
299}
300
301static inline int is_partition_valid(const struct cpuset *cs)
302{
303 return cs->partition_root_state > 0;
304}
305
306static inline int is_partition_invalid(const struct cpuset *cs)
307{
308 return cs->partition_root_state < 0;
309}
310
311/*
312 * Callers should hold callback_lock to modify partition_root_state.
313 */
314static inline void make_partition_invalid(struct cpuset *cs)
315{
316 if (is_partition_valid(cs))
317 cs->partition_root_state = -cs->partition_root_state;
318}
319
320/*
321 * Send notification event of whenever partition_root_state changes.
322 */
323static inline void notify_partition_change(struct cpuset *cs, int old_prs)
324{
325 if (old_prs == cs->partition_root_state)
326 return;
327 cgroup_file_notify(&cs->partition_file);
328
329 /* Reset prs_err if not invalid */
330 if (is_partition_valid(cs))
331 WRITE_ONCE(cs->prs_err, PERR_NONE);
332}
333
334static struct cpuset top_cpuset = {
335 .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
336 (1 << CS_MEM_EXCLUSIVE)),
337 .partition_root_state = PRS_ROOT,
338};
339
340/**
341 * cpuset_for_each_child - traverse online children of a cpuset
342 * @child_cs: loop cursor pointing to the current child
343 * @pos_css: used for iteration
344 * @parent_cs: target cpuset to walk children of
345 *
346 * Walk @child_cs through the online children of @parent_cs. Must be used
347 * with RCU read locked.
348 */
349#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
350 css_for_each_child((pos_css), &(parent_cs)->css) \
351 if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
352
353/**
354 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
355 * @des_cs: loop cursor pointing to the current descendant
356 * @pos_css: used for iteration
357 * @root_cs: target cpuset to walk ancestor of
358 *
359 * Walk @des_cs through the online descendants of @root_cs. Must be used
360 * with RCU read locked. The caller may modify @pos_css by calling
361 * css_rightmost_descendant() to skip subtree. @root_cs is included in the
362 * iteration and the first node to be visited.
363 */
364#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
365 css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
366 if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
367
368/*
369 * There are two global locks guarding cpuset structures - cpuset_rwsem and
370 * callback_lock. We also require taking task_lock() when dereferencing a
371 * task's cpuset pointer. See "The task_lock() exception", at the end of this
372 * comment. The cpuset code uses only cpuset_rwsem write lock. Other
373 * kernel subsystems can use cpuset_read_lock()/cpuset_read_unlock() to
374 * prevent change to cpuset structures.
375 *
376 * A task must hold both locks to modify cpusets. If a task holds
377 * cpuset_rwsem, it blocks others wanting that rwsem, ensuring that it
378 * is the only task able to also acquire callback_lock and be able to
379 * modify cpusets. It can perform various checks on the cpuset structure
380 * first, knowing nothing will change. It can also allocate memory while
381 * just holding cpuset_rwsem. While it is performing these checks, various
382 * callback routines can briefly acquire callback_lock to query cpusets.
383 * Once it is ready to make the changes, it takes callback_lock, blocking
384 * everyone else.
385 *
386 * Calls to the kernel memory allocator can not be made while holding
387 * callback_lock, as that would risk double tripping on callback_lock
388 * from one of the callbacks into the cpuset code from within
389 * __alloc_pages().
390 *
391 * If a task is only holding callback_lock, then it has read-only
392 * access to cpusets.
393 *
394 * Now, the task_struct fields mems_allowed and mempolicy may be changed
395 * by other task, we use alloc_lock in the task_struct fields to protect
396 * them.
397 *
398 * The cpuset_common_file_read() handlers only hold callback_lock across
399 * small pieces of code, such as when reading out possibly multi-word
400 * cpumasks and nodemasks.
401 *
402 * Accessing a task's cpuset should be done in accordance with the
403 * guidelines for accessing subsystem state in kernel/cgroup.c
404 */
405
406DEFINE_STATIC_PERCPU_RWSEM(cpuset_rwsem);
407
408void cpuset_read_lock(void)
409{
410 percpu_down_read(&cpuset_rwsem);
411}
412
413void cpuset_read_unlock(void)
414{
415 percpu_up_read(&cpuset_rwsem);
416}
417
418static DEFINE_SPINLOCK(callback_lock);
419
420static struct workqueue_struct *cpuset_migrate_mm_wq;
421
422/*
423 * CPU / memory hotplug is handled asynchronously.
424 */
425static void cpuset_hotplug_workfn(struct work_struct *work);
426static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
427
428static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
429
430static inline void check_insane_mems_config(nodemask_t *nodes)
431{
432 if (!cpusets_insane_config() &&
433 movable_only_nodes(nodes)) {
434 static_branch_enable(&cpusets_insane_config_key);
435 pr_info("Unsupported (movable nodes only) cpuset configuration detected (nmask=%*pbl)!\n"
436 "Cpuset allocations might fail even with a lot of memory available.\n",
437 nodemask_pr_args(nodes));
438 }
439}
440
441/*
442 * Cgroup v2 behavior is used on the "cpus" and "mems" control files when
443 * on default hierarchy or when the cpuset_v2_mode flag is set by mounting
444 * the v1 cpuset cgroup filesystem with the "cpuset_v2_mode" mount option.
445 * With v2 behavior, "cpus" and "mems" are always what the users have
446 * requested and won't be changed by hotplug events. Only the effective
447 * cpus or mems will be affected.
448 */
449static inline bool is_in_v2_mode(void)
450{
451 return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
452 (cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE);
453}
454
455/**
456 * partition_is_populated - check if partition has tasks
457 * @cs: partition root to be checked
458 * @excluded_child: a child cpuset to be excluded in task checking
459 * Return: true if there are tasks, false otherwise
460 *
461 * It is assumed that @cs is a valid partition root. @excluded_child should
462 * be non-NULL when this cpuset is going to become a partition itself.
463 */
464static inline bool partition_is_populated(struct cpuset *cs,
465 struct cpuset *excluded_child)
466{
467 struct cgroup_subsys_state *css;
468 struct cpuset *child;
469
470 if (cs->css.cgroup->nr_populated_csets)
471 return true;
472 if (!excluded_child && !cs->nr_subparts_cpus)
473 return cgroup_is_populated(cs->css.cgroup);
474
475 rcu_read_lock();
476 cpuset_for_each_child(child, css, cs) {
477 if (child == excluded_child)
478 continue;
479 if (is_partition_valid(child))
480 continue;
481 if (cgroup_is_populated(child->css.cgroup)) {
482 rcu_read_unlock();
483 return true;
484 }
485 }
486 rcu_read_unlock();
487 return false;
488}
489
490/*
491 * Return in pmask the portion of a task's cpusets's cpus_allowed that
492 * are online and are capable of running the task. If none are found,
493 * walk up the cpuset hierarchy until we find one that does have some
494 * appropriate cpus.
495 *
496 * One way or another, we guarantee to return some non-empty subset
497 * of cpu_online_mask.
498 *
499 * Call with callback_lock or cpuset_rwsem held.
500 */
501static void guarantee_online_cpus(struct task_struct *tsk,
502 struct cpumask *pmask)
503{
504 const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
505 struct cpuset *cs;
506
507 if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask)))
508 cpumask_copy(pmask, cpu_online_mask);
509
510 rcu_read_lock();
511 cs = task_cs(tsk);
512
513 while (!cpumask_intersects(cs->effective_cpus, pmask)) {
514 cs = parent_cs(cs);
515 if (unlikely(!cs)) {
516 /*
517 * The top cpuset doesn't have any online cpu as a
518 * consequence of a race between cpuset_hotplug_work
519 * and cpu hotplug notifier. But we know the top
520 * cpuset's effective_cpus is on its way to be
521 * identical to cpu_online_mask.
522 */
523 goto out_unlock;
524 }
525 }
526 cpumask_and(pmask, pmask, cs->effective_cpus);
527
528out_unlock:
529 rcu_read_unlock();
530}
531
532/*
533 * Return in *pmask the portion of a cpusets's mems_allowed that
534 * are online, with memory. If none are online with memory, walk
535 * up the cpuset hierarchy until we find one that does have some
536 * online mems. The top cpuset always has some mems online.
537 *
538 * One way or another, we guarantee to return some non-empty subset
539 * of node_states[N_MEMORY].
540 *
541 * Call with callback_lock or cpuset_rwsem held.
542 */
543static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
544{
545 while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
546 cs = parent_cs(cs);
547 nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
548}
549
550/*
551 * update task's spread flag if cpuset's page/slab spread flag is set
552 *
553 * Call with callback_lock or cpuset_rwsem held. The check can be skipped
554 * if on default hierarchy.
555 */
556static void cpuset_update_task_spread_flags(struct cpuset *cs,
557 struct task_struct *tsk)
558{
559 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
560 return;
561
562 if (is_spread_page(cs))
563 task_set_spread_page(tsk);
564 else
565 task_clear_spread_page(tsk);
566
567 if (is_spread_slab(cs))
568 task_set_spread_slab(tsk);
569 else
570 task_clear_spread_slab(tsk);
571}
572
573/*
574 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
575 *
576 * One cpuset is a subset of another if all its allowed CPUs and
577 * Memory Nodes are a subset of the other, and its exclusive flags
578 * are only set if the other's are set. Call holding cpuset_rwsem.
579 */
580
581static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
582{
583 return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
584 nodes_subset(p->mems_allowed, q->mems_allowed) &&
585 is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
586 is_mem_exclusive(p) <= is_mem_exclusive(q);
587}
588
589/**
590 * alloc_cpumasks - allocate three cpumasks for cpuset
591 * @cs: the cpuset that have cpumasks to be allocated.
592 * @tmp: the tmpmasks structure pointer
593 * Return: 0 if successful, -ENOMEM otherwise.
594 *
595 * Only one of the two input arguments should be non-NULL.
596 */
597static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
598{
599 cpumask_var_t *pmask1, *pmask2, *pmask3;
600
601 if (cs) {
602 pmask1 = &cs->cpus_allowed;
603 pmask2 = &cs->effective_cpus;
604 pmask3 = &cs->subparts_cpus;
605 } else {
606 pmask1 = &tmp->new_cpus;
607 pmask2 = &tmp->addmask;
608 pmask3 = &tmp->delmask;
609 }
610
611 if (!zalloc_cpumask_var(pmask1, GFP_KERNEL))
612 return -ENOMEM;
613
614 if (!zalloc_cpumask_var(pmask2, GFP_KERNEL))
615 goto free_one;
616
617 if (!zalloc_cpumask_var(pmask3, GFP_KERNEL))
618 goto free_two;
619
620 return 0;
621
622free_two:
623 free_cpumask_var(*pmask2);
624free_one:
625 free_cpumask_var(*pmask1);
626 return -ENOMEM;
627}
628
629/**
630 * free_cpumasks - free cpumasks in a tmpmasks structure
631 * @cs: the cpuset that have cpumasks to be free.
632 * @tmp: the tmpmasks structure pointer
633 */
634static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
635{
636 if (cs) {
637 free_cpumask_var(cs->cpus_allowed);
638 free_cpumask_var(cs->effective_cpus);
639 free_cpumask_var(cs->subparts_cpus);
640 }
641 if (tmp) {
642 free_cpumask_var(tmp->new_cpus);
643 free_cpumask_var(tmp->addmask);
644 free_cpumask_var(tmp->delmask);
645 }
646}
647
648/**
649 * alloc_trial_cpuset - allocate a trial cpuset
650 * @cs: the cpuset that the trial cpuset duplicates
651 */
652static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
653{
654 struct cpuset *trial;
655
656 trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
657 if (!trial)
658 return NULL;
659
660 if (alloc_cpumasks(trial, NULL)) {
661 kfree(trial);
662 return NULL;
663 }
664
665 cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
666 cpumask_copy(trial->effective_cpus, cs->effective_cpus);
667 return trial;
668}
669
670/**
671 * free_cpuset - free the cpuset
672 * @cs: the cpuset to be freed
673 */
674static inline void free_cpuset(struct cpuset *cs)
675{
676 free_cpumasks(cs, NULL);
677 kfree(cs);
678}
679
680/*
681 * validate_change_legacy() - Validate conditions specific to legacy (v1)
682 * behavior.
683 */
684static int validate_change_legacy(struct cpuset *cur, struct cpuset *trial)
685{
686 struct cgroup_subsys_state *css;
687 struct cpuset *c, *par;
688 int ret;
689
690 WARN_ON_ONCE(!rcu_read_lock_held());
691
692 /* Each of our child cpusets must be a subset of us */
693 ret = -EBUSY;
694 cpuset_for_each_child(c, css, cur)
695 if (!is_cpuset_subset(c, trial))
696 goto out;
697
698 /* On legacy hierarchy, we must be a subset of our parent cpuset. */
699 ret = -EACCES;
700 par = parent_cs(cur);
701 if (par && !is_cpuset_subset(trial, par))
702 goto out;
703
704 ret = 0;
705out:
706 return ret;
707}
708
709/*
710 * validate_change() - Used to validate that any proposed cpuset change
711 * follows the structural rules for cpusets.
712 *
713 * If we replaced the flag and mask values of the current cpuset
714 * (cur) with those values in the trial cpuset (trial), would
715 * our various subset and exclusive rules still be valid? Presumes
716 * cpuset_rwsem held.
717 *
718 * 'cur' is the address of an actual, in-use cpuset. Operations
719 * such as list traversal that depend on the actual address of the
720 * cpuset in the list must use cur below, not trial.
721 *
722 * 'trial' is the address of bulk structure copy of cur, with
723 * perhaps one or more of the fields cpus_allowed, mems_allowed,
724 * or flags changed to new, trial values.
725 *
726 * Return 0 if valid, -errno if not.
727 */
728
729static int validate_change(struct cpuset *cur, struct cpuset *trial)
730{
731 struct cgroup_subsys_state *css;
732 struct cpuset *c, *par;
733 int ret = 0;
734
735 rcu_read_lock();
736
737 if (!is_in_v2_mode())
738 ret = validate_change_legacy(cur, trial);
739 if (ret)
740 goto out;
741
742 /* Remaining checks don't apply to root cpuset */
743 if (cur == &top_cpuset)
744 goto out;
745
746 par = parent_cs(cur);
747
748 /*
749 * Cpusets with tasks - existing or newly being attached - can't
750 * be changed to have empty cpus_allowed or mems_allowed.
751 */
752 ret = -ENOSPC;
753 if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
754 if (!cpumask_empty(cur->cpus_allowed) &&
755 cpumask_empty(trial->cpus_allowed))
756 goto out;
757 if (!nodes_empty(cur->mems_allowed) &&
758 nodes_empty(trial->mems_allowed))
759 goto out;
760 }
761
762 /*
763 * We can't shrink if we won't have enough room for SCHED_DEADLINE
764 * tasks.
765 */
766 ret = -EBUSY;
767 if (is_cpu_exclusive(cur) &&
768 !cpuset_cpumask_can_shrink(cur->cpus_allowed,
769 trial->cpus_allowed))
770 goto out;
771
772 /*
773 * If either I or some sibling (!= me) is exclusive, we can't
774 * overlap
775 */
776 ret = -EINVAL;
777 cpuset_for_each_child(c, css, par) {
778 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
779 c != cur &&
780 cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
781 goto out;
782 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
783 c != cur &&
784 nodes_intersects(trial->mems_allowed, c->mems_allowed))
785 goto out;
786 }
787
788 ret = 0;
789out:
790 rcu_read_unlock();
791 return ret;
792}
793
794#ifdef CONFIG_SMP
795/*
796 * Helper routine for generate_sched_domains().
797 * Do cpusets a, b have overlapping effective cpus_allowed masks?
798 */
799static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
800{
801 return cpumask_intersects(a->effective_cpus, b->effective_cpus);
802}
803
804static void
805update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
806{
807 if (dattr->relax_domain_level < c->relax_domain_level)
808 dattr->relax_domain_level = c->relax_domain_level;
809 return;
810}
811
812static void update_domain_attr_tree(struct sched_domain_attr *dattr,
813 struct cpuset *root_cs)
814{
815 struct cpuset *cp;
816 struct cgroup_subsys_state *pos_css;
817
818 rcu_read_lock();
819 cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
820 /* skip the whole subtree if @cp doesn't have any CPU */
821 if (cpumask_empty(cp->cpus_allowed)) {
822 pos_css = css_rightmost_descendant(pos_css);
823 continue;
824 }
825
826 if (is_sched_load_balance(cp))
827 update_domain_attr(dattr, cp);
828 }
829 rcu_read_unlock();
830}
831
832/* Must be called with cpuset_rwsem held. */
833static inline int nr_cpusets(void)
834{
835 /* jump label reference count + the top-level cpuset */
836 return static_key_count(&cpusets_enabled_key.key) + 1;
837}
838
839/*
840 * generate_sched_domains()
841 *
842 * This function builds a partial partition of the systems CPUs
843 * A 'partial partition' is a set of non-overlapping subsets whose
844 * union is a subset of that set.
845 * The output of this function needs to be passed to kernel/sched/core.c
846 * partition_sched_domains() routine, which will rebuild the scheduler's
847 * load balancing domains (sched domains) as specified by that partial
848 * partition.
849 *
850 * See "What is sched_load_balance" in Documentation/admin-guide/cgroup-v1/cpusets.rst
851 * for a background explanation of this.
852 *
853 * Does not return errors, on the theory that the callers of this
854 * routine would rather not worry about failures to rebuild sched
855 * domains when operating in the severe memory shortage situations
856 * that could cause allocation failures below.
857 *
858 * Must be called with cpuset_rwsem held.
859 *
860 * The three key local variables below are:
861 * cp - cpuset pointer, used (together with pos_css) to perform a
862 * top-down scan of all cpusets. For our purposes, rebuilding
863 * the schedulers sched domains, we can ignore !is_sched_load_
864 * balance cpusets.
865 * csa - (for CpuSet Array) Array of pointers to all the cpusets
866 * that need to be load balanced, for convenient iterative
867 * access by the subsequent code that finds the best partition,
868 * i.e the set of domains (subsets) of CPUs such that the
869 * cpus_allowed of every cpuset marked is_sched_load_balance
870 * is a subset of one of these domains, while there are as
871 * many such domains as possible, each as small as possible.
872 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
873 * the kernel/sched/core.c routine partition_sched_domains() in a
874 * convenient format, that can be easily compared to the prior
875 * value to determine what partition elements (sched domains)
876 * were changed (added or removed.)
877 *
878 * Finding the best partition (set of domains):
879 * The triple nested loops below over i, j, k scan over the
880 * load balanced cpusets (using the array of cpuset pointers in
881 * csa[]) looking for pairs of cpusets that have overlapping
882 * cpus_allowed, but which don't have the same 'pn' partition
883 * number and gives them in the same partition number. It keeps
884 * looping on the 'restart' label until it can no longer find
885 * any such pairs.
886 *
887 * The union of the cpus_allowed masks from the set of
888 * all cpusets having the same 'pn' value then form the one
889 * element of the partition (one sched domain) to be passed to
890 * partition_sched_domains().
891 */
892static int generate_sched_domains(cpumask_var_t **domains,
893 struct sched_domain_attr **attributes)
894{
895 struct cpuset *cp; /* top-down scan of cpusets */
896 struct cpuset **csa; /* array of all cpuset ptrs */
897 int csn; /* how many cpuset ptrs in csa so far */
898 int i, j, k; /* indices for partition finding loops */
899 cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
900 struct sched_domain_attr *dattr; /* attributes for custom domains */
901 int ndoms = 0; /* number of sched domains in result */
902 int nslot; /* next empty doms[] struct cpumask slot */
903 struct cgroup_subsys_state *pos_css;
904 bool root_load_balance = is_sched_load_balance(&top_cpuset);
905
906 doms = NULL;
907 dattr = NULL;
908 csa = NULL;
909
910 /* Special case for the 99% of systems with one, full, sched domain */
911 if (root_load_balance && !top_cpuset.nr_subparts_cpus) {
912 ndoms = 1;
913 doms = alloc_sched_domains(ndoms);
914 if (!doms)
915 goto done;
916
917 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
918 if (dattr) {
919 *dattr = SD_ATTR_INIT;
920 update_domain_attr_tree(dattr, &top_cpuset);
921 }
922 cpumask_and(doms[0], top_cpuset.effective_cpus,
923 housekeeping_cpumask(HK_TYPE_DOMAIN));
924
925 goto done;
926 }
927
928 csa = kmalloc_array(nr_cpusets(), sizeof(cp), GFP_KERNEL);
929 if (!csa)
930 goto done;
931 csn = 0;
932
933 rcu_read_lock();
934 if (root_load_balance)
935 csa[csn++] = &top_cpuset;
936 cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
937 if (cp == &top_cpuset)
938 continue;
939 /*
940 * Continue traversing beyond @cp iff @cp has some CPUs and
941 * isn't load balancing. The former is obvious. The
942 * latter: All child cpusets contain a subset of the
943 * parent's cpus, so just skip them, and then we call
944 * update_domain_attr_tree() to calc relax_domain_level of
945 * the corresponding sched domain.
946 *
947 * If root is load-balancing, we can skip @cp if it
948 * is a subset of the root's effective_cpus.
949 */
950 if (!cpumask_empty(cp->cpus_allowed) &&
951 !(is_sched_load_balance(cp) &&
952 cpumask_intersects(cp->cpus_allowed,
953 housekeeping_cpumask(HK_TYPE_DOMAIN))))
954 continue;
955
956 if (root_load_balance &&
957 cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus))
958 continue;
959
960 if (is_sched_load_balance(cp) &&
961 !cpumask_empty(cp->effective_cpus))
962 csa[csn++] = cp;
963
964 /* skip @cp's subtree if not a partition root */
965 if (!is_partition_valid(cp))
966 pos_css = css_rightmost_descendant(pos_css);
967 }
968 rcu_read_unlock();
969
970 for (i = 0; i < csn; i++)
971 csa[i]->pn = i;
972 ndoms = csn;
973
974restart:
975 /* Find the best partition (set of sched domains) */
976 for (i = 0; i < csn; i++) {
977 struct cpuset *a = csa[i];
978 int apn = a->pn;
979
980 for (j = 0; j < csn; j++) {
981 struct cpuset *b = csa[j];
982 int bpn = b->pn;
983
984 if (apn != bpn && cpusets_overlap(a, b)) {
985 for (k = 0; k < csn; k++) {
986 struct cpuset *c = csa[k];
987
988 if (c->pn == bpn)
989 c->pn = apn;
990 }
991 ndoms--; /* one less element */
992 goto restart;
993 }
994 }
995 }
996
997 /*
998 * Now we know how many domains to create.
999 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
1000 */
1001 doms = alloc_sched_domains(ndoms);
1002 if (!doms)
1003 goto done;
1004
1005 /*
1006 * The rest of the code, including the scheduler, can deal with
1007 * dattr==NULL case. No need to abort if alloc fails.
1008 */
1009 dattr = kmalloc_array(ndoms, sizeof(struct sched_domain_attr),
1010 GFP_KERNEL);
1011
1012 for (nslot = 0, i = 0; i < csn; i++) {
1013 struct cpuset *a = csa[i];
1014 struct cpumask *dp;
1015 int apn = a->pn;
1016
1017 if (apn < 0) {
1018 /* Skip completed partitions */
1019 continue;
1020 }
1021
1022 dp = doms[nslot];
1023
1024 if (nslot == ndoms) {
1025 static int warnings = 10;
1026 if (warnings) {
1027 pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
1028 nslot, ndoms, csn, i, apn);
1029 warnings--;
1030 }
1031 continue;
1032 }
1033
1034 cpumask_clear(dp);
1035 if (dattr)
1036 *(dattr + nslot) = SD_ATTR_INIT;
1037 for (j = i; j < csn; j++) {
1038 struct cpuset *b = csa[j];
1039
1040 if (apn == b->pn) {
1041 cpumask_or(dp, dp, b->effective_cpus);
1042 cpumask_and(dp, dp, housekeeping_cpumask(HK_TYPE_DOMAIN));
1043 if (dattr)
1044 update_domain_attr_tree(dattr + nslot, b);
1045
1046 /* Done with this partition */
1047 b->pn = -1;
1048 }
1049 }
1050 nslot++;
1051 }
1052 BUG_ON(nslot != ndoms);
1053
1054done:
1055 kfree(csa);
1056
1057 /*
1058 * Fallback to the default domain if kmalloc() failed.
1059 * See comments in partition_sched_domains().
1060 */
1061 if (doms == NULL)
1062 ndoms = 1;
1063
1064 *domains = doms;
1065 *attributes = dattr;
1066 return ndoms;
1067}
1068
1069static void update_tasks_root_domain(struct cpuset *cs)
1070{
1071 struct css_task_iter it;
1072 struct task_struct *task;
1073
1074 css_task_iter_start(&cs->css, 0, &it);
1075
1076 while ((task = css_task_iter_next(&it)))
1077 dl_add_task_root_domain(task);
1078
1079 css_task_iter_end(&it);
1080}
1081
1082static void rebuild_root_domains(void)
1083{
1084 struct cpuset *cs = NULL;
1085 struct cgroup_subsys_state *pos_css;
1086
1087 percpu_rwsem_assert_held(&cpuset_rwsem);
1088 lockdep_assert_cpus_held();
1089 lockdep_assert_held(&sched_domains_mutex);
1090
1091 rcu_read_lock();
1092
1093 /*
1094 * Clear default root domain DL accounting, it will be computed again
1095 * if a task belongs to it.
1096 */
1097 dl_clear_root_domain(&def_root_domain);
1098
1099 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
1100
1101 if (cpumask_empty(cs->effective_cpus)) {
1102 pos_css = css_rightmost_descendant(pos_css);
1103 continue;
1104 }
1105
1106 css_get(&cs->css);
1107
1108 rcu_read_unlock();
1109
1110 update_tasks_root_domain(cs);
1111
1112 rcu_read_lock();
1113 css_put(&cs->css);
1114 }
1115 rcu_read_unlock();
1116}
1117
1118static void
1119partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
1120 struct sched_domain_attr *dattr_new)
1121{
1122 mutex_lock(&sched_domains_mutex);
1123 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
1124 rebuild_root_domains();
1125 mutex_unlock(&sched_domains_mutex);
1126}
1127
1128/*
1129 * Rebuild scheduler domains.
1130 *
1131 * If the flag 'sched_load_balance' of any cpuset with non-empty
1132 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
1133 * which has that flag enabled, or if any cpuset with a non-empty
1134 * 'cpus' is removed, then call this routine to rebuild the
1135 * scheduler's dynamic sched domains.
1136 *
1137 * Call with cpuset_rwsem held. Takes cpus_read_lock().
1138 */
1139static void rebuild_sched_domains_locked(void)
1140{
1141 struct cgroup_subsys_state *pos_css;
1142 struct sched_domain_attr *attr;
1143 cpumask_var_t *doms;
1144 struct cpuset *cs;
1145 int ndoms;
1146
1147 lockdep_assert_cpus_held();
1148 percpu_rwsem_assert_held(&cpuset_rwsem);
1149
1150 /*
1151 * If we have raced with CPU hotplug, return early to avoid
1152 * passing doms with offlined cpu to partition_sched_domains().
1153 * Anyways, cpuset_hotplug_workfn() will rebuild sched domains.
1154 *
1155 * With no CPUs in any subpartitions, top_cpuset's effective CPUs
1156 * should be the same as the active CPUs, so checking only top_cpuset
1157 * is enough to detect racing CPU offlines.
1158 */
1159 if (!top_cpuset.nr_subparts_cpus &&
1160 !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
1161 return;
1162
1163 /*
1164 * With subpartition CPUs, however, the effective CPUs of a partition
1165 * root should be only a subset of the active CPUs. Since a CPU in any
1166 * partition root could be offlined, all must be checked.
1167 */
1168 if (top_cpuset.nr_subparts_cpus) {
1169 rcu_read_lock();
1170 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
1171 if (!is_partition_valid(cs)) {
1172 pos_css = css_rightmost_descendant(pos_css);
1173 continue;
1174 }
1175 if (!cpumask_subset(cs->effective_cpus,
1176 cpu_active_mask)) {
1177 rcu_read_unlock();
1178 return;
1179 }
1180 }
1181 rcu_read_unlock();
1182 }
1183
1184 /* Generate domain masks and attrs */
1185 ndoms = generate_sched_domains(&doms, &attr);
1186
1187 /* Have scheduler rebuild the domains */
1188 partition_and_rebuild_sched_domains(ndoms, doms, attr);
1189}
1190#else /* !CONFIG_SMP */
1191static void rebuild_sched_domains_locked(void)
1192{
1193}
1194#endif /* CONFIG_SMP */
1195
1196void rebuild_sched_domains(void)
1197{
1198 cpus_read_lock();
1199 percpu_down_write(&cpuset_rwsem);
1200 rebuild_sched_domains_locked();
1201 percpu_up_write(&cpuset_rwsem);
1202 cpus_read_unlock();
1203}
1204
1205/**
1206 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
1207 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
1208 * @new_cpus: the temp variable for the new effective_cpus mask
1209 *
1210 * Iterate through each task of @cs updating its cpus_allowed to the
1211 * effective cpuset's. As this function is called with cpuset_rwsem held,
1212 * cpuset membership stays stable.
1213 */
1214static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
1215{
1216 struct css_task_iter it;
1217 struct task_struct *task;
1218 bool top_cs = cs == &top_cpuset;
1219
1220 css_task_iter_start(&cs->css, 0, &it);
1221 while ((task = css_task_iter_next(&it))) {
1222 /*
1223 * Percpu kthreads in top_cpuset are ignored
1224 */
1225 if (top_cs && (task->flags & PF_KTHREAD) &&
1226 kthread_is_per_cpu(task))
1227 continue;
1228
1229 cpumask_and(new_cpus, cs->effective_cpus,
1230 task_cpu_possible_mask(task));
1231 set_cpus_allowed_ptr(task, new_cpus);
1232 }
1233 css_task_iter_end(&it);
1234}
1235
1236/**
1237 * compute_effective_cpumask - Compute the effective cpumask of the cpuset
1238 * @new_cpus: the temp variable for the new effective_cpus mask
1239 * @cs: the cpuset the need to recompute the new effective_cpus mask
1240 * @parent: the parent cpuset
1241 *
1242 * If the parent has subpartition CPUs, include them in the list of
1243 * allowable CPUs in computing the new effective_cpus mask. Since offlined
1244 * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask
1245 * to mask those out.
1246 */
1247static void compute_effective_cpumask(struct cpumask *new_cpus,
1248 struct cpuset *cs, struct cpuset *parent)
1249{
1250 if (parent->nr_subparts_cpus) {
1251 cpumask_or(new_cpus, parent->effective_cpus,
1252 parent->subparts_cpus);
1253 cpumask_and(new_cpus, new_cpus, cs->cpus_allowed);
1254 cpumask_and(new_cpus, new_cpus, cpu_active_mask);
1255 } else {
1256 cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus);
1257 }
1258}
1259
1260/*
1261 * Commands for update_parent_subparts_cpumask
1262 */
1263enum subparts_cmd {
1264 partcmd_enable, /* Enable partition root */
1265 partcmd_disable, /* Disable partition root */
1266 partcmd_update, /* Update parent's subparts_cpus */
1267 partcmd_invalidate, /* Make partition invalid */
1268};
1269
1270static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1271 int turning_on);
1272/**
1273 * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
1274 * @cpuset: The cpuset that requests change in partition root state
1275 * @cmd: Partition root state change command
1276 * @newmask: Optional new cpumask for partcmd_update
1277 * @tmp: Temporary addmask and delmask
1278 * Return: 0 or a partition root state error code
1279 *
1280 * For partcmd_enable, the cpuset is being transformed from a non-partition
1281 * root to a partition root. The cpus_allowed mask of the given cpuset will
1282 * be put into parent's subparts_cpus and taken away from parent's
1283 * effective_cpus. The function will return 0 if all the CPUs listed in
1284 * cpus_allowed can be granted or an error code will be returned.
1285 *
1286 * For partcmd_disable, the cpuset is being transformed from a partition
1287 * root back to a non-partition root. Any CPUs in cpus_allowed that are in
1288 * parent's subparts_cpus will be taken away from that cpumask and put back
1289 * into parent's effective_cpus. 0 will always be returned.
1290 *
1291 * For partcmd_update, if the optional newmask is specified, the cpu list is
1292 * to be changed from cpus_allowed to newmask. Otherwise, cpus_allowed is
1293 * assumed to remain the same. The cpuset should either be a valid or invalid
1294 * partition root. The partition root state may change from valid to invalid
1295 * or vice versa. An error code will only be returned if transitioning from
1296 * invalid to valid violates the exclusivity rule.
1297 *
1298 * For partcmd_invalidate, the current partition will be made invalid.
1299 *
1300 * The partcmd_enable and partcmd_disable commands are used by
1301 * update_prstate(). An error code may be returned and the caller will check
1302 * for error.
1303 *
1304 * The partcmd_update command is used by update_cpumasks_hier() with newmask
1305 * NULL and update_cpumask() with newmask set. The partcmd_invalidate is used
1306 * by update_cpumask() with NULL newmask. In both cases, the callers won't
1307 * check for error and so partition_root_state and prs_error will be updated
1308 * directly.
1309 */
1310static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
1311 struct cpumask *newmask,
1312 struct tmpmasks *tmp)
1313{
1314 struct cpuset *parent = parent_cs(cs);
1315 int adding; /* Moving cpus from effective_cpus to subparts_cpus */
1316 int deleting; /* Moving cpus from subparts_cpus to effective_cpus */
1317 int old_prs, new_prs;
1318 int part_error = PERR_NONE; /* Partition error? */
1319
1320 percpu_rwsem_assert_held(&cpuset_rwsem);
1321
1322 /*
1323 * The parent must be a partition root.
1324 * The new cpumask, if present, or the current cpus_allowed must
1325 * not be empty.
1326 */
1327 if (!is_partition_valid(parent)) {
1328 return is_partition_invalid(parent)
1329 ? PERR_INVPARENT : PERR_NOTPART;
1330 }
1331 if ((newmask && cpumask_empty(newmask)) ||
1332 (!newmask && cpumask_empty(cs->cpus_allowed)))
1333 return PERR_CPUSEMPTY;
1334
1335 /*
1336 * new_prs will only be changed for the partcmd_update and
1337 * partcmd_invalidate commands.
1338 */
1339 adding = deleting = false;
1340 old_prs = new_prs = cs->partition_root_state;
1341 if (cmd == partcmd_enable) {
1342 /*
1343 * Enabling partition root is not allowed if cpus_allowed
1344 * doesn't overlap parent's cpus_allowed.
1345 */
1346 if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed))
1347 return PERR_INVCPUS;
1348
1349 /*
1350 * A parent can be left with no CPU as long as there is no
1351 * task directly associated with the parent partition.
1352 */
1353 if (cpumask_subset(parent->effective_cpus, cs->cpus_allowed) &&
1354 partition_is_populated(parent, cs))
1355 return PERR_NOCPUS;
1356
1357 cpumask_copy(tmp->addmask, cs->cpus_allowed);
1358 adding = true;
1359 } else if (cmd == partcmd_disable) {
1360 /*
1361 * Need to remove cpus from parent's subparts_cpus for valid
1362 * partition root.
1363 */
1364 deleting = !is_prs_invalid(old_prs) &&
1365 cpumask_and(tmp->delmask, cs->cpus_allowed,
1366 parent->subparts_cpus);
1367 } else if (cmd == partcmd_invalidate) {
1368 if (is_prs_invalid(old_prs))
1369 return 0;
1370
1371 /*
1372 * Make the current partition invalid. It is assumed that
1373 * invalidation is caused by violating cpu exclusivity rule.
1374 */
1375 deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
1376 parent->subparts_cpus);
1377 if (old_prs > 0) {
1378 new_prs = -old_prs;
1379 part_error = PERR_NOTEXCL;
1380 }
1381 } else if (newmask) {
1382 /*
1383 * partcmd_update with newmask:
1384 *
1385 * Compute add/delete mask to/from subparts_cpus
1386 *
1387 * delmask = cpus_allowed & ~newmask & parent->subparts_cpus
1388 * addmask = newmask & parent->cpus_allowed
1389 * & ~parent->subparts_cpus
1390 */
1391 cpumask_andnot(tmp->delmask, cs->cpus_allowed, newmask);
1392 deleting = cpumask_and(tmp->delmask, tmp->delmask,
1393 parent->subparts_cpus);
1394
1395 cpumask_and(tmp->addmask, newmask, parent->cpus_allowed);
1396 adding = cpumask_andnot(tmp->addmask, tmp->addmask,
1397 parent->subparts_cpus);
1398 /*
1399 * Make partition invalid if parent's effective_cpus could
1400 * become empty and there are tasks in the parent.
1401 */
1402 if (adding &&
1403 cpumask_subset(parent->effective_cpus, tmp->addmask) &&
1404 !cpumask_intersects(tmp->delmask, cpu_active_mask) &&
1405 partition_is_populated(parent, cs)) {
1406 part_error = PERR_NOCPUS;
1407 adding = false;
1408 deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
1409 parent->subparts_cpus);
1410 }
1411 } else {
1412 /*
1413 * partcmd_update w/o newmask:
1414 *
1415 * delmask = cpus_allowed & parent->subparts_cpus
1416 * addmask = cpus_allowed & parent->cpus_allowed
1417 * & ~parent->subparts_cpus
1418 *
1419 * This gets invoked either due to a hotplug event or from
1420 * update_cpumasks_hier(). This can cause the state of a
1421 * partition root to transition from valid to invalid or vice
1422 * versa. So we still need to compute the addmask and delmask.
1423
1424 * A partition error happens when:
1425 * 1) Cpuset is valid partition, but parent does not distribute
1426 * out any CPUs.
1427 * 2) Parent has tasks and all its effective CPUs will have
1428 * to be distributed out.
1429 */
1430 cpumask_and(tmp->addmask, cs->cpus_allowed,
1431 parent->cpus_allowed);
1432 adding = cpumask_andnot(tmp->addmask, tmp->addmask,
1433 parent->subparts_cpus);
1434
1435 if ((is_partition_valid(cs) && !parent->nr_subparts_cpus) ||
1436 (adding &&
1437 cpumask_subset(parent->effective_cpus, tmp->addmask) &&
1438 partition_is_populated(parent, cs))) {
1439 part_error = PERR_NOCPUS;
1440 adding = false;
1441 }
1442
1443 if (part_error && is_partition_valid(cs) &&
1444 parent->nr_subparts_cpus)
1445 deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
1446 parent->subparts_cpus);
1447 }
1448 if (part_error)
1449 WRITE_ONCE(cs->prs_err, part_error);
1450
1451 if (cmd == partcmd_update) {
1452 /*
1453 * Check for possible transition between valid and invalid
1454 * partition root.
1455 */
1456 switch (cs->partition_root_state) {
1457 case PRS_ROOT:
1458 case PRS_ISOLATED:
1459 if (part_error)
1460 new_prs = -old_prs;
1461 break;
1462 case PRS_INVALID_ROOT:
1463 case PRS_INVALID_ISOLATED:
1464 if (!part_error)
1465 new_prs = -old_prs;
1466 break;
1467 }
1468 }
1469
1470 if (!adding && !deleting && (new_prs == old_prs))
1471 return 0;
1472
1473 /*
1474 * Transitioning between invalid to valid or vice versa may require
1475 * changing CS_CPU_EXCLUSIVE and CS_SCHED_LOAD_BALANCE.
1476 */
1477 if (old_prs != new_prs) {
1478 if (is_prs_invalid(old_prs) && !is_cpu_exclusive(cs) &&
1479 (update_flag(CS_CPU_EXCLUSIVE, cs, 1) < 0))
1480 return PERR_NOTEXCL;
1481 if (is_prs_invalid(new_prs) && is_cpu_exclusive(cs))
1482 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
1483 }
1484
1485 /*
1486 * Change the parent's subparts_cpus.
1487 * Newly added CPUs will be removed from effective_cpus and
1488 * newly deleted ones will be added back to effective_cpus.
1489 */
1490 spin_lock_irq(&callback_lock);
1491 if (adding) {
1492 cpumask_or(parent->subparts_cpus,
1493 parent->subparts_cpus, tmp->addmask);
1494 cpumask_andnot(parent->effective_cpus,
1495 parent->effective_cpus, tmp->addmask);
1496 }
1497 if (deleting) {
1498 cpumask_andnot(parent->subparts_cpus,
1499 parent->subparts_cpus, tmp->delmask);
1500 /*
1501 * Some of the CPUs in subparts_cpus might have been offlined.
1502 */
1503 cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask);
1504 cpumask_or(parent->effective_cpus,
1505 parent->effective_cpus, tmp->delmask);
1506 }
1507
1508 parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
1509
1510 if (old_prs != new_prs)
1511 cs->partition_root_state = new_prs;
1512
1513 spin_unlock_irq(&callback_lock);
1514
1515 if (adding || deleting)
1516 update_tasks_cpumask(parent, tmp->new_cpus);
1517
1518 /*
1519 * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary.
1520 * rebuild_sched_domains_locked() may be called.
1521 */
1522 if (old_prs != new_prs) {
1523 if (old_prs == PRS_ISOLATED)
1524 update_flag(CS_SCHED_LOAD_BALANCE, cs, 1);
1525 else if (new_prs == PRS_ISOLATED)
1526 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1527 }
1528 notify_partition_change(cs, old_prs);
1529 return 0;
1530}
1531
1532/*
1533 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
1534 * @cs: the cpuset to consider
1535 * @tmp: temp variables for calculating effective_cpus & partition setup
1536 * @force: don't skip any descendant cpusets if set
1537 *
1538 * When configured cpumask is changed, the effective cpumasks of this cpuset
1539 * and all its descendants need to be updated.
1540 *
1541 * On legacy hierarchy, effective_cpus will be the same with cpu_allowed.
1542 *
1543 * Called with cpuset_rwsem held
1544 */
1545static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
1546 bool force)
1547{
1548 struct cpuset *cp;
1549 struct cgroup_subsys_state *pos_css;
1550 bool need_rebuild_sched_domains = false;
1551 int old_prs, new_prs;
1552
1553 rcu_read_lock();
1554 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1555 struct cpuset *parent = parent_cs(cp);
1556 bool update_parent = false;
1557
1558 compute_effective_cpumask(tmp->new_cpus, cp, parent);
1559
1560 /*
1561 * If it becomes empty, inherit the effective mask of the
1562 * parent, which is guaranteed to have some CPUs unless
1563 * it is a partition root that has explicitly distributed
1564 * out all its CPUs.
1565 */
1566 if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) {
1567 if (is_partition_valid(cp) &&
1568 cpumask_equal(cp->cpus_allowed, cp->subparts_cpus))
1569 goto update_parent_subparts;
1570
1571 cpumask_copy(tmp->new_cpus, parent->effective_cpus);
1572 if (!cp->use_parent_ecpus) {
1573 cp->use_parent_ecpus = true;
1574 parent->child_ecpus_count++;
1575 }
1576 } else if (cp->use_parent_ecpus) {
1577 cp->use_parent_ecpus = false;
1578 WARN_ON_ONCE(!parent->child_ecpus_count);
1579 parent->child_ecpus_count--;
1580 }
1581
1582 /*
1583 * Skip the whole subtree if the cpumask remains the same
1584 * and has no partition root state and force flag not set.
1585 */
1586 if (!cp->partition_root_state && !force &&
1587 cpumask_equal(tmp->new_cpus, cp->effective_cpus)) {
1588 pos_css = css_rightmost_descendant(pos_css);
1589 continue;
1590 }
1591
1592update_parent_subparts:
1593 /*
1594 * update_parent_subparts_cpumask() should have been called
1595 * for cs already in update_cpumask(). We should also call
1596 * update_tasks_cpumask() again for tasks in the parent
1597 * cpuset if the parent's subparts_cpus changes.
1598 */
1599 old_prs = new_prs = cp->partition_root_state;
1600 if ((cp != cs) && old_prs) {
1601 switch (parent->partition_root_state) {
1602 case PRS_ROOT:
1603 case PRS_ISOLATED:
1604 update_parent = true;
1605 break;
1606
1607 default:
1608 /*
1609 * When parent is not a partition root or is
1610 * invalid, child partition roots become
1611 * invalid too.
1612 */
1613 if (is_partition_valid(cp))
1614 new_prs = -cp->partition_root_state;
1615 WRITE_ONCE(cp->prs_err,
1616 is_partition_invalid(parent)
1617 ? PERR_INVPARENT : PERR_NOTPART);
1618 break;
1619 }
1620 }
1621
1622 if (!css_tryget_online(&cp->css))
1623 continue;
1624 rcu_read_unlock();
1625
1626 if (update_parent) {
1627 update_parent_subparts_cpumask(cp, partcmd_update, NULL,
1628 tmp);
1629 /*
1630 * The cpuset partition_root_state may become
1631 * invalid. Capture it.
1632 */
1633 new_prs = cp->partition_root_state;
1634 }
1635
1636 spin_lock_irq(&callback_lock);
1637
1638 if (cp->nr_subparts_cpus && !is_partition_valid(cp)) {
1639 /*
1640 * Put all active subparts_cpus back to effective_cpus.
1641 */
1642 cpumask_or(tmp->new_cpus, tmp->new_cpus,
1643 cp->subparts_cpus);
1644 cpumask_and(tmp->new_cpus, tmp->new_cpus,
1645 cpu_active_mask);
1646 cp->nr_subparts_cpus = 0;
1647 cpumask_clear(cp->subparts_cpus);
1648 }
1649
1650 cpumask_copy(cp->effective_cpus, tmp->new_cpus);
1651 if (cp->nr_subparts_cpus) {
1652 /*
1653 * Make sure that effective_cpus & subparts_cpus
1654 * are mutually exclusive.
1655 */
1656 cpumask_andnot(cp->effective_cpus, cp->effective_cpus,
1657 cp->subparts_cpus);
1658 }
1659
1660 cp->partition_root_state = new_prs;
1661 spin_unlock_irq(&callback_lock);
1662
1663 notify_partition_change(cp, old_prs);
1664
1665 WARN_ON(!is_in_v2_mode() &&
1666 !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
1667
1668 update_tasks_cpumask(cp, tmp->new_cpus);
1669
1670 /*
1671 * On legacy hierarchy, if the effective cpumask of any non-
1672 * empty cpuset is changed, we need to rebuild sched domains.
1673 * On default hierarchy, the cpuset needs to be a partition
1674 * root as well.
1675 */
1676 if (!cpumask_empty(cp->cpus_allowed) &&
1677 is_sched_load_balance(cp) &&
1678 (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
1679 is_partition_valid(cp)))
1680 need_rebuild_sched_domains = true;
1681
1682 rcu_read_lock();
1683 css_put(&cp->css);
1684 }
1685 rcu_read_unlock();
1686
1687 if (need_rebuild_sched_domains)
1688 rebuild_sched_domains_locked();
1689}
1690
1691/**
1692 * update_sibling_cpumasks - Update siblings cpumasks
1693 * @parent: Parent cpuset
1694 * @cs: Current cpuset
1695 * @tmp: Temp variables
1696 */
1697static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
1698 struct tmpmasks *tmp)
1699{
1700 struct cpuset *sibling;
1701 struct cgroup_subsys_state *pos_css;
1702
1703 percpu_rwsem_assert_held(&cpuset_rwsem);
1704
1705 /*
1706 * Check all its siblings and call update_cpumasks_hier()
1707 * if their use_parent_ecpus flag is set in order for them
1708 * to use the right effective_cpus value.
1709 *
1710 * The update_cpumasks_hier() function may sleep. So we have to
1711 * release the RCU read lock before calling it.
1712 */
1713 rcu_read_lock();
1714 cpuset_for_each_child(sibling, pos_css, parent) {
1715 if (sibling == cs)
1716 continue;
1717 if (!sibling->use_parent_ecpus)
1718 continue;
1719 if (!css_tryget_online(&sibling->css))
1720 continue;
1721
1722 rcu_read_unlock();
1723 update_cpumasks_hier(sibling, tmp, false);
1724 rcu_read_lock();
1725 css_put(&sibling->css);
1726 }
1727 rcu_read_unlock();
1728}
1729
1730/**
1731 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
1732 * @cs: the cpuset to consider
1733 * @trialcs: trial cpuset
1734 * @buf: buffer of cpu numbers written to this cpuset
1735 */
1736static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
1737 const char *buf)
1738{
1739 int retval;
1740 struct tmpmasks tmp;
1741 bool invalidate = false;
1742
1743 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
1744 if (cs == &top_cpuset)
1745 return -EACCES;
1746
1747 /*
1748 * An empty cpus_allowed is ok only if the cpuset has no tasks.
1749 * Since cpulist_parse() fails on an empty mask, we special case
1750 * that parsing. The validate_change() call ensures that cpusets
1751 * with tasks have cpus.
1752 */
1753 if (!*buf) {
1754 cpumask_clear(trialcs->cpus_allowed);
1755 } else {
1756 retval = cpulist_parse(buf, trialcs->cpus_allowed);
1757 if (retval < 0)
1758 return retval;
1759
1760 if (!cpumask_subset(trialcs->cpus_allowed,
1761 top_cpuset.cpus_allowed))
1762 return -EINVAL;
1763 }
1764
1765 /* Nothing to do if the cpus didn't change */
1766 if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
1767 return 0;
1768
1769#ifdef CONFIG_CPUMASK_OFFSTACK
1770 /*
1771 * Use the cpumasks in trialcs for tmpmasks when they are pointers
1772 * to allocated cpumasks.
1773 */
1774 tmp.addmask = trialcs->subparts_cpus;
1775 tmp.delmask = trialcs->effective_cpus;
1776 tmp.new_cpus = trialcs->cpus_allowed;
1777#endif
1778
1779 retval = validate_change(cs, trialcs);
1780
1781 if ((retval == -EINVAL) && cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
1782 struct cpuset *cp, *parent;
1783 struct cgroup_subsys_state *css;
1784
1785 /*
1786 * The -EINVAL error code indicates that partition sibling
1787 * CPU exclusivity rule has been violated. We still allow
1788 * the cpumask change to proceed while invalidating the
1789 * partition. However, any conflicting sibling partitions
1790 * have to be marked as invalid too.
1791 */
1792 invalidate = true;
1793 rcu_read_lock();
1794 parent = parent_cs(cs);
1795 cpuset_for_each_child(cp, css, parent)
1796 if (is_partition_valid(cp) &&
1797 cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) {
1798 rcu_read_unlock();
1799 update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp);
1800 rcu_read_lock();
1801 }
1802 rcu_read_unlock();
1803 retval = 0;
1804 }
1805 if (retval < 0)
1806 return retval;
1807
1808 if (cs->partition_root_state) {
1809 if (invalidate)
1810 update_parent_subparts_cpumask(cs, partcmd_invalidate,
1811 NULL, &tmp);
1812 else
1813 update_parent_subparts_cpumask(cs, partcmd_update,
1814 trialcs->cpus_allowed, &tmp);
1815 }
1816
1817 compute_effective_cpumask(trialcs->effective_cpus, trialcs,
1818 parent_cs(cs));
1819 spin_lock_irq(&callback_lock);
1820 cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
1821
1822 /*
1823 * Make sure that subparts_cpus, if not empty, is a subset of
1824 * cpus_allowed. Clear subparts_cpus if partition not valid or
1825 * empty effective cpus with tasks.
1826 */
1827 if (cs->nr_subparts_cpus) {
1828 if (!is_partition_valid(cs) ||
1829 (cpumask_subset(trialcs->effective_cpus, cs->subparts_cpus) &&
1830 partition_is_populated(cs, NULL))) {
1831 cs->nr_subparts_cpus = 0;
1832 cpumask_clear(cs->subparts_cpus);
1833 } else {
1834 cpumask_and(cs->subparts_cpus, cs->subparts_cpus,
1835 cs->cpus_allowed);
1836 cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
1837 }
1838 }
1839 spin_unlock_irq(&callback_lock);
1840
1841 /* effective_cpus will be updated here */
1842 update_cpumasks_hier(cs, &tmp, false);
1843
1844 if (cs->partition_root_state) {
1845 struct cpuset *parent = parent_cs(cs);
1846
1847 /*
1848 * For partition root, update the cpumasks of sibling
1849 * cpusets if they use parent's effective_cpus.
1850 */
1851 if (parent->child_ecpus_count)
1852 update_sibling_cpumasks(parent, cs, &tmp);
1853 }
1854 return 0;
1855}
1856
1857/*
1858 * Migrate memory region from one set of nodes to another. This is
1859 * performed asynchronously as it can be called from process migration path
1860 * holding locks involved in process management. All mm migrations are
1861 * performed in the queued order and can be waited for by flushing
1862 * cpuset_migrate_mm_wq.
1863 */
1864
1865struct cpuset_migrate_mm_work {
1866 struct work_struct work;
1867 struct mm_struct *mm;
1868 nodemask_t from;
1869 nodemask_t to;
1870};
1871
1872static void cpuset_migrate_mm_workfn(struct work_struct *work)
1873{
1874 struct cpuset_migrate_mm_work *mwork =
1875 container_of(work, struct cpuset_migrate_mm_work, work);
1876
1877 /* on a wq worker, no need to worry about %current's mems_allowed */
1878 do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
1879 mmput(mwork->mm);
1880 kfree(mwork);
1881}
1882
1883static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
1884 const nodemask_t *to)
1885{
1886 struct cpuset_migrate_mm_work *mwork;
1887
1888 if (nodes_equal(*from, *to)) {
1889 mmput(mm);
1890 return;
1891 }
1892
1893 mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
1894 if (mwork) {
1895 mwork->mm = mm;
1896 mwork->from = *from;
1897 mwork->to = *to;
1898 INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
1899 queue_work(cpuset_migrate_mm_wq, &mwork->work);
1900 } else {
1901 mmput(mm);
1902 }
1903}
1904
1905static void cpuset_post_attach(void)
1906{
1907 flush_workqueue(cpuset_migrate_mm_wq);
1908}
1909
1910/*
1911 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
1912 * @tsk: the task to change
1913 * @newmems: new nodes that the task will be set
1914 *
1915 * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed
1916 * and rebind an eventual tasks' mempolicy. If the task is allocating in
1917 * parallel, it might temporarily see an empty intersection, which results in
1918 * a seqlock check and retry before OOM or allocation failure.
1919 */
1920static void cpuset_change_task_nodemask(struct task_struct *tsk,
1921 nodemask_t *newmems)
1922{
1923 task_lock(tsk);
1924
1925 local_irq_disable();
1926 write_seqcount_begin(&tsk->mems_allowed_seq);
1927
1928 nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1929 mpol_rebind_task(tsk, newmems);
1930 tsk->mems_allowed = *newmems;
1931
1932 write_seqcount_end(&tsk->mems_allowed_seq);
1933 local_irq_enable();
1934
1935 task_unlock(tsk);
1936}
1937
1938static void *cpuset_being_rebound;
1939
1940/**
1941 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1942 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1943 *
1944 * Iterate through each task of @cs updating its mems_allowed to the
1945 * effective cpuset's. As this function is called with cpuset_rwsem held,
1946 * cpuset membership stays stable.
1947 */
1948static void update_tasks_nodemask(struct cpuset *cs)
1949{
1950 static nodemask_t newmems; /* protected by cpuset_rwsem */
1951 struct css_task_iter it;
1952 struct task_struct *task;
1953
1954 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1955
1956 guarantee_online_mems(cs, &newmems);
1957
1958 /*
1959 * The mpol_rebind_mm() call takes mmap_lock, which we couldn't
1960 * take while holding tasklist_lock. Forks can happen - the
1961 * mpol_dup() cpuset_being_rebound check will catch such forks,
1962 * and rebind their vma mempolicies too. Because we still hold
1963 * the global cpuset_rwsem, we know that no other rebind effort
1964 * will be contending for the global variable cpuset_being_rebound.
1965 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1966 * is idempotent. Also migrate pages in each mm to new nodes.
1967 */
1968 css_task_iter_start(&cs->css, 0, &it);
1969 while ((task = css_task_iter_next(&it))) {
1970 struct mm_struct *mm;
1971 bool migrate;
1972
1973 cpuset_change_task_nodemask(task, &newmems);
1974
1975 mm = get_task_mm(task);
1976 if (!mm)
1977 continue;
1978
1979 migrate = is_memory_migrate(cs);
1980
1981 mpol_rebind_mm(mm, &cs->mems_allowed);
1982 if (migrate)
1983 cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1984 else
1985 mmput(mm);
1986 }
1987 css_task_iter_end(&it);
1988
1989 /*
1990 * All the tasks' nodemasks have been updated, update
1991 * cs->old_mems_allowed.
1992 */
1993 cs->old_mems_allowed = newmems;
1994
1995 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1996 cpuset_being_rebound = NULL;
1997}
1998
1999/*
2000 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
2001 * @cs: the cpuset to consider
2002 * @new_mems: a temp variable for calculating new effective_mems
2003 *
2004 * When configured nodemask is changed, the effective nodemasks of this cpuset
2005 * and all its descendants need to be updated.
2006 *
2007 * On legacy hierarchy, effective_mems will be the same with mems_allowed.
2008 *
2009 * Called with cpuset_rwsem held
2010 */
2011static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
2012{
2013 struct cpuset *cp;
2014 struct cgroup_subsys_state *pos_css;
2015
2016 rcu_read_lock();
2017 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
2018 struct cpuset *parent = parent_cs(cp);
2019
2020 nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
2021
2022 /*
2023 * If it becomes empty, inherit the effective mask of the
2024 * parent, which is guaranteed to have some MEMs.
2025 */
2026 if (is_in_v2_mode() && nodes_empty(*new_mems))
2027 *new_mems = parent->effective_mems;
2028
2029 /* Skip the whole subtree if the nodemask remains the same. */
2030 if (nodes_equal(*new_mems, cp->effective_mems)) {
2031 pos_css = css_rightmost_descendant(pos_css);
2032 continue;
2033 }
2034
2035 if (!css_tryget_online(&cp->css))
2036 continue;
2037 rcu_read_unlock();
2038
2039 spin_lock_irq(&callback_lock);
2040 cp->effective_mems = *new_mems;
2041 spin_unlock_irq(&callback_lock);
2042
2043 WARN_ON(!is_in_v2_mode() &&
2044 !nodes_equal(cp->mems_allowed, cp->effective_mems));
2045
2046 update_tasks_nodemask(cp);
2047
2048 rcu_read_lock();
2049 css_put(&cp->css);
2050 }
2051 rcu_read_unlock();
2052}
2053
2054/*
2055 * Handle user request to change the 'mems' memory placement
2056 * of a cpuset. Needs to validate the request, update the
2057 * cpusets mems_allowed, and for each task in the cpuset,
2058 * update mems_allowed and rebind task's mempolicy and any vma
2059 * mempolicies and if the cpuset is marked 'memory_migrate',
2060 * migrate the tasks pages to the new memory.
2061 *
2062 * Call with cpuset_rwsem held. May take callback_lock during call.
2063 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
2064 * lock each such tasks mm->mmap_lock, scan its vma's and rebind
2065 * their mempolicies to the cpusets new mems_allowed.
2066 */
2067static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
2068 const char *buf)
2069{
2070 int retval;
2071
2072 /*
2073 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
2074 * it's read-only
2075 */
2076 if (cs == &top_cpuset) {
2077 retval = -EACCES;
2078 goto done;
2079 }
2080
2081 /*
2082 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
2083 * Since nodelist_parse() fails on an empty mask, we special case
2084 * that parsing. The validate_change() call ensures that cpusets
2085 * with tasks have memory.
2086 */
2087 if (!*buf) {
2088 nodes_clear(trialcs->mems_allowed);
2089 } else {
2090 retval = nodelist_parse(buf, trialcs->mems_allowed);
2091 if (retval < 0)
2092 goto done;
2093
2094 if (!nodes_subset(trialcs->mems_allowed,
2095 top_cpuset.mems_allowed)) {
2096 retval = -EINVAL;
2097 goto done;
2098 }
2099 }
2100
2101 if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
2102 retval = 0; /* Too easy - nothing to do */
2103 goto done;
2104 }
2105 retval = validate_change(cs, trialcs);
2106 if (retval < 0)
2107 goto done;
2108
2109 check_insane_mems_config(&trialcs->mems_allowed);
2110
2111 spin_lock_irq(&callback_lock);
2112 cs->mems_allowed = trialcs->mems_allowed;
2113 spin_unlock_irq(&callback_lock);
2114
2115 /* use trialcs->mems_allowed as a temp variable */
2116 update_nodemasks_hier(cs, &trialcs->mems_allowed);
2117done:
2118 return retval;
2119}
2120
2121bool current_cpuset_is_being_rebound(void)
2122{
2123 bool ret;
2124
2125 rcu_read_lock();
2126 ret = task_cs(current) == cpuset_being_rebound;
2127 rcu_read_unlock();
2128
2129 return ret;
2130}
2131
2132static int update_relax_domain_level(struct cpuset *cs, s64 val)
2133{
2134#ifdef CONFIG_SMP
2135 if (val < -1 || val >= sched_domain_level_max)
2136 return -EINVAL;
2137#endif
2138
2139 if (val != cs->relax_domain_level) {
2140 cs->relax_domain_level = val;
2141 if (!cpumask_empty(cs->cpus_allowed) &&
2142 is_sched_load_balance(cs))
2143 rebuild_sched_domains_locked();
2144 }
2145
2146 return 0;
2147}
2148
2149/**
2150 * update_tasks_flags - update the spread flags of tasks in the cpuset.
2151 * @cs: the cpuset in which each task's spread flags needs to be changed
2152 *
2153 * Iterate through each task of @cs updating its spread flags. As this
2154 * function is called with cpuset_rwsem held, cpuset membership stays
2155 * stable.
2156 */
2157static void update_tasks_flags(struct cpuset *cs)
2158{
2159 struct css_task_iter it;
2160 struct task_struct *task;
2161
2162 css_task_iter_start(&cs->css, 0, &it);
2163 while ((task = css_task_iter_next(&it)))
2164 cpuset_update_task_spread_flags(cs, task);
2165 css_task_iter_end(&it);
2166}
2167
2168/*
2169 * update_flag - read a 0 or a 1 in a file and update associated flag
2170 * bit: the bit to update (see cpuset_flagbits_t)
2171 * cs: the cpuset to update
2172 * turning_on: whether the flag is being set or cleared
2173 *
2174 * Call with cpuset_rwsem held.
2175 */
2176
2177static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
2178 int turning_on)
2179{
2180 struct cpuset *trialcs;
2181 int balance_flag_changed;
2182 int spread_flag_changed;
2183 int err;
2184
2185 trialcs = alloc_trial_cpuset(cs);
2186 if (!trialcs)
2187 return -ENOMEM;
2188
2189 if (turning_on)
2190 set_bit(bit, &trialcs->flags);
2191 else
2192 clear_bit(bit, &trialcs->flags);
2193
2194 err = validate_change(cs, trialcs);
2195 if (err < 0)
2196 goto out;
2197
2198 balance_flag_changed = (is_sched_load_balance(cs) !=
2199 is_sched_load_balance(trialcs));
2200
2201 spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
2202 || (is_spread_page(cs) != is_spread_page(trialcs)));
2203
2204 spin_lock_irq(&callback_lock);
2205 cs->flags = trialcs->flags;
2206 spin_unlock_irq(&callback_lock);
2207
2208 if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
2209 rebuild_sched_domains_locked();
2210
2211 if (spread_flag_changed)
2212 update_tasks_flags(cs);
2213out:
2214 free_cpuset(trialcs);
2215 return err;
2216}
2217
2218/**
2219 * update_prstate - update partition_root_state
2220 * @cs: the cpuset to update
2221 * @new_prs: new partition root state
2222 * Return: 0 if successful, != 0 if error
2223 *
2224 * Call with cpuset_rwsem held.
2225 */
2226static int update_prstate(struct cpuset *cs, int new_prs)
2227{
2228 int err = PERR_NONE, old_prs = cs->partition_root_state;
2229 bool sched_domain_rebuilt = false;
2230 struct cpuset *parent = parent_cs(cs);
2231 struct tmpmasks tmpmask;
2232
2233 if (old_prs == new_prs)
2234 return 0;
2235
2236 /*
2237 * For a previously invalid partition root, leave it at being
2238 * invalid if new_prs is not "member".
2239 */
2240 if (new_prs && is_prs_invalid(old_prs)) {
2241 cs->partition_root_state = -new_prs;
2242 return 0;
2243 }
2244
2245 if (alloc_cpumasks(NULL, &tmpmask))
2246 return -ENOMEM;
2247
2248 if (!old_prs) {
2249 /*
2250 * Turning on partition root requires setting the
2251 * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed
2252 * cannot be empty.
2253 */
2254 if (cpumask_empty(cs->cpus_allowed)) {
2255 err = PERR_CPUSEMPTY;
2256 goto out;
2257 }
2258
2259 err = update_flag(CS_CPU_EXCLUSIVE, cs, 1);
2260 if (err) {
2261 err = PERR_NOTEXCL;
2262 goto out;
2263 }
2264
2265 err = update_parent_subparts_cpumask(cs, partcmd_enable,
2266 NULL, &tmpmask);
2267 if (err) {
2268 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
2269 goto out;
2270 }
2271
2272 if (new_prs == PRS_ISOLATED) {
2273 /*
2274 * Disable the load balance flag should not return an
2275 * error unless the system is running out of memory.
2276 */
2277 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
2278 sched_domain_rebuilt = true;
2279 }
2280 } else if (old_prs && new_prs) {
2281 /*
2282 * A change in load balance state only, no change in cpumasks.
2283 */
2284 update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED));
2285 sched_domain_rebuilt = true;
2286 goto out; /* Sched domain is rebuilt in update_flag() */
2287 } else {
2288 /*
2289 * Switching back to member is always allowed even if it
2290 * disables child partitions.
2291 */
2292 update_parent_subparts_cpumask(cs, partcmd_disable, NULL,
2293 &tmpmask);
2294
2295 /*
2296 * If there are child partitions, they will all become invalid.
2297 */
2298 if (unlikely(cs->nr_subparts_cpus)) {
2299 spin_lock_irq(&callback_lock);
2300 cs->nr_subparts_cpus = 0;
2301 cpumask_clear(cs->subparts_cpus);
2302 compute_effective_cpumask(cs->effective_cpus, cs, parent);
2303 spin_unlock_irq(&callback_lock);
2304 }
2305
2306 /* Turning off CS_CPU_EXCLUSIVE will not return error */
2307 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
2308
2309 if (!is_sched_load_balance(cs)) {
2310 /* Make sure load balance is on */
2311 update_flag(CS_SCHED_LOAD_BALANCE, cs, 1);
2312 sched_domain_rebuilt = true;
2313 }
2314 }
2315
2316 update_tasks_cpumask(parent, tmpmask.new_cpus);
2317
2318 if (parent->child_ecpus_count)
2319 update_sibling_cpumasks(parent, cs, &tmpmask);
2320
2321 if (!sched_domain_rebuilt)
2322 rebuild_sched_domains_locked();
2323out:
2324 /*
2325 * Make partition invalid if an error happen
2326 */
2327 if (err)
2328 new_prs = -new_prs;
2329 spin_lock_irq(&callback_lock);
2330 cs->partition_root_state = new_prs;
2331 WRITE_ONCE(cs->prs_err, err);
2332 spin_unlock_irq(&callback_lock);
2333 /*
2334 * Update child cpusets, if present.
2335 * Force update if switching back to member.
2336 */
2337 if (!list_empty(&cs->css.children))
2338 update_cpumasks_hier(cs, &tmpmask, !new_prs);
2339
2340 notify_partition_change(cs, old_prs);
2341 free_cpumasks(NULL, &tmpmask);
2342 return 0;
2343}
2344
2345/*
2346 * Frequency meter - How fast is some event occurring?
2347 *
2348 * These routines manage a digitally filtered, constant time based,
2349 * event frequency meter. There are four routines:
2350 * fmeter_init() - initialize a frequency meter.
2351 * fmeter_markevent() - called each time the event happens.
2352 * fmeter_getrate() - returns the recent rate of such events.
2353 * fmeter_update() - internal routine used to update fmeter.
2354 *
2355 * A common data structure is passed to each of these routines,
2356 * which is used to keep track of the state required to manage the
2357 * frequency meter and its digital filter.
2358 *
2359 * The filter works on the number of events marked per unit time.
2360 * The filter is single-pole low-pass recursive (IIR). The time unit
2361 * is 1 second. Arithmetic is done using 32-bit integers scaled to
2362 * simulate 3 decimal digits of precision (multiplied by 1000).
2363 *
2364 * With an FM_COEF of 933, and a time base of 1 second, the filter
2365 * has a half-life of 10 seconds, meaning that if the events quit
2366 * happening, then the rate returned from the fmeter_getrate()
2367 * will be cut in half each 10 seconds, until it converges to zero.
2368 *
2369 * It is not worth doing a real infinitely recursive filter. If more
2370 * than FM_MAXTICKS ticks have elapsed since the last filter event,
2371 * just compute FM_MAXTICKS ticks worth, by which point the level
2372 * will be stable.
2373 *
2374 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
2375 * arithmetic overflow in the fmeter_update() routine.
2376 *
2377 * Given the simple 32 bit integer arithmetic used, this meter works
2378 * best for reporting rates between one per millisecond (msec) and
2379 * one per 32 (approx) seconds. At constant rates faster than one
2380 * per msec it maxes out at values just under 1,000,000. At constant
2381 * rates between one per msec, and one per second it will stabilize
2382 * to a value N*1000, where N is the rate of events per second.
2383 * At constant rates between one per second and one per 32 seconds,
2384 * it will be choppy, moving up on the seconds that have an event,
2385 * and then decaying until the next event. At rates slower than
2386 * about one in 32 seconds, it decays all the way back to zero between
2387 * each event.
2388 */
2389
2390#define FM_COEF 933 /* coefficient for half-life of 10 secs */
2391#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
2392#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
2393#define FM_SCALE 1000 /* faux fixed point scale */
2394
2395/* Initialize a frequency meter */
2396static void fmeter_init(struct fmeter *fmp)
2397{
2398 fmp->cnt = 0;
2399 fmp->val = 0;
2400 fmp->time = 0;
2401 spin_lock_init(&fmp->lock);
2402}
2403
2404/* Internal meter update - process cnt events and update value */
2405static void fmeter_update(struct fmeter *fmp)
2406{
2407 time64_t now;
2408 u32 ticks;
2409
2410 now = ktime_get_seconds();
2411 ticks = now - fmp->time;
2412
2413 if (ticks == 0)
2414 return;
2415
2416 ticks = min(FM_MAXTICKS, ticks);
2417 while (ticks-- > 0)
2418 fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
2419 fmp->time = now;
2420
2421 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
2422 fmp->cnt = 0;
2423}
2424
2425/* Process any previous ticks, then bump cnt by one (times scale). */
2426static void fmeter_markevent(struct fmeter *fmp)
2427{
2428 spin_lock(&fmp->lock);
2429 fmeter_update(fmp);
2430 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
2431 spin_unlock(&fmp->lock);
2432}
2433
2434/* Process any previous ticks, then return current value. */
2435static int fmeter_getrate(struct fmeter *fmp)
2436{
2437 int val;
2438
2439 spin_lock(&fmp->lock);
2440 fmeter_update(fmp);
2441 val = fmp->val;
2442 spin_unlock(&fmp->lock);
2443 return val;
2444}
2445
2446static struct cpuset *cpuset_attach_old_cs;
2447
2448/* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */
2449static int cpuset_can_attach(struct cgroup_taskset *tset)
2450{
2451 struct cgroup_subsys_state *css;
2452 struct cpuset *cs;
2453 struct task_struct *task;
2454 int ret;
2455
2456 /* used later by cpuset_attach() */
2457 cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
2458 cs = css_cs(css);
2459
2460 percpu_down_write(&cpuset_rwsem);
2461
2462 /* allow moving tasks into an empty cpuset if on default hierarchy */
2463 ret = -ENOSPC;
2464 if (!is_in_v2_mode() &&
2465 (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
2466 goto out_unlock;
2467
2468 /*
2469 * Task cannot be moved to a cpuset with empty effective cpus.
2470 */
2471 if (cpumask_empty(cs->effective_cpus))
2472 goto out_unlock;
2473
2474 cgroup_taskset_for_each(task, css, tset) {
2475 ret = task_can_attach(task, cs->effective_cpus);
2476 if (ret)
2477 goto out_unlock;
2478 ret = security_task_setscheduler(task);
2479 if (ret)
2480 goto out_unlock;
2481 }
2482
2483 /*
2484 * Mark attach is in progress. This makes validate_change() fail
2485 * changes which zero cpus/mems_allowed.
2486 */
2487 cs->attach_in_progress++;
2488 ret = 0;
2489out_unlock:
2490 percpu_up_write(&cpuset_rwsem);
2491 return ret;
2492}
2493
2494static void cpuset_cancel_attach(struct cgroup_taskset *tset)
2495{
2496 struct cgroup_subsys_state *css;
2497
2498 cgroup_taskset_first(tset, &css);
2499
2500 percpu_down_write(&cpuset_rwsem);
2501 css_cs(css)->attach_in_progress--;
2502 percpu_up_write(&cpuset_rwsem);
2503}
2504
2505/*
2506 * Protected by cpuset_rwsem. cpus_attach is used only by cpuset_attach()
2507 * but we can't allocate it dynamically there. Define it global and
2508 * allocate from cpuset_init().
2509 */
2510static cpumask_var_t cpus_attach;
2511
2512static void cpuset_attach(struct cgroup_taskset *tset)
2513{
2514 /* static buf protected by cpuset_rwsem */
2515 static nodemask_t cpuset_attach_nodemask_to;
2516 struct task_struct *task;
2517 struct task_struct *leader;
2518 struct cgroup_subsys_state *css;
2519 struct cpuset *cs;
2520 struct cpuset *oldcs = cpuset_attach_old_cs;
2521 bool cpus_updated, mems_updated;
2522
2523 cgroup_taskset_first(tset, &css);
2524 cs = css_cs(css);
2525
2526 lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */
2527 percpu_down_write(&cpuset_rwsem);
2528 cpus_updated = !cpumask_equal(cs->effective_cpus,
2529 oldcs->effective_cpus);
2530 mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems);
2531
2532 /*
2533 * In the default hierarchy, enabling cpuset in the child cgroups
2534 * will trigger a number of cpuset_attach() calls with no change
2535 * in effective cpus and mems. In that case, we can optimize out
2536 * by skipping the task iteration and update.
2537 */
2538 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
2539 !cpus_updated && !mems_updated) {
2540 cpuset_attach_nodemask_to = cs->effective_mems;
2541 goto out;
2542 }
2543
2544 guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
2545
2546 cgroup_taskset_for_each(task, css, tset) {
2547 if (cs != &top_cpuset)
2548 guarantee_online_cpus(task, cpus_attach);
2549 else
2550 cpumask_copy(cpus_attach, task_cpu_possible_mask(task));
2551 /*
2552 * can_attach beforehand should guarantee that this doesn't
2553 * fail. TODO: have a better way to handle failure here
2554 */
2555 WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
2556
2557 cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
2558 cpuset_update_task_spread_flags(cs, task);
2559 }
2560
2561 /*
2562 * Change mm for all threadgroup leaders. This is expensive and may
2563 * sleep and should be moved outside migration path proper. Skip it
2564 * if there is no change in effective_mems and CS_MEMORY_MIGRATE is
2565 * not set.
2566 */
2567 cpuset_attach_nodemask_to = cs->effective_mems;
2568 if (!is_memory_migrate(cs) && !mems_updated)
2569 goto out;
2570
2571 cgroup_taskset_for_each_leader(leader, css, tset) {
2572 struct mm_struct *mm = get_task_mm(leader);
2573
2574 if (mm) {
2575 mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
2576
2577 /*
2578 * old_mems_allowed is the same with mems_allowed
2579 * here, except if this task is being moved
2580 * automatically due to hotplug. In that case
2581 * @mems_allowed has been updated and is empty, so
2582 * @old_mems_allowed is the right nodesets that we
2583 * migrate mm from.
2584 */
2585 if (is_memory_migrate(cs))
2586 cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
2587 &cpuset_attach_nodemask_to);
2588 else
2589 mmput(mm);
2590 }
2591 }
2592
2593out:
2594 cs->old_mems_allowed = cpuset_attach_nodemask_to;
2595
2596 cs->attach_in_progress--;
2597 if (!cs->attach_in_progress)
2598 wake_up(&cpuset_attach_wq);
2599
2600 percpu_up_write(&cpuset_rwsem);
2601}
2602
2603/* The various types of files and directories in a cpuset file system */
2604
2605typedef enum {
2606 FILE_MEMORY_MIGRATE,
2607 FILE_CPULIST,
2608 FILE_MEMLIST,
2609 FILE_EFFECTIVE_CPULIST,
2610 FILE_EFFECTIVE_MEMLIST,
2611 FILE_SUBPARTS_CPULIST,
2612 FILE_CPU_EXCLUSIVE,
2613 FILE_MEM_EXCLUSIVE,
2614 FILE_MEM_HARDWALL,
2615 FILE_SCHED_LOAD_BALANCE,
2616 FILE_PARTITION_ROOT,
2617 FILE_SCHED_RELAX_DOMAIN_LEVEL,
2618 FILE_MEMORY_PRESSURE_ENABLED,
2619 FILE_MEMORY_PRESSURE,
2620 FILE_SPREAD_PAGE,
2621 FILE_SPREAD_SLAB,
2622} cpuset_filetype_t;
2623
2624static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
2625 u64 val)
2626{
2627 struct cpuset *cs = css_cs(css);
2628 cpuset_filetype_t type = cft->private;
2629 int retval = 0;
2630
2631 cpus_read_lock();
2632 percpu_down_write(&cpuset_rwsem);
2633 if (!is_cpuset_online(cs)) {
2634 retval = -ENODEV;
2635 goto out_unlock;
2636 }
2637
2638 switch (type) {
2639 case FILE_CPU_EXCLUSIVE:
2640 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
2641 break;
2642 case FILE_MEM_EXCLUSIVE:
2643 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
2644 break;
2645 case FILE_MEM_HARDWALL:
2646 retval = update_flag(CS_MEM_HARDWALL, cs, val);
2647 break;
2648 case FILE_SCHED_LOAD_BALANCE:
2649 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
2650 break;
2651 case FILE_MEMORY_MIGRATE:
2652 retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
2653 break;
2654 case FILE_MEMORY_PRESSURE_ENABLED:
2655 cpuset_memory_pressure_enabled = !!val;
2656 break;
2657 case FILE_SPREAD_PAGE:
2658 retval = update_flag(CS_SPREAD_PAGE, cs, val);
2659 break;
2660 case FILE_SPREAD_SLAB:
2661 retval = update_flag(CS_SPREAD_SLAB, cs, val);
2662 break;
2663 default:
2664 retval = -EINVAL;
2665 break;
2666 }
2667out_unlock:
2668 percpu_up_write(&cpuset_rwsem);
2669 cpus_read_unlock();
2670 return retval;
2671}
2672
2673static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
2674 s64 val)
2675{
2676 struct cpuset *cs = css_cs(css);
2677 cpuset_filetype_t type = cft->private;
2678 int retval = -ENODEV;
2679
2680 cpus_read_lock();
2681 percpu_down_write(&cpuset_rwsem);
2682 if (!is_cpuset_online(cs))
2683 goto out_unlock;
2684
2685 switch (type) {
2686 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
2687 retval = update_relax_domain_level(cs, val);
2688 break;
2689 default:
2690 retval = -EINVAL;
2691 break;
2692 }
2693out_unlock:
2694 percpu_up_write(&cpuset_rwsem);
2695 cpus_read_unlock();
2696 return retval;
2697}
2698
2699/*
2700 * Common handling for a write to a "cpus" or "mems" file.
2701 */
2702static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
2703 char *buf, size_t nbytes, loff_t off)
2704{
2705 struct cpuset *cs = css_cs(of_css(of));
2706 struct cpuset *trialcs;
2707 int retval = -ENODEV;
2708
2709 buf = strstrip(buf);
2710
2711 /*
2712 * CPU or memory hotunplug may leave @cs w/o any execution
2713 * resources, in which case the hotplug code asynchronously updates
2714 * configuration and transfers all tasks to the nearest ancestor
2715 * which can execute.
2716 *
2717 * As writes to "cpus" or "mems" may restore @cs's execution
2718 * resources, wait for the previously scheduled operations before
2719 * proceeding, so that we don't end up keep removing tasks added
2720 * after execution capability is restored.
2721 *
2722 * cpuset_hotplug_work calls back into cgroup core via
2723 * cgroup_transfer_tasks() and waiting for it from a cgroupfs
2724 * operation like this one can lead to a deadlock through kernfs
2725 * active_ref protection. Let's break the protection. Losing the
2726 * protection is okay as we check whether @cs is online after
2727 * grabbing cpuset_rwsem anyway. This only happens on the legacy
2728 * hierarchies.
2729 */
2730 css_get(&cs->css);
2731 kernfs_break_active_protection(of->kn);
2732 flush_work(&cpuset_hotplug_work);
2733
2734 cpus_read_lock();
2735 percpu_down_write(&cpuset_rwsem);
2736 if (!is_cpuset_online(cs))
2737 goto out_unlock;
2738
2739 trialcs = alloc_trial_cpuset(cs);
2740 if (!trialcs) {
2741 retval = -ENOMEM;
2742 goto out_unlock;
2743 }
2744
2745 switch (of_cft(of)->private) {
2746 case FILE_CPULIST:
2747 retval = update_cpumask(cs, trialcs, buf);
2748 break;
2749 case FILE_MEMLIST:
2750 retval = update_nodemask(cs, trialcs, buf);
2751 break;
2752 default:
2753 retval = -EINVAL;
2754 break;
2755 }
2756
2757 free_cpuset(trialcs);
2758out_unlock:
2759 percpu_up_write(&cpuset_rwsem);
2760 cpus_read_unlock();
2761 kernfs_unbreak_active_protection(of->kn);
2762 css_put(&cs->css);
2763 flush_workqueue(cpuset_migrate_mm_wq);
2764 return retval ?: nbytes;
2765}
2766
2767/*
2768 * These ascii lists should be read in a single call, by using a user
2769 * buffer large enough to hold the entire map. If read in smaller
2770 * chunks, there is no guarantee of atomicity. Since the display format
2771 * used, list of ranges of sequential numbers, is variable length,
2772 * and since these maps can change value dynamically, one could read
2773 * gibberish by doing partial reads while a list was changing.
2774 */
2775static int cpuset_common_seq_show(struct seq_file *sf, void *v)
2776{
2777 struct cpuset *cs = css_cs(seq_css(sf));
2778 cpuset_filetype_t type = seq_cft(sf)->private;
2779 int ret = 0;
2780
2781 spin_lock_irq(&callback_lock);
2782
2783 switch (type) {
2784 case FILE_CPULIST:
2785 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
2786 break;
2787 case FILE_MEMLIST:
2788 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
2789 break;
2790 case FILE_EFFECTIVE_CPULIST:
2791 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
2792 break;
2793 case FILE_EFFECTIVE_MEMLIST:
2794 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
2795 break;
2796 case FILE_SUBPARTS_CPULIST:
2797 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus));
2798 break;
2799 default:
2800 ret = -EINVAL;
2801 }
2802
2803 spin_unlock_irq(&callback_lock);
2804 return ret;
2805}
2806
2807static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
2808{
2809 struct cpuset *cs = css_cs(css);
2810 cpuset_filetype_t type = cft->private;
2811 switch (type) {
2812 case FILE_CPU_EXCLUSIVE:
2813 return is_cpu_exclusive(cs);
2814 case FILE_MEM_EXCLUSIVE:
2815 return is_mem_exclusive(cs);
2816 case FILE_MEM_HARDWALL:
2817 return is_mem_hardwall(cs);
2818 case FILE_SCHED_LOAD_BALANCE:
2819 return is_sched_load_balance(cs);
2820 case FILE_MEMORY_MIGRATE:
2821 return is_memory_migrate(cs);
2822 case FILE_MEMORY_PRESSURE_ENABLED:
2823 return cpuset_memory_pressure_enabled;
2824 case FILE_MEMORY_PRESSURE:
2825 return fmeter_getrate(&cs->fmeter);
2826 case FILE_SPREAD_PAGE:
2827 return is_spread_page(cs);
2828 case FILE_SPREAD_SLAB:
2829 return is_spread_slab(cs);
2830 default:
2831 BUG();
2832 }
2833
2834 /* Unreachable but makes gcc happy */
2835 return 0;
2836}
2837
2838static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
2839{
2840 struct cpuset *cs = css_cs(css);
2841 cpuset_filetype_t type = cft->private;
2842 switch (type) {
2843 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
2844 return cs->relax_domain_level;
2845 default:
2846 BUG();
2847 }
2848
2849 /* Unreachable but makes gcc happy */
2850 return 0;
2851}
2852
2853static int sched_partition_show(struct seq_file *seq, void *v)
2854{
2855 struct cpuset *cs = css_cs(seq_css(seq));
2856 const char *err, *type = NULL;
2857
2858 switch (cs->partition_root_state) {
2859 case PRS_ROOT:
2860 seq_puts(seq, "root\n");
2861 break;
2862 case PRS_ISOLATED:
2863 seq_puts(seq, "isolated\n");
2864 break;
2865 case PRS_MEMBER:
2866 seq_puts(seq, "member\n");
2867 break;
2868 case PRS_INVALID_ROOT:
2869 type = "root";
2870 fallthrough;
2871 case PRS_INVALID_ISOLATED:
2872 if (!type)
2873 type = "isolated";
2874 err = perr_strings[READ_ONCE(cs->prs_err)];
2875 if (err)
2876 seq_printf(seq, "%s invalid (%s)\n", type, err);
2877 else
2878 seq_printf(seq, "%s invalid\n", type);
2879 break;
2880 }
2881 return 0;
2882}
2883
2884static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf,
2885 size_t nbytes, loff_t off)
2886{
2887 struct cpuset *cs = css_cs(of_css(of));
2888 int val;
2889 int retval = -ENODEV;
2890
2891 buf = strstrip(buf);
2892
2893 /*
2894 * Convert "root" to ENABLED, and convert "member" to DISABLED.
2895 */
2896 if (!strcmp(buf, "root"))
2897 val = PRS_ROOT;
2898 else if (!strcmp(buf, "member"))
2899 val = PRS_MEMBER;
2900 else if (!strcmp(buf, "isolated"))
2901 val = PRS_ISOLATED;
2902 else
2903 return -EINVAL;
2904
2905 css_get(&cs->css);
2906 cpus_read_lock();
2907 percpu_down_write(&cpuset_rwsem);
2908 if (!is_cpuset_online(cs))
2909 goto out_unlock;
2910
2911 retval = update_prstate(cs, val);
2912out_unlock:
2913 percpu_up_write(&cpuset_rwsem);
2914 cpus_read_unlock();
2915 css_put(&cs->css);
2916 return retval ?: nbytes;
2917}
2918
2919/*
2920 * for the common functions, 'private' gives the type of file
2921 */
2922
2923static struct cftype legacy_files[] = {
2924 {
2925 .name = "cpus",
2926 .seq_show = cpuset_common_seq_show,
2927 .write = cpuset_write_resmask,
2928 .max_write_len = (100U + 6 * NR_CPUS),
2929 .private = FILE_CPULIST,
2930 },
2931
2932 {
2933 .name = "mems",
2934 .seq_show = cpuset_common_seq_show,
2935 .write = cpuset_write_resmask,
2936 .max_write_len = (100U + 6 * MAX_NUMNODES),
2937 .private = FILE_MEMLIST,
2938 },
2939
2940 {
2941 .name = "effective_cpus",
2942 .seq_show = cpuset_common_seq_show,
2943 .private = FILE_EFFECTIVE_CPULIST,
2944 },
2945
2946 {
2947 .name = "effective_mems",
2948 .seq_show = cpuset_common_seq_show,
2949 .private = FILE_EFFECTIVE_MEMLIST,
2950 },
2951
2952 {
2953 .name = "cpu_exclusive",
2954 .read_u64 = cpuset_read_u64,
2955 .write_u64 = cpuset_write_u64,
2956 .private = FILE_CPU_EXCLUSIVE,
2957 },
2958
2959 {
2960 .name = "mem_exclusive",
2961 .read_u64 = cpuset_read_u64,
2962 .write_u64 = cpuset_write_u64,
2963 .private = FILE_MEM_EXCLUSIVE,
2964 },
2965
2966 {
2967 .name = "mem_hardwall",
2968 .read_u64 = cpuset_read_u64,
2969 .write_u64 = cpuset_write_u64,
2970 .private = FILE_MEM_HARDWALL,
2971 },
2972
2973 {
2974 .name = "sched_load_balance",
2975 .read_u64 = cpuset_read_u64,
2976 .write_u64 = cpuset_write_u64,
2977 .private = FILE_SCHED_LOAD_BALANCE,
2978 },
2979
2980 {
2981 .name = "sched_relax_domain_level",
2982 .read_s64 = cpuset_read_s64,
2983 .write_s64 = cpuset_write_s64,
2984 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
2985 },
2986
2987 {
2988 .name = "memory_migrate",
2989 .read_u64 = cpuset_read_u64,
2990 .write_u64 = cpuset_write_u64,
2991 .private = FILE_MEMORY_MIGRATE,
2992 },
2993
2994 {
2995 .name = "memory_pressure",
2996 .read_u64 = cpuset_read_u64,
2997 .private = FILE_MEMORY_PRESSURE,
2998 },
2999
3000 {
3001 .name = "memory_spread_page",
3002 .read_u64 = cpuset_read_u64,
3003 .write_u64 = cpuset_write_u64,
3004 .private = FILE_SPREAD_PAGE,
3005 },
3006
3007 {
3008 .name = "memory_spread_slab",
3009 .read_u64 = cpuset_read_u64,
3010 .write_u64 = cpuset_write_u64,
3011 .private = FILE_SPREAD_SLAB,
3012 },
3013
3014 {
3015 .name = "memory_pressure_enabled",
3016 .flags = CFTYPE_ONLY_ON_ROOT,
3017 .read_u64 = cpuset_read_u64,
3018 .write_u64 = cpuset_write_u64,
3019 .private = FILE_MEMORY_PRESSURE_ENABLED,
3020 },
3021
3022 { } /* terminate */
3023};
3024
3025/*
3026 * This is currently a minimal set for the default hierarchy. It can be
3027 * expanded later on by migrating more features and control files from v1.
3028 */
3029static struct cftype dfl_files[] = {
3030 {
3031 .name = "cpus",
3032 .seq_show = cpuset_common_seq_show,
3033 .write = cpuset_write_resmask,
3034 .max_write_len = (100U + 6 * NR_CPUS),
3035 .private = FILE_CPULIST,
3036 .flags = CFTYPE_NOT_ON_ROOT,
3037 },
3038
3039 {
3040 .name = "mems",
3041 .seq_show = cpuset_common_seq_show,
3042 .write = cpuset_write_resmask,
3043 .max_write_len = (100U + 6 * MAX_NUMNODES),
3044 .private = FILE_MEMLIST,
3045 .flags = CFTYPE_NOT_ON_ROOT,
3046 },
3047
3048 {
3049 .name = "cpus.effective",
3050 .seq_show = cpuset_common_seq_show,
3051 .private = FILE_EFFECTIVE_CPULIST,
3052 },
3053
3054 {
3055 .name = "mems.effective",
3056 .seq_show = cpuset_common_seq_show,
3057 .private = FILE_EFFECTIVE_MEMLIST,
3058 },
3059
3060 {
3061 .name = "cpus.partition",
3062 .seq_show = sched_partition_show,
3063 .write = sched_partition_write,
3064 .private = FILE_PARTITION_ROOT,
3065 .flags = CFTYPE_NOT_ON_ROOT,
3066 .file_offset = offsetof(struct cpuset, partition_file),
3067 },
3068
3069 {
3070 .name = "cpus.subpartitions",
3071 .seq_show = cpuset_common_seq_show,
3072 .private = FILE_SUBPARTS_CPULIST,
3073 .flags = CFTYPE_DEBUG,
3074 },
3075
3076 { } /* terminate */
3077};
3078
3079
3080/**
3081 * cpuset_css_alloc - Allocate a cpuset css
3082 * @parent_css: Parent css of the control group that the new cpuset will be
3083 * part of
3084 * Return: cpuset css on success, -ENOMEM on failure.
3085 *
3086 * Allocate and initialize a new cpuset css, for non-NULL @parent_css, return
3087 * top cpuset css otherwise.
3088 */
3089static struct cgroup_subsys_state *
3090cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
3091{
3092 struct cpuset *cs;
3093
3094 if (!parent_css)
3095 return &top_cpuset.css;
3096
3097 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
3098 if (!cs)
3099 return ERR_PTR(-ENOMEM);
3100
3101 if (alloc_cpumasks(cs, NULL)) {
3102 kfree(cs);
3103 return ERR_PTR(-ENOMEM);
3104 }
3105
3106 __set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
3107 nodes_clear(cs->mems_allowed);
3108 nodes_clear(cs->effective_mems);
3109 fmeter_init(&cs->fmeter);
3110 cs->relax_domain_level = -1;
3111
3112 /* Set CS_MEMORY_MIGRATE for default hierarchy */
3113 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
3114 __set_bit(CS_MEMORY_MIGRATE, &cs->flags);
3115
3116 return &cs->css;
3117}
3118
3119static int cpuset_css_online(struct cgroup_subsys_state *css)
3120{
3121 struct cpuset *cs = css_cs(css);
3122 struct cpuset *parent = parent_cs(cs);
3123 struct cpuset *tmp_cs;
3124 struct cgroup_subsys_state *pos_css;
3125
3126 if (!parent)
3127 return 0;
3128
3129 cpus_read_lock();
3130 percpu_down_write(&cpuset_rwsem);
3131
3132 set_bit(CS_ONLINE, &cs->flags);
3133 if (is_spread_page(parent))
3134 set_bit(CS_SPREAD_PAGE, &cs->flags);
3135 if (is_spread_slab(parent))
3136 set_bit(CS_SPREAD_SLAB, &cs->flags);
3137
3138 cpuset_inc();
3139
3140 spin_lock_irq(&callback_lock);
3141 if (is_in_v2_mode()) {
3142 cpumask_copy(cs->effective_cpus, parent->effective_cpus);
3143 cs->effective_mems = parent->effective_mems;
3144 cs->use_parent_ecpus = true;
3145 parent->child_ecpus_count++;
3146 }
3147 spin_unlock_irq(&callback_lock);
3148
3149 if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
3150 goto out_unlock;
3151
3152 /*
3153 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
3154 * set. This flag handling is implemented in cgroup core for
3155 * historical reasons - the flag may be specified during mount.
3156 *
3157 * Currently, if any sibling cpusets have exclusive cpus or mem, we
3158 * refuse to clone the configuration - thereby refusing the task to
3159 * be entered, and as a result refusing the sys_unshare() or
3160 * clone() which initiated it. If this becomes a problem for some
3161 * users who wish to allow that scenario, then this could be
3162 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
3163 * (and likewise for mems) to the new cgroup.
3164 */
3165 rcu_read_lock();
3166 cpuset_for_each_child(tmp_cs, pos_css, parent) {
3167 if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
3168 rcu_read_unlock();
3169 goto out_unlock;
3170 }
3171 }
3172 rcu_read_unlock();
3173
3174 spin_lock_irq(&callback_lock);
3175 cs->mems_allowed = parent->mems_allowed;
3176 cs->effective_mems = parent->mems_allowed;
3177 cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
3178 cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
3179 spin_unlock_irq(&callback_lock);
3180out_unlock:
3181 percpu_up_write(&cpuset_rwsem);
3182 cpus_read_unlock();
3183 return 0;
3184}
3185
3186/*
3187 * If the cpuset being removed has its flag 'sched_load_balance'
3188 * enabled, then simulate turning sched_load_balance off, which
3189 * will call rebuild_sched_domains_locked(). That is not needed
3190 * in the default hierarchy where only changes in partition
3191 * will cause repartitioning.
3192 *
3193 * If the cpuset has the 'sched.partition' flag enabled, simulate
3194 * turning 'sched.partition" off.
3195 */
3196
3197static void cpuset_css_offline(struct cgroup_subsys_state *css)
3198{
3199 struct cpuset *cs = css_cs(css);
3200
3201 cpus_read_lock();
3202 percpu_down_write(&cpuset_rwsem);
3203
3204 if (is_partition_valid(cs))
3205 update_prstate(cs, 0);
3206
3207 if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
3208 is_sched_load_balance(cs))
3209 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
3210
3211 if (cs->use_parent_ecpus) {
3212 struct cpuset *parent = parent_cs(cs);
3213
3214 cs->use_parent_ecpus = false;
3215 parent->child_ecpus_count--;
3216 }
3217
3218 cpuset_dec();
3219 clear_bit(CS_ONLINE, &cs->flags);
3220
3221 percpu_up_write(&cpuset_rwsem);
3222 cpus_read_unlock();
3223}
3224
3225static void cpuset_css_free(struct cgroup_subsys_state *css)
3226{
3227 struct cpuset *cs = css_cs(css);
3228
3229 free_cpuset(cs);
3230}
3231
3232static void cpuset_bind(struct cgroup_subsys_state *root_css)
3233{
3234 percpu_down_write(&cpuset_rwsem);
3235 spin_lock_irq(&callback_lock);
3236
3237 if (is_in_v2_mode()) {
3238 cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
3239 top_cpuset.mems_allowed = node_possible_map;
3240 } else {
3241 cpumask_copy(top_cpuset.cpus_allowed,
3242 top_cpuset.effective_cpus);
3243 top_cpuset.mems_allowed = top_cpuset.effective_mems;
3244 }
3245
3246 spin_unlock_irq(&callback_lock);
3247 percpu_up_write(&cpuset_rwsem);
3248}
3249
3250/*
3251 * Make sure the new task conform to the current state of its parent,
3252 * which could have been changed by cpuset just after it inherits the
3253 * state from the parent and before it sits on the cgroup's task list.
3254 */
3255static void cpuset_fork(struct task_struct *task)
3256{
3257 if (task_css_is_root(task, cpuset_cgrp_id))
3258 return;
3259
3260 set_cpus_allowed_ptr(task, current->cpus_ptr);
3261 task->mems_allowed = current->mems_allowed;
3262}
3263
3264struct cgroup_subsys cpuset_cgrp_subsys = {
3265 .css_alloc = cpuset_css_alloc,
3266 .css_online = cpuset_css_online,
3267 .css_offline = cpuset_css_offline,
3268 .css_free = cpuset_css_free,
3269 .can_attach = cpuset_can_attach,
3270 .cancel_attach = cpuset_cancel_attach,
3271 .attach = cpuset_attach,
3272 .post_attach = cpuset_post_attach,
3273 .bind = cpuset_bind,
3274 .fork = cpuset_fork,
3275 .legacy_cftypes = legacy_files,
3276 .dfl_cftypes = dfl_files,
3277 .early_init = true,
3278 .threaded = true,
3279};
3280
3281/**
3282 * cpuset_init - initialize cpusets at system boot
3283 *
3284 * Description: Initialize top_cpuset
3285 **/
3286
3287int __init cpuset_init(void)
3288{
3289 BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
3290
3291 BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
3292 BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
3293 BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
3294
3295 cpumask_setall(top_cpuset.cpus_allowed);
3296 nodes_setall(top_cpuset.mems_allowed);
3297 cpumask_setall(top_cpuset.effective_cpus);
3298 nodes_setall(top_cpuset.effective_mems);
3299
3300 fmeter_init(&top_cpuset.fmeter);
3301 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
3302 top_cpuset.relax_domain_level = -1;
3303
3304 BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
3305
3306 return 0;
3307}
3308
3309/*
3310 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
3311 * or memory nodes, we need to walk over the cpuset hierarchy,
3312 * removing that CPU or node from all cpusets. If this removes the
3313 * last CPU or node from a cpuset, then move the tasks in the empty
3314 * cpuset to its next-highest non-empty parent.
3315 */
3316static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
3317{
3318 struct cpuset *parent;
3319
3320 /*
3321 * Find its next-highest non-empty parent, (top cpuset
3322 * has online cpus, so can't be empty).
3323 */
3324 parent = parent_cs(cs);
3325 while (cpumask_empty(parent->cpus_allowed) ||
3326 nodes_empty(parent->mems_allowed))
3327 parent = parent_cs(parent);
3328
3329 if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
3330 pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
3331 pr_cont_cgroup_name(cs->css.cgroup);
3332 pr_cont("\n");
3333 }
3334}
3335
3336static void
3337hotplug_update_tasks_legacy(struct cpuset *cs,
3338 struct cpumask *new_cpus, nodemask_t *new_mems,
3339 bool cpus_updated, bool mems_updated)
3340{
3341 bool is_empty;
3342
3343 spin_lock_irq(&callback_lock);
3344 cpumask_copy(cs->cpus_allowed, new_cpus);
3345 cpumask_copy(cs->effective_cpus, new_cpus);
3346 cs->mems_allowed = *new_mems;
3347 cs->effective_mems = *new_mems;
3348 spin_unlock_irq(&callback_lock);
3349
3350 /*
3351 * Don't call update_tasks_cpumask() if the cpuset becomes empty,
3352 * as the tasks will be migrated to an ancestor.
3353 */
3354 if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
3355 update_tasks_cpumask(cs, new_cpus);
3356 if (mems_updated && !nodes_empty(cs->mems_allowed))
3357 update_tasks_nodemask(cs);
3358
3359 is_empty = cpumask_empty(cs->cpus_allowed) ||
3360 nodes_empty(cs->mems_allowed);
3361
3362 percpu_up_write(&cpuset_rwsem);
3363
3364 /*
3365 * Move tasks to the nearest ancestor with execution resources,
3366 * This is full cgroup operation which will also call back into
3367 * cpuset. Should be done outside any lock.
3368 */
3369 if (is_empty)
3370 remove_tasks_in_empty_cpuset(cs);
3371
3372 percpu_down_write(&cpuset_rwsem);
3373}
3374
3375static void
3376hotplug_update_tasks(struct cpuset *cs,
3377 struct cpumask *new_cpus, nodemask_t *new_mems,
3378 bool cpus_updated, bool mems_updated)
3379{
3380 /* A partition root is allowed to have empty effective cpus */
3381 if (cpumask_empty(new_cpus) && !is_partition_valid(cs))
3382 cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
3383 if (nodes_empty(*new_mems))
3384 *new_mems = parent_cs(cs)->effective_mems;
3385
3386 spin_lock_irq(&callback_lock);
3387 cpumask_copy(cs->effective_cpus, new_cpus);
3388 cs->effective_mems = *new_mems;
3389 spin_unlock_irq(&callback_lock);
3390
3391 if (cpus_updated)
3392 update_tasks_cpumask(cs, new_cpus);
3393 if (mems_updated)
3394 update_tasks_nodemask(cs);
3395}
3396
3397static bool force_rebuild;
3398
3399void cpuset_force_rebuild(void)
3400{
3401 force_rebuild = true;
3402}
3403
3404/**
3405 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
3406 * @cs: cpuset in interest
3407 * @tmp: the tmpmasks structure pointer
3408 *
3409 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
3410 * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
3411 * all its tasks are moved to the nearest ancestor with both resources.
3412 */
3413static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
3414{
3415 static cpumask_t new_cpus;
3416 static nodemask_t new_mems;
3417 bool cpus_updated;
3418 bool mems_updated;
3419 struct cpuset *parent;
3420retry:
3421 wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
3422
3423 percpu_down_write(&cpuset_rwsem);
3424
3425 /*
3426 * We have raced with task attaching. We wait until attaching
3427 * is finished, so we won't attach a task to an empty cpuset.
3428 */
3429 if (cs->attach_in_progress) {
3430 percpu_up_write(&cpuset_rwsem);
3431 goto retry;
3432 }
3433
3434 parent = parent_cs(cs);
3435 compute_effective_cpumask(&new_cpus, cs, parent);
3436 nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);
3437
3438 if (cs->nr_subparts_cpus)
3439 /*
3440 * Make sure that CPUs allocated to child partitions
3441 * do not show up in effective_cpus.
3442 */
3443 cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus);
3444
3445 if (!tmp || !cs->partition_root_state)
3446 goto update_tasks;
3447
3448 /*
3449 * In the unlikely event that a partition root has empty
3450 * effective_cpus with tasks, we will have to invalidate child
3451 * partitions, if present, by setting nr_subparts_cpus to 0 to
3452 * reclaim their cpus.
3453 */
3454 if (cs->nr_subparts_cpus && is_partition_valid(cs) &&
3455 cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) {
3456 spin_lock_irq(&callback_lock);
3457 cs->nr_subparts_cpus = 0;
3458 cpumask_clear(cs->subparts_cpus);
3459 spin_unlock_irq(&callback_lock);
3460 compute_effective_cpumask(&new_cpus, cs, parent);
3461 }
3462
3463 /*
3464 * Force the partition to become invalid if either one of
3465 * the following conditions hold:
3466 * 1) empty effective cpus but not valid empty partition.
3467 * 2) parent is invalid or doesn't grant any cpus to child
3468 * partitions.
3469 */
3470 if (is_partition_valid(cs) && (!parent->nr_subparts_cpus ||
3471 (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) {
3472 int old_prs, parent_prs;
3473
3474 update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp);
3475 if (cs->nr_subparts_cpus) {
3476 spin_lock_irq(&callback_lock);
3477 cs->nr_subparts_cpus = 0;
3478 cpumask_clear(cs->subparts_cpus);
3479 spin_unlock_irq(&callback_lock);
3480 compute_effective_cpumask(&new_cpus, cs, parent);
3481 }
3482
3483 old_prs = cs->partition_root_state;
3484 parent_prs = parent->partition_root_state;
3485 if (is_partition_valid(cs)) {
3486 spin_lock_irq(&callback_lock);
3487 make_partition_invalid(cs);
3488 spin_unlock_irq(&callback_lock);
3489 if (is_prs_invalid(parent_prs))
3490 WRITE_ONCE(cs->prs_err, PERR_INVPARENT);
3491 else if (!parent_prs)
3492 WRITE_ONCE(cs->prs_err, PERR_NOTPART);
3493 else
3494 WRITE_ONCE(cs->prs_err, PERR_HOTPLUG);
3495 notify_partition_change(cs, old_prs);
3496 }
3497 cpuset_force_rebuild();
3498 }
3499
3500 /*
3501 * On the other hand, an invalid partition root may be transitioned
3502 * back to a regular one.
3503 */
3504 else if (is_partition_valid(parent) && is_partition_invalid(cs)) {
3505 update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp);
3506 if (is_partition_valid(cs))
3507 cpuset_force_rebuild();
3508 }
3509
3510update_tasks:
3511 cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
3512 mems_updated = !nodes_equal(new_mems, cs->effective_mems);
3513
3514 if (mems_updated)
3515 check_insane_mems_config(&new_mems);
3516
3517 if (is_in_v2_mode())
3518 hotplug_update_tasks(cs, &new_cpus, &new_mems,
3519 cpus_updated, mems_updated);
3520 else
3521 hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
3522 cpus_updated, mems_updated);
3523
3524 percpu_up_write(&cpuset_rwsem);
3525}
3526
3527/**
3528 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
3529 *
3530 * This function is called after either CPU or memory configuration has
3531 * changed and updates cpuset accordingly. The top_cpuset is always
3532 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
3533 * order to make cpusets transparent (of no affect) on systems that are
3534 * actively using CPU hotplug but making no active use of cpusets.
3535 *
3536 * Non-root cpusets are only affected by offlining. If any CPUs or memory
3537 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
3538 * all descendants.
3539 *
3540 * Note that CPU offlining during suspend is ignored. We don't modify
3541 * cpusets across suspend/resume cycles at all.
3542 */
3543static void cpuset_hotplug_workfn(struct work_struct *work)
3544{
3545 static cpumask_t new_cpus;
3546 static nodemask_t new_mems;
3547 bool cpus_updated, mems_updated;
3548 bool on_dfl = is_in_v2_mode();
3549 struct tmpmasks tmp, *ptmp = NULL;
3550
3551 if (on_dfl && !alloc_cpumasks(NULL, &tmp))
3552 ptmp = &tmp;
3553
3554 percpu_down_write(&cpuset_rwsem);
3555
3556 /* fetch the available cpus/mems and find out which changed how */
3557 cpumask_copy(&new_cpus, cpu_active_mask);
3558 new_mems = node_states[N_MEMORY];
3559
3560 /*
3561 * If subparts_cpus is populated, it is likely that the check below
3562 * will produce a false positive on cpus_updated when the cpu list
3563 * isn't changed. It is extra work, but it is better to be safe.
3564 */
3565 cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
3566 mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
3567
3568 /*
3569 * In the rare case that hotplug removes all the cpus in subparts_cpus,
3570 * we assumed that cpus are updated.
3571 */
3572 if (!cpus_updated && top_cpuset.nr_subparts_cpus)
3573 cpus_updated = true;
3574
3575 /* synchronize cpus_allowed to cpu_active_mask */
3576 if (cpus_updated) {
3577 spin_lock_irq(&callback_lock);
3578 if (!on_dfl)
3579 cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
3580 /*
3581 * Make sure that CPUs allocated to child partitions
3582 * do not show up in effective_cpus. If no CPU is left,
3583 * we clear the subparts_cpus & let the child partitions
3584 * fight for the CPUs again.
3585 */
3586 if (top_cpuset.nr_subparts_cpus) {
3587 if (cpumask_subset(&new_cpus,
3588 top_cpuset.subparts_cpus)) {
3589 top_cpuset.nr_subparts_cpus = 0;
3590 cpumask_clear(top_cpuset.subparts_cpus);
3591 } else {
3592 cpumask_andnot(&new_cpus, &new_cpus,
3593 top_cpuset.subparts_cpus);
3594 }
3595 }
3596 cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
3597 spin_unlock_irq(&callback_lock);
3598 /* we don't mess with cpumasks of tasks in top_cpuset */
3599 }
3600
3601 /* synchronize mems_allowed to N_MEMORY */
3602 if (mems_updated) {
3603 spin_lock_irq(&callback_lock);
3604 if (!on_dfl)
3605 top_cpuset.mems_allowed = new_mems;
3606 top_cpuset.effective_mems = new_mems;
3607 spin_unlock_irq(&callback_lock);
3608 update_tasks_nodemask(&top_cpuset);
3609 }
3610
3611 percpu_up_write(&cpuset_rwsem);
3612
3613 /* if cpus or mems changed, we need to propagate to descendants */
3614 if (cpus_updated || mems_updated) {
3615 struct cpuset *cs;
3616 struct cgroup_subsys_state *pos_css;
3617
3618 rcu_read_lock();
3619 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
3620 if (cs == &top_cpuset || !css_tryget_online(&cs->css))
3621 continue;
3622 rcu_read_unlock();
3623
3624 cpuset_hotplug_update_tasks(cs, ptmp);
3625
3626 rcu_read_lock();
3627 css_put(&cs->css);
3628 }
3629 rcu_read_unlock();
3630 }
3631
3632 /* rebuild sched domains if cpus_allowed has changed */
3633 if (cpus_updated || force_rebuild) {
3634 force_rebuild = false;
3635 rebuild_sched_domains();
3636 }
3637
3638 free_cpumasks(NULL, ptmp);
3639}
3640
3641void cpuset_update_active_cpus(void)
3642{
3643 /*
3644 * We're inside cpu hotplug critical region which usually nests
3645 * inside cgroup synchronization. Bounce actual hotplug processing
3646 * to a work item to avoid reverse locking order.
3647 */
3648 schedule_work(&cpuset_hotplug_work);
3649}
3650
3651void cpuset_wait_for_hotplug(void)
3652{
3653 flush_work(&cpuset_hotplug_work);
3654}
3655
3656/*
3657 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
3658 * Call this routine anytime after node_states[N_MEMORY] changes.
3659 * See cpuset_update_active_cpus() for CPU hotplug handling.
3660 */
3661static int cpuset_track_online_nodes(struct notifier_block *self,
3662 unsigned long action, void *arg)
3663{
3664 schedule_work(&cpuset_hotplug_work);
3665 return NOTIFY_OK;
3666}
3667
3668/**
3669 * cpuset_init_smp - initialize cpus_allowed
3670 *
3671 * Description: Finish top cpuset after cpu, node maps are initialized
3672 */
3673void __init cpuset_init_smp(void)
3674{
3675 /*
3676 * cpus_allowd/mems_allowed set to v2 values in the initial
3677 * cpuset_bind() call will be reset to v1 values in another
3678 * cpuset_bind() call when v1 cpuset is mounted.
3679 */
3680 top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
3681
3682 cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
3683 top_cpuset.effective_mems = node_states[N_MEMORY];
3684
3685 hotplug_memory_notifier(cpuset_track_online_nodes, CPUSET_CALLBACK_PRI);
3686
3687 cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
3688 BUG_ON(!cpuset_migrate_mm_wq);
3689}
3690
3691/**
3692 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
3693 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
3694 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
3695 *
3696 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
3697 * attached to the specified @tsk. Guaranteed to return some non-empty
3698 * subset of cpu_online_mask, even if this means going outside the
3699 * tasks cpuset, except when the task is in the top cpuset.
3700 **/
3701
3702void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
3703{
3704 unsigned long flags;
3705 struct cpuset *cs;
3706
3707 spin_lock_irqsave(&callback_lock, flags);
3708 rcu_read_lock();
3709
3710 cs = task_cs(tsk);
3711 if (cs != &top_cpuset)
3712 guarantee_online_cpus(tsk, pmask);
3713 /*
3714 * Tasks in the top cpuset won't get update to their cpumasks
3715 * when a hotplug online/offline event happens. So we include all
3716 * offline cpus in the allowed cpu list.
3717 */
3718 if ((cs == &top_cpuset) || cpumask_empty(pmask)) {
3719 const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
3720
3721 /*
3722 * We first exclude cpus allocated to partitions. If there is no
3723 * allowable online cpu left, we fall back to all possible cpus.
3724 */
3725 cpumask_andnot(pmask, possible_mask, top_cpuset.subparts_cpus);
3726 if (!cpumask_intersects(pmask, cpu_online_mask))
3727 cpumask_copy(pmask, possible_mask);
3728 }
3729
3730 rcu_read_unlock();
3731 spin_unlock_irqrestore(&callback_lock, flags);
3732}
3733
3734/**
3735 * cpuset_cpus_allowed_fallback - final fallback before complete catastrophe.
3736 * @tsk: pointer to task_struct with which the scheduler is struggling
3737 *
3738 * Description: In the case that the scheduler cannot find an allowed cpu in
3739 * tsk->cpus_allowed, we fall back to task_cs(tsk)->cpus_allowed. In legacy
3740 * mode however, this value is the same as task_cs(tsk)->effective_cpus,
3741 * which will not contain a sane cpumask during cases such as cpu hotplugging.
3742 * This is the absolute last resort for the scheduler and it is only used if
3743 * _every_ other avenue has been traveled.
3744 *
3745 * Returns true if the affinity of @tsk was changed, false otherwise.
3746 **/
3747
3748bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
3749{
3750 const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
3751 const struct cpumask *cs_mask;
3752 bool changed = false;
3753
3754 rcu_read_lock();
3755 cs_mask = task_cs(tsk)->cpus_allowed;
3756 if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
3757 do_set_cpus_allowed(tsk, cs_mask);
3758 changed = true;
3759 }
3760 rcu_read_unlock();
3761
3762 /*
3763 * We own tsk->cpus_allowed, nobody can change it under us.
3764 *
3765 * But we used cs && cs->cpus_allowed lockless and thus can
3766 * race with cgroup_attach_task() or update_cpumask() and get
3767 * the wrong tsk->cpus_allowed. However, both cases imply the
3768 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
3769 * which takes task_rq_lock().
3770 *
3771 * If we are called after it dropped the lock we must see all
3772 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
3773 * set any mask even if it is not right from task_cs() pov,
3774 * the pending set_cpus_allowed_ptr() will fix things.
3775 *
3776 * select_fallback_rq() will fix things ups and set cpu_possible_mask
3777 * if required.
3778 */
3779 return changed;
3780}
3781
3782void __init cpuset_init_current_mems_allowed(void)
3783{
3784 nodes_setall(current->mems_allowed);
3785}
3786
3787/**
3788 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
3789 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
3790 *
3791 * Description: Returns the nodemask_t mems_allowed of the cpuset
3792 * attached to the specified @tsk. Guaranteed to return some non-empty
3793 * subset of node_states[N_MEMORY], even if this means going outside the
3794 * tasks cpuset.
3795 **/
3796
3797nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
3798{
3799 nodemask_t mask;
3800 unsigned long flags;
3801
3802 spin_lock_irqsave(&callback_lock, flags);
3803 rcu_read_lock();
3804 guarantee_online_mems(task_cs(tsk), &mask);
3805 rcu_read_unlock();
3806 spin_unlock_irqrestore(&callback_lock, flags);
3807
3808 return mask;
3809}
3810
3811/**
3812 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. current mems_allowed
3813 * @nodemask: the nodemask to be checked
3814 *
3815 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
3816 */
3817int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
3818{
3819 return nodes_intersects(*nodemask, current->mems_allowed);
3820}
3821
3822/*
3823 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
3824 * mem_hardwall ancestor to the specified cpuset. Call holding
3825 * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
3826 * (an unusual configuration), then returns the root cpuset.
3827 */
3828static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
3829{
3830 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
3831 cs = parent_cs(cs);
3832 return cs;
3833}
3834
3835/*
3836 * __cpuset_node_allowed - Can we allocate on a memory node?
3837 * @node: is this an allowed node?
3838 * @gfp_mask: memory allocation flags
3839 *
3840 * If we're in interrupt, yes, we can always allocate. If @node is set in
3841 * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
3842 * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
3843 * yes. If current has access to memory reserves as an oom victim, yes.
3844 * Otherwise, no.
3845 *
3846 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
3847 * and do not allow allocations outside the current tasks cpuset
3848 * unless the task has been OOM killed.
3849 * GFP_KERNEL allocations are not so marked, so can escape to the
3850 * nearest enclosing hardwalled ancestor cpuset.
3851 *
3852 * Scanning up parent cpusets requires callback_lock. The
3853 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
3854 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
3855 * current tasks mems_allowed came up empty on the first pass over
3856 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
3857 * cpuset are short of memory, might require taking the callback_lock.
3858 *
3859 * The first call here from mm/page_alloc:get_page_from_freelist()
3860 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
3861 * so no allocation on a node outside the cpuset is allowed (unless
3862 * in interrupt, of course).
3863 *
3864 * The second pass through get_page_from_freelist() doesn't even call
3865 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
3866 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
3867 * in alloc_flags. That logic and the checks below have the combined
3868 * affect that:
3869 * in_interrupt - any node ok (current task context irrelevant)
3870 * GFP_ATOMIC - any node ok
3871 * tsk_is_oom_victim - any node ok
3872 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
3873 * GFP_USER - only nodes in current tasks mems allowed ok.
3874 */
3875bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
3876{
3877 struct cpuset *cs; /* current cpuset ancestors */
3878 bool allowed; /* is allocation in zone z allowed? */
3879 unsigned long flags;
3880
3881 if (in_interrupt())
3882 return true;
3883 if (node_isset(node, current->mems_allowed))
3884 return true;
3885 /*
3886 * Allow tasks that have access to memory reserves because they have
3887 * been OOM killed to get memory anywhere.
3888 */
3889 if (unlikely(tsk_is_oom_victim(current)))
3890 return true;
3891 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
3892 return false;
3893
3894 if (current->flags & PF_EXITING) /* Let dying task have memory */
3895 return true;
3896
3897 /* Not hardwall and node outside mems_allowed: scan up cpusets */
3898 spin_lock_irqsave(&callback_lock, flags);
3899
3900 rcu_read_lock();
3901 cs = nearest_hardwall_ancestor(task_cs(current));
3902 allowed = node_isset(node, cs->mems_allowed);
3903 rcu_read_unlock();
3904
3905 spin_unlock_irqrestore(&callback_lock, flags);
3906 return allowed;
3907}
3908
3909/**
3910 * cpuset_mem_spread_node() - On which node to begin search for a file page
3911 * cpuset_slab_spread_node() - On which node to begin search for a slab page
3912 *
3913 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
3914 * tasks in a cpuset with is_spread_page or is_spread_slab set),
3915 * and if the memory allocation used cpuset_mem_spread_node()
3916 * to determine on which node to start looking, as it will for
3917 * certain page cache or slab cache pages such as used for file
3918 * system buffers and inode caches, then instead of starting on the
3919 * local node to look for a free page, rather spread the starting
3920 * node around the tasks mems_allowed nodes.
3921 *
3922 * We don't have to worry about the returned node being offline
3923 * because "it can't happen", and even if it did, it would be ok.
3924 *
3925 * The routines calling guarantee_online_mems() are careful to
3926 * only set nodes in task->mems_allowed that are online. So it
3927 * should not be possible for the following code to return an
3928 * offline node. But if it did, that would be ok, as this routine
3929 * is not returning the node where the allocation must be, only
3930 * the node where the search should start. The zonelist passed to
3931 * __alloc_pages() will include all nodes. If the slab allocator
3932 * is passed an offline node, it will fall back to the local node.
3933 * See kmem_cache_alloc_node().
3934 */
3935
3936static int cpuset_spread_node(int *rotor)
3937{
3938 return *rotor = next_node_in(*rotor, current->mems_allowed);
3939}
3940
3941int cpuset_mem_spread_node(void)
3942{
3943 if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
3944 current->cpuset_mem_spread_rotor =
3945 node_random(¤t->mems_allowed);
3946
3947 return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
3948}
3949
3950int cpuset_slab_spread_node(void)
3951{
3952 if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
3953 current->cpuset_slab_spread_rotor =
3954 node_random(¤t->mems_allowed);
3955
3956 return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
3957}
3958
3959EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
3960
3961/**
3962 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
3963 * @tsk1: pointer to task_struct of some task.
3964 * @tsk2: pointer to task_struct of some other task.
3965 *
3966 * Description: Return true if @tsk1's mems_allowed intersects the
3967 * mems_allowed of @tsk2. Used by the OOM killer to determine if
3968 * one of the task's memory usage might impact the memory available
3969 * to the other.
3970 **/
3971
3972int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
3973 const struct task_struct *tsk2)
3974{
3975 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
3976}
3977
3978/**
3979 * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
3980 *
3981 * Description: Prints current's name, cpuset name, and cached copy of its
3982 * mems_allowed to the kernel log.
3983 */
3984void cpuset_print_current_mems_allowed(void)
3985{
3986 struct cgroup *cgrp;
3987
3988 rcu_read_lock();
3989
3990 cgrp = task_cs(current)->css.cgroup;
3991 pr_cont(",cpuset=");
3992 pr_cont_cgroup_name(cgrp);
3993 pr_cont(",mems_allowed=%*pbl",
3994 nodemask_pr_args(¤t->mems_allowed));
3995
3996 rcu_read_unlock();
3997}
3998
3999/*
4000 * Collection of memory_pressure is suppressed unless
4001 * this flag is enabled by writing "1" to the special
4002 * cpuset file 'memory_pressure_enabled' in the root cpuset.
4003 */
4004
4005int cpuset_memory_pressure_enabled __read_mostly;
4006
4007/*
4008 * __cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
4009 *
4010 * Keep a running average of the rate of synchronous (direct)
4011 * page reclaim efforts initiated by tasks in each cpuset.
4012 *
4013 * This represents the rate at which some task in the cpuset
4014 * ran low on memory on all nodes it was allowed to use, and
4015 * had to enter the kernels page reclaim code in an effort to
4016 * create more free memory by tossing clean pages or swapping
4017 * or writing dirty pages.
4018 *
4019 * Display to user space in the per-cpuset read-only file
4020 * "memory_pressure". Value displayed is an integer
4021 * representing the recent rate of entry into the synchronous
4022 * (direct) page reclaim by any task attached to the cpuset.
4023 */
4024
4025void __cpuset_memory_pressure_bump(void)
4026{
4027 rcu_read_lock();
4028 fmeter_markevent(&task_cs(current)->fmeter);
4029 rcu_read_unlock();
4030}
4031
4032#ifdef CONFIG_PROC_PID_CPUSET
4033/*
4034 * proc_cpuset_show()
4035 * - Print tasks cpuset path into seq_file.
4036 * - Used for /proc/<pid>/cpuset.
4037 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
4038 * doesn't really matter if tsk->cpuset changes after we read it,
4039 * and we take cpuset_rwsem, keeping cpuset_attach() from changing it
4040 * anyway.
4041 */
4042int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
4043 struct pid *pid, struct task_struct *tsk)
4044{
4045 char *buf;
4046 struct cgroup_subsys_state *css;
4047 int retval;
4048
4049 retval = -ENOMEM;
4050 buf = kmalloc(PATH_MAX, GFP_KERNEL);
4051 if (!buf)
4052 goto out;
4053
4054 css = task_get_css(tsk, cpuset_cgrp_id);
4055 retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
4056 current->nsproxy->cgroup_ns);
4057 css_put(css);
4058 if (retval >= PATH_MAX)
4059 retval = -ENAMETOOLONG;
4060 if (retval < 0)
4061 goto out_free;
4062 seq_puts(m, buf);
4063 seq_putc(m, '\n');
4064 retval = 0;
4065out_free:
4066 kfree(buf);
4067out:
4068 return retval;
4069}
4070#endif /* CONFIG_PROC_PID_CPUSET */
4071
4072/* Display task mems_allowed in /proc/<pid>/status file. */
4073void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
4074{
4075 seq_printf(m, "Mems_allowed:\t%*pb\n",
4076 nodemask_pr_args(&task->mems_allowed));
4077 seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
4078 nodemask_pr_args(&task->mems_allowed));
4079}