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1/*
2 * kernel/cpuset.c
3 *
4 * Processor and Memory placement constraints for sets of tasks.
5 *
6 * Copyright (C) 2003 BULL SA.
7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8 * Copyright (C) 2006 Google, Inc
9 *
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
12 *
13 * 2003-10-10 Written by Simon Derr.
14 * 2003-10-22 Updates by Stephen Hemminger.
15 * 2004 May-July Rework by Paul Jackson.
16 * 2006 Rework by Paul Menage to use generic cgroups
17 * 2008 Rework of the scheduler domains and CPU hotplug handling
18 * by Max Krasnyansky
19 *
20 * This file is subject to the terms and conditions of the GNU General Public
21 * License. See the file COPYING in the main directory of the Linux
22 * distribution for more details.
23 */
24
25#include <linux/cpu.h>
26#include <linux/cpumask.h>
27#include <linux/cpuset.h>
28#include <linux/err.h>
29#include <linux/errno.h>
30#include <linux/file.h>
31#include <linux/fs.h>
32#include <linux/init.h>
33#include <linux/interrupt.h>
34#include <linux/kernel.h>
35#include <linux/kmod.h>
36#include <linux/list.h>
37#include <linux/mempolicy.h>
38#include <linux/mm.h>
39#include <linux/memory.h>
40#include <linux/export.h>
41#include <linux/mount.h>
42#include <linux/fs_context.h>
43#include <linux/namei.h>
44#include <linux/pagemap.h>
45#include <linux/proc_fs.h>
46#include <linux/rcupdate.h>
47#include <linux/sched.h>
48#include <linux/sched/deadline.h>
49#include <linux/sched/mm.h>
50#include <linux/sched/task.h>
51#include <linux/seq_file.h>
52#include <linux/security.h>
53#include <linux/slab.h>
54#include <linux/spinlock.h>
55#include <linux/stat.h>
56#include <linux/string.h>
57#include <linux/time.h>
58#include <linux/time64.h>
59#include <linux/backing-dev.h>
60#include <linux/sort.h>
61#include <linux/oom.h>
62#include <linux/sched/isolation.h>
63#include <linux/uaccess.h>
64#include <linux/atomic.h>
65#include <linux/mutex.h>
66#include <linux/cgroup.h>
67#include <linux/wait.h>
68
69DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key);
70DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
71
72/* See "Frequency meter" comments, below. */
73
74struct fmeter {
75 int cnt; /* unprocessed events count */
76 int val; /* most recent output value */
77 time64_t time; /* clock (secs) when val computed */
78 spinlock_t lock; /* guards read or write of above */
79};
80
81struct cpuset {
82 struct cgroup_subsys_state css;
83
84 unsigned long flags; /* "unsigned long" so bitops work */
85
86 /*
87 * On default hierarchy:
88 *
89 * The user-configured masks can only be changed by writing to
90 * cpuset.cpus and cpuset.mems, and won't be limited by the
91 * parent masks.
92 *
93 * The effective masks is the real masks that apply to the tasks
94 * in the cpuset. They may be changed if the configured masks are
95 * changed or hotplug happens.
96 *
97 * effective_mask == configured_mask & parent's effective_mask,
98 * and if it ends up empty, it will inherit the parent's mask.
99 *
100 *
101 * On legacy hierarchy:
102 *
103 * The user-configured masks are always the same with effective masks.
104 */
105
106 /* user-configured CPUs and Memory Nodes allow to tasks */
107 cpumask_var_t cpus_allowed;
108 nodemask_t mems_allowed;
109
110 /* effective CPUs and Memory Nodes allow to tasks */
111 cpumask_var_t effective_cpus;
112 nodemask_t effective_mems;
113
114 /*
115 * CPUs allocated to child sub-partitions (default hierarchy only)
116 * - CPUs granted by the parent = effective_cpus U subparts_cpus
117 * - effective_cpus and subparts_cpus are mutually exclusive.
118 *
119 * effective_cpus contains only onlined CPUs, but subparts_cpus
120 * may have offlined ones.
121 */
122 cpumask_var_t subparts_cpus;
123
124 /*
125 * This is old Memory Nodes tasks took on.
126 *
127 * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
128 * - A new cpuset's old_mems_allowed is initialized when some
129 * task is moved into it.
130 * - old_mems_allowed is used in cpuset_migrate_mm() when we change
131 * cpuset.mems_allowed and have tasks' nodemask updated, and
132 * then old_mems_allowed is updated to mems_allowed.
133 */
134 nodemask_t old_mems_allowed;
135
136 struct fmeter fmeter; /* memory_pressure filter */
137
138 /*
139 * Tasks are being attached to this cpuset. Used to prevent
140 * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
141 */
142 int attach_in_progress;
143
144 /* partition number for rebuild_sched_domains() */
145 int pn;
146
147 /* for custom sched domain */
148 int relax_domain_level;
149
150 /* number of CPUs in subparts_cpus */
151 int nr_subparts_cpus;
152
153 /* partition root state */
154 int partition_root_state;
155
156 /*
157 * Default hierarchy only:
158 * use_parent_ecpus - set if using parent's effective_cpus
159 * child_ecpus_count - # of children with use_parent_ecpus set
160 */
161 int use_parent_ecpus;
162 int child_ecpus_count;
163};
164
165/*
166 * Partition root states:
167 *
168 * 0 - not a partition root
169 *
170 * 1 - partition root
171 *
172 * -1 - invalid partition root
173 * None of the cpus in cpus_allowed can be put into the parent's
174 * subparts_cpus. In this case, the cpuset is not a real partition
175 * root anymore. However, the CPU_EXCLUSIVE bit will still be set
176 * and the cpuset can be restored back to a partition root if the
177 * parent cpuset can give more CPUs back to this child cpuset.
178 */
179#define PRS_DISABLED 0
180#define PRS_ENABLED 1
181#define PRS_ERROR -1
182
183/*
184 * Temporary cpumasks for working with partitions that are passed among
185 * functions to avoid memory allocation in inner functions.
186 */
187struct tmpmasks {
188 cpumask_var_t addmask, delmask; /* For partition root */
189 cpumask_var_t new_cpus; /* For update_cpumasks_hier() */
190};
191
192static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
193{
194 return css ? container_of(css, struct cpuset, css) : NULL;
195}
196
197/* Retrieve the cpuset for a task */
198static inline struct cpuset *task_cs(struct task_struct *task)
199{
200 return css_cs(task_css(task, cpuset_cgrp_id));
201}
202
203static inline struct cpuset *parent_cs(struct cpuset *cs)
204{
205 return css_cs(cs->css.parent);
206}
207
208/* bits in struct cpuset flags field */
209typedef enum {
210 CS_ONLINE,
211 CS_CPU_EXCLUSIVE,
212 CS_MEM_EXCLUSIVE,
213 CS_MEM_HARDWALL,
214 CS_MEMORY_MIGRATE,
215 CS_SCHED_LOAD_BALANCE,
216 CS_SPREAD_PAGE,
217 CS_SPREAD_SLAB,
218} cpuset_flagbits_t;
219
220/* convenient tests for these bits */
221static inline bool is_cpuset_online(struct cpuset *cs)
222{
223 return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);
224}
225
226static inline int is_cpu_exclusive(const struct cpuset *cs)
227{
228 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
229}
230
231static inline int is_mem_exclusive(const struct cpuset *cs)
232{
233 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
234}
235
236static inline int is_mem_hardwall(const struct cpuset *cs)
237{
238 return test_bit(CS_MEM_HARDWALL, &cs->flags);
239}
240
241static inline int is_sched_load_balance(const struct cpuset *cs)
242{
243 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
244}
245
246static inline int is_memory_migrate(const struct cpuset *cs)
247{
248 return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
249}
250
251static inline int is_spread_page(const struct cpuset *cs)
252{
253 return test_bit(CS_SPREAD_PAGE, &cs->flags);
254}
255
256static inline int is_spread_slab(const struct cpuset *cs)
257{
258 return test_bit(CS_SPREAD_SLAB, &cs->flags);
259}
260
261static inline int is_partition_root(const struct cpuset *cs)
262{
263 return cs->partition_root_state > 0;
264}
265
266static struct cpuset top_cpuset = {
267 .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
268 (1 << CS_MEM_EXCLUSIVE)),
269 .partition_root_state = PRS_ENABLED,
270};
271
272/**
273 * cpuset_for_each_child - traverse online children of a cpuset
274 * @child_cs: loop cursor pointing to the current child
275 * @pos_css: used for iteration
276 * @parent_cs: target cpuset to walk children of
277 *
278 * Walk @child_cs through the online children of @parent_cs. Must be used
279 * with RCU read locked.
280 */
281#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
282 css_for_each_child((pos_css), &(parent_cs)->css) \
283 if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
284
285/**
286 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
287 * @des_cs: loop cursor pointing to the current descendant
288 * @pos_css: used for iteration
289 * @root_cs: target cpuset to walk ancestor of
290 *
291 * Walk @des_cs through the online descendants of @root_cs. Must be used
292 * with RCU read locked. The caller may modify @pos_css by calling
293 * css_rightmost_descendant() to skip subtree. @root_cs is included in the
294 * iteration and the first node to be visited.
295 */
296#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
297 css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
298 if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
299
300/*
301 * There are two global locks guarding cpuset structures - cpuset_mutex and
302 * callback_lock. We also require taking task_lock() when dereferencing a
303 * task's cpuset pointer. See "The task_lock() exception", at the end of this
304 * comment.
305 *
306 * A task must hold both locks to modify cpusets. If a task holds
307 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
308 * is the only task able to also acquire callback_lock and be able to
309 * modify cpusets. It can perform various checks on the cpuset structure
310 * first, knowing nothing will change. It can also allocate memory while
311 * just holding cpuset_mutex. While it is performing these checks, various
312 * callback routines can briefly acquire callback_lock to query cpusets.
313 * Once it is ready to make the changes, it takes callback_lock, blocking
314 * everyone else.
315 *
316 * Calls to the kernel memory allocator can not be made while holding
317 * callback_lock, as that would risk double tripping on callback_lock
318 * from one of the callbacks into the cpuset code from within
319 * __alloc_pages().
320 *
321 * If a task is only holding callback_lock, then it has read-only
322 * access to cpusets.
323 *
324 * Now, the task_struct fields mems_allowed and mempolicy may be changed
325 * by other task, we use alloc_lock in the task_struct fields to protect
326 * them.
327 *
328 * The cpuset_common_file_read() handlers only hold callback_lock across
329 * small pieces of code, such as when reading out possibly multi-word
330 * cpumasks and nodemasks.
331 *
332 * Accessing a task's cpuset should be done in accordance with the
333 * guidelines for accessing subsystem state in kernel/cgroup.c
334 */
335
336DEFINE_STATIC_PERCPU_RWSEM(cpuset_rwsem);
337
338void cpuset_read_lock(void)
339{
340 percpu_down_read(&cpuset_rwsem);
341}
342
343void cpuset_read_unlock(void)
344{
345 percpu_up_read(&cpuset_rwsem);
346}
347
348static DEFINE_SPINLOCK(callback_lock);
349
350static struct workqueue_struct *cpuset_migrate_mm_wq;
351
352/*
353 * CPU / memory hotplug is handled asynchronously.
354 */
355static void cpuset_hotplug_workfn(struct work_struct *work);
356static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
357
358static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
359
360/*
361 * Cgroup v2 behavior is used on the "cpus" and "mems" control files when
362 * on default hierarchy or when the cpuset_v2_mode flag is set by mounting
363 * the v1 cpuset cgroup filesystem with the "cpuset_v2_mode" mount option.
364 * With v2 behavior, "cpus" and "mems" are always what the users have
365 * requested and won't be changed by hotplug events. Only the effective
366 * cpus or mems will be affected.
367 */
368static inline bool is_in_v2_mode(void)
369{
370 return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
371 (cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE);
372}
373
374/*
375 * Return in pmask the portion of a cpusets's cpus_allowed that
376 * are online. If none are online, walk up the cpuset hierarchy
377 * until we find one that does have some online cpus.
378 *
379 * One way or another, we guarantee to return some non-empty subset
380 * of cpu_online_mask.
381 *
382 * Call with callback_lock or cpuset_mutex held.
383 */
384static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
385{
386 while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
387 cs = parent_cs(cs);
388 if (unlikely(!cs)) {
389 /*
390 * The top cpuset doesn't have any online cpu as a
391 * consequence of a race between cpuset_hotplug_work
392 * and cpu hotplug notifier. But we know the top
393 * cpuset's effective_cpus is on its way to be
394 * identical to cpu_online_mask.
395 */
396 cpumask_copy(pmask, cpu_online_mask);
397 return;
398 }
399 }
400 cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
401}
402
403/*
404 * Return in *pmask the portion of a cpusets's mems_allowed that
405 * are online, with memory. If none are online with memory, walk
406 * up the cpuset hierarchy until we find one that does have some
407 * online mems. The top cpuset always has some mems online.
408 *
409 * One way or another, we guarantee to return some non-empty subset
410 * of node_states[N_MEMORY].
411 *
412 * Call with callback_lock or cpuset_mutex held.
413 */
414static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
415{
416 while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
417 cs = parent_cs(cs);
418 nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
419}
420
421/*
422 * update task's spread flag if cpuset's page/slab spread flag is set
423 *
424 * Call with callback_lock or cpuset_mutex held.
425 */
426static void cpuset_update_task_spread_flag(struct cpuset *cs,
427 struct task_struct *tsk)
428{
429 if (is_spread_page(cs))
430 task_set_spread_page(tsk);
431 else
432 task_clear_spread_page(tsk);
433
434 if (is_spread_slab(cs))
435 task_set_spread_slab(tsk);
436 else
437 task_clear_spread_slab(tsk);
438}
439
440/*
441 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
442 *
443 * One cpuset is a subset of another if all its allowed CPUs and
444 * Memory Nodes are a subset of the other, and its exclusive flags
445 * are only set if the other's are set. Call holding cpuset_mutex.
446 */
447
448static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
449{
450 return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
451 nodes_subset(p->mems_allowed, q->mems_allowed) &&
452 is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
453 is_mem_exclusive(p) <= is_mem_exclusive(q);
454}
455
456/**
457 * alloc_cpumasks - allocate three cpumasks for cpuset
458 * @cs: the cpuset that have cpumasks to be allocated.
459 * @tmp: the tmpmasks structure pointer
460 * Return: 0 if successful, -ENOMEM otherwise.
461 *
462 * Only one of the two input arguments should be non-NULL.
463 */
464static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
465{
466 cpumask_var_t *pmask1, *pmask2, *pmask3;
467
468 if (cs) {
469 pmask1 = &cs->cpus_allowed;
470 pmask2 = &cs->effective_cpus;
471 pmask3 = &cs->subparts_cpus;
472 } else {
473 pmask1 = &tmp->new_cpus;
474 pmask2 = &tmp->addmask;
475 pmask3 = &tmp->delmask;
476 }
477
478 if (!zalloc_cpumask_var(pmask1, GFP_KERNEL))
479 return -ENOMEM;
480
481 if (!zalloc_cpumask_var(pmask2, GFP_KERNEL))
482 goto free_one;
483
484 if (!zalloc_cpumask_var(pmask3, GFP_KERNEL))
485 goto free_two;
486
487 return 0;
488
489free_two:
490 free_cpumask_var(*pmask2);
491free_one:
492 free_cpumask_var(*pmask1);
493 return -ENOMEM;
494}
495
496/**
497 * free_cpumasks - free cpumasks in a tmpmasks structure
498 * @cs: the cpuset that have cpumasks to be free.
499 * @tmp: the tmpmasks structure pointer
500 */
501static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
502{
503 if (cs) {
504 free_cpumask_var(cs->cpus_allowed);
505 free_cpumask_var(cs->effective_cpus);
506 free_cpumask_var(cs->subparts_cpus);
507 }
508 if (tmp) {
509 free_cpumask_var(tmp->new_cpus);
510 free_cpumask_var(tmp->addmask);
511 free_cpumask_var(tmp->delmask);
512 }
513}
514
515/**
516 * alloc_trial_cpuset - allocate a trial cpuset
517 * @cs: the cpuset that the trial cpuset duplicates
518 */
519static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
520{
521 struct cpuset *trial;
522
523 trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
524 if (!trial)
525 return NULL;
526
527 if (alloc_cpumasks(trial, NULL)) {
528 kfree(trial);
529 return NULL;
530 }
531
532 cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
533 cpumask_copy(trial->effective_cpus, cs->effective_cpus);
534 return trial;
535}
536
537/**
538 * free_cpuset - free the cpuset
539 * @cs: the cpuset to be freed
540 */
541static inline void free_cpuset(struct cpuset *cs)
542{
543 free_cpumasks(cs, NULL);
544 kfree(cs);
545}
546
547/*
548 * validate_change() - Used to validate that any proposed cpuset change
549 * follows the structural rules for cpusets.
550 *
551 * If we replaced the flag and mask values of the current cpuset
552 * (cur) with those values in the trial cpuset (trial), would
553 * our various subset and exclusive rules still be valid? Presumes
554 * cpuset_mutex held.
555 *
556 * 'cur' is the address of an actual, in-use cpuset. Operations
557 * such as list traversal that depend on the actual address of the
558 * cpuset in the list must use cur below, not trial.
559 *
560 * 'trial' is the address of bulk structure copy of cur, with
561 * perhaps one or more of the fields cpus_allowed, mems_allowed,
562 * or flags changed to new, trial values.
563 *
564 * Return 0 if valid, -errno if not.
565 */
566
567static int validate_change(struct cpuset *cur, struct cpuset *trial)
568{
569 struct cgroup_subsys_state *css;
570 struct cpuset *c, *par;
571 int ret;
572
573 rcu_read_lock();
574
575 /* Each of our child cpusets must be a subset of us */
576 ret = -EBUSY;
577 cpuset_for_each_child(c, css, cur)
578 if (!is_cpuset_subset(c, trial))
579 goto out;
580
581 /* Remaining checks don't apply to root cpuset */
582 ret = 0;
583 if (cur == &top_cpuset)
584 goto out;
585
586 par = parent_cs(cur);
587
588 /* On legacy hierarchy, we must be a subset of our parent cpuset. */
589 ret = -EACCES;
590 if (!is_in_v2_mode() && !is_cpuset_subset(trial, par))
591 goto out;
592
593 /*
594 * If either I or some sibling (!= me) is exclusive, we can't
595 * overlap
596 */
597 ret = -EINVAL;
598 cpuset_for_each_child(c, css, par) {
599 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
600 c != cur &&
601 cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
602 goto out;
603 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
604 c != cur &&
605 nodes_intersects(trial->mems_allowed, c->mems_allowed))
606 goto out;
607 }
608
609 /*
610 * Cpusets with tasks - existing or newly being attached - can't
611 * be changed to have empty cpus_allowed or mems_allowed.
612 */
613 ret = -ENOSPC;
614 if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
615 if (!cpumask_empty(cur->cpus_allowed) &&
616 cpumask_empty(trial->cpus_allowed))
617 goto out;
618 if (!nodes_empty(cur->mems_allowed) &&
619 nodes_empty(trial->mems_allowed))
620 goto out;
621 }
622
623 /*
624 * We can't shrink if we won't have enough room for SCHED_DEADLINE
625 * tasks.
626 */
627 ret = -EBUSY;
628 if (is_cpu_exclusive(cur) &&
629 !cpuset_cpumask_can_shrink(cur->cpus_allowed,
630 trial->cpus_allowed))
631 goto out;
632
633 ret = 0;
634out:
635 rcu_read_unlock();
636 return ret;
637}
638
639#ifdef CONFIG_SMP
640/*
641 * Helper routine for generate_sched_domains().
642 * Do cpusets a, b have overlapping effective cpus_allowed masks?
643 */
644static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
645{
646 return cpumask_intersects(a->effective_cpus, b->effective_cpus);
647}
648
649static void
650update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
651{
652 if (dattr->relax_domain_level < c->relax_domain_level)
653 dattr->relax_domain_level = c->relax_domain_level;
654 return;
655}
656
657static void update_domain_attr_tree(struct sched_domain_attr *dattr,
658 struct cpuset *root_cs)
659{
660 struct cpuset *cp;
661 struct cgroup_subsys_state *pos_css;
662
663 rcu_read_lock();
664 cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
665 /* skip the whole subtree if @cp doesn't have any CPU */
666 if (cpumask_empty(cp->cpus_allowed)) {
667 pos_css = css_rightmost_descendant(pos_css);
668 continue;
669 }
670
671 if (is_sched_load_balance(cp))
672 update_domain_attr(dattr, cp);
673 }
674 rcu_read_unlock();
675}
676
677/* Must be called with cpuset_mutex held. */
678static inline int nr_cpusets(void)
679{
680 /* jump label reference count + the top-level cpuset */
681 return static_key_count(&cpusets_enabled_key.key) + 1;
682}
683
684/*
685 * generate_sched_domains()
686 *
687 * This function builds a partial partition of the systems CPUs
688 * A 'partial partition' is a set of non-overlapping subsets whose
689 * union is a subset of that set.
690 * The output of this function needs to be passed to kernel/sched/core.c
691 * partition_sched_domains() routine, which will rebuild the scheduler's
692 * load balancing domains (sched domains) as specified by that partial
693 * partition.
694 *
695 * See "What is sched_load_balance" in Documentation/admin-guide/cgroup-v1/cpusets.rst
696 * for a background explanation of this.
697 *
698 * Does not return errors, on the theory that the callers of this
699 * routine would rather not worry about failures to rebuild sched
700 * domains when operating in the severe memory shortage situations
701 * that could cause allocation failures below.
702 *
703 * Must be called with cpuset_mutex held.
704 *
705 * The three key local variables below are:
706 * cp - cpuset pointer, used (together with pos_css) to perform a
707 * top-down scan of all cpusets. For our purposes, rebuilding
708 * the schedulers sched domains, we can ignore !is_sched_load_
709 * balance cpusets.
710 * csa - (for CpuSet Array) Array of pointers to all the cpusets
711 * that need to be load balanced, for convenient iterative
712 * access by the subsequent code that finds the best partition,
713 * i.e the set of domains (subsets) of CPUs such that the
714 * cpus_allowed of every cpuset marked is_sched_load_balance
715 * is a subset of one of these domains, while there are as
716 * many such domains as possible, each as small as possible.
717 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
718 * the kernel/sched/core.c routine partition_sched_domains() in a
719 * convenient format, that can be easily compared to the prior
720 * value to determine what partition elements (sched domains)
721 * were changed (added or removed.)
722 *
723 * Finding the best partition (set of domains):
724 * The triple nested loops below over i, j, k scan over the
725 * load balanced cpusets (using the array of cpuset pointers in
726 * csa[]) looking for pairs of cpusets that have overlapping
727 * cpus_allowed, but which don't have the same 'pn' partition
728 * number and gives them in the same partition number. It keeps
729 * looping on the 'restart' label until it can no longer find
730 * any such pairs.
731 *
732 * The union of the cpus_allowed masks from the set of
733 * all cpusets having the same 'pn' value then form the one
734 * element of the partition (one sched domain) to be passed to
735 * partition_sched_domains().
736 */
737static int generate_sched_domains(cpumask_var_t **domains,
738 struct sched_domain_attr **attributes)
739{
740 struct cpuset *cp; /* top-down scan of cpusets */
741 struct cpuset **csa; /* array of all cpuset ptrs */
742 int csn; /* how many cpuset ptrs in csa so far */
743 int i, j, k; /* indices for partition finding loops */
744 cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
745 struct sched_domain_attr *dattr; /* attributes for custom domains */
746 int ndoms = 0; /* number of sched domains in result */
747 int nslot; /* next empty doms[] struct cpumask slot */
748 struct cgroup_subsys_state *pos_css;
749 bool root_load_balance = is_sched_load_balance(&top_cpuset);
750
751 doms = NULL;
752 dattr = NULL;
753 csa = NULL;
754
755 /* Special case for the 99% of systems with one, full, sched domain */
756 if (root_load_balance && !top_cpuset.nr_subparts_cpus) {
757 ndoms = 1;
758 doms = alloc_sched_domains(ndoms);
759 if (!doms)
760 goto done;
761
762 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
763 if (dattr) {
764 *dattr = SD_ATTR_INIT;
765 update_domain_attr_tree(dattr, &top_cpuset);
766 }
767 cpumask_and(doms[0], top_cpuset.effective_cpus,
768 housekeeping_cpumask(HK_FLAG_DOMAIN));
769
770 goto done;
771 }
772
773 csa = kmalloc_array(nr_cpusets(), sizeof(cp), GFP_KERNEL);
774 if (!csa)
775 goto done;
776 csn = 0;
777
778 rcu_read_lock();
779 if (root_load_balance)
780 csa[csn++] = &top_cpuset;
781 cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
782 if (cp == &top_cpuset)
783 continue;
784 /*
785 * Continue traversing beyond @cp iff @cp has some CPUs and
786 * isn't load balancing. The former is obvious. The
787 * latter: All child cpusets contain a subset of the
788 * parent's cpus, so just skip them, and then we call
789 * update_domain_attr_tree() to calc relax_domain_level of
790 * the corresponding sched domain.
791 *
792 * If root is load-balancing, we can skip @cp if it
793 * is a subset of the root's effective_cpus.
794 */
795 if (!cpumask_empty(cp->cpus_allowed) &&
796 !(is_sched_load_balance(cp) &&
797 cpumask_intersects(cp->cpus_allowed,
798 housekeeping_cpumask(HK_FLAG_DOMAIN))))
799 continue;
800
801 if (root_load_balance &&
802 cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus))
803 continue;
804
805 if (is_sched_load_balance(cp) &&
806 !cpumask_empty(cp->effective_cpus))
807 csa[csn++] = cp;
808
809 /* skip @cp's subtree if not a partition root */
810 if (!is_partition_root(cp))
811 pos_css = css_rightmost_descendant(pos_css);
812 }
813 rcu_read_unlock();
814
815 for (i = 0; i < csn; i++)
816 csa[i]->pn = i;
817 ndoms = csn;
818
819restart:
820 /* Find the best partition (set of sched domains) */
821 for (i = 0; i < csn; i++) {
822 struct cpuset *a = csa[i];
823 int apn = a->pn;
824
825 for (j = 0; j < csn; j++) {
826 struct cpuset *b = csa[j];
827 int bpn = b->pn;
828
829 if (apn != bpn && cpusets_overlap(a, b)) {
830 for (k = 0; k < csn; k++) {
831 struct cpuset *c = csa[k];
832
833 if (c->pn == bpn)
834 c->pn = apn;
835 }
836 ndoms--; /* one less element */
837 goto restart;
838 }
839 }
840 }
841
842 /*
843 * Now we know how many domains to create.
844 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
845 */
846 doms = alloc_sched_domains(ndoms);
847 if (!doms)
848 goto done;
849
850 /*
851 * The rest of the code, including the scheduler, can deal with
852 * dattr==NULL case. No need to abort if alloc fails.
853 */
854 dattr = kmalloc_array(ndoms, sizeof(struct sched_domain_attr),
855 GFP_KERNEL);
856
857 for (nslot = 0, i = 0; i < csn; i++) {
858 struct cpuset *a = csa[i];
859 struct cpumask *dp;
860 int apn = a->pn;
861
862 if (apn < 0) {
863 /* Skip completed partitions */
864 continue;
865 }
866
867 dp = doms[nslot];
868
869 if (nslot == ndoms) {
870 static int warnings = 10;
871 if (warnings) {
872 pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
873 nslot, ndoms, csn, i, apn);
874 warnings--;
875 }
876 continue;
877 }
878
879 cpumask_clear(dp);
880 if (dattr)
881 *(dattr + nslot) = SD_ATTR_INIT;
882 for (j = i; j < csn; j++) {
883 struct cpuset *b = csa[j];
884
885 if (apn == b->pn) {
886 cpumask_or(dp, dp, b->effective_cpus);
887 cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN));
888 if (dattr)
889 update_domain_attr_tree(dattr + nslot, b);
890
891 /* Done with this partition */
892 b->pn = -1;
893 }
894 }
895 nslot++;
896 }
897 BUG_ON(nslot != ndoms);
898
899done:
900 kfree(csa);
901
902 /*
903 * Fallback to the default domain if kmalloc() failed.
904 * See comments in partition_sched_domains().
905 */
906 if (doms == NULL)
907 ndoms = 1;
908
909 *domains = doms;
910 *attributes = dattr;
911 return ndoms;
912}
913
914static void update_tasks_root_domain(struct cpuset *cs)
915{
916 struct css_task_iter it;
917 struct task_struct *task;
918
919 css_task_iter_start(&cs->css, 0, &it);
920
921 while ((task = css_task_iter_next(&it)))
922 dl_add_task_root_domain(task);
923
924 css_task_iter_end(&it);
925}
926
927static void rebuild_root_domains(void)
928{
929 struct cpuset *cs = NULL;
930 struct cgroup_subsys_state *pos_css;
931
932 percpu_rwsem_assert_held(&cpuset_rwsem);
933 lockdep_assert_cpus_held();
934 lockdep_assert_held(&sched_domains_mutex);
935
936 rcu_read_lock();
937
938 /*
939 * Clear default root domain DL accounting, it will be computed again
940 * if a task belongs to it.
941 */
942 dl_clear_root_domain(&def_root_domain);
943
944 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
945
946 if (cpumask_empty(cs->effective_cpus)) {
947 pos_css = css_rightmost_descendant(pos_css);
948 continue;
949 }
950
951 css_get(&cs->css);
952
953 rcu_read_unlock();
954
955 update_tasks_root_domain(cs);
956
957 rcu_read_lock();
958 css_put(&cs->css);
959 }
960 rcu_read_unlock();
961}
962
963static void
964partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
965 struct sched_domain_attr *dattr_new)
966{
967 mutex_lock(&sched_domains_mutex);
968 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
969 rebuild_root_domains();
970 mutex_unlock(&sched_domains_mutex);
971}
972
973/*
974 * Rebuild scheduler domains.
975 *
976 * If the flag 'sched_load_balance' of any cpuset with non-empty
977 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
978 * which has that flag enabled, or if any cpuset with a non-empty
979 * 'cpus' is removed, then call this routine to rebuild the
980 * scheduler's dynamic sched domains.
981 *
982 * Call with cpuset_mutex held. Takes get_online_cpus().
983 */
984static void rebuild_sched_domains_locked(void)
985{
986 struct cgroup_subsys_state *pos_css;
987 struct sched_domain_attr *attr;
988 cpumask_var_t *doms;
989 struct cpuset *cs;
990 int ndoms;
991
992 lockdep_assert_cpus_held();
993 percpu_rwsem_assert_held(&cpuset_rwsem);
994
995 /*
996 * If we have raced with CPU hotplug, return early to avoid
997 * passing doms with offlined cpu to partition_sched_domains().
998 * Anyways, cpuset_hotplug_workfn() will rebuild sched domains.
999 *
1000 * With no CPUs in any subpartitions, top_cpuset's effective CPUs
1001 * should be the same as the active CPUs, so checking only top_cpuset
1002 * is enough to detect racing CPU offlines.
1003 */
1004 if (!top_cpuset.nr_subparts_cpus &&
1005 !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
1006 return;
1007
1008 /*
1009 * With subpartition CPUs, however, the effective CPUs of a partition
1010 * root should be only a subset of the active CPUs. Since a CPU in any
1011 * partition root could be offlined, all must be checked.
1012 */
1013 if (top_cpuset.nr_subparts_cpus) {
1014 rcu_read_lock();
1015 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
1016 if (!is_partition_root(cs)) {
1017 pos_css = css_rightmost_descendant(pos_css);
1018 continue;
1019 }
1020 if (!cpumask_subset(cs->effective_cpus,
1021 cpu_active_mask)) {
1022 rcu_read_unlock();
1023 return;
1024 }
1025 }
1026 rcu_read_unlock();
1027 }
1028
1029 /* Generate domain masks and attrs */
1030 ndoms = generate_sched_domains(&doms, &attr);
1031
1032 /* Have scheduler rebuild the domains */
1033 partition_and_rebuild_sched_domains(ndoms, doms, attr);
1034}
1035#else /* !CONFIG_SMP */
1036static void rebuild_sched_domains_locked(void)
1037{
1038}
1039#endif /* CONFIG_SMP */
1040
1041void rebuild_sched_domains(void)
1042{
1043 get_online_cpus();
1044 percpu_down_write(&cpuset_rwsem);
1045 rebuild_sched_domains_locked();
1046 percpu_up_write(&cpuset_rwsem);
1047 put_online_cpus();
1048}
1049
1050/**
1051 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
1052 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
1053 *
1054 * Iterate through each task of @cs updating its cpus_allowed to the
1055 * effective cpuset's. As this function is called with cpuset_mutex held,
1056 * cpuset membership stays stable.
1057 */
1058static void update_tasks_cpumask(struct cpuset *cs)
1059{
1060 struct css_task_iter it;
1061 struct task_struct *task;
1062
1063 css_task_iter_start(&cs->css, 0, &it);
1064 while ((task = css_task_iter_next(&it)))
1065 set_cpus_allowed_ptr(task, cs->effective_cpus);
1066 css_task_iter_end(&it);
1067}
1068
1069/**
1070 * compute_effective_cpumask - Compute the effective cpumask of the cpuset
1071 * @new_cpus: the temp variable for the new effective_cpus mask
1072 * @cs: the cpuset the need to recompute the new effective_cpus mask
1073 * @parent: the parent cpuset
1074 *
1075 * If the parent has subpartition CPUs, include them in the list of
1076 * allowable CPUs in computing the new effective_cpus mask. Since offlined
1077 * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask
1078 * to mask those out.
1079 */
1080static void compute_effective_cpumask(struct cpumask *new_cpus,
1081 struct cpuset *cs, struct cpuset *parent)
1082{
1083 if (parent->nr_subparts_cpus) {
1084 cpumask_or(new_cpus, parent->effective_cpus,
1085 parent->subparts_cpus);
1086 cpumask_and(new_cpus, new_cpus, cs->cpus_allowed);
1087 cpumask_and(new_cpus, new_cpus, cpu_active_mask);
1088 } else {
1089 cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus);
1090 }
1091}
1092
1093/*
1094 * Commands for update_parent_subparts_cpumask
1095 */
1096enum subparts_cmd {
1097 partcmd_enable, /* Enable partition root */
1098 partcmd_disable, /* Disable partition root */
1099 partcmd_update, /* Update parent's subparts_cpus */
1100};
1101
1102/**
1103 * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
1104 * @cpuset: The cpuset that requests change in partition root state
1105 * @cmd: Partition root state change command
1106 * @newmask: Optional new cpumask for partcmd_update
1107 * @tmp: Temporary addmask and delmask
1108 * Return: 0, 1 or an error code
1109 *
1110 * For partcmd_enable, the cpuset is being transformed from a non-partition
1111 * root to a partition root. The cpus_allowed mask of the given cpuset will
1112 * be put into parent's subparts_cpus and taken away from parent's
1113 * effective_cpus. The function will return 0 if all the CPUs listed in
1114 * cpus_allowed can be granted or an error code will be returned.
1115 *
1116 * For partcmd_disable, the cpuset is being transofrmed from a partition
1117 * root back to a non-partition root. Any CPUs in cpus_allowed that are in
1118 * parent's subparts_cpus will be taken away from that cpumask and put back
1119 * into parent's effective_cpus. 0 should always be returned.
1120 *
1121 * For partcmd_update, if the optional newmask is specified, the cpu
1122 * list is to be changed from cpus_allowed to newmask. Otherwise,
1123 * cpus_allowed is assumed to remain the same. The cpuset should either
1124 * be a partition root or an invalid partition root. The partition root
1125 * state may change if newmask is NULL and none of the requested CPUs can
1126 * be granted by the parent. The function will return 1 if changes to
1127 * parent's subparts_cpus and effective_cpus happen or 0 otherwise.
1128 * Error code should only be returned when newmask is non-NULL.
1129 *
1130 * The partcmd_enable and partcmd_disable commands are used by
1131 * update_prstate(). The partcmd_update command is used by
1132 * update_cpumasks_hier() with newmask NULL and update_cpumask() with
1133 * newmask set.
1134 *
1135 * The checking is more strict when enabling partition root than the
1136 * other two commands.
1137 *
1138 * Because of the implicit cpu exclusive nature of a partition root,
1139 * cpumask changes that violates the cpu exclusivity rule will not be
1140 * permitted when checked by validate_change(). The validate_change()
1141 * function will also prevent any changes to the cpu list if it is not
1142 * a superset of children's cpu lists.
1143 */
1144static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd,
1145 struct cpumask *newmask,
1146 struct tmpmasks *tmp)
1147{
1148 struct cpuset *parent = parent_cs(cpuset);
1149 int adding; /* Moving cpus from effective_cpus to subparts_cpus */
1150 int deleting; /* Moving cpus from subparts_cpus to effective_cpus */
1151 int new_prs;
1152 bool part_error = false; /* Partition error? */
1153
1154 percpu_rwsem_assert_held(&cpuset_rwsem);
1155
1156 /*
1157 * The parent must be a partition root.
1158 * The new cpumask, if present, or the current cpus_allowed must
1159 * not be empty.
1160 */
1161 if (!is_partition_root(parent) ||
1162 (newmask && cpumask_empty(newmask)) ||
1163 (!newmask && cpumask_empty(cpuset->cpus_allowed)))
1164 return -EINVAL;
1165
1166 /*
1167 * Enabling/disabling partition root is not allowed if there are
1168 * online children.
1169 */
1170 if ((cmd != partcmd_update) && css_has_online_children(&cpuset->css))
1171 return -EBUSY;
1172
1173 /*
1174 * Enabling partition root is not allowed if not all the CPUs
1175 * can be granted from parent's effective_cpus or at least one
1176 * CPU will be left after that.
1177 */
1178 if ((cmd == partcmd_enable) &&
1179 (!cpumask_subset(cpuset->cpus_allowed, parent->effective_cpus) ||
1180 cpumask_equal(cpuset->cpus_allowed, parent->effective_cpus)))
1181 return -EINVAL;
1182
1183 /*
1184 * A cpumask update cannot make parent's effective_cpus become empty.
1185 */
1186 adding = deleting = false;
1187 new_prs = cpuset->partition_root_state;
1188 if (cmd == partcmd_enable) {
1189 cpumask_copy(tmp->addmask, cpuset->cpus_allowed);
1190 adding = true;
1191 } else if (cmd == partcmd_disable) {
1192 deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed,
1193 parent->subparts_cpus);
1194 } else if (newmask) {
1195 /*
1196 * partcmd_update with newmask:
1197 *
1198 * delmask = cpus_allowed & ~newmask & parent->subparts_cpus
1199 * addmask = newmask & parent->effective_cpus
1200 * & ~parent->subparts_cpus
1201 */
1202 cpumask_andnot(tmp->delmask, cpuset->cpus_allowed, newmask);
1203 deleting = cpumask_and(tmp->delmask, tmp->delmask,
1204 parent->subparts_cpus);
1205
1206 cpumask_and(tmp->addmask, newmask, parent->effective_cpus);
1207 adding = cpumask_andnot(tmp->addmask, tmp->addmask,
1208 parent->subparts_cpus);
1209 /*
1210 * Return error if the new effective_cpus could become empty.
1211 */
1212 if (adding &&
1213 cpumask_equal(parent->effective_cpus, tmp->addmask)) {
1214 if (!deleting)
1215 return -EINVAL;
1216 /*
1217 * As some of the CPUs in subparts_cpus might have
1218 * been offlined, we need to compute the real delmask
1219 * to confirm that.
1220 */
1221 if (!cpumask_and(tmp->addmask, tmp->delmask,
1222 cpu_active_mask))
1223 return -EINVAL;
1224 cpumask_copy(tmp->addmask, parent->effective_cpus);
1225 }
1226 } else {
1227 /*
1228 * partcmd_update w/o newmask:
1229 *
1230 * addmask = cpus_allowed & parent->effective_cpus
1231 *
1232 * Note that parent's subparts_cpus may have been
1233 * pre-shrunk in case there is a change in the cpu list.
1234 * So no deletion is needed.
1235 */
1236 adding = cpumask_and(tmp->addmask, cpuset->cpus_allowed,
1237 parent->effective_cpus);
1238 part_error = cpumask_equal(tmp->addmask,
1239 parent->effective_cpus);
1240 }
1241
1242 if (cmd == partcmd_update) {
1243 int prev_prs = cpuset->partition_root_state;
1244
1245 /*
1246 * Check for possible transition between PRS_ENABLED
1247 * and PRS_ERROR.
1248 */
1249 switch (cpuset->partition_root_state) {
1250 case PRS_ENABLED:
1251 if (part_error)
1252 new_prs = PRS_ERROR;
1253 break;
1254 case PRS_ERROR:
1255 if (!part_error)
1256 new_prs = PRS_ENABLED;
1257 break;
1258 }
1259 /*
1260 * Set part_error if previously in invalid state.
1261 */
1262 part_error = (prev_prs == PRS_ERROR);
1263 }
1264
1265 if (!part_error && (new_prs == PRS_ERROR))
1266 return 0; /* Nothing need to be done */
1267
1268 if (new_prs == PRS_ERROR) {
1269 /*
1270 * Remove all its cpus from parent's subparts_cpus.
1271 */
1272 adding = false;
1273 deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed,
1274 parent->subparts_cpus);
1275 }
1276
1277 if (!adding && !deleting && (new_prs == cpuset->partition_root_state))
1278 return 0;
1279
1280 /*
1281 * Change the parent's subparts_cpus.
1282 * Newly added CPUs will be removed from effective_cpus and
1283 * newly deleted ones will be added back to effective_cpus.
1284 */
1285 spin_lock_irq(&callback_lock);
1286 if (adding) {
1287 cpumask_or(parent->subparts_cpus,
1288 parent->subparts_cpus, tmp->addmask);
1289 cpumask_andnot(parent->effective_cpus,
1290 parent->effective_cpus, tmp->addmask);
1291 }
1292 if (deleting) {
1293 cpumask_andnot(parent->subparts_cpus,
1294 parent->subparts_cpus, tmp->delmask);
1295 /*
1296 * Some of the CPUs in subparts_cpus might have been offlined.
1297 */
1298 cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask);
1299 cpumask_or(parent->effective_cpus,
1300 parent->effective_cpus, tmp->delmask);
1301 }
1302
1303 parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
1304
1305 if (cpuset->partition_root_state != new_prs)
1306 cpuset->partition_root_state = new_prs;
1307 spin_unlock_irq(&callback_lock);
1308
1309 return cmd == partcmd_update;
1310}
1311
1312/*
1313 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
1314 * @cs: the cpuset to consider
1315 * @tmp: temp variables for calculating effective_cpus & partition setup
1316 *
1317 * When configured cpumask is changed, the effective cpumasks of this cpuset
1318 * and all its descendants need to be updated.
1319 *
1320 * On legacy hierarchy, effective_cpus will be the same with cpu_allowed.
1321 *
1322 * Called with cpuset_mutex held
1323 */
1324static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp)
1325{
1326 struct cpuset *cp;
1327 struct cgroup_subsys_state *pos_css;
1328 bool need_rebuild_sched_domains = false;
1329 int new_prs;
1330
1331 rcu_read_lock();
1332 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1333 struct cpuset *parent = parent_cs(cp);
1334
1335 compute_effective_cpumask(tmp->new_cpus, cp, parent);
1336
1337 /*
1338 * If it becomes empty, inherit the effective mask of the
1339 * parent, which is guaranteed to have some CPUs.
1340 */
1341 if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) {
1342 cpumask_copy(tmp->new_cpus, parent->effective_cpus);
1343 if (!cp->use_parent_ecpus) {
1344 cp->use_parent_ecpus = true;
1345 parent->child_ecpus_count++;
1346 }
1347 } else if (cp->use_parent_ecpus) {
1348 cp->use_parent_ecpus = false;
1349 WARN_ON_ONCE(!parent->child_ecpus_count);
1350 parent->child_ecpus_count--;
1351 }
1352
1353 /*
1354 * Skip the whole subtree if the cpumask remains the same
1355 * and has no partition root state.
1356 */
1357 if (!cp->partition_root_state &&
1358 cpumask_equal(tmp->new_cpus, cp->effective_cpus)) {
1359 pos_css = css_rightmost_descendant(pos_css);
1360 continue;
1361 }
1362
1363 /*
1364 * update_parent_subparts_cpumask() should have been called
1365 * for cs already in update_cpumask(). We should also call
1366 * update_tasks_cpumask() again for tasks in the parent
1367 * cpuset if the parent's subparts_cpus changes.
1368 */
1369 new_prs = cp->partition_root_state;
1370 if ((cp != cs) && new_prs) {
1371 switch (parent->partition_root_state) {
1372 case PRS_DISABLED:
1373 /*
1374 * If parent is not a partition root or an
1375 * invalid partition root, clear its state
1376 * and its CS_CPU_EXCLUSIVE flag.
1377 */
1378 WARN_ON_ONCE(cp->partition_root_state
1379 != PRS_ERROR);
1380 new_prs = PRS_DISABLED;
1381
1382 /*
1383 * clear_bit() is an atomic operation and
1384 * readers aren't interested in the state
1385 * of CS_CPU_EXCLUSIVE anyway. So we can
1386 * just update the flag without holding
1387 * the callback_lock.
1388 */
1389 clear_bit(CS_CPU_EXCLUSIVE, &cp->flags);
1390 break;
1391
1392 case PRS_ENABLED:
1393 if (update_parent_subparts_cpumask(cp, partcmd_update, NULL, tmp))
1394 update_tasks_cpumask(parent);
1395 break;
1396
1397 case PRS_ERROR:
1398 /*
1399 * When parent is invalid, it has to be too.
1400 */
1401 new_prs = PRS_ERROR;
1402 break;
1403 }
1404 }
1405
1406 if (!css_tryget_online(&cp->css))
1407 continue;
1408 rcu_read_unlock();
1409
1410 spin_lock_irq(&callback_lock);
1411
1412 cpumask_copy(cp->effective_cpus, tmp->new_cpus);
1413 if (cp->nr_subparts_cpus && (new_prs != PRS_ENABLED)) {
1414 cp->nr_subparts_cpus = 0;
1415 cpumask_clear(cp->subparts_cpus);
1416 } else if (cp->nr_subparts_cpus) {
1417 /*
1418 * Make sure that effective_cpus & subparts_cpus
1419 * are mutually exclusive.
1420 *
1421 * In the unlikely event that effective_cpus
1422 * becomes empty. we clear cp->nr_subparts_cpus and
1423 * let its child partition roots to compete for
1424 * CPUs again.
1425 */
1426 cpumask_andnot(cp->effective_cpus, cp->effective_cpus,
1427 cp->subparts_cpus);
1428 if (cpumask_empty(cp->effective_cpus)) {
1429 cpumask_copy(cp->effective_cpus, tmp->new_cpus);
1430 cpumask_clear(cp->subparts_cpus);
1431 cp->nr_subparts_cpus = 0;
1432 } else if (!cpumask_subset(cp->subparts_cpus,
1433 tmp->new_cpus)) {
1434 cpumask_andnot(cp->subparts_cpus,
1435 cp->subparts_cpus, tmp->new_cpus);
1436 cp->nr_subparts_cpus
1437 = cpumask_weight(cp->subparts_cpus);
1438 }
1439 }
1440
1441 if (new_prs != cp->partition_root_state)
1442 cp->partition_root_state = new_prs;
1443
1444 spin_unlock_irq(&callback_lock);
1445
1446 WARN_ON(!is_in_v2_mode() &&
1447 !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
1448
1449 update_tasks_cpumask(cp);
1450
1451 /*
1452 * On legacy hierarchy, if the effective cpumask of any non-
1453 * empty cpuset is changed, we need to rebuild sched domains.
1454 * On default hierarchy, the cpuset needs to be a partition
1455 * root as well.
1456 */
1457 if (!cpumask_empty(cp->cpus_allowed) &&
1458 is_sched_load_balance(cp) &&
1459 (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
1460 is_partition_root(cp)))
1461 need_rebuild_sched_domains = true;
1462
1463 rcu_read_lock();
1464 css_put(&cp->css);
1465 }
1466 rcu_read_unlock();
1467
1468 if (need_rebuild_sched_domains)
1469 rebuild_sched_domains_locked();
1470}
1471
1472/**
1473 * update_sibling_cpumasks - Update siblings cpumasks
1474 * @parent: Parent cpuset
1475 * @cs: Current cpuset
1476 * @tmp: Temp variables
1477 */
1478static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
1479 struct tmpmasks *tmp)
1480{
1481 struct cpuset *sibling;
1482 struct cgroup_subsys_state *pos_css;
1483
1484 /*
1485 * Check all its siblings and call update_cpumasks_hier()
1486 * if their use_parent_ecpus flag is set in order for them
1487 * to use the right effective_cpus value.
1488 */
1489 rcu_read_lock();
1490 cpuset_for_each_child(sibling, pos_css, parent) {
1491 if (sibling == cs)
1492 continue;
1493 if (!sibling->use_parent_ecpus)
1494 continue;
1495
1496 update_cpumasks_hier(sibling, tmp);
1497 }
1498 rcu_read_unlock();
1499}
1500
1501/**
1502 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
1503 * @cs: the cpuset to consider
1504 * @trialcs: trial cpuset
1505 * @buf: buffer of cpu numbers written to this cpuset
1506 */
1507static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
1508 const char *buf)
1509{
1510 int retval;
1511 struct tmpmasks tmp;
1512
1513 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
1514 if (cs == &top_cpuset)
1515 return -EACCES;
1516
1517 /*
1518 * An empty cpus_allowed is ok only if the cpuset has no tasks.
1519 * Since cpulist_parse() fails on an empty mask, we special case
1520 * that parsing. The validate_change() call ensures that cpusets
1521 * with tasks have cpus.
1522 */
1523 if (!*buf) {
1524 cpumask_clear(trialcs->cpus_allowed);
1525 } else {
1526 retval = cpulist_parse(buf, trialcs->cpus_allowed);
1527 if (retval < 0)
1528 return retval;
1529
1530 if (!cpumask_subset(trialcs->cpus_allowed,
1531 top_cpuset.cpus_allowed))
1532 return -EINVAL;
1533 }
1534
1535 /* Nothing to do if the cpus didn't change */
1536 if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
1537 return 0;
1538
1539 retval = validate_change(cs, trialcs);
1540 if (retval < 0)
1541 return retval;
1542
1543#ifdef CONFIG_CPUMASK_OFFSTACK
1544 /*
1545 * Use the cpumasks in trialcs for tmpmasks when they are pointers
1546 * to allocated cpumasks.
1547 */
1548 tmp.addmask = trialcs->subparts_cpus;
1549 tmp.delmask = trialcs->effective_cpus;
1550 tmp.new_cpus = trialcs->cpus_allowed;
1551#endif
1552
1553 if (cs->partition_root_state) {
1554 /* Cpumask of a partition root cannot be empty */
1555 if (cpumask_empty(trialcs->cpus_allowed))
1556 return -EINVAL;
1557 if (update_parent_subparts_cpumask(cs, partcmd_update,
1558 trialcs->cpus_allowed, &tmp) < 0)
1559 return -EINVAL;
1560 }
1561
1562 spin_lock_irq(&callback_lock);
1563 cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
1564
1565 /*
1566 * Make sure that subparts_cpus is a subset of cpus_allowed.
1567 */
1568 if (cs->nr_subparts_cpus) {
1569 cpumask_andnot(cs->subparts_cpus, cs->subparts_cpus,
1570 cs->cpus_allowed);
1571 cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
1572 }
1573 spin_unlock_irq(&callback_lock);
1574
1575 update_cpumasks_hier(cs, &tmp);
1576
1577 if (cs->partition_root_state) {
1578 struct cpuset *parent = parent_cs(cs);
1579
1580 /*
1581 * For partition root, update the cpumasks of sibling
1582 * cpusets if they use parent's effective_cpus.
1583 */
1584 if (parent->child_ecpus_count)
1585 update_sibling_cpumasks(parent, cs, &tmp);
1586 }
1587 return 0;
1588}
1589
1590/*
1591 * Migrate memory region from one set of nodes to another. This is
1592 * performed asynchronously as it can be called from process migration path
1593 * holding locks involved in process management. All mm migrations are
1594 * performed in the queued order and can be waited for by flushing
1595 * cpuset_migrate_mm_wq.
1596 */
1597
1598struct cpuset_migrate_mm_work {
1599 struct work_struct work;
1600 struct mm_struct *mm;
1601 nodemask_t from;
1602 nodemask_t to;
1603};
1604
1605static void cpuset_migrate_mm_workfn(struct work_struct *work)
1606{
1607 struct cpuset_migrate_mm_work *mwork =
1608 container_of(work, struct cpuset_migrate_mm_work, work);
1609
1610 /* on a wq worker, no need to worry about %current's mems_allowed */
1611 do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
1612 mmput(mwork->mm);
1613 kfree(mwork);
1614}
1615
1616static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
1617 const nodemask_t *to)
1618{
1619 struct cpuset_migrate_mm_work *mwork;
1620
1621 mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
1622 if (mwork) {
1623 mwork->mm = mm;
1624 mwork->from = *from;
1625 mwork->to = *to;
1626 INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
1627 queue_work(cpuset_migrate_mm_wq, &mwork->work);
1628 } else {
1629 mmput(mm);
1630 }
1631}
1632
1633static void cpuset_post_attach(void)
1634{
1635 flush_workqueue(cpuset_migrate_mm_wq);
1636}
1637
1638/*
1639 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
1640 * @tsk: the task to change
1641 * @newmems: new nodes that the task will be set
1642 *
1643 * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed
1644 * and rebind an eventual tasks' mempolicy. If the task is allocating in
1645 * parallel, it might temporarily see an empty intersection, which results in
1646 * a seqlock check and retry before OOM or allocation failure.
1647 */
1648static void cpuset_change_task_nodemask(struct task_struct *tsk,
1649 nodemask_t *newmems)
1650{
1651 task_lock(tsk);
1652
1653 local_irq_disable();
1654 write_seqcount_begin(&tsk->mems_allowed_seq);
1655
1656 nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1657 mpol_rebind_task(tsk, newmems);
1658 tsk->mems_allowed = *newmems;
1659
1660 write_seqcount_end(&tsk->mems_allowed_seq);
1661 local_irq_enable();
1662
1663 task_unlock(tsk);
1664}
1665
1666static void *cpuset_being_rebound;
1667
1668/**
1669 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1670 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1671 *
1672 * Iterate through each task of @cs updating its mems_allowed to the
1673 * effective cpuset's. As this function is called with cpuset_mutex held,
1674 * cpuset membership stays stable.
1675 */
1676static void update_tasks_nodemask(struct cpuset *cs)
1677{
1678 static nodemask_t newmems; /* protected by cpuset_mutex */
1679 struct css_task_iter it;
1680 struct task_struct *task;
1681
1682 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1683
1684 guarantee_online_mems(cs, &newmems);
1685
1686 /*
1687 * The mpol_rebind_mm() call takes mmap_lock, which we couldn't
1688 * take while holding tasklist_lock. Forks can happen - the
1689 * mpol_dup() cpuset_being_rebound check will catch such forks,
1690 * and rebind their vma mempolicies too. Because we still hold
1691 * the global cpuset_mutex, we know that no other rebind effort
1692 * will be contending for the global variable cpuset_being_rebound.
1693 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1694 * is idempotent. Also migrate pages in each mm to new nodes.
1695 */
1696 css_task_iter_start(&cs->css, 0, &it);
1697 while ((task = css_task_iter_next(&it))) {
1698 struct mm_struct *mm;
1699 bool migrate;
1700
1701 cpuset_change_task_nodemask(task, &newmems);
1702
1703 mm = get_task_mm(task);
1704 if (!mm)
1705 continue;
1706
1707 migrate = is_memory_migrate(cs);
1708
1709 mpol_rebind_mm(mm, &cs->mems_allowed);
1710 if (migrate)
1711 cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1712 else
1713 mmput(mm);
1714 }
1715 css_task_iter_end(&it);
1716
1717 /*
1718 * All the tasks' nodemasks have been updated, update
1719 * cs->old_mems_allowed.
1720 */
1721 cs->old_mems_allowed = newmems;
1722
1723 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1724 cpuset_being_rebound = NULL;
1725}
1726
1727/*
1728 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
1729 * @cs: the cpuset to consider
1730 * @new_mems: a temp variable for calculating new effective_mems
1731 *
1732 * When configured nodemask is changed, the effective nodemasks of this cpuset
1733 * and all its descendants need to be updated.
1734 *
1735 * On legacy hierarchy, effective_mems will be the same with mems_allowed.
1736 *
1737 * Called with cpuset_mutex held
1738 */
1739static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
1740{
1741 struct cpuset *cp;
1742 struct cgroup_subsys_state *pos_css;
1743
1744 rcu_read_lock();
1745 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1746 struct cpuset *parent = parent_cs(cp);
1747
1748 nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
1749
1750 /*
1751 * If it becomes empty, inherit the effective mask of the
1752 * parent, which is guaranteed to have some MEMs.
1753 */
1754 if (is_in_v2_mode() && nodes_empty(*new_mems))
1755 *new_mems = parent->effective_mems;
1756
1757 /* Skip the whole subtree if the nodemask remains the same. */
1758 if (nodes_equal(*new_mems, cp->effective_mems)) {
1759 pos_css = css_rightmost_descendant(pos_css);
1760 continue;
1761 }
1762
1763 if (!css_tryget_online(&cp->css))
1764 continue;
1765 rcu_read_unlock();
1766
1767 spin_lock_irq(&callback_lock);
1768 cp->effective_mems = *new_mems;
1769 spin_unlock_irq(&callback_lock);
1770
1771 WARN_ON(!is_in_v2_mode() &&
1772 !nodes_equal(cp->mems_allowed, cp->effective_mems));
1773
1774 update_tasks_nodemask(cp);
1775
1776 rcu_read_lock();
1777 css_put(&cp->css);
1778 }
1779 rcu_read_unlock();
1780}
1781
1782/*
1783 * Handle user request to change the 'mems' memory placement
1784 * of a cpuset. Needs to validate the request, update the
1785 * cpusets mems_allowed, and for each task in the cpuset,
1786 * update mems_allowed and rebind task's mempolicy and any vma
1787 * mempolicies and if the cpuset is marked 'memory_migrate',
1788 * migrate the tasks pages to the new memory.
1789 *
1790 * Call with cpuset_mutex held. May take callback_lock during call.
1791 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1792 * lock each such tasks mm->mmap_lock, scan its vma's and rebind
1793 * their mempolicies to the cpusets new mems_allowed.
1794 */
1795static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1796 const char *buf)
1797{
1798 int retval;
1799
1800 /*
1801 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1802 * it's read-only
1803 */
1804 if (cs == &top_cpuset) {
1805 retval = -EACCES;
1806 goto done;
1807 }
1808
1809 /*
1810 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1811 * Since nodelist_parse() fails on an empty mask, we special case
1812 * that parsing. The validate_change() call ensures that cpusets
1813 * with tasks have memory.
1814 */
1815 if (!*buf) {
1816 nodes_clear(trialcs->mems_allowed);
1817 } else {
1818 retval = nodelist_parse(buf, trialcs->mems_allowed);
1819 if (retval < 0)
1820 goto done;
1821
1822 if (!nodes_subset(trialcs->mems_allowed,
1823 top_cpuset.mems_allowed)) {
1824 retval = -EINVAL;
1825 goto done;
1826 }
1827 }
1828
1829 if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
1830 retval = 0; /* Too easy - nothing to do */
1831 goto done;
1832 }
1833 retval = validate_change(cs, trialcs);
1834 if (retval < 0)
1835 goto done;
1836
1837 spin_lock_irq(&callback_lock);
1838 cs->mems_allowed = trialcs->mems_allowed;
1839 spin_unlock_irq(&callback_lock);
1840
1841 /* use trialcs->mems_allowed as a temp variable */
1842 update_nodemasks_hier(cs, &trialcs->mems_allowed);
1843done:
1844 return retval;
1845}
1846
1847bool current_cpuset_is_being_rebound(void)
1848{
1849 bool ret;
1850
1851 rcu_read_lock();
1852 ret = task_cs(current) == cpuset_being_rebound;
1853 rcu_read_unlock();
1854
1855 return ret;
1856}
1857
1858static int update_relax_domain_level(struct cpuset *cs, s64 val)
1859{
1860#ifdef CONFIG_SMP
1861 if (val < -1 || val >= sched_domain_level_max)
1862 return -EINVAL;
1863#endif
1864
1865 if (val != cs->relax_domain_level) {
1866 cs->relax_domain_level = val;
1867 if (!cpumask_empty(cs->cpus_allowed) &&
1868 is_sched_load_balance(cs))
1869 rebuild_sched_domains_locked();
1870 }
1871
1872 return 0;
1873}
1874
1875/**
1876 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1877 * @cs: the cpuset in which each task's spread flags needs to be changed
1878 *
1879 * Iterate through each task of @cs updating its spread flags. As this
1880 * function is called with cpuset_mutex held, cpuset membership stays
1881 * stable.
1882 */
1883static void update_tasks_flags(struct cpuset *cs)
1884{
1885 struct css_task_iter it;
1886 struct task_struct *task;
1887
1888 css_task_iter_start(&cs->css, 0, &it);
1889 while ((task = css_task_iter_next(&it)))
1890 cpuset_update_task_spread_flag(cs, task);
1891 css_task_iter_end(&it);
1892}
1893
1894/*
1895 * update_flag - read a 0 or a 1 in a file and update associated flag
1896 * bit: the bit to update (see cpuset_flagbits_t)
1897 * cs: the cpuset to update
1898 * turning_on: whether the flag is being set or cleared
1899 *
1900 * Call with cpuset_mutex held.
1901 */
1902
1903static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1904 int turning_on)
1905{
1906 struct cpuset *trialcs;
1907 int balance_flag_changed;
1908 int spread_flag_changed;
1909 int err;
1910
1911 trialcs = alloc_trial_cpuset(cs);
1912 if (!trialcs)
1913 return -ENOMEM;
1914
1915 if (turning_on)
1916 set_bit(bit, &trialcs->flags);
1917 else
1918 clear_bit(bit, &trialcs->flags);
1919
1920 err = validate_change(cs, trialcs);
1921 if (err < 0)
1922 goto out;
1923
1924 balance_flag_changed = (is_sched_load_balance(cs) !=
1925 is_sched_load_balance(trialcs));
1926
1927 spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1928 || (is_spread_page(cs) != is_spread_page(trialcs)));
1929
1930 spin_lock_irq(&callback_lock);
1931 cs->flags = trialcs->flags;
1932 spin_unlock_irq(&callback_lock);
1933
1934 if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1935 rebuild_sched_domains_locked();
1936
1937 if (spread_flag_changed)
1938 update_tasks_flags(cs);
1939out:
1940 free_cpuset(trialcs);
1941 return err;
1942}
1943
1944/*
1945 * update_prstate - update partititon_root_state
1946 * cs: the cpuset to update
1947 * new_prs: new partition root state
1948 *
1949 * Call with cpuset_mutex held.
1950 */
1951static int update_prstate(struct cpuset *cs, int new_prs)
1952{
1953 int err, old_prs = cs->partition_root_state;
1954 struct cpuset *parent = parent_cs(cs);
1955 struct tmpmasks tmpmask;
1956
1957 if (old_prs == new_prs)
1958 return 0;
1959
1960 /*
1961 * Cannot force a partial or invalid partition root to a full
1962 * partition root.
1963 */
1964 if (new_prs && (old_prs == PRS_ERROR))
1965 return -EINVAL;
1966
1967 if (alloc_cpumasks(NULL, &tmpmask))
1968 return -ENOMEM;
1969
1970 err = -EINVAL;
1971 if (!old_prs) {
1972 /*
1973 * Turning on partition root requires setting the
1974 * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed
1975 * cannot be NULL.
1976 */
1977 if (cpumask_empty(cs->cpus_allowed))
1978 goto out;
1979
1980 err = update_flag(CS_CPU_EXCLUSIVE, cs, 1);
1981 if (err)
1982 goto out;
1983
1984 err = update_parent_subparts_cpumask(cs, partcmd_enable,
1985 NULL, &tmpmask);
1986 if (err) {
1987 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
1988 goto out;
1989 }
1990 } else {
1991 /*
1992 * Turning off partition root will clear the
1993 * CS_CPU_EXCLUSIVE bit.
1994 */
1995 if (old_prs == PRS_ERROR) {
1996 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
1997 err = 0;
1998 goto out;
1999 }
2000
2001 err = update_parent_subparts_cpumask(cs, partcmd_disable,
2002 NULL, &tmpmask);
2003 if (err)
2004 goto out;
2005
2006 /* Turning off CS_CPU_EXCLUSIVE will not return error */
2007 update_flag(CS_CPU_EXCLUSIVE, cs, 0);
2008 }
2009
2010 /*
2011 * Update cpumask of parent's tasks except when it is the top
2012 * cpuset as some system daemons cannot be mapped to other CPUs.
2013 */
2014 if (parent != &top_cpuset)
2015 update_tasks_cpumask(parent);
2016
2017 if (parent->child_ecpus_count)
2018 update_sibling_cpumasks(parent, cs, &tmpmask);
2019
2020 rebuild_sched_domains_locked();
2021out:
2022 if (!err) {
2023 spin_lock_irq(&callback_lock);
2024 cs->partition_root_state = new_prs;
2025 spin_unlock_irq(&callback_lock);
2026 }
2027
2028 free_cpumasks(NULL, &tmpmask);
2029 return err;
2030}
2031
2032/*
2033 * Frequency meter - How fast is some event occurring?
2034 *
2035 * These routines manage a digitally filtered, constant time based,
2036 * event frequency meter. There are four routines:
2037 * fmeter_init() - initialize a frequency meter.
2038 * fmeter_markevent() - called each time the event happens.
2039 * fmeter_getrate() - returns the recent rate of such events.
2040 * fmeter_update() - internal routine used to update fmeter.
2041 *
2042 * A common data structure is passed to each of these routines,
2043 * which is used to keep track of the state required to manage the
2044 * frequency meter and its digital filter.
2045 *
2046 * The filter works on the number of events marked per unit time.
2047 * The filter is single-pole low-pass recursive (IIR). The time unit
2048 * is 1 second. Arithmetic is done using 32-bit integers scaled to
2049 * simulate 3 decimal digits of precision (multiplied by 1000).
2050 *
2051 * With an FM_COEF of 933, and a time base of 1 second, the filter
2052 * has a half-life of 10 seconds, meaning that if the events quit
2053 * happening, then the rate returned from the fmeter_getrate()
2054 * will be cut in half each 10 seconds, until it converges to zero.
2055 *
2056 * It is not worth doing a real infinitely recursive filter. If more
2057 * than FM_MAXTICKS ticks have elapsed since the last filter event,
2058 * just compute FM_MAXTICKS ticks worth, by which point the level
2059 * will be stable.
2060 *
2061 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
2062 * arithmetic overflow in the fmeter_update() routine.
2063 *
2064 * Given the simple 32 bit integer arithmetic used, this meter works
2065 * best for reporting rates between one per millisecond (msec) and
2066 * one per 32 (approx) seconds. At constant rates faster than one
2067 * per msec it maxes out at values just under 1,000,000. At constant
2068 * rates between one per msec, and one per second it will stabilize
2069 * to a value N*1000, where N is the rate of events per second.
2070 * At constant rates between one per second and one per 32 seconds,
2071 * it will be choppy, moving up on the seconds that have an event,
2072 * and then decaying until the next event. At rates slower than
2073 * about one in 32 seconds, it decays all the way back to zero between
2074 * each event.
2075 */
2076
2077#define FM_COEF 933 /* coefficient for half-life of 10 secs */
2078#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
2079#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
2080#define FM_SCALE 1000 /* faux fixed point scale */
2081
2082/* Initialize a frequency meter */
2083static void fmeter_init(struct fmeter *fmp)
2084{
2085 fmp->cnt = 0;
2086 fmp->val = 0;
2087 fmp->time = 0;
2088 spin_lock_init(&fmp->lock);
2089}
2090
2091/* Internal meter update - process cnt events and update value */
2092static void fmeter_update(struct fmeter *fmp)
2093{
2094 time64_t now;
2095 u32 ticks;
2096
2097 now = ktime_get_seconds();
2098 ticks = now - fmp->time;
2099
2100 if (ticks == 0)
2101 return;
2102
2103 ticks = min(FM_MAXTICKS, ticks);
2104 while (ticks-- > 0)
2105 fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
2106 fmp->time = now;
2107
2108 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
2109 fmp->cnt = 0;
2110}
2111
2112/* Process any previous ticks, then bump cnt by one (times scale). */
2113static void fmeter_markevent(struct fmeter *fmp)
2114{
2115 spin_lock(&fmp->lock);
2116 fmeter_update(fmp);
2117 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
2118 spin_unlock(&fmp->lock);
2119}
2120
2121/* Process any previous ticks, then return current value. */
2122static int fmeter_getrate(struct fmeter *fmp)
2123{
2124 int val;
2125
2126 spin_lock(&fmp->lock);
2127 fmeter_update(fmp);
2128 val = fmp->val;
2129 spin_unlock(&fmp->lock);
2130 return val;
2131}
2132
2133static struct cpuset *cpuset_attach_old_cs;
2134
2135/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
2136static int cpuset_can_attach(struct cgroup_taskset *tset)
2137{
2138 struct cgroup_subsys_state *css;
2139 struct cpuset *cs;
2140 struct task_struct *task;
2141 int ret;
2142
2143 /* used later by cpuset_attach() */
2144 cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
2145 cs = css_cs(css);
2146
2147 percpu_down_write(&cpuset_rwsem);
2148
2149 /* allow moving tasks into an empty cpuset if on default hierarchy */
2150 ret = -ENOSPC;
2151 if (!is_in_v2_mode() &&
2152 (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
2153 goto out_unlock;
2154
2155 cgroup_taskset_for_each(task, css, tset) {
2156 ret = task_can_attach(task, cs->cpus_allowed);
2157 if (ret)
2158 goto out_unlock;
2159 ret = security_task_setscheduler(task);
2160 if (ret)
2161 goto out_unlock;
2162 }
2163
2164 /*
2165 * Mark attach is in progress. This makes validate_change() fail
2166 * changes which zero cpus/mems_allowed.
2167 */
2168 cs->attach_in_progress++;
2169 ret = 0;
2170out_unlock:
2171 percpu_up_write(&cpuset_rwsem);
2172 return ret;
2173}
2174
2175static void cpuset_cancel_attach(struct cgroup_taskset *tset)
2176{
2177 struct cgroup_subsys_state *css;
2178
2179 cgroup_taskset_first(tset, &css);
2180
2181 percpu_down_write(&cpuset_rwsem);
2182 css_cs(css)->attach_in_progress--;
2183 percpu_up_write(&cpuset_rwsem);
2184}
2185
2186/*
2187 * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
2188 * but we can't allocate it dynamically there. Define it global and
2189 * allocate from cpuset_init().
2190 */
2191static cpumask_var_t cpus_attach;
2192
2193static void cpuset_attach(struct cgroup_taskset *tset)
2194{
2195 /* static buf protected by cpuset_mutex */
2196 static nodemask_t cpuset_attach_nodemask_to;
2197 struct task_struct *task;
2198 struct task_struct *leader;
2199 struct cgroup_subsys_state *css;
2200 struct cpuset *cs;
2201 struct cpuset *oldcs = cpuset_attach_old_cs;
2202
2203 cgroup_taskset_first(tset, &css);
2204 cs = css_cs(css);
2205
2206 percpu_down_write(&cpuset_rwsem);
2207
2208 /* prepare for attach */
2209 if (cs == &top_cpuset)
2210 cpumask_copy(cpus_attach, cpu_possible_mask);
2211 else
2212 guarantee_online_cpus(cs, cpus_attach);
2213
2214 guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
2215
2216 cgroup_taskset_for_each(task, css, tset) {
2217 /*
2218 * can_attach beforehand should guarantee that this doesn't
2219 * fail. TODO: have a better way to handle failure here
2220 */
2221 WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
2222
2223 cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
2224 cpuset_update_task_spread_flag(cs, task);
2225 }
2226
2227 /*
2228 * Change mm for all threadgroup leaders. This is expensive and may
2229 * sleep and should be moved outside migration path proper.
2230 */
2231 cpuset_attach_nodemask_to = cs->effective_mems;
2232 cgroup_taskset_for_each_leader(leader, css, tset) {
2233 struct mm_struct *mm = get_task_mm(leader);
2234
2235 if (mm) {
2236 mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
2237
2238 /*
2239 * old_mems_allowed is the same with mems_allowed
2240 * here, except if this task is being moved
2241 * automatically due to hotplug. In that case
2242 * @mems_allowed has been updated and is empty, so
2243 * @old_mems_allowed is the right nodesets that we
2244 * migrate mm from.
2245 */
2246 if (is_memory_migrate(cs))
2247 cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
2248 &cpuset_attach_nodemask_to);
2249 else
2250 mmput(mm);
2251 }
2252 }
2253
2254 cs->old_mems_allowed = cpuset_attach_nodemask_to;
2255
2256 cs->attach_in_progress--;
2257 if (!cs->attach_in_progress)
2258 wake_up(&cpuset_attach_wq);
2259
2260 percpu_up_write(&cpuset_rwsem);
2261}
2262
2263/* The various types of files and directories in a cpuset file system */
2264
2265typedef enum {
2266 FILE_MEMORY_MIGRATE,
2267 FILE_CPULIST,
2268 FILE_MEMLIST,
2269 FILE_EFFECTIVE_CPULIST,
2270 FILE_EFFECTIVE_MEMLIST,
2271 FILE_SUBPARTS_CPULIST,
2272 FILE_CPU_EXCLUSIVE,
2273 FILE_MEM_EXCLUSIVE,
2274 FILE_MEM_HARDWALL,
2275 FILE_SCHED_LOAD_BALANCE,
2276 FILE_PARTITION_ROOT,
2277 FILE_SCHED_RELAX_DOMAIN_LEVEL,
2278 FILE_MEMORY_PRESSURE_ENABLED,
2279 FILE_MEMORY_PRESSURE,
2280 FILE_SPREAD_PAGE,
2281 FILE_SPREAD_SLAB,
2282} cpuset_filetype_t;
2283
2284static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
2285 u64 val)
2286{
2287 struct cpuset *cs = css_cs(css);
2288 cpuset_filetype_t type = cft->private;
2289 int retval = 0;
2290
2291 get_online_cpus();
2292 percpu_down_write(&cpuset_rwsem);
2293 if (!is_cpuset_online(cs)) {
2294 retval = -ENODEV;
2295 goto out_unlock;
2296 }
2297
2298 switch (type) {
2299 case FILE_CPU_EXCLUSIVE:
2300 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
2301 break;
2302 case FILE_MEM_EXCLUSIVE:
2303 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
2304 break;
2305 case FILE_MEM_HARDWALL:
2306 retval = update_flag(CS_MEM_HARDWALL, cs, val);
2307 break;
2308 case FILE_SCHED_LOAD_BALANCE:
2309 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
2310 break;
2311 case FILE_MEMORY_MIGRATE:
2312 retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
2313 break;
2314 case FILE_MEMORY_PRESSURE_ENABLED:
2315 cpuset_memory_pressure_enabled = !!val;
2316 break;
2317 case FILE_SPREAD_PAGE:
2318 retval = update_flag(CS_SPREAD_PAGE, cs, val);
2319 break;
2320 case FILE_SPREAD_SLAB:
2321 retval = update_flag(CS_SPREAD_SLAB, cs, val);
2322 break;
2323 default:
2324 retval = -EINVAL;
2325 break;
2326 }
2327out_unlock:
2328 percpu_up_write(&cpuset_rwsem);
2329 put_online_cpus();
2330 return retval;
2331}
2332
2333static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
2334 s64 val)
2335{
2336 struct cpuset *cs = css_cs(css);
2337 cpuset_filetype_t type = cft->private;
2338 int retval = -ENODEV;
2339
2340 get_online_cpus();
2341 percpu_down_write(&cpuset_rwsem);
2342 if (!is_cpuset_online(cs))
2343 goto out_unlock;
2344
2345 switch (type) {
2346 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
2347 retval = update_relax_domain_level(cs, val);
2348 break;
2349 default:
2350 retval = -EINVAL;
2351 break;
2352 }
2353out_unlock:
2354 percpu_up_write(&cpuset_rwsem);
2355 put_online_cpus();
2356 return retval;
2357}
2358
2359/*
2360 * Common handling for a write to a "cpus" or "mems" file.
2361 */
2362static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
2363 char *buf, size_t nbytes, loff_t off)
2364{
2365 struct cpuset *cs = css_cs(of_css(of));
2366 struct cpuset *trialcs;
2367 int retval = -ENODEV;
2368
2369 buf = strstrip(buf);
2370
2371 /*
2372 * CPU or memory hotunplug may leave @cs w/o any execution
2373 * resources, in which case the hotplug code asynchronously updates
2374 * configuration and transfers all tasks to the nearest ancestor
2375 * which can execute.
2376 *
2377 * As writes to "cpus" or "mems" may restore @cs's execution
2378 * resources, wait for the previously scheduled operations before
2379 * proceeding, so that we don't end up keep removing tasks added
2380 * after execution capability is restored.
2381 *
2382 * cpuset_hotplug_work calls back into cgroup core via
2383 * cgroup_transfer_tasks() and waiting for it from a cgroupfs
2384 * operation like this one can lead to a deadlock through kernfs
2385 * active_ref protection. Let's break the protection. Losing the
2386 * protection is okay as we check whether @cs is online after
2387 * grabbing cpuset_mutex anyway. This only happens on the legacy
2388 * hierarchies.
2389 */
2390 css_get(&cs->css);
2391 kernfs_break_active_protection(of->kn);
2392 flush_work(&cpuset_hotplug_work);
2393
2394 get_online_cpus();
2395 percpu_down_write(&cpuset_rwsem);
2396 if (!is_cpuset_online(cs))
2397 goto out_unlock;
2398
2399 trialcs = alloc_trial_cpuset(cs);
2400 if (!trialcs) {
2401 retval = -ENOMEM;
2402 goto out_unlock;
2403 }
2404
2405 switch (of_cft(of)->private) {
2406 case FILE_CPULIST:
2407 retval = update_cpumask(cs, trialcs, buf);
2408 break;
2409 case FILE_MEMLIST:
2410 retval = update_nodemask(cs, trialcs, buf);
2411 break;
2412 default:
2413 retval = -EINVAL;
2414 break;
2415 }
2416
2417 free_cpuset(trialcs);
2418out_unlock:
2419 percpu_up_write(&cpuset_rwsem);
2420 put_online_cpus();
2421 kernfs_unbreak_active_protection(of->kn);
2422 css_put(&cs->css);
2423 flush_workqueue(cpuset_migrate_mm_wq);
2424 return retval ?: nbytes;
2425}
2426
2427/*
2428 * These ascii lists should be read in a single call, by using a user
2429 * buffer large enough to hold the entire map. If read in smaller
2430 * chunks, there is no guarantee of atomicity. Since the display format
2431 * used, list of ranges of sequential numbers, is variable length,
2432 * and since these maps can change value dynamically, one could read
2433 * gibberish by doing partial reads while a list was changing.
2434 */
2435static int cpuset_common_seq_show(struct seq_file *sf, void *v)
2436{
2437 struct cpuset *cs = css_cs(seq_css(sf));
2438 cpuset_filetype_t type = seq_cft(sf)->private;
2439 int ret = 0;
2440
2441 spin_lock_irq(&callback_lock);
2442
2443 switch (type) {
2444 case FILE_CPULIST:
2445 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
2446 break;
2447 case FILE_MEMLIST:
2448 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
2449 break;
2450 case FILE_EFFECTIVE_CPULIST:
2451 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
2452 break;
2453 case FILE_EFFECTIVE_MEMLIST:
2454 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
2455 break;
2456 case FILE_SUBPARTS_CPULIST:
2457 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus));
2458 break;
2459 default:
2460 ret = -EINVAL;
2461 }
2462
2463 spin_unlock_irq(&callback_lock);
2464 return ret;
2465}
2466
2467static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
2468{
2469 struct cpuset *cs = css_cs(css);
2470 cpuset_filetype_t type = cft->private;
2471 switch (type) {
2472 case FILE_CPU_EXCLUSIVE:
2473 return is_cpu_exclusive(cs);
2474 case FILE_MEM_EXCLUSIVE:
2475 return is_mem_exclusive(cs);
2476 case FILE_MEM_HARDWALL:
2477 return is_mem_hardwall(cs);
2478 case FILE_SCHED_LOAD_BALANCE:
2479 return is_sched_load_balance(cs);
2480 case FILE_MEMORY_MIGRATE:
2481 return is_memory_migrate(cs);
2482 case FILE_MEMORY_PRESSURE_ENABLED:
2483 return cpuset_memory_pressure_enabled;
2484 case FILE_MEMORY_PRESSURE:
2485 return fmeter_getrate(&cs->fmeter);
2486 case FILE_SPREAD_PAGE:
2487 return is_spread_page(cs);
2488 case FILE_SPREAD_SLAB:
2489 return is_spread_slab(cs);
2490 default:
2491 BUG();
2492 }
2493
2494 /* Unreachable but makes gcc happy */
2495 return 0;
2496}
2497
2498static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
2499{
2500 struct cpuset *cs = css_cs(css);
2501 cpuset_filetype_t type = cft->private;
2502 switch (type) {
2503 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
2504 return cs->relax_domain_level;
2505 default:
2506 BUG();
2507 }
2508
2509 /* Unreachable but makes gcc happy */
2510 return 0;
2511}
2512
2513static int sched_partition_show(struct seq_file *seq, void *v)
2514{
2515 struct cpuset *cs = css_cs(seq_css(seq));
2516
2517 switch (cs->partition_root_state) {
2518 case PRS_ENABLED:
2519 seq_puts(seq, "root\n");
2520 break;
2521 case PRS_DISABLED:
2522 seq_puts(seq, "member\n");
2523 break;
2524 case PRS_ERROR:
2525 seq_puts(seq, "root invalid\n");
2526 break;
2527 }
2528 return 0;
2529}
2530
2531static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf,
2532 size_t nbytes, loff_t off)
2533{
2534 struct cpuset *cs = css_cs(of_css(of));
2535 int val;
2536 int retval = -ENODEV;
2537
2538 buf = strstrip(buf);
2539
2540 /*
2541 * Convert "root" to ENABLED, and convert "member" to DISABLED.
2542 */
2543 if (!strcmp(buf, "root"))
2544 val = PRS_ENABLED;
2545 else if (!strcmp(buf, "member"))
2546 val = PRS_DISABLED;
2547 else
2548 return -EINVAL;
2549
2550 css_get(&cs->css);
2551 get_online_cpus();
2552 percpu_down_write(&cpuset_rwsem);
2553 if (!is_cpuset_online(cs))
2554 goto out_unlock;
2555
2556 retval = update_prstate(cs, val);
2557out_unlock:
2558 percpu_up_write(&cpuset_rwsem);
2559 put_online_cpus();
2560 css_put(&cs->css);
2561 return retval ?: nbytes;
2562}
2563
2564/*
2565 * for the common functions, 'private' gives the type of file
2566 */
2567
2568static struct cftype legacy_files[] = {
2569 {
2570 .name = "cpus",
2571 .seq_show = cpuset_common_seq_show,
2572 .write = cpuset_write_resmask,
2573 .max_write_len = (100U + 6 * NR_CPUS),
2574 .private = FILE_CPULIST,
2575 },
2576
2577 {
2578 .name = "mems",
2579 .seq_show = cpuset_common_seq_show,
2580 .write = cpuset_write_resmask,
2581 .max_write_len = (100U + 6 * MAX_NUMNODES),
2582 .private = FILE_MEMLIST,
2583 },
2584
2585 {
2586 .name = "effective_cpus",
2587 .seq_show = cpuset_common_seq_show,
2588 .private = FILE_EFFECTIVE_CPULIST,
2589 },
2590
2591 {
2592 .name = "effective_mems",
2593 .seq_show = cpuset_common_seq_show,
2594 .private = FILE_EFFECTIVE_MEMLIST,
2595 },
2596
2597 {
2598 .name = "cpu_exclusive",
2599 .read_u64 = cpuset_read_u64,
2600 .write_u64 = cpuset_write_u64,
2601 .private = FILE_CPU_EXCLUSIVE,
2602 },
2603
2604 {
2605 .name = "mem_exclusive",
2606 .read_u64 = cpuset_read_u64,
2607 .write_u64 = cpuset_write_u64,
2608 .private = FILE_MEM_EXCLUSIVE,
2609 },
2610
2611 {
2612 .name = "mem_hardwall",
2613 .read_u64 = cpuset_read_u64,
2614 .write_u64 = cpuset_write_u64,
2615 .private = FILE_MEM_HARDWALL,
2616 },
2617
2618 {
2619 .name = "sched_load_balance",
2620 .read_u64 = cpuset_read_u64,
2621 .write_u64 = cpuset_write_u64,
2622 .private = FILE_SCHED_LOAD_BALANCE,
2623 },
2624
2625 {
2626 .name = "sched_relax_domain_level",
2627 .read_s64 = cpuset_read_s64,
2628 .write_s64 = cpuset_write_s64,
2629 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
2630 },
2631
2632 {
2633 .name = "memory_migrate",
2634 .read_u64 = cpuset_read_u64,
2635 .write_u64 = cpuset_write_u64,
2636 .private = FILE_MEMORY_MIGRATE,
2637 },
2638
2639 {
2640 .name = "memory_pressure",
2641 .read_u64 = cpuset_read_u64,
2642 .private = FILE_MEMORY_PRESSURE,
2643 },
2644
2645 {
2646 .name = "memory_spread_page",
2647 .read_u64 = cpuset_read_u64,
2648 .write_u64 = cpuset_write_u64,
2649 .private = FILE_SPREAD_PAGE,
2650 },
2651
2652 {
2653 .name = "memory_spread_slab",
2654 .read_u64 = cpuset_read_u64,
2655 .write_u64 = cpuset_write_u64,
2656 .private = FILE_SPREAD_SLAB,
2657 },
2658
2659 {
2660 .name = "memory_pressure_enabled",
2661 .flags = CFTYPE_ONLY_ON_ROOT,
2662 .read_u64 = cpuset_read_u64,
2663 .write_u64 = cpuset_write_u64,
2664 .private = FILE_MEMORY_PRESSURE_ENABLED,
2665 },
2666
2667 { } /* terminate */
2668};
2669
2670/*
2671 * This is currently a minimal set for the default hierarchy. It can be
2672 * expanded later on by migrating more features and control files from v1.
2673 */
2674static struct cftype dfl_files[] = {
2675 {
2676 .name = "cpus",
2677 .seq_show = cpuset_common_seq_show,
2678 .write = cpuset_write_resmask,
2679 .max_write_len = (100U + 6 * NR_CPUS),
2680 .private = FILE_CPULIST,
2681 .flags = CFTYPE_NOT_ON_ROOT,
2682 },
2683
2684 {
2685 .name = "mems",
2686 .seq_show = cpuset_common_seq_show,
2687 .write = cpuset_write_resmask,
2688 .max_write_len = (100U + 6 * MAX_NUMNODES),
2689 .private = FILE_MEMLIST,
2690 .flags = CFTYPE_NOT_ON_ROOT,
2691 },
2692
2693 {
2694 .name = "cpus.effective",
2695 .seq_show = cpuset_common_seq_show,
2696 .private = FILE_EFFECTIVE_CPULIST,
2697 },
2698
2699 {
2700 .name = "mems.effective",
2701 .seq_show = cpuset_common_seq_show,
2702 .private = FILE_EFFECTIVE_MEMLIST,
2703 },
2704
2705 {
2706 .name = "cpus.partition",
2707 .seq_show = sched_partition_show,
2708 .write = sched_partition_write,
2709 .private = FILE_PARTITION_ROOT,
2710 .flags = CFTYPE_NOT_ON_ROOT,
2711 },
2712
2713 {
2714 .name = "cpus.subpartitions",
2715 .seq_show = cpuset_common_seq_show,
2716 .private = FILE_SUBPARTS_CPULIST,
2717 .flags = CFTYPE_DEBUG,
2718 },
2719
2720 { } /* terminate */
2721};
2722
2723
2724/*
2725 * cpuset_css_alloc - allocate a cpuset css
2726 * cgrp: control group that the new cpuset will be part of
2727 */
2728
2729static struct cgroup_subsys_state *
2730cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
2731{
2732 struct cpuset *cs;
2733
2734 if (!parent_css)
2735 return &top_cpuset.css;
2736
2737 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
2738 if (!cs)
2739 return ERR_PTR(-ENOMEM);
2740
2741 if (alloc_cpumasks(cs, NULL)) {
2742 kfree(cs);
2743 return ERR_PTR(-ENOMEM);
2744 }
2745
2746 set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
2747 nodes_clear(cs->mems_allowed);
2748 nodes_clear(cs->effective_mems);
2749 fmeter_init(&cs->fmeter);
2750 cs->relax_domain_level = -1;
2751
2752 return &cs->css;
2753}
2754
2755static int cpuset_css_online(struct cgroup_subsys_state *css)
2756{
2757 struct cpuset *cs = css_cs(css);
2758 struct cpuset *parent = parent_cs(cs);
2759 struct cpuset *tmp_cs;
2760 struct cgroup_subsys_state *pos_css;
2761
2762 if (!parent)
2763 return 0;
2764
2765 get_online_cpus();
2766 percpu_down_write(&cpuset_rwsem);
2767
2768 set_bit(CS_ONLINE, &cs->flags);
2769 if (is_spread_page(parent))
2770 set_bit(CS_SPREAD_PAGE, &cs->flags);
2771 if (is_spread_slab(parent))
2772 set_bit(CS_SPREAD_SLAB, &cs->flags);
2773
2774 cpuset_inc();
2775
2776 spin_lock_irq(&callback_lock);
2777 if (is_in_v2_mode()) {
2778 cpumask_copy(cs->effective_cpus, parent->effective_cpus);
2779 cs->effective_mems = parent->effective_mems;
2780 cs->use_parent_ecpus = true;
2781 parent->child_ecpus_count++;
2782 }
2783 spin_unlock_irq(&callback_lock);
2784
2785 if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
2786 goto out_unlock;
2787
2788 /*
2789 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
2790 * set. This flag handling is implemented in cgroup core for
2791 * histrical reasons - the flag may be specified during mount.
2792 *
2793 * Currently, if any sibling cpusets have exclusive cpus or mem, we
2794 * refuse to clone the configuration - thereby refusing the task to
2795 * be entered, and as a result refusing the sys_unshare() or
2796 * clone() which initiated it. If this becomes a problem for some
2797 * users who wish to allow that scenario, then this could be
2798 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
2799 * (and likewise for mems) to the new cgroup.
2800 */
2801 rcu_read_lock();
2802 cpuset_for_each_child(tmp_cs, pos_css, parent) {
2803 if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
2804 rcu_read_unlock();
2805 goto out_unlock;
2806 }
2807 }
2808 rcu_read_unlock();
2809
2810 spin_lock_irq(&callback_lock);
2811 cs->mems_allowed = parent->mems_allowed;
2812 cs->effective_mems = parent->mems_allowed;
2813 cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
2814 cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
2815 spin_unlock_irq(&callback_lock);
2816out_unlock:
2817 percpu_up_write(&cpuset_rwsem);
2818 put_online_cpus();
2819 return 0;
2820}
2821
2822/*
2823 * If the cpuset being removed has its flag 'sched_load_balance'
2824 * enabled, then simulate turning sched_load_balance off, which
2825 * will call rebuild_sched_domains_locked(). That is not needed
2826 * in the default hierarchy where only changes in partition
2827 * will cause repartitioning.
2828 *
2829 * If the cpuset has the 'sched.partition' flag enabled, simulate
2830 * turning 'sched.partition" off.
2831 */
2832
2833static void cpuset_css_offline(struct cgroup_subsys_state *css)
2834{
2835 struct cpuset *cs = css_cs(css);
2836
2837 get_online_cpus();
2838 percpu_down_write(&cpuset_rwsem);
2839
2840 if (is_partition_root(cs))
2841 update_prstate(cs, 0);
2842
2843 if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
2844 is_sched_load_balance(cs))
2845 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
2846
2847 if (cs->use_parent_ecpus) {
2848 struct cpuset *parent = parent_cs(cs);
2849
2850 cs->use_parent_ecpus = false;
2851 parent->child_ecpus_count--;
2852 }
2853
2854 cpuset_dec();
2855 clear_bit(CS_ONLINE, &cs->flags);
2856
2857 percpu_up_write(&cpuset_rwsem);
2858 put_online_cpus();
2859}
2860
2861static void cpuset_css_free(struct cgroup_subsys_state *css)
2862{
2863 struct cpuset *cs = css_cs(css);
2864
2865 free_cpuset(cs);
2866}
2867
2868static void cpuset_bind(struct cgroup_subsys_state *root_css)
2869{
2870 percpu_down_write(&cpuset_rwsem);
2871 spin_lock_irq(&callback_lock);
2872
2873 if (is_in_v2_mode()) {
2874 cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
2875 top_cpuset.mems_allowed = node_possible_map;
2876 } else {
2877 cpumask_copy(top_cpuset.cpus_allowed,
2878 top_cpuset.effective_cpus);
2879 top_cpuset.mems_allowed = top_cpuset.effective_mems;
2880 }
2881
2882 spin_unlock_irq(&callback_lock);
2883 percpu_up_write(&cpuset_rwsem);
2884}
2885
2886/*
2887 * Make sure the new task conform to the current state of its parent,
2888 * which could have been changed by cpuset just after it inherits the
2889 * state from the parent and before it sits on the cgroup's task list.
2890 */
2891static void cpuset_fork(struct task_struct *task)
2892{
2893 if (task_css_is_root(task, cpuset_cgrp_id))
2894 return;
2895
2896 set_cpus_allowed_ptr(task, current->cpus_ptr);
2897 task->mems_allowed = current->mems_allowed;
2898}
2899
2900struct cgroup_subsys cpuset_cgrp_subsys = {
2901 .css_alloc = cpuset_css_alloc,
2902 .css_online = cpuset_css_online,
2903 .css_offline = cpuset_css_offline,
2904 .css_free = cpuset_css_free,
2905 .can_attach = cpuset_can_attach,
2906 .cancel_attach = cpuset_cancel_attach,
2907 .attach = cpuset_attach,
2908 .post_attach = cpuset_post_attach,
2909 .bind = cpuset_bind,
2910 .fork = cpuset_fork,
2911 .legacy_cftypes = legacy_files,
2912 .dfl_cftypes = dfl_files,
2913 .early_init = true,
2914 .threaded = true,
2915};
2916
2917/**
2918 * cpuset_init - initialize cpusets at system boot
2919 *
2920 * Description: Initialize top_cpuset
2921 **/
2922
2923int __init cpuset_init(void)
2924{
2925 BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
2926
2927 BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
2928 BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
2929 BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
2930
2931 cpumask_setall(top_cpuset.cpus_allowed);
2932 nodes_setall(top_cpuset.mems_allowed);
2933 cpumask_setall(top_cpuset.effective_cpus);
2934 nodes_setall(top_cpuset.effective_mems);
2935
2936 fmeter_init(&top_cpuset.fmeter);
2937 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
2938 top_cpuset.relax_domain_level = -1;
2939
2940 BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
2941
2942 return 0;
2943}
2944
2945/*
2946 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2947 * or memory nodes, we need to walk over the cpuset hierarchy,
2948 * removing that CPU or node from all cpusets. If this removes the
2949 * last CPU or node from a cpuset, then move the tasks in the empty
2950 * cpuset to its next-highest non-empty parent.
2951 */
2952static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2953{
2954 struct cpuset *parent;
2955
2956 /*
2957 * Find its next-highest non-empty parent, (top cpuset
2958 * has online cpus, so can't be empty).
2959 */
2960 parent = parent_cs(cs);
2961 while (cpumask_empty(parent->cpus_allowed) ||
2962 nodes_empty(parent->mems_allowed))
2963 parent = parent_cs(parent);
2964
2965 if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
2966 pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
2967 pr_cont_cgroup_name(cs->css.cgroup);
2968 pr_cont("\n");
2969 }
2970}
2971
2972static void
2973hotplug_update_tasks_legacy(struct cpuset *cs,
2974 struct cpumask *new_cpus, nodemask_t *new_mems,
2975 bool cpus_updated, bool mems_updated)
2976{
2977 bool is_empty;
2978
2979 spin_lock_irq(&callback_lock);
2980 cpumask_copy(cs->cpus_allowed, new_cpus);
2981 cpumask_copy(cs->effective_cpus, new_cpus);
2982 cs->mems_allowed = *new_mems;
2983 cs->effective_mems = *new_mems;
2984 spin_unlock_irq(&callback_lock);
2985
2986 /*
2987 * Don't call update_tasks_cpumask() if the cpuset becomes empty,
2988 * as the tasks will be migratecd to an ancestor.
2989 */
2990 if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
2991 update_tasks_cpumask(cs);
2992 if (mems_updated && !nodes_empty(cs->mems_allowed))
2993 update_tasks_nodemask(cs);
2994
2995 is_empty = cpumask_empty(cs->cpus_allowed) ||
2996 nodes_empty(cs->mems_allowed);
2997
2998 percpu_up_write(&cpuset_rwsem);
2999
3000 /*
3001 * Move tasks to the nearest ancestor with execution resources,
3002 * This is full cgroup operation which will also call back into
3003 * cpuset. Should be done outside any lock.
3004 */
3005 if (is_empty)
3006 remove_tasks_in_empty_cpuset(cs);
3007
3008 percpu_down_write(&cpuset_rwsem);
3009}
3010
3011static void
3012hotplug_update_tasks(struct cpuset *cs,
3013 struct cpumask *new_cpus, nodemask_t *new_mems,
3014 bool cpus_updated, bool mems_updated)
3015{
3016 if (cpumask_empty(new_cpus))
3017 cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
3018 if (nodes_empty(*new_mems))
3019 *new_mems = parent_cs(cs)->effective_mems;
3020
3021 spin_lock_irq(&callback_lock);
3022 cpumask_copy(cs->effective_cpus, new_cpus);
3023 cs->effective_mems = *new_mems;
3024 spin_unlock_irq(&callback_lock);
3025
3026 if (cpus_updated)
3027 update_tasks_cpumask(cs);
3028 if (mems_updated)
3029 update_tasks_nodemask(cs);
3030}
3031
3032static bool force_rebuild;
3033
3034void cpuset_force_rebuild(void)
3035{
3036 force_rebuild = true;
3037}
3038
3039/**
3040 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
3041 * @cs: cpuset in interest
3042 * @tmp: the tmpmasks structure pointer
3043 *
3044 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
3045 * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
3046 * all its tasks are moved to the nearest ancestor with both resources.
3047 */
3048static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
3049{
3050 static cpumask_t new_cpus;
3051 static nodemask_t new_mems;
3052 bool cpus_updated;
3053 bool mems_updated;
3054 struct cpuset *parent;
3055retry:
3056 wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
3057
3058 percpu_down_write(&cpuset_rwsem);
3059
3060 /*
3061 * We have raced with task attaching. We wait until attaching
3062 * is finished, so we won't attach a task to an empty cpuset.
3063 */
3064 if (cs->attach_in_progress) {
3065 percpu_up_write(&cpuset_rwsem);
3066 goto retry;
3067 }
3068
3069 parent = parent_cs(cs);
3070 compute_effective_cpumask(&new_cpus, cs, parent);
3071 nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);
3072
3073 if (cs->nr_subparts_cpus)
3074 /*
3075 * Make sure that CPUs allocated to child partitions
3076 * do not show up in effective_cpus.
3077 */
3078 cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus);
3079
3080 if (!tmp || !cs->partition_root_state)
3081 goto update_tasks;
3082
3083 /*
3084 * In the unlikely event that a partition root has empty
3085 * effective_cpus or its parent becomes erroneous, we have to
3086 * transition it to the erroneous state.
3087 */
3088 if (is_partition_root(cs) && (cpumask_empty(&new_cpus) ||
3089 (parent->partition_root_state == PRS_ERROR))) {
3090 if (cs->nr_subparts_cpus) {
3091 spin_lock_irq(&callback_lock);
3092 cs->nr_subparts_cpus = 0;
3093 cpumask_clear(cs->subparts_cpus);
3094 spin_unlock_irq(&callback_lock);
3095 compute_effective_cpumask(&new_cpus, cs, parent);
3096 }
3097
3098 /*
3099 * If the effective_cpus is empty because the child
3100 * partitions take away all the CPUs, we can keep
3101 * the current partition and let the child partitions
3102 * fight for available CPUs.
3103 */
3104 if ((parent->partition_root_state == PRS_ERROR) ||
3105 cpumask_empty(&new_cpus)) {
3106 update_parent_subparts_cpumask(cs, partcmd_disable,
3107 NULL, tmp);
3108 spin_lock_irq(&callback_lock);
3109 cs->partition_root_state = PRS_ERROR;
3110 spin_unlock_irq(&callback_lock);
3111 }
3112 cpuset_force_rebuild();
3113 }
3114
3115 /*
3116 * On the other hand, an erroneous partition root may be transitioned
3117 * back to a regular one or a partition root with no CPU allocated
3118 * from the parent may change to erroneous.
3119 */
3120 if (is_partition_root(parent) &&
3121 ((cs->partition_root_state == PRS_ERROR) ||
3122 !cpumask_intersects(&new_cpus, parent->subparts_cpus)) &&
3123 update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp))
3124 cpuset_force_rebuild();
3125
3126update_tasks:
3127 cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
3128 mems_updated = !nodes_equal(new_mems, cs->effective_mems);
3129
3130 if (is_in_v2_mode())
3131 hotplug_update_tasks(cs, &new_cpus, &new_mems,
3132 cpus_updated, mems_updated);
3133 else
3134 hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
3135 cpus_updated, mems_updated);
3136
3137 percpu_up_write(&cpuset_rwsem);
3138}
3139
3140/**
3141 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
3142 *
3143 * This function is called after either CPU or memory configuration has
3144 * changed and updates cpuset accordingly. The top_cpuset is always
3145 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
3146 * order to make cpusets transparent (of no affect) on systems that are
3147 * actively using CPU hotplug but making no active use of cpusets.
3148 *
3149 * Non-root cpusets are only affected by offlining. If any CPUs or memory
3150 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
3151 * all descendants.
3152 *
3153 * Note that CPU offlining during suspend is ignored. We don't modify
3154 * cpusets across suspend/resume cycles at all.
3155 */
3156static void cpuset_hotplug_workfn(struct work_struct *work)
3157{
3158 static cpumask_t new_cpus;
3159 static nodemask_t new_mems;
3160 bool cpus_updated, mems_updated;
3161 bool on_dfl = is_in_v2_mode();
3162 struct tmpmasks tmp, *ptmp = NULL;
3163
3164 if (on_dfl && !alloc_cpumasks(NULL, &tmp))
3165 ptmp = &tmp;
3166
3167 percpu_down_write(&cpuset_rwsem);
3168
3169 /* fetch the available cpus/mems and find out which changed how */
3170 cpumask_copy(&new_cpus, cpu_active_mask);
3171 new_mems = node_states[N_MEMORY];
3172
3173 /*
3174 * If subparts_cpus is populated, it is likely that the check below
3175 * will produce a false positive on cpus_updated when the cpu list
3176 * isn't changed. It is extra work, but it is better to be safe.
3177 */
3178 cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
3179 mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
3180
3181 /*
3182 * In the rare case that hotplug removes all the cpus in subparts_cpus,
3183 * we assumed that cpus are updated.
3184 */
3185 if (!cpus_updated && top_cpuset.nr_subparts_cpus)
3186 cpus_updated = true;
3187
3188 /* synchronize cpus_allowed to cpu_active_mask */
3189 if (cpus_updated) {
3190 spin_lock_irq(&callback_lock);
3191 if (!on_dfl)
3192 cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
3193 /*
3194 * Make sure that CPUs allocated to child partitions
3195 * do not show up in effective_cpus. If no CPU is left,
3196 * we clear the subparts_cpus & let the child partitions
3197 * fight for the CPUs again.
3198 */
3199 if (top_cpuset.nr_subparts_cpus) {
3200 if (cpumask_subset(&new_cpus,
3201 top_cpuset.subparts_cpus)) {
3202 top_cpuset.nr_subparts_cpus = 0;
3203 cpumask_clear(top_cpuset.subparts_cpus);
3204 } else {
3205 cpumask_andnot(&new_cpus, &new_cpus,
3206 top_cpuset.subparts_cpus);
3207 }
3208 }
3209 cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
3210 spin_unlock_irq(&callback_lock);
3211 /* we don't mess with cpumasks of tasks in top_cpuset */
3212 }
3213
3214 /* synchronize mems_allowed to N_MEMORY */
3215 if (mems_updated) {
3216 spin_lock_irq(&callback_lock);
3217 if (!on_dfl)
3218 top_cpuset.mems_allowed = new_mems;
3219 top_cpuset.effective_mems = new_mems;
3220 spin_unlock_irq(&callback_lock);
3221 update_tasks_nodemask(&top_cpuset);
3222 }
3223
3224 percpu_up_write(&cpuset_rwsem);
3225
3226 /* if cpus or mems changed, we need to propagate to descendants */
3227 if (cpus_updated || mems_updated) {
3228 struct cpuset *cs;
3229 struct cgroup_subsys_state *pos_css;
3230
3231 rcu_read_lock();
3232 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
3233 if (cs == &top_cpuset || !css_tryget_online(&cs->css))
3234 continue;
3235 rcu_read_unlock();
3236
3237 cpuset_hotplug_update_tasks(cs, ptmp);
3238
3239 rcu_read_lock();
3240 css_put(&cs->css);
3241 }
3242 rcu_read_unlock();
3243 }
3244
3245 /* rebuild sched domains if cpus_allowed has changed */
3246 if (cpus_updated || force_rebuild) {
3247 force_rebuild = false;
3248 rebuild_sched_domains();
3249 }
3250
3251 free_cpumasks(NULL, ptmp);
3252}
3253
3254void cpuset_update_active_cpus(void)
3255{
3256 /*
3257 * We're inside cpu hotplug critical region which usually nests
3258 * inside cgroup synchronization. Bounce actual hotplug processing
3259 * to a work item to avoid reverse locking order.
3260 */
3261 schedule_work(&cpuset_hotplug_work);
3262}
3263
3264void cpuset_wait_for_hotplug(void)
3265{
3266 flush_work(&cpuset_hotplug_work);
3267}
3268
3269/*
3270 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
3271 * Call this routine anytime after node_states[N_MEMORY] changes.
3272 * See cpuset_update_active_cpus() for CPU hotplug handling.
3273 */
3274static int cpuset_track_online_nodes(struct notifier_block *self,
3275 unsigned long action, void *arg)
3276{
3277 schedule_work(&cpuset_hotplug_work);
3278 return NOTIFY_OK;
3279}
3280
3281static struct notifier_block cpuset_track_online_nodes_nb = {
3282 .notifier_call = cpuset_track_online_nodes,
3283 .priority = 10, /* ??! */
3284};
3285
3286/**
3287 * cpuset_init_smp - initialize cpus_allowed
3288 *
3289 * Description: Finish top cpuset after cpu, node maps are initialized
3290 */
3291void __init cpuset_init_smp(void)
3292{
3293 cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
3294 top_cpuset.mems_allowed = node_states[N_MEMORY];
3295 top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
3296
3297 cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
3298 top_cpuset.effective_mems = node_states[N_MEMORY];
3299
3300 register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
3301
3302 cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
3303 BUG_ON(!cpuset_migrate_mm_wq);
3304}
3305
3306/**
3307 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
3308 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
3309 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
3310 *
3311 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
3312 * attached to the specified @tsk. Guaranteed to return some non-empty
3313 * subset of cpu_online_mask, even if this means going outside the
3314 * tasks cpuset.
3315 **/
3316
3317void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
3318{
3319 unsigned long flags;
3320
3321 spin_lock_irqsave(&callback_lock, flags);
3322 rcu_read_lock();
3323 guarantee_online_cpus(task_cs(tsk), pmask);
3324 rcu_read_unlock();
3325 spin_unlock_irqrestore(&callback_lock, flags);
3326}
3327
3328/**
3329 * cpuset_cpus_allowed_fallback - final fallback before complete catastrophe.
3330 * @tsk: pointer to task_struct with which the scheduler is struggling
3331 *
3332 * Description: In the case that the scheduler cannot find an allowed cpu in
3333 * tsk->cpus_allowed, we fall back to task_cs(tsk)->cpus_allowed. In legacy
3334 * mode however, this value is the same as task_cs(tsk)->effective_cpus,
3335 * which will not contain a sane cpumask during cases such as cpu hotplugging.
3336 * This is the absolute last resort for the scheduler and it is only used if
3337 * _every_ other avenue has been traveled.
3338 **/
3339
3340void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
3341{
3342 rcu_read_lock();
3343 do_set_cpus_allowed(tsk, is_in_v2_mode() ?
3344 task_cs(tsk)->cpus_allowed : cpu_possible_mask);
3345 rcu_read_unlock();
3346
3347 /*
3348 * We own tsk->cpus_allowed, nobody can change it under us.
3349 *
3350 * But we used cs && cs->cpus_allowed lockless and thus can
3351 * race with cgroup_attach_task() or update_cpumask() and get
3352 * the wrong tsk->cpus_allowed. However, both cases imply the
3353 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
3354 * which takes task_rq_lock().
3355 *
3356 * If we are called after it dropped the lock we must see all
3357 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
3358 * set any mask even if it is not right from task_cs() pov,
3359 * the pending set_cpus_allowed_ptr() will fix things.
3360 *
3361 * select_fallback_rq() will fix things ups and set cpu_possible_mask
3362 * if required.
3363 */
3364}
3365
3366void __init cpuset_init_current_mems_allowed(void)
3367{
3368 nodes_setall(current->mems_allowed);
3369}
3370
3371/**
3372 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
3373 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
3374 *
3375 * Description: Returns the nodemask_t mems_allowed of the cpuset
3376 * attached to the specified @tsk. Guaranteed to return some non-empty
3377 * subset of node_states[N_MEMORY], even if this means going outside the
3378 * tasks cpuset.
3379 **/
3380
3381nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
3382{
3383 nodemask_t mask;
3384 unsigned long flags;
3385
3386 spin_lock_irqsave(&callback_lock, flags);
3387 rcu_read_lock();
3388 guarantee_online_mems(task_cs(tsk), &mask);
3389 rcu_read_unlock();
3390 spin_unlock_irqrestore(&callback_lock, flags);
3391
3392 return mask;
3393}
3394
3395/**
3396 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. current mems_allowed
3397 * @nodemask: the nodemask to be checked
3398 *
3399 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
3400 */
3401int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
3402{
3403 return nodes_intersects(*nodemask, current->mems_allowed);
3404}
3405
3406/*
3407 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
3408 * mem_hardwall ancestor to the specified cpuset. Call holding
3409 * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
3410 * (an unusual configuration), then returns the root cpuset.
3411 */
3412static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
3413{
3414 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
3415 cs = parent_cs(cs);
3416 return cs;
3417}
3418
3419/**
3420 * cpuset_node_allowed - Can we allocate on a memory node?
3421 * @node: is this an allowed node?
3422 * @gfp_mask: memory allocation flags
3423 *
3424 * If we're in interrupt, yes, we can always allocate. If @node is set in
3425 * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
3426 * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
3427 * yes. If current has access to memory reserves as an oom victim, yes.
3428 * Otherwise, no.
3429 *
3430 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
3431 * and do not allow allocations outside the current tasks cpuset
3432 * unless the task has been OOM killed.
3433 * GFP_KERNEL allocations are not so marked, so can escape to the
3434 * nearest enclosing hardwalled ancestor cpuset.
3435 *
3436 * Scanning up parent cpusets requires callback_lock. The
3437 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
3438 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
3439 * current tasks mems_allowed came up empty on the first pass over
3440 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
3441 * cpuset are short of memory, might require taking the callback_lock.
3442 *
3443 * The first call here from mm/page_alloc:get_page_from_freelist()
3444 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
3445 * so no allocation on a node outside the cpuset is allowed (unless
3446 * in interrupt, of course).
3447 *
3448 * The second pass through get_page_from_freelist() doesn't even call
3449 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
3450 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
3451 * in alloc_flags. That logic and the checks below have the combined
3452 * affect that:
3453 * in_interrupt - any node ok (current task context irrelevant)
3454 * GFP_ATOMIC - any node ok
3455 * tsk_is_oom_victim - any node ok
3456 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
3457 * GFP_USER - only nodes in current tasks mems allowed ok.
3458 */
3459bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
3460{
3461 struct cpuset *cs; /* current cpuset ancestors */
3462 int allowed; /* is allocation in zone z allowed? */
3463 unsigned long flags;
3464
3465 if (in_interrupt())
3466 return true;
3467 if (node_isset(node, current->mems_allowed))
3468 return true;
3469 /*
3470 * Allow tasks that have access to memory reserves because they have
3471 * been OOM killed to get memory anywhere.
3472 */
3473 if (unlikely(tsk_is_oom_victim(current)))
3474 return true;
3475 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
3476 return false;
3477
3478 if (current->flags & PF_EXITING) /* Let dying task have memory */
3479 return true;
3480
3481 /* Not hardwall and node outside mems_allowed: scan up cpusets */
3482 spin_lock_irqsave(&callback_lock, flags);
3483
3484 rcu_read_lock();
3485 cs = nearest_hardwall_ancestor(task_cs(current));
3486 allowed = node_isset(node, cs->mems_allowed);
3487 rcu_read_unlock();
3488
3489 spin_unlock_irqrestore(&callback_lock, flags);
3490 return allowed;
3491}
3492
3493/**
3494 * cpuset_mem_spread_node() - On which node to begin search for a file page
3495 * cpuset_slab_spread_node() - On which node to begin search for a slab page
3496 *
3497 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
3498 * tasks in a cpuset with is_spread_page or is_spread_slab set),
3499 * and if the memory allocation used cpuset_mem_spread_node()
3500 * to determine on which node to start looking, as it will for
3501 * certain page cache or slab cache pages such as used for file
3502 * system buffers and inode caches, then instead of starting on the
3503 * local node to look for a free page, rather spread the starting
3504 * node around the tasks mems_allowed nodes.
3505 *
3506 * We don't have to worry about the returned node being offline
3507 * because "it can't happen", and even if it did, it would be ok.
3508 *
3509 * The routines calling guarantee_online_mems() are careful to
3510 * only set nodes in task->mems_allowed that are online. So it
3511 * should not be possible for the following code to return an
3512 * offline node. But if it did, that would be ok, as this routine
3513 * is not returning the node where the allocation must be, only
3514 * the node where the search should start. The zonelist passed to
3515 * __alloc_pages() will include all nodes. If the slab allocator
3516 * is passed an offline node, it will fall back to the local node.
3517 * See kmem_cache_alloc_node().
3518 */
3519
3520static int cpuset_spread_node(int *rotor)
3521{
3522 return *rotor = next_node_in(*rotor, current->mems_allowed);
3523}
3524
3525int cpuset_mem_spread_node(void)
3526{
3527 if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
3528 current->cpuset_mem_spread_rotor =
3529 node_random(¤t->mems_allowed);
3530
3531 return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
3532}
3533
3534int cpuset_slab_spread_node(void)
3535{
3536 if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
3537 current->cpuset_slab_spread_rotor =
3538 node_random(¤t->mems_allowed);
3539
3540 return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
3541}
3542
3543EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
3544
3545/**
3546 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
3547 * @tsk1: pointer to task_struct of some task.
3548 * @tsk2: pointer to task_struct of some other task.
3549 *
3550 * Description: Return true if @tsk1's mems_allowed intersects the
3551 * mems_allowed of @tsk2. Used by the OOM killer to determine if
3552 * one of the task's memory usage might impact the memory available
3553 * to the other.
3554 **/
3555
3556int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
3557 const struct task_struct *tsk2)
3558{
3559 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
3560}
3561
3562/**
3563 * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
3564 *
3565 * Description: Prints current's name, cpuset name, and cached copy of its
3566 * mems_allowed to the kernel log.
3567 */
3568void cpuset_print_current_mems_allowed(void)
3569{
3570 struct cgroup *cgrp;
3571
3572 rcu_read_lock();
3573
3574 cgrp = task_cs(current)->css.cgroup;
3575 pr_cont(",cpuset=");
3576 pr_cont_cgroup_name(cgrp);
3577 pr_cont(",mems_allowed=%*pbl",
3578 nodemask_pr_args(¤t->mems_allowed));
3579
3580 rcu_read_unlock();
3581}
3582
3583/*
3584 * Collection of memory_pressure is suppressed unless
3585 * this flag is enabled by writing "1" to the special
3586 * cpuset file 'memory_pressure_enabled' in the root cpuset.
3587 */
3588
3589int cpuset_memory_pressure_enabled __read_mostly;
3590
3591/**
3592 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
3593 *
3594 * Keep a running average of the rate of synchronous (direct)
3595 * page reclaim efforts initiated by tasks in each cpuset.
3596 *
3597 * This represents the rate at which some task in the cpuset
3598 * ran low on memory on all nodes it was allowed to use, and
3599 * had to enter the kernels page reclaim code in an effort to
3600 * create more free memory by tossing clean pages or swapping
3601 * or writing dirty pages.
3602 *
3603 * Display to user space in the per-cpuset read-only file
3604 * "memory_pressure". Value displayed is an integer
3605 * representing the recent rate of entry into the synchronous
3606 * (direct) page reclaim by any task attached to the cpuset.
3607 **/
3608
3609void __cpuset_memory_pressure_bump(void)
3610{
3611 rcu_read_lock();
3612 fmeter_markevent(&task_cs(current)->fmeter);
3613 rcu_read_unlock();
3614}
3615
3616#ifdef CONFIG_PROC_PID_CPUSET
3617/*
3618 * proc_cpuset_show()
3619 * - Print tasks cpuset path into seq_file.
3620 * - Used for /proc/<pid>/cpuset.
3621 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
3622 * doesn't really matter if tsk->cpuset changes after we read it,
3623 * and we take cpuset_mutex, keeping cpuset_attach() from changing it
3624 * anyway.
3625 */
3626int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
3627 struct pid *pid, struct task_struct *tsk)
3628{
3629 char *buf;
3630 struct cgroup_subsys_state *css;
3631 int retval;
3632
3633 retval = -ENOMEM;
3634 buf = kmalloc(PATH_MAX, GFP_KERNEL);
3635 if (!buf)
3636 goto out;
3637
3638 css = task_get_css(tsk, cpuset_cgrp_id);
3639 retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
3640 current->nsproxy->cgroup_ns);
3641 css_put(css);
3642 if (retval >= PATH_MAX)
3643 retval = -ENAMETOOLONG;
3644 if (retval < 0)
3645 goto out_free;
3646 seq_puts(m, buf);
3647 seq_putc(m, '\n');
3648 retval = 0;
3649out_free:
3650 kfree(buf);
3651out:
3652 return retval;
3653}
3654#endif /* CONFIG_PROC_PID_CPUSET */
3655
3656/* Display task mems_allowed in /proc/<pid>/status file. */
3657void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
3658{
3659 seq_printf(m, "Mems_allowed:\t%*pb\n",
3660 nodemask_pr_args(&task->mems_allowed));
3661 seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
3662 nodemask_pr_args(&task->mems_allowed));
3663}