Root/kernel/cpuset.c

1/*
2 * kernel/cpuset.c
3 *
4 * Processor and Memory placement constraints for sets of tasks.
5 *
6 * Copyright (C) 2003 BULL SA.
7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8 * Copyright (C) 2006 Google, Inc
9 *
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
12 *
13 * 2003-10-10 Written by Simon Derr.
14 * 2003-10-22 Updates by Stephen Hemminger.
15 * 2004 May-July Rework by Paul Jackson.
16 * 2006 Rework by Paul Menage to use generic cgroups
17 * 2008 Rework of the scheduler domains and CPU hotplug handling
18 * by Max Krasnyansky
19 *
20 * This file is subject to the terms and conditions of the GNU General Public
21 * License. See the file COPYING in the main directory of the Linux
22 * distribution for more details.
23 */
24
25#include <linux/cpu.h>
26#include <linux/cpumask.h>
27#include <linux/cpuset.h>
28#include <linux/err.h>
29#include <linux/errno.h>
30#include <linux/file.h>
31#include <linux/fs.h>
32#include <linux/init.h>
33#include <linux/interrupt.h>
34#include <linux/kernel.h>
35#include <linux/kmod.h>
36#include <linux/list.h>
37#include <linux/mempolicy.h>
38#include <linux/mm.h>
39#include <linux/memory.h>
40#include <linux/export.h>
41#include <linux/mount.h>
42#include <linux/namei.h>
43#include <linux/pagemap.h>
44#include <linux/proc_fs.h>
45#include <linux/rcupdate.h>
46#include <linux/sched.h>
47#include <linux/seq_file.h>
48#include <linux/security.h>
49#include <linux/slab.h>
50#include <linux/spinlock.h>
51#include <linux/stat.h>
52#include <linux/string.h>
53#include <linux/time.h>
54#include <linux/backing-dev.h>
55#include <linux/sort.h>
56
57#include <asm/uaccess.h>
58#include <linux/atomic.h>
59#include <linux/mutex.h>
60#include <linux/workqueue.h>
61#include <linux/cgroup.h>
62#include <linux/wait.h>
63
64/*
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.
68 */
69int number_of_cpusets __read_mostly;
70
71/* See "Frequency meter" comments, below. */
72
73struct fmeter {
74    int cnt; /* unprocessed events count */
75    int val; /* most recent output value */
76    time_t time; /* clock (secs) when val computed */
77    spinlock_t lock; /* guards read or write of above */
78};
79
80struct cpuset {
81    struct cgroup_subsys_state css;
82
83    unsigned long flags; /* "unsigned long" so bitops work */
84    cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
85    nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
86
87    /*
88     * This is old Memory Nodes tasks took on.
89     *
90     * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
91     * - A new cpuset's old_mems_allowed is initialized when some
92     * task is moved into it.
93     * - old_mems_allowed is used in cpuset_migrate_mm() when we change
94     * cpuset.mems_allowed and have tasks' nodemask updated, and
95     * then old_mems_allowed is updated to mems_allowed.
96     */
97    nodemask_t old_mems_allowed;
98
99    struct fmeter fmeter; /* memory_pressure filter */
100
101    /*
102     * Tasks are being attached to this cpuset. Used to prevent
103     * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
104     */
105    int attach_in_progress;
106
107    /* partition number for rebuild_sched_domains() */
108    int pn;
109
110    /* for custom sched domain */
111    int relax_domain_level;
112};
113
114static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
115{
116    return css ? container_of(css, struct cpuset, css) : NULL;
117}
118
119/* Retrieve the cpuset for a task */
120static inline struct cpuset *task_cs(struct task_struct *task)
121{
122    return css_cs(task_css(task, cpuset_cgrp_id));
123}
124
125static inline struct cpuset *parent_cs(struct cpuset *cs)
126{
127    return css_cs(css_parent(&cs->css));
128}
129
130#ifdef CONFIG_NUMA
131static inline bool task_has_mempolicy(struct task_struct *task)
132{
133    return task->mempolicy;
134}
135#else
136static inline bool task_has_mempolicy(struct task_struct *task)
137{
138    return false;
139}
140#endif
141
142
143/* bits in struct cpuset flags field */
144typedef enum {
145    CS_ONLINE,
146    CS_CPU_EXCLUSIVE,
147    CS_MEM_EXCLUSIVE,
148    CS_MEM_HARDWALL,
149    CS_MEMORY_MIGRATE,
150    CS_SCHED_LOAD_BALANCE,
151    CS_SPREAD_PAGE,
152    CS_SPREAD_SLAB,
153} cpuset_flagbits_t;
154
155/* convenient tests for these bits */
156static inline bool is_cpuset_online(const struct cpuset *cs)
157{
158    return test_bit(CS_ONLINE, &cs->flags);
159}
160
161static inline int is_cpu_exclusive(const struct cpuset *cs)
162{
163    return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
164}
165
166static inline int is_mem_exclusive(const struct cpuset *cs)
167{
168    return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
169}
170
171static inline int is_mem_hardwall(const struct cpuset *cs)
172{
173    return test_bit(CS_MEM_HARDWALL, &cs->flags);
174}
175
176static inline int is_sched_load_balance(const struct cpuset *cs)
177{
178    return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
179}
180
181static inline int is_memory_migrate(const struct cpuset *cs)
182{
183    return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
184}
185
186static inline int is_spread_page(const struct cpuset *cs)
187{
188    return test_bit(CS_SPREAD_PAGE, &cs->flags);
189}
190
191static inline int is_spread_slab(const struct cpuset *cs)
192{
193    return test_bit(CS_SPREAD_SLAB, &cs->flags);
194}
195
196static struct cpuset top_cpuset = {
197    .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
198          (1 << CS_MEM_EXCLUSIVE)),
199};
200
201/**
202 * cpuset_for_each_child - traverse online children of a cpuset
203 * @child_cs: loop cursor pointing to the current child
204 * @pos_css: used for iteration
205 * @parent_cs: target cpuset to walk children of
206 *
207 * Walk @child_cs through the online children of @parent_cs. Must be used
208 * with RCU read locked.
209 */
210#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
211    css_for_each_child((pos_css), &(parent_cs)->css) \
212        if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
213
214/**
215 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
216 * @des_cs: loop cursor pointing to the current descendant
217 * @pos_css: used for iteration
218 * @root_cs: target cpuset to walk ancestor of
219 *
220 * Walk @des_cs through the online descendants of @root_cs. Must be used
221 * with RCU read locked. The caller may modify @pos_css by calling
222 * css_rightmost_descendant() to skip subtree. @root_cs is included in the
223 * iteration and the first node to be visited.
224 */
225#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
226    css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
227        if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
228
229/*
230 * There are two global mutexes guarding cpuset structures - cpuset_mutex
231 * and callback_mutex. The latter may nest inside the former. We also
232 * require taking task_lock() when dereferencing a task's cpuset pointer.
233 * See "The task_lock() exception", at the end of this comment.
234 *
235 * A task must hold both mutexes to modify cpusets. If a task holds
236 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
237 * is the only task able to also acquire callback_mutex and be able to
238 * modify cpusets. It can perform various checks on the cpuset structure
239 * first, knowing nothing will change. It can also allocate memory while
240 * just holding cpuset_mutex. While it is performing these checks, various
241 * callback routines can briefly acquire callback_mutex to query cpusets.
242 * Once it is ready to make the changes, it takes callback_mutex, blocking
243 * everyone else.
244 *
245 * Calls to the kernel memory allocator can not be made while holding
246 * callback_mutex, as that would risk double tripping on callback_mutex
247 * from one of the callbacks into the cpuset code from within
248 * __alloc_pages().
249 *
250 * If a task is only holding callback_mutex, then it has read-only
251 * access to cpusets.
252 *
253 * Now, the task_struct fields mems_allowed and mempolicy may be changed
254 * by other task, we use alloc_lock in the task_struct fields to protect
255 * them.
256 *
257 * The cpuset_common_file_read() handlers only hold callback_mutex across
258 * small pieces of code, such as when reading out possibly multi-word
259 * cpumasks and nodemasks.
260 *
261 * Accessing a task's cpuset should be done in accordance with the
262 * guidelines for accessing subsystem state in kernel/cgroup.c
263 */
264
265static DEFINE_MUTEX(cpuset_mutex);
266static DEFINE_MUTEX(callback_mutex);
267
268/*
269 * CPU / memory hotplug is handled asynchronously.
270 */
271static void cpuset_hotplug_workfn(struct work_struct *work);
272static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
273
274static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
275
276/*
277 * This is ugly, but preserves the userspace API for existing cpuset
278 * users. If someone tries to mount the "cpuset" filesystem, we
279 * silently switch it to mount "cgroup" instead
280 */
281static struct dentry *cpuset_mount(struct file_system_type *fs_type,
282             int flags, const char *unused_dev_name, void *data)
283{
284    struct file_system_type *cgroup_fs = get_fs_type("cgroup");
285    struct dentry *ret = ERR_PTR(-ENODEV);
286    if (cgroup_fs) {
287        char mountopts[] =
288            "cpuset,noprefix,"
289            "release_agent=/sbin/cpuset_release_agent";
290        ret = cgroup_fs->mount(cgroup_fs, flags,
291                       unused_dev_name, mountopts);
292        put_filesystem(cgroup_fs);
293    }
294    return ret;
295}
296
297static struct file_system_type cpuset_fs_type = {
298    .name = "cpuset",
299    .mount = cpuset_mount,
300};
301
302/*
303 * Return in pmask the portion of a cpusets's cpus_allowed that
304 * are online. If none are online, walk up the cpuset hierarchy
305 * until we find one that does have some online cpus. The top
306 * cpuset always has some cpus online.
307 *
308 * One way or another, we guarantee to return some non-empty subset
309 * of cpu_online_mask.
310 *
311 * Call with callback_mutex held.
312 */
313static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
314{
315    while (!cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
316        cs = parent_cs(cs);
317    cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
318}
319
320/*
321 * Return in *pmask the portion of a cpusets's mems_allowed that
322 * are online, with memory. If none are online with memory, walk
323 * up the cpuset hierarchy until we find one that does have some
324 * online mems. The top cpuset always has some mems online.
325 *
326 * One way or another, we guarantee to return some non-empty subset
327 * of node_states[N_MEMORY].
328 *
329 * Call with callback_mutex held.
330 */
331static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
332{
333    while (!nodes_intersects(cs->mems_allowed, node_states[N_MEMORY]))
334        cs = parent_cs(cs);
335    nodes_and(*pmask, cs->mems_allowed, node_states[N_MEMORY]);
336}
337
338/*
339 * update task's spread flag if cpuset's page/slab spread flag is set
340 *
341 * Called with callback_mutex/cpuset_mutex held
342 */
343static void cpuset_update_task_spread_flag(struct cpuset *cs,
344                    struct task_struct *tsk)
345{
346    if (is_spread_page(cs))
347        tsk->flags |= PF_SPREAD_PAGE;
348    else
349        tsk->flags &= ~PF_SPREAD_PAGE;
350    if (is_spread_slab(cs))
351        tsk->flags |= PF_SPREAD_SLAB;
352    else
353        tsk->flags &= ~PF_SPREAD_SLAB;
354}
355
356/*
357 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
358 *
359 * One cpuset is a subset of another if all its allowed CPUs and
360 * Memory Nodes are a subset of the other, and its exclusive flags
361 * are only set if the other's are set. Call holding cpuset_mutex.
362 */
363
364static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
365{
366    return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
367        nodes_subset(p->mems_allowed, q->mems_allowed) &&
368        is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
369        is_mem_exclusive(p) <= is_mem_exclusive(q);
370}
371
372/**
373 * alloc_trial_cpuset - allocate a trial cpuset
374 * @cs: the cpuset that the trial cpuset duplicates
375 */
376static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
377{
378    struct cpuset *trial;
379
380    trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
381    if (!trial)
382        return NULL;
383
384    if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
385        kfree(trial);
386        return NULL;
387    }
388    cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
389
390    return trial;
391}
392
393/**
394 * free_trial_cpuset - free the trial cpuset
395 * @trial: the trial cpuset to be freed
396 */
397static void free_trial_cpuset(struct cpuset *trial)
398{
399    free_cpumask_var(trial->cpus_allowed);
400    kfree(trial);
401}
402
403/*
404 * validate_change() - Used to validate that any proposed cpuset change
405 * follows the structural rules for cpusets.
406 *
407 * If we replaced the flag and mask values of the current cpuset
408 * (cur) with those values in the trial cpuset (trial), would
409 * our various subset and exclusive rules still be valid? Presumes
410 * cpuset_mutex held.
411 *
412 * 'cur' is the address of an actual, in-use cpuset. Operations
413 * such as list traversal that depend on the actual address of the
414 * cpuset in the list must use cur below, not trial.
415 *
416 * 'trial' is the address of bulk structure copy of cur, with
417 * perhaps one or more of the fields cpus_allowed, mems_allowed,
418 * or flags changed to new, trial values.
419 *
420 * Return 0 if valid, -errno if not.
421 */
422
423static int validate_change(struct cpuset *cur, struct cpuset *trial)
424{
425    struct cgroup_subsys_state *css;
426    struct cpuset *c, *par;
427    int ret;
428
429    rcu_read_lock();
430
431    /* Each of our child cpusets must be a subset of us */
432    ret = -EBUSY;
433    cpuset_for_each_child(c, css, cur)
434        if (!is_cpuset_subset(c, trial))
435            goto out;
436
437    /* Remaining checks don't apply to root cpuset */
438    ret = 0;
439    if (cur == &top_cpuset)
440        goto out;
441
442    par = parent_cs(cur);
443
444    /* We must be a subset of our parent cpuset */
445    ret = -EACCES;
446    if (!is_cpuset_subset(trial, par))
447        goto out;
448
449    /*
450     * If either I or some sibling (!= me) is exclusive, we can't
451     * overlap
452     */
453    ret = -EINVAL;
454    cpuset_for_each_child(c, css, par) {
455        if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
456            c != cur &&
457            cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
458            goto out;
459        if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
460            c != cur &&
461            nodes_intersects(trial->mems_allowed, c->mems_allowed))
462            goto out;
463    }
464
465    /*
466     * Cpusets with tasks - existing or newly being attached - can't
467     * be changed to have empty cpus_allowed or mems_allowed.
468     */
469    ret = -ENOSPC;
470    if ((cgroup_has_tasks(cur->css.cgroup) || cur->attach_in_progress)) {
471        if (!cpumask_empty(cur->cpus_allowed) &&
472            cpumask_empty(trial->cpus_allowed))
473            goto out;
474        if (!nodes_empty(cur->mems_allowed) &&
475            nodes_empty(trial->mems_allowed))
476            goto out;
477    }
478
479    ret = 0;
480out:
481    rcu_read_unlock();
482    return ret;
483}
484
485#ifdef CONFIG_SMP
486/*
487 * Helper routine for generate_sched_domains().
488 * Do cpusets a, b have overlapping cpus_allowed masks?
489 */
490static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
491{
492    return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
493}
494
495static void
496update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
497{
498    if (dattr->relax_domain_level < c->relax_domain_level)
499        dattr->relax_domain_level = c->relax_domain_level;
500    return;
501}
502
503static void update_domain_attr_tree(struct sched_domain_attr *dattr,
504                    struct cpuset *root_cs)
505{
506    struct cpuset *cp;
507    struct cgroup_subsys_state *pos_css;
508
509    rcu_read_lock();
510    cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
511        if (cp == root_cs)
512            continue;
513
514        /* skip the whole subtree if @cp doesn't have any CPU */
515        if (cpumask_empty(cp->cpus_allowed)) {
516            pos_css = css_rightmost_descendant(pos_css);
517            continue;
518        }
519
520        if (is_sched_load_balance(cp))
521            update_domain_attr(dattr, cp);
522    }
523    rcu_read_unlock();
524}
525
526/*
527 * generate_sched_domains()
528 *
529 * This function builds a partial partition of the systems CPUs
530 * A 'partial partition' is a set of non-overlapping subsets whose
531 * union is a subset of that set.
532 * The output of this function needs to be passed to kernel/sched/core.c
533 * partition_sched_domains() routine, which will rebuild the scheduler's
534 * load balancing domains (sched domains) as specified by that partial
535 * partition.
536 *
537 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
538 * for a background explanation of this.
539 *
540 * Does not return errors, on the theory that the callers of this
541 * routine would rather not worry about failures to rebuild sched
542 * domains when operating in the severe memory shortage situations
543 * that could cause allocation failures below.
544 *
545 * Must be called with cpuset_mutex held.
546 *
547 * The three key local variables below are:
548 * q - a linked-list queue of cpuset pointers, used to implement a
549 * top-down scan of all cpusets. This scan loads a pointer
550 * to each cpuset marked is_sched_load_balance into the
551 * array 'csa'. For our purposes, rebuilding the schedulers
552 * sched domains, we can ignore !is_sched_load_balance cpusets.
553 * csa - (for CpuSet Array) Array of pointers to all the cpusets
554 * that need to be load balanced, for convenient iterative
555 * access by the subsequent code that finds the best partition,
556 * i.e the set of domains (subsets) of CPUs such that the
557 * cpus_allowed of every cpuset marked is_sched_load_balance
558 * is a subset of one of these domains, while there are as
559 * many such domains as possible, each as small as possible.
560 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
561 * the kernel/sched/core.c routine partition_sched_domains() in a
562 * convenient format, that can be easily compared to the prior
563 * value to determine what partition elements (sched domains)
564 * were changed (added or removed.)
565 *
566 * Finding the best partition (set of domains):
567 * The triple nested loops below over i, j, k scan over the
568 * load balanced cpusets (using the array of cpuset pointers in
569 * csa[]) looking for pairs of cpusets that have overlapping
570 * cpus_allowed, but which don't have the same 'pn' partition
571 * number and gives them in the same partition number. It keeps
572 * looping on the 'restart' label until it can no longer find
573 * any such pairs.
574 *
575 * The union of the cpus_allowed masks from the set of
576 * all cpusets having the same 'pn' value then form the one
577 * element of the partition (one sched domain) to be passed to
578 * partition_sched_domains().
579 */
580static int generate_sched_domains(cpumask_var_t **domains,
581            struct sched_domain_attr **attributes)
582{
583    struct cpuset *cp; /* scans q */
584    struct cpuset **csa; /* array of all cpuset ptrs */
585    int csn; /* how many cpuset ptrs in csa so far */
586    int i, j, k; /* indices for partition finding loops */
587    cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
588    struct sched_domain_attr *dattr; /* attributes for custom domains */
589    int ndoms = 0; /* number of sched domains in result */
590    int nslot; /* next empty doms[] struct cpumask slot */
591    struct cgroup_subsys_state *pos_css;
592
593    doms = NULL;
594    dattr = NULL;
595    csa = NULL;
596
597    /* Special case for the 99% of systems with one, full, sched domain */
598    if (is_sched_load_balance(&top_cpuset)) {
599        ndoms = 1;
600        doms = alloc_sched_domains(ndoms);
601        if (!doms)
602            goto done;
603
604        dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
605        if (dattr) {
606            *dattr = SD_ATTR_INIT;
607            update_domain_attr_tree(dattr, &top_cpuset);
608        }
609        cpumask_copy(doms[0], top_cpuset.cpus_allowed);
610
611        goto done;
612    }
613
614    csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
615    if (!csa)
616        goto done;
617    csn = 0;
618
619    rcu_read_lock();
620    cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
621        if (cp == &top_cpuset)
622            continue;
623        /*
624         * Continue traversing beyond @cp iff @cp has some CPUs and
625         * isn't load balancing. The former is obvious. The
626         * latter: All child cpusets contain a subset of the
627         * parent's cpus, so just skip them, and then we call
628         * update_domain_attr_tree() to calc relax_domain_level of
629         * the corresponding sched domain.
630         */
631        if (!cpumask_empty(cp->cpus_allowed) &&
632            !is_sched_load_balance(cp))
633            continue;
634
635        if (is_sched_load_balance(cp))
636            csa[csn++] = cp;
637
638        /* skip @cp's subtree */
639        pos_css = css_rightmost_descendant(pos_css);
640    }
641    rcu_read_unlock();
642
643    for (i = 0; i < csn; i++)
644        csa[i]->pn = i;
645    ndoms = csn;
646
647restart:
648    /* Find the best partition (set of sched domains) */
649    for (i = 0; i < csn; i++) {
650        struct cpuset *a = csa[i];
651        int apn = a->pn;
652
653        for (j = 0; j < csn; j++) {
654            struct cpuset *b = csa[j];
655            int bpn = b->pn;
656
657            if (apn != bpn && cpusets_overlap(a, b)) {
658                for (k = 0; k < csn; k++) {
659                    struct cpuset *c = csa[k];
660
661                    if (c->pn == bpn)
662                        c->pn = apn;
663                }
664                ndoms--; /* one less element */
665                goto restart;
666            }
667        }
668    }
669
670    /*
671     * Now we know how many domains to create.
672     * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
673     */
674    doms = alloc_sched_domains(ndoms);
675    if (!doms)
676        goto done;
677
678    /*
679     * The rest of the code, including the scheduler, can deal with
680     * dattr==NULL case. No need to abort if alloc fails.
681     */
682    dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
683
684    for (nslot = 0, i = 0; i < csn; i++) {
685        struct cpuset *a = csa[i];
686        struct cpumask *dp;
687        int apn = a->pn;
688
689        if (apn < 0) {
690            /* Skip completed partitions */
691            continue;
692        }
693
694        dp = doms[nslot];
695
696        if (nslot == ndoms) {
697            static int warnings = 10;
698            if (warnings) {
699                printk(KERN_WARNING
700                 "rebuild_sched_domains confused:"
701                  " nslot %d, ndoms %d, csn %d, i %d,"
702                  " apn %d\n",
703                  nslot, ndoms, csn, i, apn);
704                warnings--;
705            }
706            continue;
707        }
708
709        cpumask_clear(dp);
710        if (dattr)
711            *(dattr + nslot) = SD_ATTR_INIT;
712        for (j = i; j < csn; j++) {
713            struct cpuset *b = csa[j];
714
715            if (apn == b->pn) {
716                cpumask_or(dp, dp, b->cpus_allowed);
717                if (dattr)
718                    update_domain_attr_tree(dattr + nslot, b);
719
720                /* Done with this partition */
721                b->pn = -1;
722            }
723        }
724        nslot++;
725    }
726    BUG_ON(nslot != ndoms);
727
728done:
729    kfree(csa);
730
731    /*
732     * Fallback to the default domain if kmalloc() failed.
733     * See comments in partition_sched_domains().
734     */
735    if (doms == NULL)
736        ndoms = 1;
737
738    *domains = doms;
739    *attributes = dattr;
740    return ndoms;
741}
742
743/*
744 * Rebuild scheduler domains.
745 *
746 * If the flag 'sched_load_balance' of any cpuset with non-empty
747 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
748 * which has that flag enabled, or if any cpuset with a non-empty
749 * 'cpus' is removed, then call this routine to rebuild the
750 * scheduler's dynamic sched domains.
751 *
752 * Call with cpuset_mutex held. Takes get_online_cpus().
753 */
754static void rebuild_sched_domains_locked(void)
755{
756    struct sched_domain_attr *attr;
757    cpumask_var_t *doms;
758    int ndoms;
759
760    lockdep_assert_held(&cpuset_mutex);
761    get_online_cpus();
762
763    /*
764     * We have raced with CPU hotplug. Don't do anything to avoid
765     * passing doms with offlined cpu to partition_sched_domains().
766     * Anyways, hotplug work item will rebuild sched domains.
767     */
768    if (!cpumask_equal(top_cpuset.cpus_allowed, cpu_active_mask))
769        goto out;
770
771    /* Generate domain masks and attrs */
772    ndoms = generate_sched_domains(&doms, &attr);
773
774    /* Have scheduler rebuild the domains */
775    partition_sched_domains(ndoms, doms, attr);
776out:
777    put_online_cpus();
778}
779#else /* !CONFIG_SMP */
780static void rebuild_sched_domains_locked(void)
781{
782}
783#endif /* CONFIG_SMP */
784
785void rebuild_sched_domains(void)
786{
787    mutex_lock(&cpuset_mutex);
788    rebuild_sched_domains_locked();
789    mutex_unlock(&cpuset_mutex);
790}
791
792/*
793 * effective_cpumask_cpuset - return nearest ancestor with non-empty cpus
794 * @cs: the cpuset in interest
795 *
796 * A cpuset's effective cpumask is the cpumask of the nearest ancestor
797 * with non-empty cpus. We use effective cpumask whenever:
798 * - we update tasks' cpus_allowed. (they take on the ancestor's cpumask
799 * if the cpuset they reside in has no cpus)
800 * - we want to retrieve task_cs(tsk)'s cpus_allowed.
801 *
802 * Called with cpuset_mutex held. cpuset_cpus_allowed_fallback() is an
803 * exception. See comments there.
804 */
805static struct cpuset *effective_cpumask_cpuset(struct cpuset *cs)
806{
807    while (cpumask_empty(cs->cpus_allowed))
808        cs = parent_cs(cs);
809    return cs;
810}
811
812/*
813 * effective_nodemask_cpuset - return nearest ancestor with non-empty mems
814 * @cs: the cpuset in interest
815 *
816 * A cpuset's effective nodemask is the nodemask of the nearest ancestor
817 * with non-empty memss. We use effective nodemask whenever:
818 * - we update tasks' mems_allowed. (they take on the ancestor's nodemask
819 * if the cpuset they reside in has no mems)
820 * - we want to retrieve task_cs(tsk)'s mems_allowed.
821 *
822 * Called with cpuset_mutex held.
823 */
824static struct cpuset *effective_nodemask_cpuset(struct cpuset *cs)
825{
826    while (nodes_empty(cs->mems_allowed))
827        cs = parent_cs(cs);
828    return cs;
829}
830
831/**
832 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
833 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
834 *
835 * Iterate through each task of @cs updating its cpus_allowed to the
836 * effective cpuset's. As this function is called with cpuset_mutex held,
837 * cpuset membership stays stable.
838 */
839static void update_tasks_cpumask(struct cpuset *cs)
840{
841    struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
842    struct css_task_iter it;
843    struct task_struct *task;
844
845    css_task_iter_start(&cs->css, &it);
846    while ((task = css_task_iter_next(&it)))
847        set_cpus_allowed_ptr(task, cpus_cs->cpus_allowed);
848    css_task_iter_end(&it);
849}
850
851/*
852 * update_tasks_cpumask_hier - Update the cpumasks of tasks in the hierarchy.
853 * @root_cs: the root cpuset of the hierarchy
854 * @update_root: update root cpuset or not?
855 *
856 * This will update cpumasks of tasks in @root_cs and all other empty cpusets
857 * which take on cpumask of @root_cs.
858 *
859 * Called with cpuset_mutex held
860 */
861static void update_tasks_cpumask_hier(struct cpuset *root_cs, bool update_root)
862{
863    struct cpuset *cp;
864    struct cgroup_subsys_state *pos_css;
865
866    rcu_read_lock();
867    cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
868        if (cp == root_cs) {
869            if (!update_root)
870                continue;
871        } else {
872            /* skip the whole subtree if @cp have some CPU */
873            if (!cpumask_empty(cp->cpus_allowed)) {
874                pos_css = css_rightmost_descendant(pos_css);
875                continue;
876            }
877        }
878        if (!css_tryget(&cp->css))
879            continue;
880        rcu_read_unlock();
881
882        update_tasks_cpumask(cp);
883
884        rcu_read_lock();
885        css_put(&cp->css);
886    }
887    rcu_read_unlock();
888}
889
890/**
891 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
892 * @cs: the cpuset to consider
893 * @buf: buffer of cpu numbers written to this cpuset
894 */
895static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
896              const char *buf)
897{
898    int retval;
899    int is_load_balanced;
900
901    /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
902    if (cs == &top_cpuset)
903        return -EACCES;
904
905    /*
906     * An empty cpus_allowed is ok only if the cpuset has no tasks.
907     * Since cpulist_parse() fails on an empty mask, we special case
908     * that parsing. The validate_change() call ensures that cpusets
909     * with tasks have cpus.
910     */
911    if (!*buf) {
912        cpumask_clear(trialcs->cpus_allowed);
913    } else {
914        retval = cpulist_parse(buf, trialcs->cpus_allowed);
915        if (retval < 0)
916            return retval;
917
918        if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
919            return -EINVAL;
920    }
921
922    /* Nothing to do if the cpus didn't change */
923    if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
924        return 0;
925
926    retval = validate_change(cs, trialcs);
927    if (retval < 0)
928        return retval;
929
930    is_load_balanced = is_sched_load_balance(trialcs);
931
932    mutex_lock(&callback_mutex);
933    cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
934    mutex_unlock(&callback_mutex);
935
936    update_tasks_cpumask_hier(cs, true);
937
938    if (is_load_balanced)
939        rebuild_sched_domains_locked();
940    return 0;
941}
942
943/*
944 * cpuset_migrate_mm
945 *
946 * Migrate memory region from one set of nodes to another.
947 *
948 * Temporarilly set tasks mems_allowed to target nodes of migration,
949 * so that the migration code can allocate pages on these nodes.
950 *
951 * While the mm_struct we are migrating is typically from some
952 * other task, the task_struct mems_allowed that we are hacking
953 * is for our current task, which must allocate new pages for that
954 * migrating memory region.
955 */
956
957static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
958                            const nodemask_t *to)
959{
960    struct task_struct *tsk = current;
961    struct cpuset *mems_cs;
962
963    tsk->mems_allowed = *to;
964
965    do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
966
967    rcu_read_lock();
968    mems_cs = effective_nodemask_cpuset(task_cs(tsk));
969    guarantee_online_mems(mems_cs, &tsk->mems_allowed);
970    rcu_read_unlock();
971}
972
973/*
974 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
975 * @tsk: the task to change
976 * @newmems: new nodes that the task will be set
977 *
978 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
979 * we structure updates as setting all new allowed nodes, then clearing newly
980 * disallowed ones.
981 */
982static void cpuset_change_task_nodemask(struct task_struct *tsk,
983                    nodemask_t *newmems)
984{
985    bool need_loop;
986
987    /*
988     * Allow tasks that have access to memory reserves because they have
989     * been OOM killed to get memory anywhere.
990     */
991    if (unlikely(test_thread_flag(TIF_MEMDIE)))
992        return;
993    if (current->flags & PF_EXITING) /* Let dying task have memory */
994        return;
995
996    task_lock(tsk);
997    /*
998     * Determine if a loop is necessary if another thread is doing
999     * read_mems_allowed_begin(). If at least one node remains unchanged and
1000     * tsk does not have a mempolicy, then an empty nodemask will not be
1001     * possible when mems_allowed is larger than a word.
1002     */
1003    need_loop = task_has_mempolicy(tsk) ||
1004            !nodes_intersects(*newmems, tsk->mems_allowed);
1005
1006    if (need_loop) {
1007        local_irq_disable();
1008        write_seqcount_begin(&tsk->mems_allowed_seq);
1009    }
1010
1011    nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1012    mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
1013
1014    mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1015    tsk->mems_allowed = *newmems;
1016
1017    if (need_loop) {
1018        write_seqcount_end(&tsk->mems_allowed_seq);
1019        local_irq_enable();
1020    }
1021
1022    task_unlock(tsk);
1023}
1024
1025static void *cpuset_being_rebound;
1026
1027/**
1028 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1029 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1030 *
1031 * Iterate through each task of @cs updating its mems_allowed to the
1032 * effective cpuset's. As this function is called with cpuset_mutex held,
1033 * cpuset membership stays stable.
1034 */
1035static void update_tasks_nodemask(struct cpuset *cs)
1036{
1037    static nodemask_t newmems; /* protected by cpuset_mutex */
1038    struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
1039    struct css_task_iter it;
1040    struct task_struct *task;
1041
1042    cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1043
1044    guarantee_online_mems(mems_cs, &newmems);
1045
1046    /*
1047     * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1048     * take while holding tasklist_lock. Forks can happen - the
1049     * mpol_dup() cpuset_being_rebound check will catch such forks,
1050     * and rebind their vma mempolicies too. Because we still hold
1051     * the global cpuset_mutex, we know that no other rebind effort
1052     * will be contending for the global variable cpuset_being_rebound.
1053     * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1054     * is idempotent. Also migrate pages in each mm to new nodes.
1055     */
1056    css_task_iter_start(&cs->css, &it);
1057    while ((task = css_task_iter_next(&it))) {
1058        struct mm_struct *mm;
1059        bool migrate;
1060
1061        cpuset_change_task_nodemask(task, &newmems);
1062
1063        mm = get_task_mm(task);
1064        if (!mm)
1065            continue;
1066
1067        migrate = is_memory_migrate(cs);
1068
1069        mpol_rebind_mm(mm, &cs->mems_allowed);
1070        if (migrate)
1071            cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1072        mmput(mm);
1073    }
1074    css_task_iter_end(&it);
1075
1076    /*
1077     * All the tasks' nodemasks have been updated, update
1078     * cs->old_mems_allowed.
1079     */
1080    cs->old_mems_allowed = newmems;
1081
1082    /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1083    cpuset_being_rebound = NULL;
1084}
1085
1086/*
1087 * update_tasks_nodemask_hier - Update the nodemasks of tasks in the hierarchy.
1088 * @cs: the root cpuset of the hierarchy
1089 * @update_root: update the root cpuset or not?
1090 *
1091 * This will update nodemasks of tasks in @root_cs and all other empty cpusets
1092 * which take on nodemask of @root_cs.
1093 *
1094 * Called with cpuset_mutex held
1095 */
1096static void update_tasks_nodemask_hier(struct cpuset *root_cs, bool update_root)
1097{
1098    struct cpuset *cp;
1099    struct cgroup_subsys_state *pos_css;
1100
1101    rcu_read_lock();
1102    cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
1103        if (cp == root_cs) {
1104            if (!update_root)
1105                continue;
1106        } else {
1107            /* skip the whole subtree if @cp have some CPU */
1108            if (!nodes_empty(cp->mems_allowed)) {
1109                pos_css = css_rightmost_descendant(pos_css);
1110                continue;
1111            }
1112        }
1113        if (!css_tryget(&cp->css))
1114            continue;
1115        rcu_read_unlock();
1116
1117        update_tasks_nodemask(cp);
1118
1119        rcu_read_lock();
1120        css_put(&cp->css);
1121    }
1122    rcu_read_unlock();
1123}
1124
1125/*
1126 * Handle user request to change the 'mems' memory placement
1127 * of a cpuset. Needs to validate the request, update the
1128 * cpusets mems_allowed, and for each task in the cpuset,
1129 * update mems_allowed and rebind task's mempolicy and any vma
1130 * mempolicies and if the cpuset is marked 'memory_migrate',
1131 * migrate the tasks pages to the new memory.
1132 *
1133 * Call with cpuset_mutex held. May take callback_mutex during call.
1134 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1135 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1136 * their mempolicies to the cpusets new mems_allowed.
1137 */
1138static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1139               const char *buf)
1140{
1141    int retval;
1142
1143    /*
1144     * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
1145     * it's read-only
1146     */
1147    if (cs == &top_cpuset) {
1148        retval = -EACCES;
1149        goto done;
1150    }
1151
1152    /*
1153     * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1154     * Since nodelist_parse() fails on an empty mask, we special case
1155     * that parsing. The validate_change() call ensures that cpusets
1156     * with tasks have memory.
1157     */
1158    if (!*buf) {
1159        nodes_clear(trialcs->mems_allowed);
1160    } else {
1161        retval = nodelist_parse(buf, trialcs->mems_allowed);
1162        if (retval < 0)
1163            goto done;
1164
1165        if (!nodes_subset(trialcs->mems_allowed,
1166                node_states[N_MEMORY])) {
1167            retval = -EINVAL;
1168            goto done;
1169        }
1170    }
1171
1172    if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
1173        retval = 0; /* Too easy - nothing to do */
1174        goto done;
1175    }
1176    retval = validate_change(cs, trialcs);
1177    if (retval < 0)
1178        goto done;
1179
1180    mutex_lock(&callback_mutex);
1181    cs->mems_allowed = trialcs->mems_allowed;
1182    mutex_unlock(&callback_mutex);
1183
1184    update_tasks_nodemask_hier(cs, true);
1185done:
1186    return retval;
1187}
1188
1189int current_cpuset_is_being_rebound(void)
1190{
1191    return task_cs(current) == cpuset_being_rebound;
1192}
1193
1194static int update_relax_domain_level(struct cpuset *cs, s64 val)
1195{
1196#ifdef CONFIG_SMP
1197    if (val < -1 || val >= sched_domain_level_max)
1198        return -EINVAL;
1199#endif
1200
1201    if (val != cs->relax_domain_level) {
1202        cs->relax_domain_level = val;
1203        if (!cpumask_empty(cs->cpus_allowed) &&
1204            is_sched_load_balance(cs))
1205            rebuild_sched_domains_locked();
1206    }
1207
1208    return 0;
1209}
1210
1211/**
1212 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1213 * @cs: the cpuset in which each task's spread flags needs to be changed
1214 *
1215 * Iterate through each task of @cs updating its spread flags. As this
1216 * function is called with cpuset_mutex held, cpuset membership stays
1217 * stable.
1218 */
1219static void update_tasks_flags(struct cpuset *cs)
1220{
1221    struct css_task_iter it;
1222    struct task_struct *task;
1223
1224    css_task_iter_start(&cs->css, &it);
1225    while ((task = css_task_iter_next(&it)))
1226        cpuset_update_task_spread_flag(cs, task);
1227    css_task_iter_end(&it);
1228}
1229
1230/*
1231 * update_flag - read a 0 or a 1 in a file and update associated flag
1232 * bit: the bit to update (see cpuset_flagbits_t)
1233 * cs: the cpuset to update
1234 * turning_on: whether the flag is being set or cleared
1235 *
1236 * Call with cpuset_mutex held.
1237 */
1238
1239static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1240               int turning_on)
1241{
1242    struct cpuset *trialcs;
1243    int balance_flag_changed;
1244    int spread_flag_changed;
1245    int err;
1246
1247    trialcs = alloc_trial_cpuset(cs);
1248    if (!trialcs)
1249        return -ENOMEM;
1250
1251    if (turning_on)
1252        set_bit(bit, &trialcs->flags);
1253    else
1254        clear_bit(bit, &trialcs->flags);
1255
1256    err = validate_change(cs, trialcs);
1257    if (err < 0)
1258        goto out;
1259
1260    balance_flag_changed = (is_sched_load_balance(cs) !=
1261                is_sched_load_balance(trialcs));
1262
1263    spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1264            || (is_spread_page(cs) != is_spread_page(trialcs)));
1265
1266    mutex_lock(&callback_mutex);
1267    cs->flags = trialcs->flags;
1268    mutex_unlock(&callback_mutex);
1269
1270    if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1271        rebuild_sched_domains_locked();
1272
1273    if (spread_flag_changed)
1274        update_tasks_flags(cs);
1275out:
1276    free_trial_cpuset(trialcs);
1277    return err;
1278}
1279
1280/*
1281 * Frequency meter - How fast is some event occurring?
1282 *
1283 * These routines manage a digitally filtered, constant time based,
1284 * event frequency meter. There are four routines:
1285 * fmeter_init() - initialize a frequency meter.
1286 * fmeter_markevent() - called each time the event happens.
1287 * fmeter_getrate() - returns the recent rate of such events.
1288 * fmeter_update() - internal routine used to update fmeter.
1289 *
1290 * A common data structure is passed to each of these routines,
1291 * which is used to keep track of the state required to manage the
1292 * frequency meter and its digital filter.
1293 *
1294 * The filter works on the number of events marked per unit time.
1295 * The filter is single-pole low-pass recursive (IIR). The time unit
1296 * is 1 second. Arithmetic is done using 32-bit integers scaled to
1297 * simulate 3 decimal digits of precision (multiplied by 1000).
1298 *
1299 * With an FM_COEF of 933, and a time base of 1 second, the filter
1300 * has a half-life of 10 seconds, meaning that if the events quit
1301 * happening, then the rate returned from the fmeter_getrate()
1302 * will be cut in half each 10 seconds, until it converges to zero.
1303 *
1304 * It is not worth doing a real infinitely recursive filter. If more
1305 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1306 * just compute FM_MAXTICKS ticks worth, by which point the level
1307 * will be stable.
1308 *
1309 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1310 * arithmetic overflow in the fmeter_update() routine.
1311 *
1312 * Given the simple 32 bit integer arithmetic used, this meter works
1313 * best for reporting rates between one per millisecond (msec) and
1314 * one per 32 (approx) seconds. At constant rates faster than one
1315 * per msec it maxes out at values just under 1,000,000. At constant
1316 * rates between one per msec, and one per second it will stabilize
1317 * to a value N*1000, where N is the rate of events per second.
1318 * At constant rates between one per second and one per 32 seconds,
1319 * it will be choppy, moving up on the seconds that have an event,
1320 * and then decaying until the next event. At rates slower than
1321 * about one in 32 seconds, it decays all the way back to zero between
1322 * each event.
1323 */
1324
1325#define FM_COEF 933 /* coefficient for half-life of 10 secs */
1326#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1327#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1328#define FM_SCALE 1000 /* faux fixed point scale */
1329
1330/* Initialize a frequency meter */
1331static void fmeter_init(struct fmeter *fmp)
1332{
1333    fmp->cnt = 0;
1334    fmp->val = 0;
1335    fmp->time = 0;
1336    spin_lock_init(&fmp->lock);
1337}
1338
1339/* Internal meter update - process cnt events and update value */
1340static void fmeter_update(struct fmeter *fmp)
1341{
1342    time_t now = get_seconds();
1343    time_t ticks = now - fmp->time;
1344
1345    if (ticks == 0)
1346        return;
1347
1348    ticks = min(FM_MAXTICKS, ticks);
1349    while (ticks-- > 0)
1350        fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1351    fmp->time = now;
1352
1353    fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1354    fmp->cnt = 0;
1355}
1356
1357/* Process any previous ticks, then bump cnt by one (times scale). */
1358static void fmeter_markevent(struct fmeter *fmp)
1359{
1360    spin_lock(&fmp->lock);
1361    fmeter_update(fmp);
1362    fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1363    spin_unlock(&fmp->lock);
1364}
1365
1366/* Process any previous ticks, then return current value. */
1367static int fmeter_getrate(struct fmeter *fmp)
1368{
1369    int val;
1370
1371    spin_lock(&fmp->lock);
1372    fmeter_update(fmp);
1373    val = fmp->val;
1374    spin_unlock(&fmp->lock);
1375    return val;
1376}
1377
1378static struct cpuset *cpuset_attach_old_cs;
1379
1380/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
1381static int cpuset_can_attach(struct cgroup_subsys_state *css,
1382                 struct cgroup_taskset *tset)
1383{
1384    struct cpuset *cs = css_cs(css);
1385    struct task_struct *task;
1386    int ret;
1387
1388    /* used later by cpuset_attach() */
1389    cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));
1390
1391    mutex_lock(&cpuset_mutex);
1392
1393    /*
1394     * We allow to move tasks into an empty cpuset if sane_behavior
1395     * flag is set.
1396     */
1397    ret = -ENOSPC;
1398    if (!cgroup_sane_behavior(css->cgroup) &&
1399        (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
1400        goto out_unlock;
1401
1402    cgroup_taskset_for_each(task, tset) {
1403        /*
1404         * Kthreads which disallow setaffinity shouldn't be moved
1405         * to a new cpuset; we don't want to change their cpu
1406         * affinity and isolating such threads by their set of
1407         * allowed nodes is unnecessary. Thus, cpusets are not
1408         * applicable for such threads. This prevents checking for
1409         * success of set_cpus_allowed_ptr() on all attached tasks
1410         * before cpus_allowed may be changed.
1411         */
1412        ret = -EINVAL;
1413        if (task->flags & PF_NO_SETAFFINITY)
1414            goto out_unlock;
1415        ret = security_task_setscheduler(task);
1416        if (ret)
1417            goto out_unlock;
1418    }
1419
1420    /*
1421     * Mark attach is in progress. This makes validate_change() fail
1422     * changes which zero cpus/mems_allowed.
1423     */
1424    cs->attach_in_progress++;
1425    ret = 0;
1426out_unlock:
1427    mutex_unlock(&cpuset_mutex);
1428    return ret;
1429}
1430
1431static void cpuset_cancel_attach(struct cgroup_subsys_state *css,
1432                 struct cgroup_taskset *tset)
1433{
1434    mutex_lock(&cpuset_mutex);
1435    css_cs(css)->attach_in_progress--;
1436    mutex_unlock(&cpuset_mutex);
1437}
1438
1439/*
1440 * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
1441 * but we can't allocate it dynamically there. Define it global and
1442 * allocate from cpuset_init().
1443 */
1444static cpumask_var_t cpus_attach;
1445
1446static void cpuset_attach(struct cgroup_subsys_state *css,
1447              struct cgroup_taskset *tset)
1448{
1449    /* static buf protected by cpuset_mutex */
1450    static nodemask_t cpuset_attach_nodemask_to;
1451    struct mm_struct *mm;
1452    struct task_struct *task;
1453    struct task_struct *leader = cgroup_taskset_first(tset);
1454    struct cpuset *cs = css_cs(css);
1455    struct cpuset *oldcs = cpuset_attach_old_cs;
1456    struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
1457    struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
1458
1459    mutex_lock(&cpuset_mutex);
1460
1461    /* prepare for attach */
1462    if (cs == &top_cpuset)
1463        cpumask_copy(cpus_attach, cpu_possible_mask);
1464    else
1465        guarantee_online_cpus(cpus_cs, cpus_attach);
1466
1467    guarantee_online_mems(mems_cs, &cpuset_attach_nodemask_to);
1468
1469    cgroup_taskset_for_each(task, tset) {
1470        /*
1471         * can_attach beforehand should guarantee that this doesn't
1472         * fail. TODO: have a better way to handle failure here
1473         */
1474        WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
1475
1476        cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
1477        cpuset_update_task_spread_flag(cs, task);
1478    }
1479
1480    /*
1481     * Change mm, possibly for multiple threads in a threadgroup. This is
1482     * expensive and may sleep.
1483     */
1484    cpuset_attach_nodemask_to = cs->mems_allowed;
1485    mm = get_task_mm(leader);
1486    if (mm) {
1487        struct cpuset *mems_oldcs = effective_nodemask_cpuset(oldcs);
1488
1489        mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
1490
1491        /*
1492         * old_mems_allowed is the same with mems_allowed here, except
1493         * if this task is being moved automatically due to hotplug.
1494         * In that case @mems_allowed has been updated and is empty,
1495         * so @old_mems_allowed is the right nodesets that we migrate
1496         * mm from.
1497         */
1498        if (is_memory_migrate(cs)) {
1499            cpuset_migrate_mm(mm, &mems_oldcs->old_mems_allowed,
1500                      &cpuset_attach_nodemask_to);
1501        }
1502        mmput(mm);
1503    }
1504
1505    cs->old_mems_allowed = cpuset_attach_nodemask_to;
1506
1507    cs->attach_in_progress--;
1508    if (!cs->attach_in_progress)
1509        wake_up(&cpuset_attach_wq);
1510
1511    mutex_unlock(&cpuset_mutex);
1512}
1513
1514/* The various types of files and directories in a cpuset file system */
1515
1516typedef enum {
1517    FILE_MEMORY_MIGRATE,
1518    FILE_CPULIST,
1519    FILE_MEMLIST,
1520    FILE_CPU_EXCLUSIVE,
1521    FILE_MEM_EXCLUSIVE,
1522    FILE_MEM_HARDWALL,
1523    FILE_SCHED_LOAD_BALANCE,
1524    FILE_SCHED_RELAX_DOMAIN_LEVEL,
1525    FILE_MEMORY_PRESSURE_ENABLED,
1526    FILE_MEMORY_PRESSURE,
1527    FILE_SPREAD_PAGE,
1528    FILE_SPREAD_SLAB,
1529} cpuset_filetype_t;
1530
1531static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
1532                u64 val)
1533{
1534    struct cpuset *cs = css_cs(css);
1535    cpuset_filetype_t type = cft->private;
1536    int retval = 0;
1537
1538    mutex_lock(&cpuset_mutex);
1539    if (!is_cpuset_online(cs)) {
1540        retval = -ENODEV;
1541        goto out_unlock;
1542    }
1543
1544    switch (type) {
1545    case FILE_CPU_EXCLUSIVE:
1546        retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1547        break;
1548    case FILE_MEM_EXCLUSIVE:
1549        retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1550        break;
1551    case FILE_MEM_HARDWALL:
1552        retval = update_flag(CS_MEM_HARDWALL, cs, val);
1553        break;
1554    case FILE_SCHED_LOAD_BALANCE:
1555        retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1556        break;
1557    case FILE_MEMORY_MIGRATE:
1558        retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1559        break;
1560    case FILE_MEMORY_PRESSURE_ENABLED:
1561        cpuset_memory_pressure_enabled = !!val;
1562        break;
1563    case FILE_MEMORY_PRESSURE:
1564        retval = -EACCES;
1565        break;
1566    case FILE_SPREAD_PAGE:
1567        retval = update_flag(CS_SPREAD_PAGE, cs, val);
1568        break;
1569    case FILE_SPREAD_SLAB:
1570        retval = update_flag(CS_SPREAD_SLAB, cs, val);
1571        break;
1572    default:
1573        retval = -EINVAL;
1574        break;
1575    }
1576out_unlock:
1577    mutex_unlock(&cpuset_mutex);
1578    return retval;
1579}
1580
1581static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
1582                s64 val)
1583{
1584    struct cpuset *cs = css_cs(css);
1585    cpuset_filetype_t type = cft->private;
1586    int retval = -ENODEV;
1587
1588    mutex_lock(&cpuset_mutex);
1589    if (!is_cpuset_online(cs))
1590        goto out_unlock;
1591
1592    switch (type) {
1593    case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1594        retval = update_relax_domain_level(cs, val);
1595        break;
1596    default:
1597        retval = -EINVAL;
1598        break;
1599    }
1600out_unlock:
1601    mutex_unlock(&cpuset_mutex);
1602    return retval;
1603}
1604
1605/*
1606 * Common handling for a write to a "cpus" or "mems" file.
1607 */
1608static int cpuset_write_resmask(struct cgroup_subsys_state *css,
1609                struct cftype *cft, char *buf)
1610{
1611    struct cpuset *cs = css_cs(css);
1612    struct cpuset *trialcs;
1613    int retval = -ENODEV;
1614
1615    /*
1616     * CPU or memory hotunplug may leave @cs w/o any execution
1617     * resources, in which case the hotplug code asynchronously updates
1618     * configuration and transfers all tasks to the nearest ancestor
1619     * which can execute.
1620     *
1621     * As writes to "cpus" or "mems" may restore @cs's execution
1622     * resources, wait for the previously scheduled operations before
1623     * proceeding, so that we don't end up keep removing tasks added
1624     * after execution capability is restored.
1625     */
1626    flush_work(&cpuset_hotplug_work);
1627
1628    mutex_lock(&cpuset_mutex);
1629    if (!is_cpuset_online(cs))
1630        goto out_unlock;
1631
1632    trialcs = alloc_trial_cpuset(cs);
1633    if (!trialcs) {
1634        retval = -ENOMEM;
1635        goto out_unlock;
1636    }
1637
1638    switch (cft->private) {
1639    case FILE_CPULIST:
1640        retval = update_cpumask(cs, trialcs, buf);
1641        break;
1642    case FILE_MEMLIST:
1643        retval = update_nodemask(cs, trialcs, buf);
1644        break;
1645    default:
1646        retval = -EINVAL;
1647        break;
1648    }
1649
1650    free_trial_cpuset(trialcs);
1651out_unlock:
1652    mutex_unlock(&cpuset_mutex);
1653    return retval;
1654}
1655
1656/*
1657 * These ascii lists should be read in a single call, by using a user
1658 * buffer large enough to hold the entire map. If read in smaller
1659 * chunks, there is no guarantee of atomicity. Since the display format
1660 * used, list of ranges of sequential numbers, is variable length,
1661 * and since these maps can change value dynamically, one could read
1662 * gibberish by doing partial reads while a list was changing.
1663 */
1664static int cpuset_common_seq_show(struct seq_file *sf, void *v)
1665{
1666    struct cpuset *cs = css_cs(seq_css(sf));
1667    cpuset_filetype_t type = seq_cft(sf)->private;
1668    ssize_t count;
1669    char *buf, *s;
1670    int ret = 0;
1671
1672    count = seq_get_buf(sf, &buf);
1673    s = buf;
1674
1675    mutex_lock(&callback_mutex);
1676
1677    switch (type) {
1678    case FILE_CPULIST:
1679        s += cpulist_scnprintf(s, count, cs->cpus_allowed);
1680        break;
1681    case FILE_MEMLIST:
1682        s += nodelist_scnprintf(s, count, cs->mems_allowed);
1683        break;
1684    default:
1685        ret = -EINVAL;
1686        goto out_unlock;
1687    }
1688
1689    if (s < buf + count - 1) {
1690        *s++ = '\n';
1691        seq_commit(sf, s - buf);
1692    } else {
1693        seq_commit(sf, -1);
1694    }
1695out_unlock:
1696    mutex_unlock(&callback_mutex);
1697    return ret;
1698}
1699
1700static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
1701{
1702    struct cpuset *cs = css_cs(css);
1703    cpuset_filetype_t type = cft->private;
1704    switch (type) {
1705    case FILE_CPU_EXCLUSIVE:
1706        return is_cpu_exclusive(cs);
1707    case FILE_MEM_EXCLUSIVE:
1708        return is_mem_exclusive(cs);
1709    case FILE_MEM_HARDWALL:
1710        return is_mem_hardwall(cs);
1711    case FILE_SCHED_LOAD_BALANCE:
1712        return is_sched_load_balance(cs);
1713    case FILE_MEMORY_MIGRATE:
1714        return is_memory_migrate(cs);
1715    case FILE_MEMORY_PRESSURE_ENABLED:
1716        return cpuset_memory_pressure_enabled;
1717    case FILE_MEMORY_PRESSURE:
1718        return fmeter_getrate(&cs->fmeter);
1719    case FILE_SPREAD_PAGE:
1720        return is_spread_page(cs);
1721    case FILE_SPREAD_SLAB:
1722        return is_spread_slab(cs);
1723    default:
1724        BUG();
1725    }
1726
1727    /* Unreachable but makes gcc happy */
1728    return 0;
1729}
1730
1731static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
1732{
1733    struct cpuset *cs = css_cs(css);
1734    cpuset_filetype_t type = cft->private;
1735    switch (type) {
1736    case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1737        return cs->relax_domain_level;
1738    default:
1739        BUG();
1740    }
1741
1742    /* Unrechable but makes gcc happy */
1743    return 0;
1744}
1745
1746
1747/*
1748 * for the common functions, 'private' gives the type of file
1749 */
1750
1751static struct cftype files[] = {
1752    {
1753        .name = "cpus",
1754        .seq_show = cpuset_common_seq_show,
1755        .write_string = cpuset_write_resmask,
1756        .max_write_len = (100U + 6 * NR_CPUS),
1757        .private = FILE_CPULIST,
1758    },
1759
1760    {
1761        .name = "mems",
1762        .seq_show = cpuset_common_seq_show,
1763        .write_string = cpuset_write_resmask,
1764        .max_write_len = (100U + 6 * MAX_NUMNODES),
1765        .private = FILE_MEMLIST,
1766    },
1767
1768    {
1769        .name = "cpu_exclusive",
1770        .read_u64 = cpuset_read_u64,
1771        .write_u64 = cpuset_write_u64,
1772        .private = FILE_CPU_EXCLUSIVE,
1773    },
1774
1775    {
1776        .name = "mem_exclusive",
1777        .read_u64 = cpuset_read_u64,
1778        .write_u64 = cpuset_write_u64,
1779        .private = FILE_MEM_EXCLUSIVE,
1780    },
1781
1782    {
1783        .name = "mem_hardwall",
1784        .read_u64 = cpuset_read_u64,
1785        .write_u64 = cpuset_write_u64,
1786        .private = FILE_MEM_HARDWALL,
1787    },
1788
1789    {
1790        .name = "sched_load_balance",
1791        .read_u64 = cpuset_read_u64,
1792        .write_u64 = cpuset_write_u64,
1793        .private = FILE_SCHED_LOAD_BALANCE,
1794    },
1795
1796    {
1797        .name = "sched_relax_domain_level",
1798        .read_s64 = cpuset_read_s64,
1799        .write_s64 = cpuset_write_s64,
1800        .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1801    },
1802
1803    {
1804        .name = "memory_migrate",
1805        .read_u64 = cpuset_read_u64,
1806        .write_u64 = cpuset_write_u64,
1807        .private = FILE_MEMORY_MIGRATE,
1808    },
1809
1810    {
1811        .name = "memory_pressure",
1812        .read_u64 = cpuset_read_u64,
1813        .write_u64 = cpuset_write_u64,
1814        .private = FILE_MEMORY_PRESSURE,
1815        .mode = S_IRUGO,
1816    },
1817
1818    {
1819        .name = "memory_spread_page",
1820        .read_u64 = cpuset_read_u64,
1821        .write_u64 = cpuset_write_u64,
1822        .private = FILE_SPREAD_PAGE,
1823    },
1824
1825    {
1826        .name = "memory_spread_slab",
1827        .read_u64 = cpuset_read_u64,
1828        .write_u64 = cpuset_write_u64,
1829        .private = FILE_SPREAD_SLAB,
1830    },
1831
1832    {
1833        .name = "memory_pressure_enabled",
1834        .flags = CFTYPE_ONLY_ON_ROOT,
1835        .read_u64 = cpuset_read_u64,
1836        .write_u64 = cpuset_write_u64,
1837        .private = FILE_MEMORY_PRESSURE_ENABLED,
1838    },
1839
1840    { } /* terminate */
1841};
1842
1843/*
1844 * cpuset_css_alloc - allocate a cpuset css
1845 * cgrp: control group that the new cpuset will be part of
1846 */
1847
1848static struct cgroup_subsys_state *
1849cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
1850{
1851    struct cpuset *cs;
1852
1853    if (!parent_css)
1854        return &top_cpuset.css;
1855
1856    cs = kzalloc(sizeof(*cs), GFP_KERNEL);
1857    if (!cs)
1858        return ERR_PTR(-ENOMEM);
1859    if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
1860        kfree(cs);
1861        return ERR_PTR(-ENOMEM);
1862    }
1863
1864    set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1865    cpumask_clear(cs->cpus_allowed);
1866    nodes_clear(cs->mems_allowed);
1867    fmeter_init(&cs->fmeter);
1868    cs->relax_domain_level = -1;
1869
1870    return &cs->css;
1871}
1872
1873static int cpuset_css_online(struct cgroup_subsys_state *css)
1874{
1875    struct cpuset *cs = css_cs(css);
1876    struct cpuset *parent = parent_cs(cs);
1877    struct cpuset *tmp_cs;
1878    struct cgroup_subsys_state *pos_css;
1879
1880    if (!parent)
1881        return 0;
1882
1883    mutex_lock(&cpuset_mutex);
1884
1885    set_bit(CS_ONLINE, &cs->flags);
1886    if (is_spread_page(parent))
1887        set_bit(CS_SPREAD_PAGE, &cs->flags);
1888    if (is_spread_slab(parent))
1889        set_bit(CS_SPREAD_SLAB, &cs->flags);
1890
1891    number_of_cpusets++;
1892
1893    if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
1894        goto out_unlock;
1895
1896    /*
1897     * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
1898     * set. This flag handling is implemented in cgroup core for
1899     * histrical reasons - the flag may be specified during mount.
1900     *
1901     * Currently, if any sibling cpusets have exclusive cpus or mem, we
1902     * refuse to clone the configuration - thereby refusing the task to
1903     * be entered, and as a result refusing the sys_unshare() or
1904     * clone() which initiated it. If this becomes a problem for some
1905     * users who wish to allow that scenario, then this could be
1906     * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1907     * (and likewise for mems) to the new cgroup.
1908     */
1909    rcu_read_lock();
1910    cpuset_for_each_child(tmp_cs, pos_css, parent) {
1911        if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
1912            rcu_read_unlock();
1913            goto out_unlock;
1914        }
1915    }
1916    rcu_read_unlock();
1917
1918    mutex_lock(&callback_mutex);
1919    cs->mems_allowed = parent->mems_allowed;
1920    cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
1921    mutex_unlock(&callback_mutex);
1922out_unlock:
1923    mutex_unlock(&cpuset_mutex);
1924    return 0;
1925}
1926
1927/*
1928 * If the cpuset being removed has its flag 'sched_load_balance'
1929 * enabled, then simulate turning sched_load_balance off, which
1930 * will call rebuild_sched_domains_locked().
1931 */
1932
1933static void cpuset_css_offline(struct cgroup_subsys_state *css)
1934{
1935    struct cpuset *cs = css_cs(css);
1936
1937    mutex_lock(&cpuset_mutex);
1938
1939    if (is_sched_load_balance(cs))
1940        update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1941
1942    number_of_cpusets--;
1943    clear_bit(CS_ONLINE, &cs->flags);
1944
1945    mutex_unlock(&cpuset_mutex);
1946}
1947
1948static void cpuset_css_free(struct cgroup_subsys_state *css)
1949{
1950    struct cpuset *cs = css_cs(css);
1951
1952    free_cpumask_var(cs->cpus_allowed);
1953    kfree(cs);
1954}
1955
1956struct cgroup_subsys cpuset_cgrp_subsys = {
1957    .css_alloc = cpuset_css_alloc,
1958    .css_online = cpuset_css_online,
1959    .css_offline = cpuset_css_offline,
1960    .css_free = cpuset_css_free,
1961    .can_attach = cpuset_can_attach,
1962    .cancel_attach = cpuset_cancel_attach,
1963    .attach = cpuset_attach,
1964    .base_cftypes = files,
1965    .early_init = 1,
1966};
1967
1968/**
1969 * cpuset_init - initialize cpusets at system boot
1970 *
1971 * Description: Initialize top_cpuset and the cpuset internal file system,
1972 **/
1973
1974int __init cpuset_init(void)
1975{
1976    int err = 0;
1977
1978    if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
1979        BUG();
1980
1981    cpumask_setall(top_cpuset.cpus_allowed);
1982    nodes_setall(top_cpuset.mems_allowed);
1983
1984    fmeter_init(&top_cpuset.fmeter);
1985    set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1986    top_cpuset.relax_domain_level = -1;
1987
1988    err = register_filesystem(&cpuset_fs_type);
1989    if (err < 0)
1990        return err;
1991
1992    if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
1993        BUG();
1994
1995    number_of_cpusets = 1;
1996    return 0;
1997}
1998
1999/*
2000 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
2001 * or memory nodes, we need to walk over the cpuset hierarchy,
2002 * removing that CPU or node from all cpusets. If this removes the
2003 * last CPU or node from a cpuset, then move the tasks in the empty
2004 * cpuset to its next-highest non-empty parent.
2005 */
2006static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2007{
2008    struct cpuset *parent;
2009
2010    /*
2011     * Find its next-highest non-empty parent, (top cpuset
2012     * has online cpus, so can't be empty).
2013     */
2014    parent = parent_cs(cs);
2015    while (cpumask_empty(parent->cpus_allowed) ||
2016            nodes_empty(parent->mems_allowed))
2017        parent = parent_cs(parent);
2018
2019    if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
2020        printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset ");
2021        pr_cont_cgroup_name(cs->css.cgroup);
2022        pr_cont("\n");
2023    }
2024}
2025
2026/**
2027 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
2028 * @cs: cpuset in interest
2029 *
2030 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
2031 * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
2032 * all its tasks are moved to the nearest ancestor with both resources.
2033 */
2034static void cpuset_hotplug_update_tasks(struct cpuset *cs)
2035{
2036    static cpumask_t off_cpus;
2037    static nodemask_t off_mems;
2038    bool is_empty;
2039    bool sane = cgroup_sane_behavior(cs->css.cgroup);
2040
2041retry:
2042    wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
2043
2044    mutex_lock(&cpuset_mutex);
2045
2046    /*
2047     * We have raced with task attaching. We wait until attaching
2048     * is finished, so we won't attach a task to an empty cpuset.
2049     */
2050    if (cs->attach_in_progress) {
2051        mutex_unlock(&cpuset_mutex);
2052        goto retry;
2053    }
2054
2055    cpumask_andnot(&off_cpus, cs->cpus_allowed, top_cpuset.cpus_allowed);
2056    nodes_andnot(off_mems, cs->mems_allowed, top_cpuset.mems_allowed);
2057
2058    mutex_lock(&callback_mutex);
2059    cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, &off_cpus);
2060    mutex_unlock(&callback_mutex);
2061
2062    /*
2063     * If sane_behavior flag is set, we need to update tasks' cpumask
2064     * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
2065     * call update_tasks_cpumask() if the cpuset becomes empty, as
2066     * the tasks in it will be migrated to an ancestor.
2067     */
2068    if ((sane && cpumask_empty(cs->cpus_allowed)) ||
2069        (!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed)))
2070        update_tasks_cpumask(cs);
2071
2072    mutex_lock(&callback_mutex);
2073    nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
2074    mutex_unlock(&callback_mutex);
2075
2076    /*
2077     * If sane_behavior flag is set, we need to update tasks' nodemask
2078     * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
2079     * call update_tasks_nodemask() if the cpuset becomes empty, as
2080     * the tasks in it will be migratd to an ancestor.
2081     */
2082    if ((sane && nodes_empty(cs->mems_allowed)) ||
2083        (!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed)))
2084        update_tasks_nodemask(cs);
2085
2086    is_empty = cpumask_empty(cs->cpus_allowed) ||
2087        nodes_empty(cs->mems_allowed);
2088
2089    mutex_unlock(&cpuset_mutex);
2090
2091    /*
2092     * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
2093     *
2094     * Otherwise move tasks to the nearest ancestor with execution
2095     * resources. This is full cgroup operation which will
2096     * also call back into cpuset. Should be done outside any lock.
2097     */
2098    if (!sane && is_empty)
2099        remove_tasks_in_empty_cpuset(cs);
2100}
2101
2102/**
2103 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
2104 *
2105 * This function is called after either CPU or memory configuration has
2106 * changed and updates cpuset accordingly. The top_cpuset is always
2107 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
2108 * order to make cpusets transparent (of no affect) on systems that are
2109 * actively using CPU hotplug but making no active use of cpusets.
2110 *
2111 * Non-root cpusets are only affected by offlining. If any CPUs or memory
2112 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
2113 * all descendants.
2114 *
2115 * Note that CPU offlining during suspend is ignored. We don't modify
2116 * cpusets across suspend/resume cycles at all.
2117 */
2118static void cpuset_hotplug_workfn(struct work_struct *work)
2119{
2120    static cpumask_t new_cpus;
2121    static nodemask_t new_mems;
2122    bool cpus_updated, mems_updated;
2123
2124    mutex_lock(&cpuset_mutex);
2125
2126    /* fetch the available cpus/mems and find out which changed how */
2127    cpumask_copy(&new_cpus, cpu_active_mask);
2128    new_mems = node_states[N_MEMORY];
2129
2130    cpus_updated = !cpumask_equal(top_cpuset.cpus_allowed, &new_cpus);
2131    mems_updated = !nodes_equal(top_cpuset.mems_allowed, new_mems);
2132
2133    /* synchronize cpus_allowed to cpu_active_mask */
2134    if (cpus_updated) {
2135        mutex_lock(&callback_mutex);
2136        cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
2137        mutex_unlock(&callback_mutex);
2138        /* we don't mess with cpumasks of tasks in top_cpuset */
2139    }
2140
2141    /* synchronize mems_allowed to N_MEMORY */
2142    if (mems_updated) {
2143        mutex_lock(&callback_mutex);
2144        top_cpuset.mems_allowed = new_mems;
2145        mutex_unlock(&callback_mutex);
2146        update_tasks_nodemask(&top_cpuset);
2147    }
2148
2149    mutex_unlock(&cpuset_mutex);
2150
2151    /* if cpus or mems changed, we need to propagate to descendants */
2152    if (cpus_updated || mems_updated) {
2153        struct cpuset *cs;
2154        struct cgroup_subsys_state *pos_css;
2155
2156        rcu_read_lock();
2157        cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
2158            if (cs == &top_cpuset || !css_tryget(&cs->css))
2159                continue;
2160            rcu_read_unlock();
2161
2162            cpuset_hotplug_update_tasks(cs);
2163
2164            rcu_read_lock();
2165            css_put(&cs->css);
2166        }
2167        rcu_read_unlock();
2168    }
2169
2170    /* rebuild sched domains if cpus_allowed has changed */
2171    if (cpus_updated)
2172        rebuild_sched_domains();
2173}
2174
2175void cpuset_update_active_cpus(bool cpu_online)
2176{
2177    /*
2178     * We're inside cpu hotplug critical region which usually nests
2179     * inside cgroup synchronization. Bounce actual hotplug processing
2180     * to a work item to avoid reverse locking order.
2181     *
2182     * We still need to do partition_sched_domains() synchronously;
2183     * otherwise, the scheduler will get confused and put tasks to the
2184     * dead CPU. Fall back to the default single domain.
2185     * cpuset_hotplug_workfn() will rebuild it as necessary.
2186     */
2187    partition_sched_domains(1, NULL, NULL);
2188    schedule_work(&cpuset_hotplug_work);
2189}
2190
2191/*
2192 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
2193 * Call this routine anytime after node_states[N_MEMORY] changes.
2194 * See cpuset_update_active_cpus() for CPU hotplug handling.
2195 */
2196static int cpuset_track_online_nodes(struct notifier_block *self,
2197                unsigned long action, void *arg)
2198{
2199    schedule_work(&cpuset_hotplug_work);
2200    return NOTIFY_OK;
2201}
2202
2203static struct notifier_block cpuset_track_online_nodes_nb = {
2204    .notifier_call = cpuset_track_online_nodes,
2205    .priority = 10, /* ??! */
2206};
2207
2208/**
2209 * cpuset_init_smp - initialize cpus_allowed
2210 *
2211 * Description: Finish top cpuset after cpu, node maps are initialized
2212 */
2213void __init cpuset_init_smp(void)
2214{
2215    cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2216    top_cpuset.mems_allowed = node_states[N_MEMORY];
2217    top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
2218
2219    register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
2220}
2221
2222/**
2223 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2224 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2225 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2226 *
2227 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2228 * attached to the specified @tsk. Guaranteed to return some non-empty
2229 * subset of cpu_online_mask, even if this means going outside the
2230 * tasks cpuset.
2231 **/
2232
2233void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
2234{
2235    struct cpuset *cpus_cs;
2236
2237    mutex_lock(&callback_mutex);
2238    rcu_read_lock();
2239    cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
2240    guarantee_online_cpus(cpus_cs, pmask);
2241    rcu_read_unlock();
2242    mutex_unlock(&callback_mutex);
2243}
2244
2245void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2246{
2247    struct cpuset *cpus_cs;
2248
2249    rcu_read_lock();
2250    cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
2251    do_set_cpus_allowed(tsk, cpus_cs->cpus_allowed);
2252    rcu_read_unlock();
2253
2254    /*
2255     * We own tsk->cpus_allowed, nobody can change it under us.
2256     *
2257     * But we used cs && cs->cpus_allowed lockless and thus can
2258     * race with cgroup_attach_task() or update_cpumask() and get
2259     * the wrong tsk->cpus_allowed. However, both cases imply the
2260     * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2261     * which takes task_rq_lock().
2262     *
2263     * If we are called after it dropped the lock we must see all
2264     * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2265     * set any mask even if it is not right from task_cs() pov,
2266     * the pending set_cpus_allowed_ptr() will fix things.
2267     *
2268     * select_fallback_rq() will fix things ups and set cpu_possible_mask
2269     * if required.
2270     */
2271}
2272
2273void cpuset_init_current_mems_allowed(void)
2274{
2275    nodes_setall(current->mems_allowed);
2276}
2277
2278/**
2279 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2280 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2281 *
2282 * Description: Returns the nodemask_t mems_allowed of the cpuset
2283 * attached to the specified @tsk. Guaranteed to return some non-empty
2284 * subset of node_states[N_MEMORY], even if this means going outside the
2285 * tasks cpuset.
2286 **/
2287
2288nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2289{
2290    struct cpuset *mems_cs;
2291    nodemask_t mask;
2292
2293    mutex_lock(&callback_mutex);
2294    rcu_read_lock();
2295    mems_cs = effective_nodemask_cpuset(task_cs(tsk));
2296    guarantee_online_mems(mems_cs, &mask);
2297    rcu_read_unlock();
2298    mutex_unlock(&callback_mutex);
2299
2300    return mask;
2301}
2302
2303/**
2304 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2305 * @nodemask: the nodemask to be checked
2306 *
2307 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2308 */
2309int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2310{
2311    return nodes_intersects(*nodemask, current->mems_allowed);
2312}
2313
2314/*
2315 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2316 * mem_hardwall ancestor to the specified cpuset. Call holding
2317 * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
2318 * (an unusual configuration), then returns the root cpuset.
2319 */
2320static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
2321{
2322    while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
2323        cs = parent_cs(cs);
2324    return cs;
2325}
2326
2327/**
2328 * cpuset_node_allowed_softwall - Can we allocate on a memory node?
2329 * @node: is this an allowed node?
2330 * @gfp_mask: memory allocation flags
2331 *
2332 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2333 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2334 * yes. If it's not a __GFP_HARDWALL request and this node is in the nearest
2335 * hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been
2336 * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2337 * flag, yes.
2338 * Otherwise, no.
2339 *
2340 * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
2341 * cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall()
2342 * might sleep, and might allow a node from an enclosing cpuset.
2343 *
2344 * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
2345 * cpusets, and never sleeps.
2346 *
2347 * The __GFP_THISNODE placement logic is really handled elsewhere,
2348 * by forcibly using a zonelist starting at a specified node, and by
2349 * (in get_page_from_freelist()) refusing to consider the zones for
2350 * any node on the zonelist except the first. By the time any such
2351 * calls get to this routine, we should just shut up and say 'yes'.
2352 *
2353 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2354 * and do not allow allocations outside the current tasks cpuset
2355 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2356 * GFP_KERNEL allocations are not so marked, so can escape to the
2357 * nearest enclosing hardwalled ancestor cpuset.
2358 *
2359 * Scanning up parent cpusets requires callback_mutex. The
2360 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2361 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2362 * current tasks mems_allowed came up empty on the first pass over
2363 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
2364 * cpuset are short of memory, might require taking the callback_mutex
2365 * mutex.
2366 *
2367 * The first call here from mm/page_alloc:get_page_from_freelist()
2368 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2369 * so no allocation on a node outside the cpuset is allowed (unless
2370 * in interrupt, of course).
2371 *
2372 * The second pass through get_page_from_freelist() doesn't even call
2373 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2374 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2375 * in alloc_flags. That logic and the checks below have the combined
2376 * affect that:
2377 * in_interrupt - any node ok (current task context irrelevant)
2378 * GFP_ATOMIC - any node ok
2379 * TIF_MEMDIE - any node ok
2380 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
2381 * GFP_USER - only nodes in current tasks mems allowed ok.
2382 *
2383 * Rule:
2384 * Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2385 * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2386 * the code that might scan up ancestor cpusets and sleep.
2387 */
2388int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
2389{
2390    struct cpuset *cs; /* current cpuset ancestors */
2391    int allowed; /* is allocation in zone z allowed? */
2392
2393    if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2394        return 1;
2395    might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2396    if (node_isset(node, current->mems_allowed))
2397        return 1;
2398    /*
2399     * Allow tasks that have access to memory reserves because they have
2400     * been OOM killed to get memory anywhere.
2401     */
2402    if (unlikely(test_thread_flag(TIF_MEMDIE)))
2403        return 1;
2404    if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
2405        return 0;
2406
2407    if (current->flags & PF_EXITING) /* Let dying task have memory */
2408        return 1;
2409
2410    /* Not hardwall and node outside mems_allowed: scan up cpusets */
2411    mutex_lock(&callback_mutex);
2412
2413    rcu_read_lock();
2414    cs = nearest_hardwall_ancestor(task_cs(current));
2415    allowed = node_isset(node, cs->mems_allowed);
2416    rcu_read_unlock();
2417
2418    mutex_unlock(&callback_mutex);
2419    return allowed;
2420}
2421
2422/*
2423 * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
2424 * @node: is this an allowed node?
2425 * @gfp_mask: memory allocation flags
2426 *
2427 * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2428 * set, yes, we can always allocate. If node is in our task's mems_allowed,
2429 * yes. If the task has been OOM killed and has access to memory reserves as
2430 * specified by the TIF_MEMDIE flag, yes.
2431 * Otherwise, no.
2432 *
2433 * The __GFP_THISNODE placement logic is really handled elsewhere,
2434 * by forcibly using a zonelist starting at a specified node, and by
2435 * (in get_page_from_freelist()) refusing to consider the zones for
2436 * any node on the zonelist except the first. By the time any such
2437 * calls get to this routine, we should just shut up and say 'yes'.
2438 *
2439 * Unlike the cpuset_node_allowed_softwall() variant, above,
2440 * this variant requires that the node be in the current task's
2441 * mems_allowed or that we're in interrupt. It does not scan up the
2442 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2443 * It never sleeps.
2444 */
2445int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2446{
2447    if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2448        return 1;
2449    if (node_isset(node, current->mems_allowed))
2450        return 1;
2451    /*
2452     * Allow tasks that have access to memory reserves because they have
2453     * been OOM killed to get memory anywhere.
2454     */
2455    if (unlikely(test_thread_flag(TIF_MEMDIE)))
2456        return 1;
2457    return 0;
2458}
2459
2460/**
2461 * cpuset_mem_spread_node() - On which node to begin search for a file page
2462 * cpuset_slab_spread_node() - On which node to begin search for a slab page
2463 *
2464 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2465 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2466 * and if the memory allocation used cpuset_mem_spread_node()
2467 * to determine on which node to start looking, as it will for
2468 * certain page cache or slab cache pages such as used for file
2469 * system buffers and inode caches, then instead of starting on the
2470 * local node to look for a free page, rather spread the starting
2471 * node around the tasks mems_allowed nodes.
2472 *
2473 * We don't have to worry about the returned node being offline
2474 * because "it can't happen", and even if it did, it would be ok.
2475 *
2476 * The routines calling guarantee_online_mems() are careful to
2477 * only set nodes in task->mems_allowed that are online. So it
2478 * should not be possible for the following code to return an
2479 * offline node. But if it did, that would be ok, as this routine
2480 * is not returning the node where the allocation must be, only
2481 * the node where the search should start. The zonelist passed to
2482 * __alloc_pages() will include all nodes. If the slab allocator
2483 * is passed an offline node, it will fall back to the local node.
2484 * See kmem_cache_alloc_node().
2485 */
2486
2487static int cpuset_spread_node(int *rotor)
2488{
2489    int node;
2490
2491    node = next_node(*rotor, current->mems_allowed);
2492    if (node == MAX_NUMNODES)
2493        node = first_node(current->mems_allowed);
2494    *rotor = node;
2495    return node;
2496}
2497
2498int cpuset_mem_spread_node(void)
2499{
2500    if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
2501        current->cpuset_mem_spread_rotor =
2502            node_random(&current->mems_allowed);
2503
2504    return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
2505}
2506
2507int cpuset_slab_spread_node(void)
2508{
2509    if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
2510        current->cpuset_slab_spread_rotor =
2511            node_random(&current->mems_allowed);
2512
2513    return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
2514}
2515
2516EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2517
2518/**
2519 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2520 * @tsk1: pointer to task_struct of some task.
2521 * @tsk2: pointer to task_struct of some other task.
2522 *
2523 * Description: Return true if @tsk1's mems_allowed intersects the
2524 * mems_allowed of @tsk2. Used by the OOM killer to determine if
2525 * one of the task's memory usage might impact the memory available
2526 * to the other.
2527 **/
2528
2529int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2530                   const struct task_struct *tsk2)
2531{
2532    return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2533}
2534
2535#define CPUSET_NODELIST_LEN (256)
2536
2537/**
2538 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2539 * @task: pointer to task_struct of some task.
2540 *
2541 * Description: Prints @task's name, cpuset name, and cached copy of its
2542 * mems_allowed to the kernel log.
2543 */
2544void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2545{
2546     /* Statically allocated to prevent using excess stack. */
2547    static char cpuset_nodelist[CPUSET_NODELIST_LEN];
2548    static DEFINE_SPINLOCK(cpuset_buffer_lock);
2549    struct cgroup *cgrp;
2550
2551    spin_lock(&cpuset_buffer_lock);
2552    rcu_read_lock();
2553
2554    cgrp = task_cs(tsk)->css.cgroup;
2555    nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2556               tsk->mems_allowed);
2557    printk(KERN_INFO "%s cpuset=", tsk->comm);
2558    pr_cont_cgroup_name(cgrp);
2559    pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
2560
2561    rcu_read_unlock();
2562    spin_unlock(&cpuset_buffer_lock);
2563}
2564
2565/*
2566 * Collection of memory_pressure is suppressed unless
2567 * this flag is enabled by writing "1" to the special
2568 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2569 */
2570
2571int cpuset_memory_pressure_enabled __read_mostly;
2572
2573/**
2574 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2575 *
2576 * Keep a running average of the rate of synchronous (direct)
2577 * page reclaim efforts initiated by tasks in each cpuset.
2578 *
2579 * This represents the rate at which some task in the cpuset
2580 * ran low on memory on all nodes it was allowed to use, and
2581 * had to enter the kernels page reclaim code in an effort to
2582 * create more free memory by tossing clean pages or swapping
2583 * or writing dirty pages.
2584 *
2585 * Display to user space in the per-cpuset read-only file
2586 * "memory_pressure". Value displayed is an integer
2587 * representing the recent rate of entry into the synchronous
2588 * (direct) page reclaim by any task attached to the cpuset.
2589 **/
2590
2591void __cpuset_memory_pressure_bump(void)
2592{
2593    rcu_read_lock();
2594    fmeter_markevent(&task_cs(current)->fmeter);
2595    rcu_read_unlock();
2596}
2597
2598#ifdef CONFIG_PROC_PID_CPUSET
2599/*
2600 * proc_cpuset_show()
2601 * - Print tasks cpuset path into seq_file.
2602 * - Used for /proc/<pid>/cpuset.
2603 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2604 * doesn't really matter if tsk->cpuset changes after we read it,
2605 * and we take cpuset_mutex, keeping cpuset_attach() from changing it
2606 * anyway.
2607 */
2608int proc_cpuset_show(struct seq_file *m, void *unused_v)
2609{
2610    struct pid *pid;
2611    struct task_struct *tsk;
2612    char *buf, *p;
2613    struct cgroup_subsys_state *css;
2614    int retval;
2615
2616    retval = -ENOMEM;
2617    buf = kmalloc(PATH_MAX, GFP_KERNEL);
2618    if (!buf)
2619        goto out;
2620
2621    retval = -ESRCH;
2622    pid = m->private;
2623    tsk = get_pid_task(pid, PIDTYPE_PID);
2624    if (!tsk)
2625        goto out_free;
2626
2627    retval = -ENAMETOOLONG;
2628    rcu_read_lock();
2629    css = task_css(tsk, cpuset_cgrp_id);
2630    p = cgroup_path(css->cgroup, buf, PATH_MAX);
2631    rcu_read_unlock();
2632    if (!p)
2633        goto out_put_task;
2634    seq_puts(m, p);
2635    seq_putc(m, '\n');
2636    retval = 0;
2637out_put_task:
2638    put_task_struct(tsk);
2639out_free:
2640    kfree(buf);
2641out:
2642    return retval;
2643}
2644#endif /* CONFIG_PROC_PID_CPUSET */
2645
2646/* Display task mems_allowed in /proc/<pid>/status file. */
2647void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2648{
2649    seq_printf(m, "Mems_allowed:\t");
2650    seq_nodemask(m, &task->mems_allowed);
2651    seq_printf(m, "\n");
2652    seq_printf(m, "Mems_allowed_list:\t");
2653    seq_nodemask_list(m, &task->mems_allowed);
2654    seq_printf(m, "\n");
2655}
2656

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