4 * Processor and Memory placement constraints for sets of tasks.
6 * Copyright (C) 2003 BULL SA.
7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8 * Copyright (C) 2006 Google, Inc
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
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
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.
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>
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>
39 #include <linux/memory.h>
40 #include <linux/export.h>
41 #include <linux/mount.h>
42 #include <linux/namei.h>
43 #include <linux/pagemap.h>
44 #include <linux/proc_fs.h>
45 #include <linux/rcupdate.h>
46 #include <linux/sched.h>
47 #include <linux/seq_file.h>
48 #include <linux/security.h>
49 #include <linux/slab.h>
50 #include <linux/spinlock.h>
51 #include <linux/stat.h>
52 #include <linux/string.h>
53 #include <linux/time.h>
54 #include <linux/backing-dev.h>
55 #include <linux/sort.h>
57 #include <asm/uaccess.h>
58 #include <linux/atomic.h>
59 #include <linux/mutex.h>
60 #include <linux/workqueue.h>
61 #include <linux/cgroup.h>
62 #include <linux/wait.h>
65 * Tracks how many cpusets are currently defined in system.
66 * When there is only one cpuset (the root cpuset) we can
67 * short circuit some hooks.
69 int number_of_cpusets __read_mostly
;
71 /* Forward declare cgroup structures */
72 struct cgroup_subsys cpuset_subsys
;
75 /* See "Frequency meter" comments, below. */
78 int cnt
; /* unprocessed events count */
79 int val
; /* most recent output value */
80 time_t time
; /* clock (secs) when val computed */
81 spinlock_t lock
; /* guards read or write of above */
85 struct cgroup_subsys_state css
;
87 unsigned long flags
; /* "unsigned long" so bitops work */
88 cpumask_var_t cpus_allowed
; /* CPUs allowed to tasks in cpuset */
89 nodemask_t mems_allowed
; /* Memory Nodes allowed to tasks */
92 * This is old Memory Nodes tasks took on.
94 * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
95 * - A new cpuset's old_mems_allowed is initialized when some
96 * task is moved into it.
97 * - old_mems_allowed is used in cpuset_migrate_mm() when we change
98 * cpuset.mems_allowed and have tasks' nodemask updated, and
99 * then old_mems_allowed is updated to mems_allowed.
101 nodemask_t old_mems_allowed
;
103 struct fmeter fmeter
; /* memory_pressure filter */
106 * Tasks are being attached to this cpuset. Used to prevent
107 * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
109 int attach_in_progress
;
111 /* partition number for rebuild_sched_domains() */
114 /* for custom sched domain */
115 int relax_domain_level
;
118 /* Retrieve the cpuset for a cgroup */
119 static inline struct cpuset
*cgroup_cs(struct cgroup
*cgrp
)
121 return container_of(cgroup_subsys_state(cgrp
, cpuset_subsys_id
),
125 /* Retrieve the cpuset for a task */
126 static inline struct cpuset
*task_cs(struct task_struct
*task
)
128 return container_of(task_subsys_state(task
, cpuset_subsys_id
),
132 static inline struct cpuset
*parent_cs(const struct cpuset
*cs
)
134 struct cgroup
*pcgrp
= cs
->css
.cgroup
->parent
;
137 return cgroup_cs(pcgrp
);
142 static inline bool task_has_mempolicy(struct task_struct
*task
)
144 return task
->mempolicy
;
147 static inline bool task_has_mempolicy(struct task_struct
*task
)
154 /* bits in struct cpuset flags field */
161 CS_SCHED_LOAD_BALANCE
,
166 /* convenient tests for these bits */
167 static inline bool is_cpuset_online(const struct cpuset
*cs
)
169 return test_bit(CS_ONLINE
, &cs
->flags
);
172 static inline int is_cpu_exclusive(const struct cpuset
*cs
)
174 return test_bit(CS_CPU_EXCLUSIVE
, &cs
->flags
);
177 static inline int is_mem_exclusive(const struct cpuset
*cs
)
179 return test_bit(CS_MEM_EXCLUSIVE
, &cs
->flags
);
182 static inline int is_mem_hardwall(const struct cpuset
*cs
)
184 return test_bit(CS_MEM_HARDWALL
, &cs
->flags
);
187 static inline int is_sched_load_balance(const struct cpuset
*cs
)
189 return test_bit(CS_SCHED_LOAD_BALANCE
, &cs
->flags
);
192 static inline int is_memory_migrate(const struct cpuset
*cs
)
194 return test_bit(CS_MEMORY_MIGRATE
, &cs
->flags
);
197 static inline int is_spread_page(const struct cpuset
*cs
)
199 return test_bit(CS_SPREAD_PAGE
, &cs
->flags
);
202 static inline int is_spread_slab(const struct cpuset
*cs
)
204 return test_bit(CS_SPREAD_SLAB
, &cs
->flags
);
207 static struct cpuset top_cpuset
= {
208 .flags
= ((1 << CS_ONLINE
) | (1 << CS_CPU_EXCLUSIVE
) |
209 (1 << CS_MEM_EXCLUSIVE
)),
213 * cpuset_for_each_child - traverse online children of a cpuset
214 * @child_cs: loop cursor pointing to the current child
215 * @pos_cgrp: used for iteration
216 * @parent_cs: target cpuset to walk children of
218 * Walk @child_cs through the online children of @parent_cs. Must be used
219 * with RCU read locked.
221 #define cpuset_for_each_child(child_cs, pos_cgrp, parent_cs) \
222 cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup) \
223 if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp)))))
226 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
227 * @des_cs: loop cursor pointing to the current descendant
228 * @pos_cgrp: used for iteration
229 * @root_cs: target cpuset to walk ancestor of
231 * Walk @des_cs through the online descendants of @root_cs. Must be used
232 * with RCU read locked. The caller may modify @pos_cgrp by calling
233 * cgroup_rightmost_descendant() to skip subtree.
235 #define cpuset_for_each_descendant_pre(des_cs, pos_cgrp, root_cs) \
236 cgroup_for_each_descendant_pre((pos_cgrp), (root_cs)->css.cgroup) \
237 if (is_cpuset_online(((des_cs) = cgroup_cs((pos_cgrp)))))
240 * There are two global mutexes guarding cpuset structures - cpuset_mutex
241 * and callback_mutex. The latter may nest inside the former. We also
242 * require taking task_lock() when dereferencing a task's cpuset pointer.
243 * See "The task_lock() exception", at the end of this comment.
245 * A task must hold both mutexes to modify cpusets. If a task holds
246 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
247 * is the only task able to also acquire callback_mutex and be able to
248 * modify cpusets. It can perform various checks on the cpuset structure
249 * first, knowing nothing will change. It can also allocate memory while
250 * just holding cpuset_mutex. While it is performing these checks, various
251 * callback routines can briefly acquire callback_mutex to query cpusets.
252 * Once it is ready to make the changes, it takes callback_mutex, blocking
255 * Calls to the kernel memory allocator can not be made while holding
256 * callback_mutex, as that would risk double tripping on callback_mutex
257 * from one of the callbacks into the cpuset code from within
260 * If a task is only holding callback_mutex, then it has read-only
263 * Now, the task_struct fields mems_allowed and mempolicy may be changed
264 * by other task, we use alloc_lock in the task_struct fields to protect
267 * The cpuset_common_file_read() handlers only hold callback_mutex across
268 * small pieces of code, such as when reading out possibly multi-word
269 * cpumasks and nodemasks.
271 * Accessing a task's cpuset should be done in accordance with the
272 * guidelines for accessing subsystem state in kernel/cgroup.c
275 static DEFINE_MUTEX(cpuset_mutex
);
276 static DEFINE_MUTEX(callback_mutex
);
279 * CPU / memory hotplug is handled asynchronously.
281 static void cpuset_hotplug_workfn(struct work_struct
*work
);
282 static DECLARE_WORK(cpuset_hotplug_work
, cpuset_hotplug_workfn
);
284 static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq
);
287 * This is ugly, but preserves the userspace API for existing cpuset
288 * users. If someone tries to mount the "cpuset" filesystem, we
289 * silently switch it to mount "cgroup" instead
291 static struct dentry
*cpuset_mount(struct file_system_type
*fs_type
,
292 int flags
, const char *unused_dev_name
, void *data
)
294 struct file_system_type
*cgroup_fs
= get_fs_type("cgroup");
295 struct dentry
*ret
= ERR_PTR(-ENODEV
);
299 "release_agent=/sbin/cpuset_release_agent";
300 ret
= cgroup_fs
->mount(cgroup_fs
, flags
,
301 unused_dev_name
, mountopts
);
302 put_filesystem(cgroup_fs
);
307 static struct file_system_type cpuset_fs_type
= {
309 .mount
= cpuset_mount
,
313 * Return in pmask the portion of a cpusets's cpus_allowed that
314 * are online. If none are online, walk up the cpuset hierarchy
315 * until we find one that does have some online cpus. The top
316 * cpuset always has some cpus online.
318 * One way or another, we guarantee to return some non-empty subset
319 * of cpu_online_mask.
321 * Call with callback_mutex held.
323 static void guarantee_online_cpus(const struct cpuset
*cs
,
324 struct cpumask
*pmask
)
326 while (!cpumask_intersects(cs
->cpus_allowed
, cpu_online_mask
))
328 cpumask_and(pmask
, cs
->cpus_allowed
, cpu_online_mask
);
332 * Return in *pmask the portion of a cpusets's mems_allowed that
333 * are online, with memory. If none are online with memory, walk
334 * up the cpuset hierarchy until we find one that does have some
335 * online mems. The top cpuset always has some mems online.
337 * One way or another, we guarantee to return some non-empty subset
338 * of node_states[N_MEMORY].
340 * Call with callback_mutex held.
342 static void guarantee_online_mems(const struct cpuset
*cs
, nodemask_t
*pmask
)
344 while (!nodes_intersects(cs
->mems_allowed
, node_states
[N_MEMORY
]))
346 nodes_and(*pmask
, cs
->mems_allowed
, node_states
[N_MEMORY
]);
350 * update task's spread flag if cpuset's page/slab spread flag is set
352 * Called with callback_mutex/cpuset_mutex held
354 static void cpuset_update_task_spread_flag(struct cpuset
*cs
,
355 struct task_struct
*tsk
)
357 if (is_spread_page(cs
))
358 tsk
->flags
|= PF_SPREAD_PAGE
;
360 tsk
->flags
&= ~PF_SPREAD_PAGE
;
361 if (is_spread_slab(cs
))
362 tsk
->flags
|= PF_SPREAD_SLAB
;
364 tsk
->flags
&= ~PF_SPREAD_SLAB
;
368 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
370 * One cpuset is a subset of another if all its allowed CPUs and
371 * Memory Nodes are a subset of the other, and its exclusive flags
372 * are only set if the other's are set. Call holding cpuset_mutex.
375 static int is_cpuset_subset(const struct cpuset
*p
, const struct cpuset
*q
)
377 return cpumask_subset(p
->cpus_allowed
, q
->cpus_allowed
) &&
378 nodes_subset(p
->mems_allowed
, q
->mems_allowed
) &&
379 is_cpu_exclusive(p
) <= is_cpu_exclusive(q
) &&
380 is_mem_exclusive(p
) <= is_mem_exclusive(q
);
384 * alloc_trial_cpuset - allocate a trial cpuset
385 * @cs: the cpuset that the trial cpuset duplicates
387 static struct cpuset
*alloc_trial_cpuset(const struct cpuset
*cs
)
389 struct cpuset
*trial
;
391 trial
= kmemdup(cs
, sizeof(*cs
), GFP_KERNEL
);
395 if (!alloc_cpumask_var(&trial
->cpus_allowed
, GFP_KERNEL
)) {
399 cpumask_copy(trial
->cpus_allowed
, cs
->cpus_allowed
);
405 * free_trial_cpuset - free the trial cpuset
406 * @trial: the trial cpuset to be freed
408 static void free_trial_cpuset(struct cpuset
*trial
)
410 free_cpumask_var(trial
->cpus_allowed
);
415 * validate_change() - Used to validate that any proposed cpuset change
416 * follows the structural rules for cpusets.
418 * If we replaced the flag and mask values of the current cpuset
419 * (cur) with those values in the trial cpuset (trial), would
420 * our various subset and exclusive rules still be valid? Presumes
423 * 'cur' is the address of an actual, in-use cpuset. Operations
424 * such as list traversal that depend on the actual address of the
425 * cpuset in the list must use cur below, not trial.
427 * 'trial' is the address of bulk structure copy of cur, with
428 * perhaps one or more of the fields cpus_allowed, mems_allowed,
429 * or flags changed to new, trial values.
431 * Return 0 if valid, -errno if not.
434 static int validate_change(const struct cpuset
*cur
, const struct cpuset
*trial
)
437 struct cpuset
*c
, *par
;
442 /* Each of our child cpusets must be a subset of us */
444 cpuset_for_each_child(c
, cgrp
, cur
)
445 if (!is_cpuset_subset(c
, trial
))
448 /* Remaining checks don't apply to root cpuset */
450 if (cur
== &top_cpuset
)
453 par
= parent_cs(cur
);
455 /* We must be a subset of our parent cpuset */
457 if (!is_cpuset_subset(trial
, par
))
461 * If either I or some sibling (!= me) is exclusive, we can't
465 cpuset_for_each_child(c
, cgrp
, par
) {
466 if ((is_cpu_exclusive(trial
) || is_cpu_exclusive(c
)) &&
468 cpumask_intersects(trial
->cpus_allowed
, c
->cpus_allowed
))
470 if ((is_mem_exclusive(trial
) || is_mem_exclusive(c
)) &&
472 nodes_intersects(trial
->mems_allowed
, c
->mems_allowed
))
477 * Cpusets with tasks - existing or newly being attached - can't
478 * be changed to have empty cpus_allowed or mems_allowed.
481 if ((cgroup_task_count(cur
->css
.cgroup
) || cur
->attach_in_progress
)) {
482 if (!cpumask_empty(cur
->cpus_allowed
) &&
483 cpumask_empty(trial
->cpus_allowed
))
485 if (!nodes_empty(cur
->mems_allowed
) &&
486 nodes_empty(trial
->mems_allowed
))
498 * Helper routine for generate_sched_domains().
499 * Do cpusets a, b have overlapping cpus_allowed masks?
501 static int cpusets_overlap(struct cpuset
*a
, struct cpuset
*b
)
503 return cpumask_intersects(a
->cpus_allowed
, b
->cpus_allowed
);
507 update_domain_attr(struct sched_domain_attr
*dattr
, struct cpuset
*c
)
509 if (dattr
->relax_domain_level
< c
->relax_domain_level
)
510 dattr
->relax_domain_level
= c
->relax_domain_level
;
514 static void update_domain_attr_tree(struct sched_domain_attr
*dattr
,
515 struct cpuset
*root_cs
)
518 struct cgroup
*pos_cgrp
;
521 cpuset_for_each_descendant_pre(cp
, pos_cgrp
, root_cs
) {
522 /* skip the whole subtree if @cp doesn't have any CPU */
523 if (cpumask_empty(cp
->cpus_allowed
)) {
524 pos_cgrp
= cgroup_rightmost_descendant(pos_cgrp
);
528 if (is_sched_load_balance(cp
))
529 update_domain_attr(dattr
, cp
);
535 * generate_sched_domains()
537 * This function builds a partial partition of the systems CPUs
538 * A 'partial partition' is a set of non-overlapping subsets whose
539 * union is a subset of that set.
540 * The output of this function needs to be passed to kernel/sched/core.c
541 * partition_sched_domains() routine, which will rebuild the scheduler's
542 * load balancing domains (sched domains) as specified by that partial
545 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
546 * for a background explanation of this.
548 * Does not return errors, on the theory that the callers of this
549 * routine would rather not worry about failures to rebuild sched
550 * domains when operating in the severe memory shortage situations
551 * that could cause allocation failures below.
553 * Must be called with cpuset_mutex held.
555 * The three key local variables below are:
556 * q - a linked-list queue of cpuset pointers, used to implement a
557 * top-down scan of all cpusets. This scan loads a pointer
558 * to each cpuset marked is_sched_load_balance into the
559 * array 'csa'. For our purposes, rebuilding the schedulers
560 * sched domains, we can ignore !is_sched_load_balance cpusets.
561 * csa - (for CpuSet Array) Array of pointers to all the cpusets
562 * that need to be load balanced, for convenient iterative
563 * access by the subsequent code that finds the best partition,
564 * i.e the set of domains (subsets) of CPUs such that the
565 * cpus_allowed of every cpuset marked is_sched_load_balance
566 * is a subset of one of these domains, while there are as
567 * many such domains as possible, each as small as possible.
568 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
569 * the kernel/sched/core.c routine partition_sched_domains() in a
570 * convenient format, that can be easily compared to the prior
571 * value to determine what partition elements (sched domains)
572 * were changed (added or removed.)
574 * Finding the best partition (set of domains):
575 * The triple nested loops below over i, j, k scan over the
576 * load balanced cpusets (using the array of cpuset pointers in
577 * csa[]) looking for pairs of cpusets that have overlapping
578 * cpus_allowed, but which don't have the same 'pn' partition
579 * number and gives them in the same partition number. It keeps
580 * looping on the 'restart' label until it can no longer find
583 * The union of the cpus_allowed masks from the set of
584 * all cpusets having the same 'pn' value then form the one
585 * element of the partition (one sched domain) to be passed to
586 * partition_sched_domains().
588 static int generate_sched_domains(cpumask_var_t
**domains
,
589 struct sched_domain_attr
**attributes
)
591 struct cpuset
*cp
; /* scans q */
592 struct cpuset
**csa
; /* array of all cpuset ptrs */
593 int csn
; /* how many cpuset ptrs in csa so far */
594 int i
, j
, k
; /* indices for partition finding loops */
595 cpumask_var_t
*doms
; /* resulting partition; i.e. sched domains */
596 struct sched_domain_attr
*dattr
; /* attributes for custom domains */
597 int ndoms
= 0; /* number of sched domains in result */
598 int nslot
; /* next empty doms[] struct cpumask slot */
599 struct cgroup
*pos_cgrp
;
605 /* Special case for the 99% of systems with one, full, sched domain */
606 if (is_sched_load_balance(&top_cpuset
)) {
608 doms
= alloc_sched_domains(ndoms
);
612 dattr
= kmalloc(sizeof(struct sched_domain_attr
), GFP_KERNEL
);
614 *dattr
= SD_ATTR_INIT
;
615 update_domain_attr_tree(dattr
, &top_cpuset
);
617 cpumask_copy(doms
[0], top_cpuset
.cpus_allowed
);
622 csa
= kmalloc(number_of_cpusets
* sizeof(cp
), GFP_KERNEL
);
628 cpuset_for_each_descendant_pre(cp
, pos_cgrp
, &top_cpuset
) {
630 * Continue traversing beyond @cp iff @cp has some CPUs and
631 * isn't load balancing. The former is obvious. The
632 * latter: All child cpusets contain a subset of the
633 * parent's cpus, so just skip them, and then we call
634 * update_domain_attr_tree() to calc relax_domain_level of
635 * the corresponding sched domain.
637 if (!cpumask_empty(cp
->cpus_allowed
) &&
638 !is_sched_load_balance(cp
))
641 if (is_sched_load_balance(cp
))
644 /* skip @cp's subtree */
645 pos_cgrp
= cgroup_rightmost_descendant(pos_cgrp
);
649 for (i
= 0; i
< csn
; i
++)
654 /* Find the best partition (set of sched domains) */
655 for (i
= 0; i
< csn
; i
++) {
656 struct cpuset
*a
= csa
[i
];
659 for (j
= 0; j
< csn
; j
++) {
660 struct cpuset
*b
= csa
[j
];
663 if (apn
!= bpn
&& cpusets_overlap(a
, b
)) {
664 for (k
= 0; k
< csn
; k
++) {
665 struct cpuset
*c
= csa
[k
];
670 ndoms
--; /* one less element */
677 * Now we know how many domains to create.
678 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
680 doms
= alloc_sched_domains(ndoms
);
685 * The rest of the code, including the scheduler, can deal with
686 * dattr==NULL case. No need to abort if alloc fails.
688 dattr
= kmalloc(ndoms
* sizeof(struct sched_domain_attr
), GFP_KERNEL
);
690 for (nslot
= 0, i
= 0; i
< csn
; i
++) {
691 struct cpuset
*a
= csa
[i
];
696 /* Skip completed partitions */
702 if (nslot
== ndoms
) {
703 static int warnings
= 10;
706 "rebuild_sched_domains confused:"
707 " nslot %d, ndoms %d, csn %d, i %d,"
709 nslot
, ndoms
, csn
, i
, apn
);
717 *(dattr
+ nslot
) = SD_ATTR_INIT
;
718 for (j
= i
; j
< csn
; j
++) {
719 struct cpuset
*b
= csa
[j
];
722 cpumask_or(dp
, dp
, b
->cpus_allowed
);
724 update_domain_attr_tree(dattr
+ nslot
, b
);
726 /* Done with this partition */
732 BUG_ON(nslot
!= ndoms
);
738 * Fallback to the default domain if kmalloc() failed.
739 * See comments in partition_sched_domains().
750 * Rebuild scheduler domains.
752 * If the flag 'sched_load_balance' of any cpuset with non-empty
753 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
754 * which has that flag enabled, or if any cpuset with a non-empty
755 * 'cpus' is removed, then call this routine to rebuild the
756 * scheduler's dynamic sched domains.
758 * Call with cpuset_mutex held. Takes get_online_cpus().
760 static void rebuild_sched_domains_locked(void)
762 struct sched_domain_attr
*attr
;
766 lockdep_assert_held(&cpuset_mutex
);
770 * We have raced with CPU hotplug. Don't do anything to avoid
771 * passing doms with offlined cpu to partition_sched_domains().
772 * Anyways, hotplug work item will rebuild sched domains.
774 if (!cpumask_equal(top_cpuset
.cpus_allowed
, cpu_active_mask
))
777 /* Generate domain masks and attrs */
778 ndoms
= generate_sched_domains(&doms
, &attr
);
780 /* Have scheduler rebuild the domains */
781 partition_sched_domains(ndoms
, doms
, attr
);
785 #else /* !CONFIG_SMP */
786 static void rebuild_sched_domains_locked(void)
789 #endif /* CONFIG_SMP */
791 void rebuild_sched_domains(void)
793 mutex_lock(&cpuset_mutex
);
794 rebuild_sched_domains_locked();
795 mutex_unlock(&cpuset_mutex
);
799 * effective_cpumask_cpuset - return nearest ancestor with non-empty cpus
800 * @cs: the cpuset in interest
802 * A cpuset's effective cpumask is the cpumask of the nearest ancestor
803 * with non-empty cpus. We use effective cpumask whenever:
804 * - we update tasks' cpus_allowed. (they take on the ancestor's cpumask
805 * if the cpuset they reside in has no cpus)
806 * - we want to retrieve task_cs(tsk)'s cpus_allowed.
808 * Called with cpuset_mutex held. cpuset_cpus_allowed_fallback() is an
809 * exception. See comments there.
811 static struct cpuset
*effective_cpumask_cpuset(struct cpuset
*cs
)
813 while (cpumask_empty(cs
->cpus_allowed
))
819 * effective_nodemask_cpuset - return nearest ancestor with non-empty mems
820 * @cs: the cpuset in interest
822 * A cpuset's effective nodemask is the nodemask of the nearest ancestor
823 * with non-empty memss. We use effective nodemask whenever:
824 * - we update tasks' mems_allowed. (they take on the ancestor's nodemask
825 * if the cpuset they reside in has no mems)
826 * - we want to retrieve task_cs(tsk)'s mems_allowed.
828 * Called with cpuset_mutex held.
830 static struct cpuset
*effective_nodemask_cpuset(struct cpuset
*cs
)
832 while (nodes_empty(cs
->mems_allowed
))
838 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
840 * @scan: struct cgroup_scanner containing the cgroup of the task
842 * Called by cgroup_scan_tasks() for each task in a cgroup whose
843 * cpus_allowed mask needs to be changed.
845 * We don't need to re-check for the cgroup/cpuset membership, since we're
846 * holding cpuset_mutex at this point.
848 static void cpuset_change_cpumask(struct task_struct
*tsk
,
849 struct cgroup_scanner
*scan
)
851 struct cpuset
*cpus_cs
;
853 cpus_cs
= effective_cpumask_cpuset(cgroup_cs(scan
->cg
));
854 set_cpus_allowed_ptr(tsk
, cpus_cs
->cpus_allowed
);
858 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
859 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
860 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
862 * Called with cpuset_mutex held
864 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
865 * calling callback functions for each.
867 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
870 static void update_tasks_cpumask(struct cpuset
*cs
, struct ptr_heap
*heap
)
872 struct cgroup_scanner scan
;
874 scan
.cg
= cs
->css
.cgroup
;
875 scan
.test_task
= NULL
;
876 scan
.process_task
= cpuset_change_cpumask
;
878 cgroup_scan_tasks(&scan
);
882 * update_tasks_cpumask_hier - Update the cpumasks of tasks in the hierarchy.
883 * @root_cs: the root cpuset of the hierarchy
884 * @update_root: update root cpuset or not?
885 * @heap: the heap used by cgroup_scan_tasks()
887 * This will update cpumasks of tasks in @root_cs and all other empty cpusets
888 * which take on cpumask of @root_cs.
890 * Called with cpuset_mutex held
892 static void update_tasks_cpumask_hier(struct cpuset
*root_cs
,
893 bool update_root
, struct ptr_heap
*heap
)
896 struct cgroup
*pos_cgrp
;
899 update_tasks_cpumask(root_cs
, heap
);
902 cpuset_for_each_descendant_pre(cp
, pos_cgrp
, root_cs
) {
903 /* skip the whole subtree if @cp have some CPU */
904 if (!cpumask_empty(cp
->cpus_allowed
)) {
905 pos_cgrp
= cgroup_rightmost_descendant(pos_cgrp
);
908 if (!css_tryget(&cp
->css
))
912 update_tasks_cpumask(cp
, heap
);
921 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
922 * @cs: the cpuset to consider
923 * @buf: buffer of cpu numbers written to this cpuset
925 static int update_cpumask(struct cpuset
*cs
, struct cpuset
*trialcs
,
928 struct ptr_heap heap
;
930 int is_load_balanced
;
932 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
933 if (cs
== &top_cpuset
)
937 * An empty cpus_allowed is ok only if the cpuset has no tasks.
938 * Since cpulist_parse() fails on an empty mask, we special case
939 * that parsing. The validate_change() call ensures that cpusets
940 * with tasks have cpus.
943 cpumask_clear(trialcs
->cpus_allowed
);
945 retval
= cpulist_parse(buf
, trialcs
->cpus_allowed
);
949 if (!cpumask_subset(trialcs
->cpus_allowed
, cpu_active_mask
))
953 /* Nothing to do if the cpus didn't change */
954 if (cpumask_equal(cs
->cpus_allowed
, trialcs
->cpus_allowed
))
957 retval
= validate_change(cs
, trialcs
);
961 retval
= heap_init(&heap
, PAGE_SIZE
, GFP_KERNEL
, NULL
);
965 is_load_balanced
= is_sched_load_balance(trialcs
);
967 mutex_lock(&callback_mutex
);
968 cpumask_copy(cs
->cpus_allowed
, trialcs
->cpus_allowed
);
969 mutex_unlock(&callback_mutex
);
971 update_tasks_cpumask_hier(cs
, true, &heap
);
975 if (is_load_balanced
)
976 rebuild_sched_domains_locked();
983 * Migrate memory region from one set of nodes to another.
985 * Temporarilly set tasks mems_allowed to target nodes of migration,
986 * so that the migration code can allocate pages on these nodes.
988 * Call holding cpuset_mutex, so current's cpuset won't change
989 * during this call, as manage_mutex holds off any cpuset_attach()
990 * calls. Therefore we don't need to take task_lock around the
991 * call to guarantee_online_mems(), as we know no one is changing
994 * While the mm_struct we are migrating is typically from some
995 * other task, the task_struct mems_allowed that we are hacking
996 * is for our current task, which must allocate new pages for that
997 * migrating memory region.
1000 static void cpuset_migrate_mm(struct mm_struct
*mm
, const nodemask_t
*from
,
1001 const nodemask_t
*to
)
1003 struct task_struct
*tsk
= current
;
1004 struct cpuset
*mems_cs
;
1006 tsk
->mems_allowed
= *to
;
1008 do_migrate_pages(mm
, from
, to
, MPOL_MF_MOVE_ALL
);
1010 mems_cs
= effective_nodemask_cpuset(task_cs(tsk
));
1011 guarantee_online_mems(mems_cs
, &tsk
->mems_allowed
);
1015 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
1016 * @tsk: the task to change
1017 * @newmems: new nodes that the task will be set
1019 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
1020 * we structure updates as setting all new allowed nodes, then clearing newly
1023 static void cpuset_change_task_nodemask(struct task_struct
*tsk
,
1024 nodemask_t
*newmems
)
1029 * Allow tasks that have access to memory reserves because they have
1030 * been OOM killed to get memory anywhere.
1032 if (unlikely(test_thread_flag(TIF_MEMDIE
)))
1034 if (current
->flags
& PF_EXITING
) /* Let dying task have memory */
1039 * Determine if a loop is necessary if another thread is doing
1040 * get_mems_allowed(). If at least one node remains unchanged and
1041 * tsk does not have a mempolicy, then an empty nodemask will not be
1042 * possible when mems_allowed is larger than a word.
1044 need_loop
= task_has_mempolicy(tsk
) ||
1045 !nodes_intersects(*newmems
, tsk
->mems_allowed
);
1048 write_seqcount_begin(&tsk
->mems_allowed_seq
);
1050 nodes_or(tsk
->mems_allowed
, tsk
->mems_allowed
, *newmems
);
1051 mpol_rebind_task(tsk
, newmems
, MPOL_REBIND_STEP1
);
1053 mpol_rebind_task(tsk
, newmems
, MPOL_REBIND_STEP2
);
1054 tsk
->mems_allowed
= *newmems
;
1057 write_seqcount_end(&tsk
->mems_allowed_seq
);
1063 * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
1064 * of it to cpuset's new mems_allowed, and migrate pages to new nodes if
1065 * memory_migrate flag is set. Called with cpuset_mutex held.
1067 static void cpuset_change_nodemask(struct task_struct
*p
,
1068 struct cgroup_scanner
*scan
)
1070 struct cpuset
*cs
= cgroup_cs(scan
->cg
);
1071 struct mm_struct
*mm
;
1073 nodemask_t
*newmems
= scan
->data
;
1075 cpuset_change_task_nodemask(p
, newmems
);
1077 mm
= get_task_mm(p
);
1081 migrate
= is_memory_migrate(cs
);
1083 mpol_rebind_mm(mm
, &cs
->mems_allowed
);
1085 cpuset_migrate_mm(mm
, &cs
->old_mems_allowed
, newmems
);
1089 static void *cpuset_being_rebound
;
1092 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1093 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1094 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1096 * Called with cpuset_mutex held
1097 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1100 static void update_tasks_nodemask(struct cpuset
*cs
, struct ptr_heap
*heap
)
1102 static nodemask_t newmems
; /* protected by cpuset_mutex */
1103 struct cgroup_scanner scan
;
1104 struct cpuset
*mems_cs
= effective_nodemask_cpuset(cs
);
1106 cpuset_being_rebound
= cs
; /* causes mpol_dup() rebind */
1108 guarantee_online_mems(mems_cs
, &newmems
);
1110 scan
.cg
= cs
->css
.cgroup
;
1111 scan
.test_task
= NULL
;
1112 scan
.process_task
= cpuset_change_nodemask
;
1114 scan
.data
= &newmems
;
1117 * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1118 * take while holding tasklist_lock. Forks can happen - the
1119 * mpol_dup() cpuset_being_rebound check will catch such forks,
1120 * and rebind their vma mempolicies too. Because we still hold
1121 * the global cpuset_mutex, we know that no other rebind effort
1122 * will be contending for the global variable cpuset_being_rebound.
1123 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1124 * is idempotent. Also migrate pages in each mm to new nodes.
1126 cgroup_scan_tasks(&scan
);
1129 * All the tasks' nodemasks have been updated, update
1130 * cs->old_mems_allowed.
1132 cs
->old_mems_allowed
= newmems
;
1134 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1135 cpuset_being_rebound
= NULL
;
1139 * update_tasks_nodemask_hier - Update the nodemasks of tasks in the hierarchy.
1140 * @cs: the root cpuset of the hierarchy
1141 * @update_root: update the root cpuset or not?
1142 * @heap: the heap used by cgroup_scan_tasks()
1144 * This will update nodemasks of tasks in @root_cs and all other empty cpusets
1145 * which take on nodemask of @root_cs.
1147 * Called with cpuset_mutex held
1149 static void update_tasks_nodemask_hier(struct cpuset
*root_cs
,
1150 bool update_root
, struct ptr_heap
*heap
)
1153 struct cgroup
*pos_cgrp
;
1156 update_tasks_nodemask(root_cs
, heap
);
1159 cpuset_for_each_descendant_pre(cp
, pos_cgrp
, root_cs
) {
1160 /* skip the whole subtree if @cp have some CPU */
1161 if (!nodes_empty(cp
->mems_allowed
)) {
1162 pos_cgrp
= cgroup_rightmost_descendant(pos_cgrp
);
1165 if (!css_tryget(&cp
->css
))
1169 update_tasks_nodemask(cp
, heap
);
1178 * Handle user request to change the 'mems' memory placement
1179 * of a cpuset. Needs to validate the request, update the
1180 * cpusets mems_allowed, and for each task in the cpuset,
1181 * update mems_allowed and rebind task's mempolicy and any vma
1182 * mempolicies and if the cpuset is marked 'memory_migrate',
1183 * migrate the tasks pages to the new memory.
1185 * Call with cpuset_mutex held. May take callback_mutex during call.
1186 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1187 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1188 * their mempolicies to the cpusets new mems_allowed.
1190 static int update_nodemask(struct cpuset
*cs
, struct cpuset
*trialcs
,
1194 struct ptr_heap heap
;
1197 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1200 if (cs
== &top_cpuset
) {
1206 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1207 * Since nodelist_parse() fails on an empty mask, we special case
1208 * that parsing. The validate_change() call ensures that cpusets
1209 * with tasks have memory.
1212 nodes_clear(trialcs
->mems_allowed
);
1214 retval
= nodelist_parse(buf
, trialcs
->mems_allowed
);
1218 if (!nodes_subset(trialcs
->mems_allowed
,
1219 node_states
[N_MEMORY
])) {
1225 if (nodes_equal(cs
->mems_allowed
, trialcs
->mems_allowed
)) {
1226 retval
= 0; /* Too easy - nothing to do */
1229 retval
= validate_change(cs
, trialcs
);
1233 retval
= heap_init(&heap
, PAGE_SIZE
, GFP_KERNEL
, NULL
);
1237 mutex_lock(&callback_mutex
);
1238 cs
->mems_allowed
= trialcs
->mems_allowed
;
1239 mutex_unlock(&callback_mutex
);
1241 update_tasks_nodemask_hier(cs
, true, &heap
);
1248 int current_cpuset_is_being_rebound(void)
1250 return task_cs(current
) == cpuset_being_rebound
;
1253 static int update_relax_domain_level(struct cpuset
*cs
, s64 val
)
1256 if (val
< -1 || val
>= sched_domain_level_max
)
1260 if (val
!= cs
->relax_domain_level
) {
1261 cs
->relax_domain_level
= val
;
1262 if (!cpumask_empty(cs
->cpus_allowed
) &&
1263 is_sched_load_balance(cs
))
1264 rebuild_sched_domains_locked();
1271 * cpuset_change_flag - make a task's spread flags the same as its cpuset's
1272 * @tsk: task to be updated
1273 * @scan: struct cgroup_scanner containing the cgroup of the task
1275 * Called by cgroup_scan_tasks() for each task in a cgroup.
1277 * We don't need to re-check for the cgroup/cpuset membership, since we're
1278 * holding cpuset_mutex at this point.
1280 static void cpuset_change_flag(struct task_struct
*tsk
,
1281 struct cgroup_scanner
*scan
)
1283 cpuset_update_task_spread_flag(cgroup_cs(scan
->cg
), tsk
);
1287 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1288 * @cs: the cpuset in which each task's spread flags needs to be changed
1289 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1291 * Called with cpuset_mutex held
1293 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1294 * calling callback functions for each.
1296 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1299 static void update_tasks_flags(struct cpuset
*cs
, struct ptr_heap
*heap
)
1301 struct cgroup_scanner scan
;
1303 scan
.cg
= cs
->css
.cgroup
;
1304 scan
.test_task
= NULL
;
1305 scan
.process_task
= cpuset_change_flag
;
1307 cgroup_scan_tasks(&scan
);
1311 * update_flag - read a 0 or a 1 in a file and update associated flag
1312 * bit: the bit to update (see cpuset_flagbits_t)
1313 * cs: the cpuset to update
1314 * turning_on: whether the flag is being set or cleared
1316 * Call with cpuset_mutex held.
1319 static int update_flag(cpuset_flagbits_t bit
, struct cpuset
*cs
,
1322 struct cpuset
*trialcs
;
1323 int balance_flag_changed
;
1324 int spread_flag_changed
;
1325 struct ptr_heap heap
;
1328 trialcs
= alloc_trial_cpuset(cs
);
1333 set_bit(bit
, &trialcs
->flags
);
1335 clear_bit(bit
, &trialcs
->flags
);
1337 err
= validate_change(cs
, trialcs
);
1341 err
= heap_init(&heap
, PAGE_SIZE
, GFP_KERNEL
, NULL
);
1345 balance_flag_changed
= (is_sched_load_balance(cs
) !=
1346 is_sched_load_balance(trialcs
));
1348 spread_flag_changed
= ((is_spread_slab(cs
) != is_spread_slab(trialcs
))
1349 || (is_spread_page(cs
) != is_spread_page(trialcs
)));
1351 mutex_lock(&callback_mutex
);
1352 cs
->flags
= trialcs
->flags
;
1353 mutex_unlock(&callback_mutex
);
1355 if (!cpumask_empty(trialcs
->cpus_allowed
) && balance_flag_changed
)
1356 rebuild_sched_domains_locked();
1358 if (spread_flag_changed
)
1359 update_tasks_flags(cs
, &heap
);
1362 free_trial_cpuset(trialcs
);
1367 * Frequency meter - How fast is some event occurring?
1369 * These routines manage a digitally filtered, constant time based,
1370 * event frequency meter. There are four routines:
1371 * fmeter_init() - initialize a frequency meter.
1372 * fmeter_markevent() - called each time the event happens.
1373 * fmeter_getrate() - returns the recent rate of such events.
1374 * fmeter_update() - internal routine used to update fmeter.
1376 * A common data structure is passed to each of these routines,
1377 * which is used to keep track of the state required to manage the
1378 * frequency meter and its digital filter.
1380 * The filter works on the number of events marked per unit time.
1381 * The filter is single-pole low-pass recursive (IIR). The time unit
1382 * is 1 second. Arithmetic is done using 32-bit integers scaled to
1383 * simulate 3 decimal digits of precision (multiplied by 1000).
1385 * With an FM_COEF of 933, and a time base of 1 second, the filter
1386 * has a half-life of 10 seconds, meaning that if the events quit
1387 * happening, then the rate returned from the fmeter_getrate()
1388 * will be cut in half each 10 seconds, until it converges to zero.
1390 * It is not worth doing a real infinitely recursive filter. If more
1391 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1392 * just compute FM_MAXTICKS ticks worth, by which point the level
1395 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1396 * arithmetic overflow in the fmeter_update() routine.
1398 * Given the simple 32 bit integer arithmetic used, this meter works
1399 * best for reporting rates between one per millisecond (msec) and
1400 * one per 32 (approx) seconds. At constant rates faster than one
1401 * per msec it maxes out at values just under 1,000,000. At constant
1402 * rates between one per msec, and one per second it will stabilize
1403 * to a value N*1000, where N is the rate of events per second.
1404 * At constant rates between one per second and one per 32 seconds,
1405 * it will be choppy, moving up on the seconds that have an event,
1406 * and then decaying until the next event. At rates slower than
1407 * about one in 32 seconds, it decays all the way back to zero between
1411 #define FM_COEF 933 /* coefficient for half-life of 10 secs */
1412 #define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1413 #define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1414 #define FM_SCALE 1000 /* faux fixed point scale */
1416 /* Initialize a frequency meter */
1417 static void fmeter_init(struct fmeter
*fmp
)
1422 spin_lock_init(&fmp
->lock
);
1425 /* Internal meter update - process cnt events and update value */
1426 static void fmeter_update(struct fmeter
*fmp
)
1428 time_t now
= get_seconds();
1429 time_t ticks
= now
- fmp
->time
;
1434 ticks
= min(FM_MAXTICKS
, ticks
);
1436 fmp
->val
= (FM_COEF
* fmp
->val
) / FM_SCALE
;
1439 fmp
->val
+= ((FM_SCALE
- FM_COEF
) * fmp
->cnt
) / FM_SCALE
;
1443 /* Process any previous ticks, then bump cnt by one (times scale). */
1444 static void fmeter_markevent(struct fmeter
*fmp
)
1446 spin_lock(&fmp
->lock
);
1448 fmp
->cnt
= min(FM_MAXCNT
, fmp
->cnt
+ FM_SCALE
);
1449 spin_unlock(&fmp
->lock
);
1452 /* Process any previous ticks, then return current value. */
1453 static int fmeter_getrate(struct fmeter
*fmp
)
1457 spin_lock(&fmp
->lock
);
1460 spin_unlock(&fmp
->lock
);
1464 /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
1465 static int cpuset_can_attach(struct cgroup
*cgrp
, struct cgroup_taskset
*tset
)
1467 struct cpuset
*cs
= cgroup_cs(cgrp
);
1468 struct task_struct
*task
;
1471 mutex_lock(&cpuset_mutex
);
1474 * We allow to move tasks into an empty cpuset if sane_behavior
1478 if (!cgroup_sane_behavior(cgrp
) &&
1479 (cpumask_empty(cs
->cpus_allowed
) || nodes_empty(cs
->mems_allowed
)))
1482 cgroup_taskset_for_each(task
, cgrp
, tset
) {
1484 * Kthreads which disallow setaffinity shouldn't be moved
1485 * to a new cpuset; we don't want to change their cpu
1486 * affinity and isolating such threads by their set of
1487 * allowed nodes is unnecessary. Thus, cpusets are not
1488 * applicable for such threads. This prevents checking for
1489 * success of set_cpus_allowed_ptr() on all attached tasks
1490 * before cpus_allowed may be changed.
1493 if (task
->flags
& PF_NO_SETAFFINITY
)
1495 ret
= security_task_setscheduler(task
);
1501 * Mark attach is in progress. This makes validate_change() fail
1502 * changes which zero cpus/mems_allowed.
1504 cs
->attach_in_progress
++;
1507 mutex_unlock(&cpuset_mutex
);
1511 static void cpuset_cancel_attach(struct cgroup
*cgrp
,
1512 struct cgroup_taskset
*tset
)
1514 mutex_lock(&cpuset_mutex
);
1515 cgroup_cs(cgrp
)->attach_in_progress
--;
1516 mutex_unlock(&cpuset_mutex
);
1520 * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
1521 * but we can't allocate it dynamically there. Define it global and
1522 * allocate from cpuset_init().
1524 static cpumask_var_t cpus_attach
;
1526 static void cpuset_attach(struct cgroup
*cgrp
, struct cgroup_taskset
*tset
)
1528 /* static buf protected by cpuset_mutex */
1529 static nodemask_t cpuset_attach_nodemask_to
;
1530 struct mm_struct
*mm
;
1531 struct task_struct
*task
;
1532 struct task_struct
*leader
= cgroup_taskset_first(tset
);
1533 struct cgroup
*oldcgrp
= cgroup_taskset_cur_cgroup(tset
);
1534 struct cpuset
*cs
= cgroup_cs(cgrp
);
1535 struct cpuset
*oldcs
= cgroup_cs(oldcgrp
);
1536 struct cpuset
*cpus_cs
= effective_cpumask_cpuset(cs
);
1537 struct cpuset
*mems_cs
= effective_nodemask_cpuset(cs
);
1539 mutex_lock(&cpuset_mutex
);
1541 /* prepare for attach */
1542 if (cs
== &top_cpuset
)
1543 cpumask_copy(cpus_attach
, cpu_possible_mask
);
1545 guarantee_online_cpus(cpus_cs
, cpus_attach
);
1547 guarantee_online_mems(mems_cs
, &cpuset_attach_nodemask_to
);
1549 cgroup_taskset_for_each(task
, cgrp
, tset
) {
1551 * can_attach beforehand should guarantee that this doesn't
1552 * fail. TODO: have a better way to handle failure here
1554 WARN_ON_ONCE(set_cpus_allowed_ptr(task
, cpus_attach
));
1556 cpuset_change_task_nodemask(task
, &cpuset_attach_nodemask_to
);
1557 cpuset_update_task_spread_flag(cs
, task
);
1561 * Change mm, possibly for multiple threads in a threadgroup. This is
1562 * expensive and may sleep.
1564 cpuset_attach_nodemask_to
= cs
->mems_allowed
;
1565 mm
= get_task_mm(leader
);
1567 struct cpuset
*mems_oldcs
= effective_nodemask_cpuset(oldcs
);
1569 mpol_rebind_mm(mm
, &cpuset_attach_nodemask_to
);
1572 * old_mems_allowed is the same with mems_allowed here, except
1573 * if this task is being moved automatically due to hotplug.
1574 * In that case @mems_allowed has been updated and is empty,
1575 * so @old_mems_allowed is the right nodesets that we migrate
1578 if (is_memory_migrate(cs
)) {
1579 cpuset_migrate_mm(mm
, &mems_oldcs
->old_mems_allowed
,
1580 &cpuset_attach_nodemask_to
);
1585 cs
->old_mems_allowed
= cpuset_attach_nodemask_to
;
1587 cs
->attach_in_progress
--;
1588 if (!cs
->attach_in_progress
)
1589 wake_up(&cpuset_attach_wq
);
1591 mutex_unlock(&cpuset_mutex
);
1594 /* The various types of files and directories in a cpuset file system */
1597 FILE_MEMORY_MIGRATE
,
1603 FILE_SCHED_LOAD_BALANCE
,
1604 FILE_SCHED_RELAX_DOMAIN_LEVEL
,
1605 FILE_MEMORY_PRESSURE_ENABLED
,
1606 FILE_MEMORY_PRESSURE
,
1609 } cpuset_filetype_t
;
1611 static int cpuset_write_u64(struct cgroup
*cgrp
, struct cftype
*cft
, u64 val
)
1613 struct cpuset
*cs
= cgroup_cs(cgrp
);
1614 cpuset_filetype_t type
= cft
->private;
1617 mutex_lock(&cpuset_mutex
);
1618 if (!is_cpuset_online(cs
)) {
1624 case FILE_CPU_EXCLUSIVE
:
1625 retval
= update_flag(CS_CPU_EXCLUSIVE
, cs
, val
);
1627 case FILE_MEM_EXCLUSIVE
:
1628 retval
= update_flag(CS_MEM_EXCLUSIVE
, cs
, val
);
1630 case FILE_MEM_HARDWALL
:
1631 retval
= update_flag(CS_MEM_HARDWALL
, cs
, val
);
1633 case FILE_SCHED_LOAD_BALANCE
:
1634 retval
= update_flag(CS_SCHED_LOAD_BALANCE
, cs
, val
);
1636 case FILE_MEMORY_MIGRATE
:
1637 retval
= update_flag(CS_MEMORY_MIGRATE
, cs
, val
);
1639 case FILE_MEMORY_PRESSURE_ENABLED
:
1640 cpuset_memory_pressure_enabled
= !!val
;
1642 case FILE_MEMORY_PRESSURE
:
1645 case FILE_SPREAD_PAGE
:
1646 retval
= update_flag(CS_SPREAD_PAGE
, cs
, val
);
1648 case FILE_SPREAD_SLAB
:
1649 retval
= update_flag(CS_SPREAD_SLAB
, cs
, val
);
1656 mutex_unlock(&cpuset_mutex
);
1660 static int cpuset_write_s64(struct cgroup
*cgrp
, struct cftype
*cft
, s64 val
)
1662 struct cpuset
*cs
= cgroup_cs(cgrp
);
1663 cpuset_filetype_t type
= cft
->private;
1664 int retval
= -ENODEV
;
1666 mutex_lock(&cpuset_mutex
);
1667 if (!is_cpuset_online(cs
))
1671 case FILE_SCHED_RELAX_DOMAIN_LEVEL
:
1672 retval
= update_relax_domain_level(cs
, val
);
1679 mutex_unlock(&cpuset_mutex
);
1684 * Common handling for a write to a "cpus" or "mems" file.
1686 static int cpuset_write_resmask(struct cgroup
*cgrp
, struct cftype
*cft
,
1689 struct cpuset
*cs
= cgroup_cs(cgrp
);
1690 struct cpuset
*trialcs
;
1691 int retval
= -ENODEV
;
1694 * CPU or memory hotunplug may leave @cs w/o any execution
1695 * resources, in which case the hotplug code asynchronously updates
1696 * configuration and transfers all tasks to the nearest ancestor
1697 * which can execute.
1699 * As writes to "cpus" or "mems" may restore @cs's execution
1700 * resources, wait for the previously scheduled operations before
1701 * proceeding, so that we don't end up keep removing tasks added
1702 * after execution capability is restored.
1704 flush_work(&cpuset_hotplug_work
);
1706 mutex_lock(&cpuset_mutex
);
1707 if (!is_cpuset_online(cs
))
1710 trialcs
= alloc_trial_cpuset(cs
);
1716 switch (cft
->private) {
1718 retval
= update_cpumask(cs
, trialcs
, buf
);
1721 retval
= update_nodemask(cs
, trialcs
, buf
);
1728 free_trial_cpuset(trialcs
);
1730 mutex_unlock(&cpuset_mutex
);
1735 * These ascii lists should be read in a single call, by using a user
1736 * buffer large enough to hold the entire map. If read in smaller
1737 * chunks, there is no guarantee of atomicity. Since the display format
1738 * used, list of ranges of sequential numbers, is variable length,
1739 * and since these maps can change value dynamically, one could read
1740 * gibberish by doing partial reads while a list was changing.
1741 * A single large read to a buffer that crosses a page boundary is
1742 * ok, because the result being copied to user land is not recomputed
1743 * across a page fault.
1746 static size_t cpuset_sprintf_cpulist(char *page
, struct cpuset
*cs
)
1750 mutex_lock(&callback_mutex
);
1751 count
= cpulist_scnprintf(page
, PAGE_SIZE
, cs
->cpus_allowed
);
1752 mutex_unlock(&callback_mutex
);
1757 static size_t cpuset_sprintf_memlist(char *page
, struct cpuset
*cs
)
1761 mutex_lock(&callback_mutex
);
1762 count
= nodelist_scnprintf(page
, PAGE_SIZE
, cs
->mems_allowed
);
1763 mutex_unlock(&callback_mutex
);
1768 static ssize_t
cpuset_common_file_read(struct cgroup
*cgrp
,
1772 size_t nbytes
, loff_t
*ppos
)
1774 struct cpuset
*cs
= cgroup_cs(cgrp
);
1775 cpuset_filetype_t type
= cft
->private;
1780 if (!(page
= (char *)__get_free_page(GFP_TEMPORARY
)))
1787 s
+= cpuset_sprintf_cpulist(s
, cs
);
1790 s
+= cpuset_sprintf_memlist(s
, cs
);
1798 retval
= simple_read_from_buffer(buf
, nbytes
, ppos
, page
, s
- page
);
1800 free_page((unsigned long)page
);
1804 static u64
cpuset_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
1806 struct cpuset
*cs
= cgroup_cs(cgrp
);
1807 cpuset_filetype_t type
= cft
->private;
1809 case FILE_CPU_EXCLUSIVE
:
1810 return is_cpu_exclusive(cs
);
1811 case FILE_MEM_EXCLUSIVE
:
1812 return is_mem_exclusive(cs
);
1813 case FILE_MEM_HARDWALL
:
1814 return is_mem_hardwall(cs
);
1815 case FILE_SCHED_LOAD_BALANCE
:
1816 return is_sched_load_balance(cs
);
1817 case FILE_MEMORY_MIGRATE
:
1818 return is_memory_migrate(cs
);
1819 case FILE_MEMORY_PRESSURE_ENABLED
:
1820 return cpuset_memory_pressure_enabled
;
1821 case FILE_MEMORY_PRESSURE
:
1822 return fmeter_getrate(&cs
->fmeter
);
1823 case FILE_SPREAD_PAGE
:
1824 return is_spread_page(cs
);
1825 case FILE_SPREAD_SLAB
:
1826 return is_spread_slab(cs
);
1831 /* Unreachable but makes gcc happy */
1835 static s64
cpuset_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
)
1837 struct cpuset
*cs
= cgroup_cs(cgrp
);
1838 cpuset_filetype_t type
= cft
->private;
1840 case FILE_SCHED_RELAX_DOMAIN_LEVEL
:
1841 return cs
->relax_domain_level
;
1846 /* Unrechable but makes gcc happy */
1852 * for the common functions, 'private' gives the type of file
1855 static struct cftype files
[] = {
1858 .read
= cpuset_common_file_read
,
1859 .write_string
= cpuset_write_resmask
,
1860 .max_write_len
= (100U + 6 * NR_CPUS
),
1861 .private = FILE_CPULIST
,
1866 .read
= cpuset_common_file_read
,
1867 .write_string
= cpuset_write_resmask
,
1868 .max_write_len
= (100U + 6 * MAX_NUMNODES
),
1869 .private = FILE_MEMLIST
,
1873 .name
= "cpu_exclusive",
1874 .read_u64
= cpuset_read_u64
,
1875 .write_u64
= cpuset_write_u64
,
1876 .private = FILE_CPU_EXCLUSIVE
,
1880 .name
= "mem_exclusive",
1881 .read_u64
= cpuset_read_u64
,
1882 .write_u64
= cpuset_write_u64
,
1883 .private = FILE_MEM_EXCLUSIVE
,
1887 .name
= "mem_hardwall",
1888 .read_u64
= cpuset_read_u64
,
1889 .write_u64
= cpuset_write_u64
,
1890 .private = FILE_MEM_HARDWALL
,
1894 .name
= "sched_load_balance",
1895 .read_u64
= cpuset_read_u64
,
1896 .write_u64
= cpuset_write_u64
,
1897 .private = FILE_SCHED_LOAD_BALANCE
,
1901 .name
= "sched_relax_domain_level",
1902 .read_s64
= cpuset_read_s64
,
1903 .write_s64
= cpuset_write_s64
,
1904 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL
,
1908 .name
= "memory_migrate",
1909 .read_u64
= cpuset_read_u64
,
1910 .write_u64
= cpuset_write_u64
,
1911 .private = FILE_MEMORY_MIGRATE
,
1915 .name
= "memory_pressure",
1916 .read_u64
= cpuset_read_u64
,
1917 .write_u64
= cpuset_write_u64
,
1918 .private = FILE_MEMORY_PRESSURE
,
1923 .name
= "memory_spread_page",
1924 .read_u64
= cpuset_read_u64
,
1925 .write_u64
= cpuset_write_u64
,
1926 .private = FILE_SPREAD_PAGE
,
1930 .name
= "memory_spread_slab",
1931 .read_u64
= cpuset_read_u64
,
1932 .write_u64
= cpuset_write_u64
,
1933 .private = FILE_SPREAD_SLAB
,
1937 .name
= "memory_pressure_enabled",
1938 .flags
= CFTYPE_ONLY_ON_ROOT
,
1939 .read_u64
= cpuset_read_u64
,
1940 .write_u64
= cpuset_write_u64
,
1941 .private = FILE_MEMORY_PRESSURE_ENABLED
,
1948 * cpuset_css_alloc - allocate a cpuset css
1949 * cgrp: control group that the new cpuset will be part of
1952 static struct cgroup_subsys_state
*cpuset_css_alloc(struct cgroup
*cgrp
)
1957 return &top_cpuset
.css
;
1959 cs
= kzalloc(sizeof(*cs
), GFP_KERNEL
);
1961 return ERR_PTR(-ENOMEM
);
1962 if (!alloc_cpumask_var(&cs
->cpus_allowed
, GFP_KERNEL
)) {
1964 return ERR_PTR(-ENOMEM
);
1967 set_bit(CS_SCHED_LOAD_BALANCE
, &cs
->flags
);
1968 cpumask_clear(cs
->cpus_allowed
);
1969 nodes_clear(cs
->mems_allowed
);
1970 fmeter_init(&cs
->fmeter
);
1971 cs
->relax_domain_level
= -1;
1976 static int cpuset_css_online(struct cgroup
*cgrp
)
1978 struct cpuset
*cs
= cgroup_cs(cgrp
);
1979 struct cpuset
*parent
= parent_cs(cs
);
1980 struct cpuset
*tmp_cs
;
1981 struct cgroup
*pos_cg
;
1986 mutex_lock(&cpuset_mutex
);
1988 set_bit(CS_ONLINE
, &cs
->flags
);
1989 if (is_spread_page(parent
))
1990 set_bit(CS_SPREAD_PAGE
, &cs
->flags
);
1991 if (is_spread_slab(parent
))
1992 set_bit(CS_SPREAD_SLAB
, &cs
->flags
);
1994 number_of_cpusets
++;
1996 if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
))
2000 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
2001 * set. This flag handling is implemented in cgroup core for
2002 * histrical reasons - the flag may be specified during mount.
2004 * Currently, if any sibling cpusets have exclusive cpus or mem, we
2005 * refuse to clone the configuration - thereby refusing the task to
2006 * be entered, and as a result refusing the sys_unshare() or
2007 * clone() which initiated it. If this becomes a problem for some
2008 * users who wish to allow that scenario, then this could be
2009 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
2010 * (and likewise for mems) to the new cgroup.
2013 cpuset_for_each_child(tmp_cs
, pos_cg
, parent
) {
2014 if (is_mem_exclusive(tmp_cs
) || is_cpu_exclusive(tmp_cs
)) {
2021 mutex_lock(&callback_mutex
);
2022 cs
->mems_allowed
= parent
->mems_allowed
;
2023 cpumask_copy(cs
->cpus_allowed
, parent
->cpus_allowed
);
2024 mutex_unlock(&callback_mutex
);
2026 mutex_unlock(&cpuset_mutex
);
2030 static void cpuset_css_offline(struct cgroup
*cgrp
)
2032 struct cpuset
*cs
= cgroup_cs(cgrp
);
2034 mutex_lock(&cpuset_mutex
);
2036 if (is_sched_load_balance(cs
))
2037 update_flag(CS_SCHED_LOAD_BALANCE
, cs
, 0);
2039 number_of_cpusets
--;
2040 clear_bit(CS_ONLINE
, &cs
->flags
);
2042 mutex_unlock(&cpuset_mutex
);
2046 * If the cpuset being removed has its flag 'sched_load_balance'
2047 * enabled, then simulate turning sched_load_balance off, which
2048 * will call rebuild_sched_domains_locked().
2051 static void cpuset_css_free(struct cgroup
*cgrp
)
2053 struct cpuset
*cs
= cgroup_cs(cgrp
);
2055 free_cpumask_var(cs
->cpus_allowed
);
2059 struct cgroup_subsys cpuset_subsys
= {
2061 .css_alloc
= cpuset_css_alloc
,
2062 .css_online
= cpuset_css_online
,
2063 .css_offline
= cpuset_css_offline
,
2064 .css_free
= cpuset_css_free
,
2065 .can_attach
= cpuset_can_attach
,
2066 .cancel_attach
= cpuset_cancel_attach
,
2067 .attach
= cpuset_attach
,
2068 .subsys_id
= cpuset_subsys_id
,
2069 .base_cftypes
= files
,
2074 * cpuset_init - initialize cpusets at system boot
2076 * Description: Initialize top_cpuset and the cpuset internal file system,
2079 int __init
cpuset_init(void)
2083 if (!alloc_cpumask_var(&top_cpuset
.cpus_allowed
, GFP_KERNEL
))
2086 cpumask_setall(top_cpuset
.cpus_allowed
);
2087 nodes_setall(top_cpuset
.mems_allowed
);
2089 fmeter_init(&top_cpuset
.fmeter
);
2090 set_bit(CS_SCHED_LOAD_BALANCE
, &top_cpuset
.flags
);
2091 top_cpuset
.relax_domain_level
= -1;
2093 err
= register_filesystem(&cpuset_fs_type
);
2097 if (!alloc_cpumask_var(&cpus_attach
, GFP_KERNEL
))
2100 number_of_cpusets
= 1;
2105 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2106 * or memory nodes, we need to walk over the cpuset hierarchy,
2107 * removing that CPU or node from all cpusets. If this removes the
2108 * last CPU or node from a cpuset, then move the tasks in the empty
2109 * cpuset to its next-highest non-empty parent.
2111 static void remove_tasks_in_empty_cpuset(struct cpuset
*cs
)
2113 struct cpuset
*parent
;
2116 * Find its next-highest non-empty parent, (top cpuset
2117 * has online cpus, so can't be empty).
2119 parent
= parent_cs(cs
);
2120 while (cpumask_empty(parent
->cpus_allowed
) ||
2121 nodes_empty(parent
->mems_allowed
))
2122 parent
= parent_cs(parent
);
2124 if (cgroup_transfer_tasks(parent
->css
.cgroup
, cs
->css
.cgroup
)) {
2126 printk(KERN_ERR
"cpuset: failed to transfer tasks out of empty cpuset %s\n",
2127 cgroup_name(cs
->css
.cgroup
));
2133 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
2134 * @cs: cpuset in interest
2136 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
2137 * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
2138 * all its tasks are moved to the nearest ancestor with both resources.
2140 static void cpuset_hotplug_update_tasks(struct cpuset
*cs
)
2142 static cpumask_t off_cpus
;
2143 static nodemask_t off_mems
;
2145 bool sane
= cgroup_sane_behavior(cs
->css
.cgroup
);
2148 wait_event(cpuset_attach_wq
, cs
->attach_in_progress
== 0);
2150 mutex_lock(&cpuset_mutex
);
2153 * We have raced with task attaching. We wait until attaching
2154 * is finished, so we won't attach a task to an empty cpuset.
2156 if (cs
->attach_in_progress
) {
2157 mutex_unlock(&cpuset_mutex
);
2161 cpumask_andnot(&off_cpus
, cs
->cpus_allowed
, top_cpuset
.cpus_allowed
);
2162 nodes_andnot(off_mems
, cs
->mems_allowed
, top_cpuset
.mems_allowed
);
2164 mutex_lock(&callback_mutex
);
2165 cpumask_andnot(cs
->cpus_allowed
, cs
->cpus_allowed
, &off_cpus
);
2166 mutex_unlock(&callback_mutex
);
2169 * If sane_behavior flag is set, we need to update tasks' cpumask
2170 * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
2171 * call update_tasks_cpumask() if the cpuset becomes empty, as
2172 * the tasks in it will be migrated to an ancestor.
2174 if ((sane
&& cpumask_empty(cs
->cpus_allowed
)) ||
2175 (!cpumask_empty(&off_cpus
) && !cpumask_empty(cs
->cpus_allowed
)))
2176 update_tasks_cpumask(cs
, NULL
);
2178 mutex_lock(&callback_mutex
);
2179 nodes_andnot(cs
->mems_allowed
, cs
->mems_allowed
, off_mems
);
2180 mutex_unlock(&callback_mutex
);
2183 * If sane_behavior flag is set, we need to update tasks' nodemask
2184 * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
2185 * call update_tasks_nodemask() if the cpuset becomes empty, as
2186 * the tasks in it will be migratd to an ancestor.
2188 if ((sane
&& nodes_empty(cs
->mems_allowed
)) ||
2189 (!nodes_empty(off_mems
) && !nodes_empty(cs
->mems_allowed
)))
2190 update_tasks_nodemask(cs
, NULL
);
2192 is_empty
= cpumask_empty(cs
->cpus_allowed
) ||
2193 nodes_empty(cs
->mems_allowed
);
2195 mutex_unlock(&cpuset_mutex
);
2198 * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
2200 * Otherwise move tasks to the nearest ancestor with execution
2201 * resources. This is full cgroup operation which will
2202 * also call back into cpuset. Should be done outside any lock.
2204 if (!sane
&& is_empty
)
2205 remove_tasks_in_empty_cpuset(cs
);
2209 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
2211 * This function is called after either CPU or memory configuration has
2212 * changed and updates cpuset accordingly. The top_cpuset is always
2213 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
2214 * order to make cpusets transparent (of no affect) on systems that are
2215 * actively using CPU hotplug but making no active use of cpusets.
2217 * Non-root cpusets are only affected by offlining. If any CPUs or memory
2218 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
2221 * Note that CPU offlining during suspend is ignored. We don't modify
2222 * cpusets across suspend/resume cycles at all.
2224 static void cpuset_hotplug_workfn(struct work_struct
*work
)
2226 static cpumask_t new_cpus
;
2227 static nodemask_t new_mems
;
2228 bool cpus_updated
, mems_updated
;
2230 mutex_lock(&cpuset_mutex
);
2232 /* fetch the available cpus/mems and find out which changed how */
2233 cpumask_copy(&new_cpus
, cpu_active_mask
);
2234 new_mems
= node_states
[N_MEMORY
];
2236 cpus_updated
= !cpumask_equal(top_cpuset
.cpus_allowed
, &new_cpus
);
2237 mems_updated
= !nodes_equal(top_cpuset
.mems_allowed
, new_mems
);
2239 /* synchronize cpus_allowed to cpu_active_mask */
2241 mutex_lock(&callback_mutex
);
2242 cpumask_copy(top_cpuset
.cpus_allowed
, &new_cpus
);
2243 mutex_unlock(&callback_mutex
);
2244 /* we don't mess with cpumasks of tasks in top_cpuset */
2247 /* synchronize mems_allowed to N_MEMORY */
2249 mutex_lock(&callback_mutex
);
2250 top_cpuset
.mems_allowed
= new_mems
;
2251 mutex_unlock(&callback_mutex
);
2252 update_tasks_nodemask(&top_cpuset
, NULL
);
2255 mutex_unlock(&cpuset_mutex
);
2257 /* if cpus or mems changed, we need to propagate to descendants */
2258 if (cpus_updated
|| mems_updated
) {
2260 struct cgroup
*pos_cgrp
;
2263 cpuset_for_each_descendant_pre(cs
, pos_cgrp
, &top_cpuset
) {
2264 if (!css_tryget(&cs
->css
))
2268 cpuset_hotplug_update_tasks(cs
);
2276 /* rebuild sched domains if cpus_allowed has changed */
2278 rebuild_sched_domains();
2281 void cpuset_update_active_cpus(bool cpu_online
)
2284 * We're inside cpu hotplug critical region which usually nests
2285 * inside cgroup synchronization. Bounce actual hotplug processing
2286 * to a work item to avoid reverse locking order.
2288 * We still need to do partition_sched_domains() synchronously;
2289 * otherwise, the scheduler will get confused and put tasks to the
2290 * dead CPU. Fall back to the default single domain.
2291 * cpuset_hotplug_workfn() will rebuild it as necessary.
2293 partition_sched_domains(1, NULL
, NULL
);
2294 schedule_work(&cpuset_hotplug_work
);
2298 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
2299 * Call this routine anytime after node_states[N_MEMORY] changes.
2300 * See cpuset_update_active_cpus() for CPU hotplug handling.
2302 static int cpuset_track_online_nodes(struct notifier_block
*self
,
2303 unsigned long action
, void *arg
)
2305 schedule_work(&cpuset_hotplug_work
);
2309 static struct notifier_block cpuset_track_online_nodes_nb
= {
2310 .notifier_call
= cpuset_track_online_nodes
,
2311 .priority
= 10, /* ??! */
2315 * cpuset_init_smp - initialize cpus_allowed
2317 * Description: Finish top cpuset after cpu, node maps are initialized
2319 void __init
cpuset_init_smp(void)
2321 cpumask_copy(top_cpuset
.cpus_allowed
, cpu_active_mask
);
2322 top_cpuset
.mems_allowed
= node_states
[N_MEMORY
];
2323 top_cpuset
.old_mems_allowed
= top_cpuset
.mems_allowed
;
2325 register_hotmemory_notifier(&cpuset_track_online_nodes_nb
);
2329 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2330 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2331 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2333 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2334 * attached to the specified @tsk. Guaranteed to return some non-empty
2335 * subset of cpu_online_mask, even if this means going outside the
2339 void cpuset_cpus_allowed(struct task_struct
*tsk
, struct cpumask
*pmask
)
2341 struct cpuset
*cpus_cs
;
2343 mutex_lock(&callback_mutex
);
2345 cpus_cs
= effective_cpumask_cpuset(task_cs(tsk
));
2346 guarantee_online_cpus(cpus_cs
, pmask
);
2348 mutex_unlock(&callback_mutex
);
2351 void cpuset_cpus_allowed_fallback(struct task_struct
*tsk
)
2353 const struct cpuset
*cpus_cs
;
2356 cpus_cs
= effective_cpumask_cpuset(task_cs(tsk
));
2357 do_set_cpus_allowed(tsk
, cpus_cs
->cpus_allowed
);
2361 * We own tsk->cpus_allowed, nobody can change it under us.
2363 * But we used cs && cs->cpus_allowed lockless and thus can
2364 * race with cgroup_attach_task() or update_cpumask() and get
2365 * the wrong tsk->cpus_allowed. However, both cases imply the
2366 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2367 * which takes task_rq_lock().
2369 * If we are called after it dropped the lock we must see all
2370 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2371 * set any mask even if it is not right from task_cs() pov,
2372 * the pending set_cpus_allowed_ptr() will fix things.
2374 * select_fallback_rq() will fix things ups and set cpu_possible_mask
2379 void cpuset_init_current_mems_allowed(void)
2381 nodes_setall(current
->mems_allowed
);
2385 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2386 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2388 * Description: Returns the nodemask_t mems_allowed of the cpuset
2389 * attached to the specified @tsk. Guaranteed to return some non-empty
2390 * subset of node_states[N_MEMORY], even if this means going outside the
2394 nodemask_t
cpuset_mems_allowed(struct task_struct
*tsk
)
2396 struct cpuset
*mems_cs
;
2399 mutex_lock(&callback_mutex
);
2401 mems_cs
= effective_nodemask_cpuset(task_cs(tsk
));
2402 guarantee_online_mems(mems_cs
, &mask
);
2404 mutex_unlock(&callback_mutex
);
2410 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2411 * @nodemask: the nodemask to be checked
2413 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2415 int cpuset_nodemask_valid_mems_allowed(nodemask_t
*nodemask
)
2417 return nodes_intersects(*nodemask
, current
->mems_allowed
);
2421 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2422 * mem_hardwall ancestor to the specified cpuset. Call holding
2423 * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
2424 * (an unusual configuration), then returns the root cpuset.
2426 static const struct cpuset
*nearest_hardwall_ancestor(const struct cpuset
*cs
)
2428 while (!(is_mem_exclusive(cs
) || is_mem_hardwall(cs
)) && parent_cs(cs
))
2434 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
2435 * @node: is this an allowed node?
2436 * @gfp_mask: memory allocation flags
2438 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2439 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2440 * yes. If it's not a __GFP_HARDWALL request and this node is in the nearest
2441 * hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been
2442 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2446 * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
2447 * cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall()
2448 * might sleep, and might allow a node from an enclosing cpuset.
2450 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
2451 * cpusets, and never sleeps.
2453 * The __GFP_THISNODE placement logic is really handled elsewhere,
2454 * by forcibly using a zonelist starting at a specified node, and by
2455 * (in get_page_from_freelist()) refusing to consider the zones for
2456 * any node on the zonelist except the first. By the time any such
2457 * calls get to this routine, we should just shut up and say 'yes'.
2459 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2460 * and do not allow allocations outside the current tasks cpuset
2461 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2462 * GFP_KERNEL allocations are not so marked, so can escape to the
2463 * nearest enclosing hardwalled ancestor cpuset.
2465 * Scanning up parent cpusets requires callback_mutex. The
2466 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2467 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2468 * current tasks mems_allowed came up empty on the first pass over
2469 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
2470 * cpuset are short of memory, might require taking the callback_mutex
2473 * The first call here from mm/page_alloc:get_page_from_freelist()
2474 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2475 * so no allocation on a node outside the cpuset is allowed (unless
2476 * in interrupt, of course).
2478 * The second pass through get_page_from_freelist() doesn't even call
2479 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2480 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2481 * in alloc_flags. That logic and the checks below have the combined
2483 * in_interrupt - any node ok (current task context irrelevant)
2484 * GFP_ATOMIC - any node ok
2485 * TIF_MEMDIE - any node ok
2486 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
2487 * GFP_USER - only nodes in current tasks mems allowed ok.
2490 * Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2491 * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2492 * the code that might scan up ancestor cpusets and sleep.
2494 int __cpuset_node_allowed_softwall(int node
, gfp_t gfp_mask
)
2496 const struct cpuset
*cs
; /* current cpuset ancestors */
2497 int allowed
; /* is allocation in zone z allowed? */
2499 if (in_interrupt() || (gfp_mask
& __GFP_THISNODE
))
2501 might_sleep_if(!(gfp_mask
& __GFP_HARDWALL
));
2502 if (node_isset(node
, current
->mems_allowed
))
2505 * Allow tasks that have access to memory reserves because they have
2506 * been OOM killed to get memory anywhere.
2508 if (unlikely(test_thread_flag(TIF_MEMDIE
)))
2510 if (gfp_mask
& __GFP_HARDWALL
) /* If hardwall request, stop here */
2513 if (current
->flags
& PF_EXITING
) /* Let dying task have memory */
2516 /* Not hardwall and node outside mems_allowed: scan up cpusets */
2517 mutex_lock(&callback_mutex
);
2520 cs
= nearest_hardwall_ancestor(task_cs(current
));
2521 task_unlock(current
);
2523 allowed
= node_isset(node
, cs
->mems_allowed
);
2524 mutex_unlock(&callback_mutex
);
2529 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
2530 * @node: is this an allowed node?
2531 * @gfp_mask: memory allocation flags
2533 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2534 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2535 * yes. If the task has been OOM killed and has access to memory reserves as
2536 * specified by the TIF_MEMDIE flag, yes.
2539 * The __GFP_THISNODE placement logic is really handled elsewhere,
2540 * by forcibly using a zonelist starting at a specified node, and by
2541 * (in get_page_from_freelist()) refusing to consider the zones for
2542 * any node on the zonelist except the first. By the time any such
2543 * calls get to this routine, we should just shut up and say 'yes'.
2545 * Unlike the cpuset_node_allowed_softwall() variant, above,
2546 * this variant requires that the node be in the current task's
2547 * mems_allowed or that we're in interrupt. It does not scan up the
2548 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2551 int __cpuset_node_allowed_hardwall(int node
, gfp_t gfp_mask
)
2553 if (in_interrupt() || (gfp_mask
& __GFP_THISNODE
))
2555 if (node_isset(node
, current
->mems_allowed
))
2558 * Allow tasks that have access to memory reserves because they have
2559 * been OOM killed to get memory anywhere.
2561 if (unlikely(test_thread_flag(TIF_MEMDIE
)))
2567 * cpuset_mem_spread_node() - On which node to begin search for a file page
2568 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2570 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2571 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2572 * and if the memory allocation used cpuset_mem_spread_node()
2573 * to determine on which node to start looking, as it will for
2574 * certain page cache or slab cache pages such as used for file
2575 * system buffers and inode caches, then instead of starting on the
2576 * local node to look for a free page, rather spread the starting
2577 * node around the tasks mems_allowed nodes.
2579 * We don't have to worry about the returned node being offline
2580 * because "it can't happen", and even if it did, it would be ok.
2582 * The routines calling guarantee_online_mems() are careful to
2583 * only set nodes in task->mems_allowed that are online. So it
2584 * should not be possible for the following code to return an
2585 * offline node. But if it did, that would be ok, as this routine
2586 * is not returning the node where the allocation must be, only
2587 * the node where the search should start. The zonelist passed to
2588 * __alloc_pages() will include all nodes. If the slab allocator
2589 * is passed an offline node, it will fall back to the local node.
2590 * See kmem_cache_alloc_node().
2593 static int cpuset_spread_node(int *rotor
)
2597 node
= next_node(*rotor
, current
->mems_allowed
);
2598 if (node
== MAX_NUMNODES
)
2599 node
= first_node(current
->mems_allowed
);
2604 int cpuset_mem_spread_node(void)
2606 if (current
->cpuset_mem_spread_rotor
== NUMA_NO_NODE
)
2607 current
->cpuset_mem_spread_rotor
=
2608 node_random(¤t
->mems_allowed
);
2610 return cpuset_spread_node(¤t
->cpuset_mem_spread_rotor
);
2613 int cpuset_slab_spread_node(void)
2615 if (current
->cpuset_slab_spread_rotor
== NUMA_NO_NODE
)
2616 current
->cpuset_slab_spread_rotor
=
2617 node_random(¤t
->mems_allowed
);
2619 return cpuset_spread_node(¤t
->cpuset_slab_spread_rotor
);
2622 EXPORT_SYMBOL_GPL(cpuset_mem_spread_node
);
2625 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2626 * @tsk1: pointer to task_struct of some task.
2627 * @tsk2: pointer to task_struct of some other task.
2629 * Description: Return true if @tsk1's mems_allowed intersects the
2630 * mems_allowed of @tsk2. Used by the OOM killer to determine if
2631 * one of the task's memory usage might impact the memory available
2635 int cpuset_mems_allowed_intersects(const struct task_struct
*tsk1
,
2636 const struct task_struct
*tsk2
)
2638 return nodes_intersects(tsk1
->mems_allowed
, tsk2
->mems_allowed
);
2641 #define CPUSET_NODELIST_LEN (256)
2644 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2645 * @task: pointer to task_struct of some task.
2647 * Description: Prints @task's name, cpuset name, and cached copy of its
2648 * mems_allowed to the kernel log. Must hold task_lock(task) to allow
2649 * dereferencing task_cs(task).
2651 void cpuset_print_task_mems_allowed(struct task_struct
*tsk
)
2653 /* Statically allocated to prevent using excess stack. */
2654 static char cpuset_nodelist
[CPUSET_NODELIST_LEN
];
2655 static DEFINE_SPINLOCK(cpuset_buffer_lock
);
2657 struct cgroup
*cgrp
= task_cs(tsk
)->css
.cgroup
;
2660 spin_lock(&cpuset_buffer_lock
);
2662 nodelist_scnprintf(cpuset_nodelist
, CPUSET_NODELIST_LEN
,
2664 printk(KERN_INFO
"%s cpuset=%s mems_allowed=%s\n",
2665 tsk
->comm
, cgroup_name(cgrp
), cpuset_nodelist
);
2667 spin_unlock(&cpuset_buffer_lock
);
2672 * Collection of memory_pressure is suppressed unless
2673 * this flag is enabled by writing "1" to the special
2674 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2677 int cpuset_memory_pressure_enabled __read_mostly
;
2680 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2682 * Keep a running average of the rate of synchronous (direct)
2683 * page reclaim efforts initiated by tasks in each cpuset.
2685 * This represents the rate at which some task in the cpuset
2686 * ran low on memory on all nodes it was allowed to use, and
2687 * had to enter the kernels page reclaim code in an effort to
2688 * create more free memory by tossing clean pages or swapping
2689 * or writing dirty pages.
2691 * Display to user space in the per-cpuset read-only file
2692 * "memory_pressure". Value displayed is an integer
2693 * representing the recent rate of entry into the synchronous
2694 * (direct) page reclaim by any task attached to the cpuset.
2697 void __cpuset_memory_pressure_bump(void)
2700 fmeter_markevent(&task_cs(current
)->fmeter
);
2701 task_unlock(current
);
2704 #ifdef CONFIG_PROC_PID_CPUSET
2706 * proc_cpuset_show()
2707 * - Print tasks cpuset path into seq_file.
2708 * - Used for /proc/<pid>/cpuset.
2709 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2710 * doesn't really matter if tsk->cpuset changes after we read it,
2711 * and we take cpuset_mutex, keeping cpuset_attach() from changing it
2714 int proc_cpuset_show(struct seq_file
*m
, void *unused_v
)
2717 struct task_struct
*tsk
;
2719 struct cgroup_subsys_state
*css
;
2723 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
2729 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
2734 css
= task_subsys_state(tsk
, cpuset_subsys_id
);
2735 retval
= cgroup_path(css
->cgroup
, buf
, PAGE_SIZE
);
2742 put_task_struct(tsk
);
2748 #endif /* CONFIG_PROC_PID_CPUSET */
2750 /* Display task mems_allowed in /proc/<pid>/status file. */
2751 void cpuset_task_status_allowed(struct seq_file
*m
, struct task_struct
*task
)
2753 seq_printf(m
, "Mems_allowed:\t");
2754 seq_nodemask(m
, &task
->mems_allowed
);
2755 seq_printf(m
, "\n");
2756 seq_printf(m
, "Mems_allowed_list:\t");
2757 seq_nodemask_list(m
, &task
->mems_allowed
);
2758 seq_printf(m
, "\n");