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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/module.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 <asm/atomic.h>
59	#include <linux/mutex.h>
60	#include <linux/workqueue.h>
61	#include <linux/cgroup.h>
62
63	/*
64	* Workqueue for cpuset related tasks.
65	*
66	* Using kevent workqueue may cause deadlock when memory_migrate
67	* is set. So we create a separate workqueue thread for cpuset.
68	*/
69	static struct workqueue_struct *cpuset_wq;
70
71	/*
72	* Tracks how many cpusets are currently defined in system.
73	* When there is only one cpuset (the root cpuset) we can
74	* short circuit some hooks.
75	*/
76	int number_of_cpusets __read_mostly;
77
78	/* Forward declare cgroup structures */
79	struct cgroup_subsys cpuset_subsys;
80	struct cpuset;
81
82	/* See "Frequency meter" comments, below. */
83
84	struct fmeter {
85	int cnt; /* unprocessed events count */
86	int val; /* most recent output value */
87	time_t time; /* clock (secs) when val computed */
88	spinlock_t lock; /* guards read or write of above */
89	};
90
91	struct cpuset {
92	struct cgroup_subsys_state css;
93
94	unsigned long flags; /* "unsigned long" so bitops work */
95	cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
96	nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
97
98	struct cpuset parent; / my parent */
99
100	struct fmeter fmeter; /* memory_pressure filter */
101
102	/* partition number for rebuild_sched_domains() */
103	int pn;
104
105	/* for custom sched domain */
106	int relax_domain_level;
107
108	/* used for walking a cpuset hierarchy */
109	struct list_head stack_list;
110	};
111
112	/* Retrieve the cpuset for a cgroup */
113	static inline struct cpuset cgroup_cs(struct cgroup cont)
114	{
115	return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
116	struct cpuset, css);
117	}
118
119	/* Retrieve the cpuset for a task */
120	static inline struct cpuset task_cs(struct task_struct task)
121	{
122	return container_of(task_subsys_state(task, cpuset_subsys_id),
123	struct cpuset, css);
124	}
125
126	/* bits in struct cpuset flags field */
127	typedef enum {
128	CS_CPU_EXCLUSIVE,
129	CS_MEM_EXCLUSIVE,
130	CS_MEM_HARDWALL,
131	CS_MEMORY_MIGRATE,
132	CS_SCHED_LOAD_BALANCE,
133	CS_SPREAD_PAGE,
134	CS_SPREAD_SLAB,
135	} cpuset_flagbits_t;
136
137	/* convenient tests for these bits */
138	static inline int is_cpu_exclusive(const struct cpuset *cs)
139	{
140	return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
141	}
142
143	static inline int is_mem_exclusive(const struct cpuset *cs)
144	{
145	return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
146	}
147
148	static inline int is_mem_hardwall(const struct cpuset *cs)
149	{
150	return test_bit(CS_MEM_HARDWALL, &cs->flags);
151	}
152
153	static inline int is_sched_load_balance(const struct cpuset *cs)
154	{
155	return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
156	}
157
158	static inline int is_memory_migrate(const struct cpuset *cs)
159	{
160	return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
161	}
162
163	static inline int is_spread_page(const struct cpuset *cs)
164	{
165	return test_bit(CS_SPREAD_PAGE, &cs->flags);
166	}
167
168	static inline int is_spread_slab(const struct cpuset *cs)
169	{
170	return test_bit(CS_SPREAD_SLAB, &cs->flags);
171	}
172
173	static struct cpuset top_cpuset = {
174	.flags = ((1 << CS_CPU_EXCLUSIVE) \| (1 << CS_MEM_EXCLUSIVE)),
175	};
176
177	/*
178	* There are two global mutexes guarding cpuset structures. The first
179	* is the main control groups cgroup_mutex, accessed via
180	* cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific
181	* callback_mutex, below. They can nest. It is ok to first take
182	* cgroup_mutex, then nest callback_mutex. We also require taking
183	* task_lock() when dereferencing a task's cpuset pointer. See "The
184	* task_lock() exception", at the end of this comment.
185	*
186	* A task must hold both mutexes to modify cpusets. If a task
187	* holds cgroup_mutex, then it blocks others wanting that mutex,
188	* ensuring that it is the only task able to also acquire callback_mutex
189	* and be able to modify cpusets. It can perform various checks on
190	* the cpuset structure first, knowing nothing will change. It can
191	* also allocate memory while just holding cgroup_mutex. While it is
192	* performing these checks, various callback routines can briefly
193	* acquire callback_mutex to query cpusets. Once it is ready to make
194	* the changes, it takes callback_mutex, blocking everyone else.
195	*
196	* Calls to the kernel memory allocator can not be made while holding
197	* callback_mutex, as that would risk double tripping on callback_mutex
198	* from one of the callbacks into the cpuset code from within
199	* __alloc_pages().
200	*
201	* If a task is only holding callback_mutex, then it has read-only
202	* access to cpusets.
203	*
204	* Now, the task_struct fields mems_allowed and mempolicy may be changed
205	* by other task, we use alloc_lock in the task_struct fields to protect
206	* them.
207	*
208	* The cpuset_common_file_read() handlers only hold callback_mutex across
209	* small pieces of code, such as when reading out possibly multi-word
210	* cpumasks and nodemasks.
211	*
212	* Accessing a task's cpuset should be done in accordance with the
213	* guidelines for accessing subsystem state in kernel/cgroup.c
214	*/
215
216	static DEFINE_MUTEX(callback_mutex);
217
218	/*
219	* cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
220	* buffers. They are statically allocated to prevent using excess stack
221	* when calling cpuset_print_task_mems_allowed().
222	*/
223	#define CPUSET_NAME_LEN (128)
224	#define CPUSET_NODELIST_LEN (256)
225	static char cpuset_name[CPUSET_NAME_LEN];
226	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
227	static DEFINE_SPINLOCK(cpuset_buffer_lock);
228
229	/*
230	* This is ugly, but preserves the userspace API for existing cpuset
231	* users. If someone tries to mount the "cpuset" filesystem, we
232	* silently switch it to mount "cgroup" instead
233	*/
234	static struct dentry cpuset_mount(struct file_system_type fs_type,
235	int flags, const char unused_dev_name, void data)
236	{
237	struct file_system_type *cgroup_fs = get_fs_type("cgroup");
238	struct dentry *ret = ERR_PTR(-ENODEV);
239	if (cgroup_fs) {
240	char mountopts[] =
241	"cpuset,noprefix,"
242	"release_agent=/sbin/cpuset_release_agent";
243	ret = cgroup_fs->mount(cgroup_fs, flags,
244	unused_dev_name, mountopts);
245	put_filesystem(cgroup_fs);
246	}
247	return ret;
248	}
249
250	static struct file_system_type cpuset_fs_type = {
251	.name = "cpuset",
252	.mount = cpuset_mount,
253	};
254
255	/*
256	* Return in pmask the portion of a cpusets's cpus_allowed that
257	* are online. If none are online, walk up the cpuset hierarchy
258	* until we find one that does have some online cpus. If we get
259	* all the way to the top and still haven't found any online cpus,
260	* return cpu_online_map. Or if passed a NULL cs from an exit'ing
261	* task, return cpu_online_map.
262	*
263	* One way or another, we guarantee to return some non-empty subset
264	* of cpu_online_map.
265	*
266	* Call with callback_mutex held.
267	*/
268
269	static void guarantee_online_cpus(const struct cpuset *cs,
270	struct cpumask *pmask)
271	{
272	while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
273	cs = cs->parent;
274	if (cs)
275	cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
276	else
277	cpumask_copy(pmask, cpu_online_mask);
278	BUG_ON(!cpumask_intersects(pmask, cpu_online_mask));
279	}
280
281	/*
282	* Return in *pmask the portion of a cpusets's mems_allowed that
283	* are online, with memory. If none are online with memory, walk
284	* up the cpuset hierarchy until we find one that does have some
285	* online mems. If we get all the way to the top and still haven't
286	* found any online mems, return node_states[N_HIGH_MEMORY].
287	*
288	* One way or another, we guarantee to return some non-empty subset
289	* of node_states[N_HIGH_MEMORY].
290	*
291	* Call with callback_mutex held.
292	*/
293
294	static void guarantee_online_mems(const struct cpuset cs, nodemask_t pmask)
295	{
296	while (cs && !nodes_intersects(cs->mems_allowed,
297	node_states[N_HIGH_MEMORY]))
298	cs = cs->parent;
299	if (cs)
300	nodes_and(*pmask, cs->mems_allowed,
301	node_states[N_HIGH_MEMORY]);
302	else
303	*pmask = node_states[N_HIGH_MEMORY];
304	BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
305	}
306
307	/*
308	* update task's spread flag if cpuset's page/slab spread flag is set
309	*
310	* Called with callback_mutex/cgroup_mutex held
311	*/
312	static void cpuset_update_task_spread_flag(struct cpuset *cs,
313	struct task_struct *tsk)
314	{
315	if (is_spread_page(cs))
316	tsk->flags \|= PF_SPREAD_PAGE;
317	else
318	tsk->flags &= ~PF_SPREAD_PAGE;
319	if (is_spread_slab(cs))
320	tsk->flags \|= PF_SPREAD_SLAB;
321	else
322	tsk->flags &= ~PF_SPREAD_SLAB;
323	}
324
325	/*
326	* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
327	*
328	* One cpuset is a subset of another if all its allowed CPUs and
329	* Memory Nodes are a subset of the other, and its exclusive flags
330	* are only set if the other's are set. Call holding cgroup_mutex.
331	*/
332
333	static int is_cpuset_subset(const struct cpuset p, const struct cpuset q)
334	{
335	return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
336	nodes_subset(p->mems_allowed, q->mems_allowed) &&
337	is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
338	is_mem_exclusive(p) <= is_mem_exclusive(q);
339	}
340
341	/**
342	* alloc_trial_cpuset - allocate a trial cpuset
343	* @cs: the cpuset that the trial cpuset duplicates
344	*/
345	static struct cpuset alloc_trial_cpuset(const struct cpuset cs)
346	{
347	struct cpuset *trial;
348
349	trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
350	if (!trial)
351	return NULL;
352
353	if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) {
354	kfree(trial);
355	return NULL;
356	}
357	cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
358
359	return trial;
360	}
361
362	/**
363	* free_trial_cpuset - free the trial cpuset
364	* @trial: the trial cpuset to be freed
365	*/
366	static void free_trial_cpuset(struct cpuset *trial)
367	{
368	free_cpumask_var(trial->cpus_allowed);
369	kfree(trial);
370	}
371
372	/*
373	* validate_change() - Used to validate that any proposed cpuset change
374	* follows the structural rules for cpusets.
375	*
376	* If we replaced the flag and mask values of the current cpuset
377	* (cur) with those values in the trial cpuset (trial), would
378	* our various subset and exclusive rules still be valid? Presumes
379	* cgroup_mutex held.
380	*
381	* 'cur' is the address of an actual, in-use cpuset. Operations
382	* such as list traversal that depend on the actual address of the
383	* cpuset in the list must use cur below, not trial.
384	*
385	* 'trial' is the address of bulk structure copy of cur, with
386	* perhaps one or more of the fields cpus_allowed, mems_allowed,
387	* or flags changed to new, trial values.
388	*
389	* Return 0 if valid, -errno if not.
390	*/
391
392	static int validate_change(const struct cpuset cur, const struct cpuset trial)
393	{
394	struct cgroup *cont;
395	struct cpuset c, par;
396
397	/* Each of our child cpusets must be a subset of us */
398	list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
399	if (!is_cpuset_subset(cgroup_cs(cont), trial))
400	return -EBUSY;
401	}
402
403	/* Remaining checks don't apply to root cpuset */
404	if (cur == &top_cpuset)
405	return 0;
406
407	par = cur->parent;
408
409	/* We must be a subset of our parent cpuset */
410	if (!is_cpuset_subset(trial, par))
411	return -EACCES;
412
413	/*
414	* If either I or some sibling (!= me) is exclusive, we can't
415	* overlap
416	*/
417	list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
418	c = cgroup_cs(cont);
419	if ((is_cpu_exclusive(trial) \|\| is_cpu_exclusive(c)) &&
420	c != cur &&
421	cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
422	return -EINVAL;
423	if ((is_mem_exclusive(trial) \|\| is_mem_exclusive(c)) &&
424	c != cur &&
425	nodes_intersects(trial->mems_allowed, c->mems_allowed))
426	return -EINVAL;
427	}
428
429	/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
430	if (cgroup_task_count(cur->css.cgroup)) {
431	if (cpumask_empty(trial->cpus_allowed) \|\|
432	nodes_empty(trial->mems_allowed)) {
433	return -ENOSPC;
434	}
435	}
436
437	return 0;
438	}
439
440	#ifdef CONFIG_SMP
441	/*
442	* Helper routine for generate_sched_domains().
443	* Do cpusets a, b have overlapping cpus_allowed masks?
444	*/
445	static int cpusets_overlap(struct cpuset a, struct cpuset b)
446	{
447	return cpumask_intersects(a->cpus_allowed, b->cpus_allowed);
448	}
449
450	static void
451	update_domain_attr(struct sched_domain_attr dattr, struct cpuset c)
452	{
453	if (dattr->relax_domain_level < c->relax_domain_level)
454	dattr->relax_domain_level = c->relax_domain_level;
455	return;
456	}
457
458	static void
459	update_domain_attr_tree(struct sched_domain_attr dattr, struct cpuset c)
460	{
461	LIST_HEAD(q);
462
463	list_add(&c->stack_list, &q);
464	while (!list_empty(&q)) {
465	struct cpuset *cp;
466	struct cgroup *cont;
467	struct cpuset *child;
468
469	cp = list_first_entry(&q, struct cpuset, stack_list);
470	list_del(q.next);
471
472	if (cpumask_empty(cp->cpus_allowed))
473	continue;
474
475	if (is_sched_load_balance(cp))
476	update_domain_attr(dattr, cp);
477
478	list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
479	child = cgroup_cs(cont);
480	list_add_tail(&child->stack_list, &q);
481	}
482	}
483	}
484
485	/*
486	* generate_sched_domains()
487	*
488	* This function builds a partial partition of the systems CPUs
489	* A 'partial partition' is a set of non-overlapping subsets whose
490	* union is a subset of that set.
491	* The output of this function needs to be passed to kernel/sched.c
492	* partition_sched_domains() routine, which will rebuild the scheduler's
493	* load balancing domains (sched domains) as specified by that partial
494	* partition.
495	*
496	* See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
497	* for a background explanation of this.
498	*
499	* Does not return errors, on the theory that the callers of this
500	* routine would rather not worry about failures to rebuild sched
501	* domains when operating in the severe memory shortage situations
502	* that could cause allocation failures below.
503	*
504	* Must be called with cgroup_lock held.
505	*
506	* The three key local variables below are:
507	* q - a linked-list queue of cpuset pointers, used to implement a
508	* top-down scan of all cpusets. This scan loads a pointer
509	* to each cpuset marked is_sched_load_balance into the
510	* array 'csa'. For our purposes, rebuilding the schedulers
511	* sched domains, we can ignore !is_sched_load_balance cpusets.
512	* csa - (for CpuSet Array) Array of pointers to all the cpusets
513	* that need to be load balanced, for convenient iterative
514	* access by the subsequent code that finds the best partition,
515	* i.e the set of domains (subsets) of CPUs such that the
516	* cpus_allowed of every cpuset marked is_sched_load_balance
517	* is a subset of one of these domains, while there are as
518	* many such domains as possible, each as small as possible.
519	* doms - Conversion of 'csa' to an array of cpumasks, for passing to
520	* the kernel/sched.c routine partition_sched_domains() in a
521	* convenient format, that can be easily compared to the prior
522	* value to determine what partition elements (sched domains)
523	* were changed (added or removed.)
524	*
525	* Finding the best partition (set of domains):
526	* The triple nested loops below over i, j, k scan over the
527	* load balanced cpusets (using the array of cpuset pointers in
528	* csa[]) looking for pairs of cpusets that have overlapping
529	* cpus_allowed, but which don't have the same 'pn' partition
530	* number and gives them in the same partition number. It keeps
531	* looping on the 'restart' label until it can no longer find
532	* any such pairs.
533	*
534	* The union of the cpus_allowed masks from the set of
535	* all cpusets having the same 'pn' value then form the one
536	* element of the partition (one sched domain) to be passed to
537	* partition_sched_domains().
538	*/
539	static int generate_sched_domains(cpumask_var_t **domains,
540	struct sched_domain_attr **attributes)
541	{
542	LIST_HEAD(q); /* queue of cpusets to be scanned */
543	struct cpuset cp; / scans q */
544	struct cpuset *csa; / array of all cpuset ptrs */
545	int csn; /* how many cpuset ptrs in csa so far */
546	int i, j, k; /* indices for partition finding loops */
547	cpumask_var_t doms; / resulting partition; i.e. sched domains */
548	struct sched_domain_attr dattr; / attributes for custom domains */
549	int ndoms = 0; /* number of sched domains in result */
550	int nslot; /* next empty doms[] struct cpumask slot */
551
552	doms = NULL;
553	dattr = NULL;
554	csa = NULL;
555
556	/* Special case for the 99% of systems with one, full, sched domain */
557	if (is_sched_load_balance(&top_cpuset)) {
558	ndoms = 1;
559	doms = alloc_sched_domains(ndoms);
560	if (!doms)
561	goto done;
562
563	dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
564	if (dattr) {
565	*dattr = SD_ATTR_INIT;
566	update_domain_attr_tree(dattr, &top_cpuset);
567	}
568	cpumask_copy(doms[0], top_cpuset.cpus_allowed);
569
570	goto done;
571	}
572
573	csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
574	if (!csa)
575	goto done;
576	csn = 0;
577
578	list_add(&top_cpuset.stack_list, &q);
579	while (!list_empty(&q)) {
580	struct cgroup *cont;
581	struct cpuset child; / scans child cpusets of cp */
582
583	cp = list_first_entry(&q, struct cpuset, stack_list);
584	list_del(q.next);
585
586	if (cpumask_empty(cp->cpus_allowed))
587	continue;
588
589	/*
590	* All child cpusets contain a subset of the parent's cpus, so
591	* just skip them, and then we call update_domain_attr_tree()
592	* to calc relax_domain_level of the corresponding sched
593	* domain.
594	*/
595	if (is_sched_load_balance(cp)) {
596	csa[csn++] = cp;
597	continue;
598	}
599
600	list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
601	child = cgroup_cs(cont);
602	list_add_tail(&child->stack_list, &q);
603	}
604	}
605
606	for (i = 0; i < csn; i++)
607	csa[i]->pn = i;
608	ndoms = csn;
609
610	restart:
611	/* Find the best partition (set of sched domains) */
612	for (i = 0; i < csn; i++) {
613	struct cpuset *a = csa[i];
614	int apn = a->pn;
615
616	for (j = 0; j < csn; j++) {
617	struct cpuset *b = csa[j];
618	int bpn = b->pn;
619
620	if (apn != bpn && cpusets_overlap(a, b)) {
621	for (k = 0; k < csn; k++) {
622	struct cpuset *c = csa[k];
623
624	if (c->pn == bpn)
625	c->pn = apn;
626	}
627	ndoms--; /* one less element */
628	goto restart;
629	}
630	}
631	}
632
633	/*
634	* Now we know how many domains to create.
635	* Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
636	*/
637	doms = alloc_sched_domains(ndoms);
638	if (!doms)
639	goto done;
640
641	/*
642	* The rest of the code, including the scheduler, can deal with
643	* dattr==NULL case. No need to abort if alloc fails.
644	*/
645	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
646
647	for (nslot = 0, i = 0; i < csn; i++) {
648	struct cpuset *a = csa[i];
649	struct cpumask *dp;
650	int apn = a->pn;
651
652	if (apn < 0) {
653	/* Skip completed partitions */
654	continue;
655	}
656
657	dp = doms[nslot];
658
659	if (nslot == ndoms) {
660	static int warnings = 10;
661	if (warnings) {
662	printk(KERN_WARNING
663	"rebuild_sched_domains confused:"
664	" nslot %d, ndoms %d, csn %d, i %d,"
665	" apn %d\n",
666	nslot, ndoms, csn, i, apn);
667	warnings--;
668	}
669	continue;
670	}
671
672	cpumask_clear(dp);
673	if (dattr)
674	*(dattr + nslot) = SD_ATTR_INIT;
675	for (j = i; j < csn; j++) {
676	struct cpuset *b = csa[j];
677
678	if (apn == b->pn) {
679	cpumask_or(dp, dp, b->cpus_allowed);
680	if (dattr)
681	update_domain_attr_tree(dattr + nslot, b);
682
683	/* Done with this partition */
684	b->pn = -1;
685	}
686	}
687	nslot++;
688	}
689	BUG_ON(nslot != ndoms);
690
691	done:
692	kfree(csa);
693
694	/*
695	* Fallback to the default domain if kmalloc() failed.
696	* See comments in partition_sched_domains().
697	*/
698	if (doms == NULL)
699	ndoms = 1;
700
701	*domains = doms;
702	*attributes = dattr;
703	return ndoms;
704	}
705
706	/*
707	* Rebuild scheduler domains.
708	*
709	* Call with neither cgroup_mutex held nor within get_online_cpus().
710	* Takes both cgroup_mutex and get_online_cpus().
711	*
712	* Cannot be directly called from cpuset code handling changes
713	* to the cpuset pseudo-filesystem, because it cannot be called
714	* from code that already holds cgroup_mutex.
715	*/
716	static void do_rebuild_sched_domains(struct work_struct *unused)
717	{
718	struct sched_domain_attr *attr;
719	cpumask_var_t *doms;
720	int ndoms;
721
722	get_online_cpus();
723
724	/* Generate domain masks and attrs */
725	cgroup_lock();
726	ndoms = generate_sched_domains(&doms, &attr);
727	cgroup_unlock();
728
729	/* Have scheduler rebuild the domains */
730	partition_sched_domains(ndoms, doms, attr);
731
732	put_online_cpus();
733	}
734	#else /* !CONFIG_SMP */
735	static void do_rebuild_sched_domains(struct work_struct *unused)
736	{
737	}
738
739	static int generate_sched_domains(cpumask_var_t **domains,
740	struct sched_domain_attr **attributes)
741	{
742	*domains = NULL;
743	return 1;
744	}
745	#endif /* CONFIG_SMP */
746
747	static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
748
749	/*
750	* Rebuild scheduler domains, asynchronously via workqueue.
751	*
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.
757	*
758	* The rebuild_sched_domains() and partition_sched_domains()
759	* routines must nest cgroup_lock() inside get_online_cpus(),
760	* but such cpuset changes as these must nest that locking the
761	* other way, holding cgroup_lock() for much of the code.
762	*
763	* So in order to avoid an ABBA deadlock, the cpuset code handling
764	* these user changes delegates the actual sched domain rebuilding
765	* to a separate workqueue thread, which ends up processing the
766	* above do_rebuild_sched_domains() function.
767	*/
768	static void async_rebuild_sched_domains(void)
769	{
770	queue_work(cpuset_wq, &rebuild_sched_domains_work);
771	}
772
773	/*
774	* Accomplishes the same scheduler domain rebuild as the above
775	* async_rebuild_sched_domains(), however it directly calls the
776	* rebuild routine synchronously rather than calling it via an
777	* asynchronous work thread.
778	*
779	* This can only be called from code that is not holding
780	* cgroup_mutex (not nested in a cgroup_lock() call.)
781	*/
782	void rebuild_sched_domains(void)
783	{
784	do_rebuild_sched_domains(NULL);
785	}
786
787	/**
788	* cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
789	* @tsk: task to test
790	* @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
791	*
792	* Call with cgroup_mutex held. May take callback_mutex during call.
793	* Called for each task in a cgroup by cgroup_scan_tasks().
794	* Return nonzero if this tasks's cpus_allowed mask should be changed (in other
795	* words, if its mask is not equal to its cpuset's mask).
796	*/
797	static int cpuset_test_cpumask(struct task_struct *tsk,
798	struct cgroup_scanner *scan)
799	{
800	return !cpumask_equal(&tsk->cpus_allowed,
801	(cgroup_cs(scan->cg))->cpus_allowed);
802	}
803
804	/**
805	* cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
806	* @tsk: task to test
807	* @scan: struct cgroup_scanner containing the cgroup of the task
808	*
809	* Called by cgroup_scan_tasks() for each task in a cgroup whose
810	* cpus_allowed mask needs to be changed.
811	*
812	* We don't need to re-check for the cgroup/cpuset membership, since we're
813	* holding cgroup_lock() at this point.
814	*/
815	static void cpuset_change_cpumask(struct task_struct *tsk,
816	struct cgroup_scanner *scan)
817	{
818	set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
819	}
820
821	/**
822	* update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
823	* @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
824	* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
825	*
826	* Called with cgroup_mutex held
827	*
828	* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
829	* calling callback functions for each.
830	*
831	* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
832	* if @heap != NULL.
833	*/
834	static void update_tasks_cpumask(struct cpuset cs, struct ptr_heap heap)
835	{
836	struct cgroup_scanner scan;
837
838	scan.cg = cs->css.cgroup;
839	scan.test_task = cpuset_test_cpumask;
840	scan.process_task = cpuset_change_cpumask;
841	scan.heap = heap;
842	cgroup_scan_tasks(&scan);
843	}
844
845	/**
846	* update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
847	* @cs: the cpuset to consider
848	* @buf: buffer of cpu numbers written to this cpuset
849	*/
850	static int update_cpumask(struct cpuset cs, struct cpuset trialcs,
851	const char *buf)
852	{
853	struct ptr_heap heap;
854	int retval;
855	int is_load_balanced;
856
857	/* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
858	if (cs == &top_cpuset)
859	return -EACCES;
860
861	/*
862	* An empty cpus_allowed is ok only if the cpuset has no tasks.
863	* Since cpulist_parse() fails on an empty mask, we special case
864	* that parsing. The validate_change() call ensures that cpusets
865	* with tasks have cpus.
866	*/
867	if (!*buf) {
868	cpumask_clear(trialcs->cpus_allowed);
869	} else {
870	retval = cpulist_parse(buf, trialcs->cpus_allowed);
871	if (retval < 0)
872	return retval;
873
874	if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
875	return -EINVAL;
876	}
877	retval = validate_change(cs, trialcs);
878	if (retval < 0)
879	return retval;
880
881	/* Nothing to do if the cpus didn't change */
882	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
883	return 0;
884
885	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
886	if (retval)
887	return retval;
888
889	is_load_balanced = is_sched_load_balance(trialcs);
890
891	mutex_lock(&callback_mutex);
892	cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
893	mutex_unlock(&callback_mutex);
894
895	/*
896	* Scan tasks in the cpuset, and update the cpumasks of any
897	* that need an update.
898	*/
899	update_tasks_cpumask(cs, &heap);
900
901	heap_free(&heap);
902
903	if (is_load_balanced)
904	async_rebuild_sched_domains();
905	return 0;
906	}
907
908	/*
909	* cpuset_migrate_mm
910	*
911	* Migrate memory region from one set of nodes to another.
912	*
913	* Temporarilly set tasks mems_allowed to target nodes of migration,
914	* so that the migration code can allocate pages on these nodes.
915	*
916	* Call holding cgroup_mutex, so current's cpuset won't change
917	* during this call, as manage_mutex holds off any cpuset_attach()
918	* calls. Therefore we don't need to take task_lock around the
919	* call to guarantee_online_mems(), as we know no one is changing
920	* our task's cpuset.
921	*
922	* While the mm_struct we are migrating is typically from some
923	* other task, the task_struct mems_allowed that we are hacking
924	* is for our current task, which must allocate new pages for that
925	* migrating memory region.
926	*/
927
928	static void cpuset_migrate_mm(struct mm_struct mm, const nodemask_t from,
929	const nodemask_t *to)
930	{
931	struct task_struct *tsk = current;
932
933	tsk->mems_allowed = *to;
934
935	do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
936
937	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
938	}
939
940	/*
941	* cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
942	* @tsk: the task to change
943	* @newmems: new nodes that the task will be set
944	*
945	* In order to avoid seeing no nodes if the old and new nodes are disjoint,
946	* we structure updates as setting all new allowed nodes, then clearing newly
947	* disallowed ones.
948	*/
949	static void cpuset_change_task_nodemask(struct task_struct *tsk,
950	nodemask_t *newmems)
951	{
952	repeat:
953	/*
954	* Allow tasks that have access to memory reserves because they have
955	* been OOM killed to get memory anywhere.
956	*/
957	if (unlikely(test_thread_flag(TIF_MEMDIE)))
958	return;
959	if (current->flags & PF_EXITING) /* Let dying task have memory */
960	return;
961
962	task_lock(tsk);
963	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
964	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
965
966
967	/*
968	* ensure checking ->mems_allowed_change_disable after setting all new
969	* allowed nodes.
970	*
971	* the read-side task can see an nodemask with new allowed nodes and
972	* old allowed nodes. and if it allocates page when cpuset clears newly
973	* disallowed ones continuous, it can see the new allowed bits.
974	*
975	* And if setting all new allowed nodes is after the checking, setting
976	* all new allowed nodes and clearing newly disallowed ones will be done
977	* continuous, and the read-side task may find no node to alloc page.
978	*/
979	smp_mb();
980
981	/*
982	* Allocation of memory is very fast, we needn't sleep when waiting
983	* for the read-side.
984	*/
985	while (ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
986	task_unlock(tsk);
987	if (!task_curr(tsk))
988	yield();
989	goto repeat;
990	}
991
992	/*
993	* ensure checking ->mems_allowed_change_disable before clearing all new
994	* disallowed nodes.
995	*
996	* if clearing newly disallowed bits before the checking, the read-side
997	* task may find no node to alloc page.
998	*/
999	smp_mb();
1000
1001	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
1002	tsk->mems_allowed = *newmems;
1003	task_unlock(tsk);
1004	}
1005
1006	/*
1007	* Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
1008	* of it to cpuset's new mems_allowed, and migrate pages to new nodes if
1009	* memory_migrate flag is set. Called with cgroup_mutex held.
1010	*/
1011	static void cpuset_change_nodemask(struct task_struct *p,
1012	struct cgroup_scanner *scan)
1013	{
1014	struct mm_struct *mm;
1015	struct cpuset *cs;
1016	int migrate;
1017	const nodemask_t *oldmem = scan->data;
1018	NODEMASK_ALLOC(nodemask_t, newmems, GFP_KERNEL);
1019
1020	if (!newmems)
1021	return;
1022
1023	cs = cgroup_cs(scan->cg);
1024	guarantee_online_mems(cs, newmems);
1025
1026	cpuset_change_task_nodemask(p, newmems);
1027
1028	NODEMASK_FREE(newmems);
1029
1030	mm = get_task_mm(p);
1031	if (!mm)
1032	return;
1033
1034	migrate = is_memory_migrate(cs);
1035
1036	mpol_rebind_mm(mm, &cs->mems_allowed);
1037	if (migrate)
1038	cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
1039	mmput(mm);
1040	}
1041
1042	static void *cpuset_being_rebound;
1043
1044	/**
1045	* update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1046	* @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1047	* @oldmem: old mems_allowed of cpuset cs
1048	* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1049	*
1050	* Called with cgroup_mutex held
1051	* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1052	* if @heap != NULL.
1053	*/
1054	static void update_tasks_nodemask(struct cpuset cs, const nodemask_t oldmem,
1055	struct ptr_heap *heap)
1056	{
1057	struct cgroup_scanner scan;
1058
1059	cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1060
1061	scan.cg = cs->css.cgroup;
1062	scan.test_task = NULL;
1063	scan.process_task = cpuset_change_nodemask;
1064	scan.heap = heap;
1065	scan.data = (nodemask_t *)oldmem;
1066
1067	/*
1068	* The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1069	* take while holding tasklist_lock. Forks can happen - the
1070	* mpol_dup() cpuset_being_rebound check will catch such forks,
1071	* and rebind their vma mempolicies too. Because we still hold
1072	* the global cgroup_mutex, we know that no other rebind effort
1073	* will be contending for the global variable cpuset_being_rebound.
1074	* It's ok if we rebind the same mm twice; mpol_rebind_mm()
1075	* is idempotent. Also migrate pages in each mm to new nodes.
1076	*/
1077	cgroup_scan_tasks(&scan);
1078
1079	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1080	cpuset_being_rebound = NULL;
1081	}
1082
1083	/*
1084	* Handle user request to change the 'mems' memory placement
1085	* of a cpuset. Needs to validate the request, update the
1086	* cpusets mems_allowed, and for each task in the cpuset,
1087	* update mems_allowed and rebind task's mempolicy and any vma
1088	* mempolicies and if the cpuset is marked 'memory_migrate',
1089	* migrate the tasks pages to the new memory.
1090	*
1091	* Call with cgroup_mutex held. May take callback_mutex during call.
1092	* Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1093	* lock each such tasks mm->mmap_sem, scan its vma's and rebind
1094	* their mempolicies to the cpusets new mems_allowed.
1095	*/
1096	static int update_nodemask(struct cpuset cs, struct cpuset trialcs,
1097	const char *buf)
1098	{
1099	NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
1100	int retval;
1101	struct ptr_heap heap;
1102
1103	if (!oldmem)
1104	return -ENOMEM;
1105
1106	/*
1107	* top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
1108	* it's read-only
1109	*/
1110	if (cs == &top_cpuset) {
1111	retval = -EACCES;
1112	goto done;
1113	}
1114
1115	/*
1116	* An empty mems_allowed is ok iff there are no tasks in the cpuset.
1117	* Since nodelist_parse() fails on an empty mask, we special case
1118	* that parsing. The validate_change() call ensures that cpusets
1119	* with tasks have memory.
1120	*/
1121	if (!*buf) {
1122	nodes_clear(trialcs->mems_allowed);
1123	} else {
1124	retval = nodelist_parse(buf, trialcs->mems_allowed);
1125	if (retval < 0)
1126	goto done;
1127
1128	if (!nodes_subset(trialcs->mems_allowed,
1129	node_states[N_HIGH_MEMORY])) {
1130	retval = -EINVAL;
1131	goto done;
1132	}
1133	}
1134	*oldmem = cs->mems_allowed;
1135	if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
1136	retval = 0; /* Too easy - nothing to do */
1137	goto done;
1138	}
1139	retval = validate_change(cs, trialcs);
1140	if (retval < 0)
1141	goto done;
1142
1143	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
1144	if (retval < 0)
1145	goto done;
1146
1147	mutex_lock(&callback_mutex);
1148	cs->mems_allowed = trialcs->mems_allowed;
1149	mutex_unlock(&callback_mutex);
1150
1151	update_tasks_nodemask(cs, oldmem, &heap);
1152
1153	heap_free(&heap);
1154	done:
1155	NODEMASK_FREE(oldmem);
1156	return retval;
1157	}
1158
1159	int current_cpuset_is_being_rebound(void)
1160	{
1161	return task_cs(current) == cpuset_being_rebound;
1162	}
1163
1164	static int update_relax_domain_level(struct cpuset *cs, s64 val)
1165	{
1166	#ifdef CONFIG_SMP
1167	if (val < -1 \|\| val >= SD_LV_MAX)
1168	return -EINVAL;
1169	#endif
1170
1171	if (val != cs->relax_domain_level) {
1172	cs->relax_domain_level = val;
1173	if (!cpumask_empty(cs->cpus_allowed) &&
1174	is_sched_load_balance(cs))
1175	async_rebuild_sched_domains();
1176	}
1177
1178	return 0;
1179	}
1180
1181	/*
1182	* cpuset_change_flag - make a task's spread flags the same as its cpuset's
1183	* @tsk: task to be updated
1184	* @scan: struct cgroup_scanner containing the cgroup of the task
1185	*
1186	* Called by cgroup_scan_tasks() for each task in a cgroup.
1187	*
1188	* We don't need to re-check for the cgroup/cpuset membership, since we're
1189	* holding cgroup_lock() at this point.
1190	*/
1191	static void cpuset_change_flag(struct task_struct *tsk,
1192	struct cgroup_scanner *scan)
1193	{
1194	cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk);
1195	}
1196
1197	/*
1198	* update_tasks_flags - update the spread flags of tasks in the cpuset.
1199	* @cs: the cpuset in which each task's spread flags needs to be changed
1200	* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
1201	*
1202	* Called with cgroup_mutex held
1203	*
1204	* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1205	* calling callback functions for each.
1206	*
1207	* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
1208	* if @heap != NULL.
1209	*/
1210	static void update_tasks_flags(struct cpuset cs, struct ptr_heap heap)
1211	{
1212	struct cgroup_scanner scan;
1213
1214	scan.cg = cs->css.cgroup;
1215	scan.test_task = NULL;
1216	scan.process_task = cpuset_change_flag;
1217	scan.heap = heap;
1218	cgroup_scan_tasks(&scan);
1219	}
1220
1221	/*
1222	* update_flag - read a 0 or a 1 in a file and update associated flag
1223	* bit: the bit to update (see cpuset_flagbits_t)
1224	* cs: the cpuset to update
1225	* turning_on: whether the flag is being set or cleared
1226	*
1227	* Call with cgroup_mutex held.
1228	*/
1229
1230	static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1231	int turning_on)
1232	{
1233	struct cpuset *trialcs;
1234	int balance_flag_changed;
1235	int spread_flag_changed;
1236	struct ptr_heap heap;
1237	int err;
1238
1239	trialcs = alloc_trial_cpuset(cs);
1240	if (!trialcs)
1241	return -ENOMEM;
1242
1243	if (turning_on)
1244	set_bit(bit, &trialcs->flags);
1245	else
1246	clear_bit(bit, &trialcs->flags);
1247
1248	err = validate_change(cs, trialcs);
1249	if (err < 0)
1250	goto out;
1251
1252	err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
1253	if (err < 0)
1254	goto out;
1255
1256	balance_flag_changed = (is_sched_load_balance(cs) !=
1257	is_sched_load_balance(trialcs));
1258
1259	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1260	\|\| (is_spread_page(cs) != is_spread_page(trialcs)));
1261
1262	mutex_lock(&callback_mutex);
1263	cs->flags = trialcs->flags;
1264	mutex_unlock(&callback_mutex);
1265
1266	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
1267	async_rebuild_sched_domains();
1268
1269	if (spread_flag_changed)
1270	update_tasks_flags(cs, &heap);
1271	heap_free(&heap);
1272	out:
1273	free_trial_cpuset(trialcs);
1274	return err;
1275	}
1276
1277	/*
1278	* Frequency meter - How fast is some event occurring?
1279	*
1280	* These routines manage a digitally filtered, constant time based,
1281	* event frequency meter. There are four routines:
1282	* fmeter_init() - initialize a frequency meter.
1283	* fmeter_markevent() - called each time the event happens.
1284	* fmeter_getrate() - returns the recent rate of such events.
1285	* fmeter_update() - internal routine used to update fmeter.
1286	*
1287	* A common data structure is passed to each of these routines,
1288	* which is used to keep track of the state required to manage the
1289	* frequency meter and its digital filter.
1290	*
1291	* The filter works on the number of events marked per unit time.
1292	* The filter is single-pole low-pass recursive (IIR). The time unit
1293	* is 1 second. Arithmetic is done using 32-bit integers scaled to
1294	* simulate 3 decimal digits of precision (multiplied by 1000).
1295	*
1296	* With an FM_COEF of 933, and a time base of 1 second, the filter
1297	* has a half-life of 10 seconds, meaning that if the events quit
1298	* happening, then the rate returned from the fmeter_getrate()
1299	* will be cut in half each 10 seconds, until it converges to zero.
1300	*
1301	* It is not worth doing a real infinitely recursive filter. If more
1302	* than FM_MAXTICKS ticks have elapsed since the last filter event,
1303	* just compute FM_MAXTICKS ticks worth, by which point the level
1304	* will be stable.
1305	*
1306	* Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1307	* arithmetic overflow in the fmeter_update() routine.
1308	*
1309	* Given the simple 32 bit integer arithmetic used, this meter works
1310	* best for reporting rates between one per millisecond (msec) and
1311	* one per 32 (approx) seconds. At constant rates faster than one
1312	* per msec it maxes out at values just under 1,000,000. At constant
1313	* rates between one per msec, and one per second it will stabilize
1314	* to a value N*1000, where N is the rate of events per second.
1315	* At constant rates between one per second and one per 32 seconds,
1316	* it will be choppy, moving up on the seconds that have an event,
1317	* and then decaying until the next event. At rates slower than
1318	* about one in 32 seconds, it decays all the way back to zero between
1319	* each event.
1320	*/
1321
1322	#define FM_COEF 933 /* coefficient for half-life of 10 secs */
1323	#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1324	#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1325	#define FM_SCALE 1000 /* faux fixed point scale */
1326
1327	/* Initialize a frequency meter */
1328	static void fmeter_init(struct fmeter *fmp)
1329	{
1330	fmp->cnt = 0;
1331	fmp->val = 0;
1332	fmp->time = 0;
1333	spin_lock_init(&fmp->lock);
1334	}
1335
1336	/* Internal meter update - process cnt events and update value */
1337	static void fmeter_update(struct fmeter *fmp)
1338	{
1339	time_t now = get_seconds();
1340	time_t ticks = now - fmp->time;
1341
1342	if (ticks == 0)
1343	return;
1344
1345	ticks = min(FM_MAXTICKS, ticks);
1346	while (ticks-- > 0)
1347	fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1348	fmp->time = now;
1349
1350	fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1351	fmp->cnt = 0;
1352	}
1353
1354	/* Process any previous ticks, then bump cnt by one (times scale). */
1355	static void fmeter_markevent(struct fmeter *fmp)
1356	{
1357	spin_lock(&fmp->lock);
1358	fmeter_update(fmp);
1359	fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1360	spin_unlock(&fmp->lock);
1361	}
1362
1363	/* Process any previous ticks, then return current value. */
1364	static int fmeter_getrate(struct fmeter *fmp)
1365	{
1366	int val;
1367
1368	spin_lock(&fmp->lock);
1369	fmeter_update(fmp);
1370	val = fmp->val;
1371	spin_unlock(&fmp->lock);
1372	return val;
1373	}
1374
1375	/* Protected by cgroup_lock */
1376	static cpumask_var_t cpus_attach;
1377
1378	/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1379	static int cpuset_can_attach(struct cgroup_subsys ss, struct cgroup cont,
1380	struct task_struct *tsk, bool threadgroup)
1381	{
1382	int ret;
1383	struct cpuset *cs = cgroup_cs(cont);
1384
1385	if (cpumask_empty(cs->cpus_allowed) \|\| nodes_empty(cs->mems_allowed))
1386	return -ENOSPC;
1387
1388	/*
1389	* Kthreads bound to specific cpus cannot be moved to a new cpuset; we
1390	* cannot change their cpu affinity and isolating such threads by their
1391	* set of allowed nodes is unnecessary. Thus, cpusets are not
1392	* applicable for such threads. This prevents checking for success of
1393	* set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may
1394	* be changed.
1395	*/
1396	if (tsk->flags & PF_THREAD_BOUND)
1397	return -EINVAL;
1398
1399	ret = security_task_setscheduler(tsk);
1400	if (ret)
1401	return ret;
1402	if (threadgroup) {
1403	struct task_struct *c;
1404
1405	rcu_read_lock();
1406	list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
1407	ret = security_task_setscheduler(c);
1408	if (ret) {
1409	rcu_read_unlock();
1410	return ret;
1411	}
1412	}
1413	rcu_read_unlock();
1414	}
1415	return 0;
1416	}
1417
1418	static void cpuset_attach_task(struct task_struct tsk, nodemask_t to,
1419	struct cpuset *cs)
1420	{
1421	int err;
1422	/*
1423	* can_attach beforehand should guarantee that this doesn't fail.
1424	* TODO: have a better way to handle failure here
1425	*/
1426	err = set_cpus_allowed_ptr(tsk, cpus_attach);
1427	WARN_ON_ONCE(err);
1428
1429	cpuset_change_task_nodemask(tsk, to);
1430	cpuset_update_task_spread_flag(cs, tsk);
1431
1432	}
1433
1434	static void cpuset_attach(struct cgroup_subsys ss, struct cgroup cont,
1435	struct cgroup oldcont, struct task_struct tsk,
1436	bool threadgroup)
1437	{
1438	struct mm_struct *mm;
1439	struct cpuset *cs = cgroup_cs(cont);
1440	struct cpuset *oldcs = cgroup_cs(oldcont);
1441	NODEMASK_ALLOC(nodemask_t, from, GFP_KERNEL);
1442	NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL);
1443
1444	if (from == NULL \|\| to == NULL)
1445	goto alloc_fail;
1446
1447	if (cs == &top_cpuset) {
1448	cpumask_copy(cpus_attach, cpu_possible_mask);
1449	} else {
1450	guarantee_online_cpus(cs, cpus_attach);
1451	}
1452	guarantee_online_mems(cs, to);
1453
1454	/* do per-task migration stuff possibly for each in the threadgroup */
1455	cpuset_attach_task(tsk, to, cs);
1456	if (threadgroup) {
1457	struct task_struct *c;
1458	rcu_read_lock();
1459	list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
1460	cpuset_attach_task(c, to, cs);
1461	}
1462	rcu_read_unlock();
1463	}
1464
1465	/* change mm; only needs to be done once even if threadgroup */
1466	*from = oldcs->mems_allowed;
1467	*to = cs->mems_allowed;
1468	mm = get_task_mm(tsk);
1469	if (mm) {
1470	mpol_rebind_mm(mm, to);
1471	if (is_memory_migrate(cs))
1472	cpuset_migrate_mm(mm, from, to);
1473	mmput(mm);
1474	}
1475
1476	alloc_fail:
1477	NODEMASK_FREE(from);
1478	NODEMASK_FREE(to);
1479	}
1480
1481	/* The various types of files and directories in a cpuset file system */
1482
1483	typedef enum {
1484	FILE_MEMORY_MIGRATE,
1485	FILE_CPULIST,
1486	FILE_MEMLIST,
1487	FILE_CPU_EXCLUSIVE,
1488	FILE_MEM_EXCLUSIVE,
1489	FILE_MEM_HARDWALL,
1490	FILE_SCHED_LOAD_BALANCE,
1491	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1492	FILE_MEMORY_PRESSURE_ENABLED,
1493	FILE_MEMORY_PRESSURE,
1494	FILE_SPREAD_PAGE,
1495	FILE_SPREAD_SLAB,
1496	} cpuset_filetype_t;
1497
1498	static int cpuset_write_u64(struct cgroup cgrp, struct cftype cft, u64 val)
1499	{
1500	int retval = 0;
1501	struct cpuset *cs = cgroup_cs(cgrp);
1502	cpuset_filetype_t type = cft->private;
1503
1504	if (!cgroup_lock_live_group(cgrp))
1505	return -ENODEV;
1506
1507	switch (type) {
1508	case FILE_CPU_EXCLUSIVE:
1509	retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1510	break;
1511	case FILE_MEM_EXCLUSIVE:
1512	retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1513	break;
1514	case FILE_MEM_HARDWALL:
1515	retval = update_flag(CS_MEM_HARDWALL, cs, val);
1516	break;
1517	case FILE_SCHED_LOAD_BALANCE:
1518	retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1519	break;
1520	case FILE_MEMORY_MIGRATE:
1521	retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1522	break;
1523	case FILE_MEMORY_PRESSURE_ENABLED:
1524	cpuset_memory_pressure_enabled = !!val;
1525	break;
1526	case FILE_MEMORY_PRESSURE:
1527	retval = -EACCES;
1528	break;
1529	case FILE_SPREAD_PAGE:
1530	retval = update_flag(CS_SPREAD_PAGE, cs, val);
1531	break;
1532	case FILE_SPREAD_SLAB:
1533	retval = update_flag(CS_SPREAD_SLAB, cs, val);
1534	break;
1535	default:
1536	retval = -EINVAL;
1537	break;
1538	}
1539	cgroup_unlock();
1540	return retval;
1541	}
1542
1543	static int cpuset_write_s64(struct cgroup cgrp, struct cftype cft, s64 val)
1544	{
1545	int retval = 0;
1546	struct cpuset *cs = cgroup_cs(cgrp);
1547	cpuset_filetype_t type = cft->private;
1548
1549	if (!cgroup_lock_live_group(cgrp))
1550	return -ENODEV;
1551
1552	switch (type) {
1553	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1554	retval = update_relax_domain_level(cs, val);
1555	break;
1556	default:
1557	retval = -EINVAL;
1558	break;
1559	}
1560	cgroup_unlock();
1561	return retval;
1562	}
1563
1564	/*
1565	* Common handling for a write to a "cpus" or "mems" file.
1566	*/
1567	static int cpuset_write_resmask(struct cgroup cgrp, struct cftype cft,
1568	const char *buf)
1569	{
1570	int retval = 0;
1571	struct cpuset *cs = cgroup_cs(cgrp);
1572	struct cpuset *trialcs;
1573
1574	if (!cgroup_lock_live_group(cgrp))
1575	return -ENODEV;
1576
1577	trialcs = alloc_trial_cpuset(cs);
1578	if (!trialcs) {
1579	retval = -ENOMEM;
1580	goto out;
1581	}
1582
1583	switch (cft->private) {
1584	case FILE_CPULIST:
1585	retval = update_cpumask(cs, trialcs, buf);
1586	break;
1587	case FILE_MEMLIST:
1588	retval = update_nodemask(cs, trialcs, buf);
1589	break;
1590	default:
1591	retval = -EINVAL;
1592	break;
1593	}
1594
1595	free_trial_cpuset(trialcs);
1596	out:
1597	cgroup_unlock();
1598	return retval;
1599	}
1600
1601	/*
1602	* These ascii lists should be read in a single call, by using a user
1603	* buffer large enough to hold the entire map. If read in smaller
1604	* chunks, there is no guarantee of atomicity. Since the display format
1605	* used, list of ranges of sequential numbers, is variable length,
1606	* and since these maps can change value dynamically, one could read
1607	* gibberish by doing partial reads while a list was changing.
1608	* A single large read to a buffer that crosses a page boundary is
1609	* ok, because the result being copied to user land is not recomputed
1610	* across a page fault.
1611	*/
1612
1613	static int cpuset_sprintf_cpulist(char page, struct cpuset cs)
1614	{
1615	int ret;
1616
1617	mutex_lock(&callback_mutex);
1618	ret = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
1619	mutex_unlock(&callback_mutex);
1620
1621	return ret;
1622	}
1623
1624	static int cpuset_sprintf_memlist(char page, struct cpuset cs)
1625	{
1626	NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL);
1627	int retval;
1628
1629	if (mask == NULL)
1630	return -ENOMEM;
1631
1632	mutex_lock(&callback_mutex);
1633	*mask = cs->mems_allowed;
1634	mutex_unlock(&callback_mutex);
1635
1636	retval = nodelist_scnprintf(page, PAGE_SIZE, *mask);
1637
1638	NODEMASK_FREE(mask);
1639
1640	return retval;
1641	}
1642
1643	static ssize_t cpuset_common_file_read(struct cgroup *cont,
1644	struct cftype *cft,
1645	struct file *file,
1646	char __user *buf,
1647	size_t nbytes, loff_t *ppos)
1648	{
1649	struct cpuset *cs = cgroup_cs(cont);
1650	cpuset_filetype_t type = cft->private;
1651	char *page;
1652	ssize_t retval = 0;
1653	char *s;
1654
1655	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
1656	return -ENOMEM;
1657
1658	s = page;
1659
1660	switch (type) {
1661	case FILE_CPULIST:
1662	s += cpuset_sprintf_cpulist(s, cs);
1663	break;
1664	case FILE_MEMLIST:
1665	s += cpuset_sprintf_memlist(s, cs);
1666	break;
1667	default:
1668	retval = -EINVAL;
1669	goto out;
1670	}
1671	*s++ = '\n';
1672
1673	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
1674	out:
1675	free_page((unsigned long)page);
1676	return retval;
1677	}
1678
1679	static u64 cpuset_read_u64(struct cgroup cont, struct cftype cft)
1680	{
1681	struct cpuset *cs = cgroup_cs(cont);
1682	cpuset_filetype_t type = cft->private;
1683	switch (type) {
1684	case FILE_CPU_EXCLUSIVE:
1685	return is_cpu_exclusive(cs);
1686	case FILE_MEM_EXCLUSIVE:
1687	return is_mem_exclusive(cs);
1688	case FILE_MEM_HARDWALL:
1689	return is_mem_hardwall(cs);
1690	case FILE_SCHED_LOAD_BALANCE:
1691	return is_sched_load_balance(cs);
1692	case FILE_MEMORY_MIGRATE:
1693	return is_memory_migrate(cs);
1694	case FILE_MEMORY_PRESSURE_ENABLED:
1695	return cpuset_memory_pressure_enabled;
1696	case FILE_MEMORY_PRESSURE:
1697	return fmeter_getrate(&cs->fmeter);
1698	case FILE_SPREAD_PAGE:
1699	return is_spread_page(cs);
1700	case FILE_SPREAD_SLAB:
1701	return is_spread_slab(cs);
1702	default:
1703	BUG();
1704	}
1705
1706	/* Unreachable but makes gcc happy */
1707	return 0;
1708	}
1709
1710	static s64 cpuset_read_s64(struct cgroup cont, struct cftype cft)
1711	{
1712	struct cpuset *cs = cgroup_cs(cont);
1713	cpuset_filetype_t type = cft->private;
1714	switch (type) {
1715	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1716	return cs->relax_domain_level;
1717	default:
1718	BUG();
1719	}
1720
1721	/* Unrechable but makes gcc happy */
1722	return 0;
1723	}
1724
1725
1726	/*
1727	* for the common functions, 'private' gives the type of file
1728	*/
1729
1730	static struct cftype files[] = {
1731	{
1732	.name = "cpus",
1733	.read = cpuset_common_file_read,
1734	.write_string = cpuset_write_resmask,
1735	.max_write_len = (100U + 6 * NR_CPUS),
1736	.private = FILE_CPULIST,
1737	},
1738
1739	{
1740	.name = "mems",
1741	.read = cpuset_common_file_read,
1742	.write_string = cpuset_write_resmask,
1743	.max_write_len = (100U + 6 * MAX_NUMNODES),
1744	.private = FILE_MEMLIST,
1745	},
1746
1747	{
1748	.name = "cpu_exclusive",
1749	.read_u64 = cpuset_read_u64,
1750	.write_u64 = cpuset_write_u64,
1751	.private = FILE_CPU_EXCLUSIVE,
1752	},
1753
1754	{
1755	.name = "mem_exclusive",
1756	.read_u64 = cpuset_read_u64,
1757	.write_u64 = cpuset_write_u64,
1758	.private = FILE_MEM_EXCLUSIVE,
1759	},
1760
1761	{
1762	.name = "mem_hardwall",
1763	.read_u64 = cpuset_read_u64,
1764	.write_u64 = cpuset_write_u64,
1765	.private = FILE_MEM_HARDWALL,
1766	},
1767
1768	{
1769	.name = "sched_load_balance",
1770	.read_u64 = cpuset_read_u64,
1771	.write_u64 = cpuset_write_u64,
1772	.private = FILE_SCHED_LOAD_BALANCE,
1773	},
1774
1775	{
1776	.name = "sched_relax_domain_level",
1777	.read_s64 = cpuset_read_s64,
1778	.write_s64 = cpuset_write_s64,
1779	.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1780	},
1781
1782	{
1783	.name = "memory_migrate",
1784	.read_u64 = cpuset_read_u64,
1785	.write_u64 = cpuset_write_u64,
1786	.private = FILE_MEMORY_MIGRATE,
1787	},
1788
1789	{
1790	.name = "memory_pressure",
1791	.read_u64 = cpuset_read_u64,
1792	.write_u64 = cpuset_write_u64,
1793	.private = FILE_MEMORY_PRESSURE,
1794	.mode = S_IRUGO,
1795	},
1796
1797	{
1798	.name = "memory_spread_page",
1799	.read_u64 = cpuset_read_u64,
1800	.write_u64 = cpuset_write_u64,
1801	.private = FILE_SPREAD_PAGE,
1802	},
1803
1804	{
1805	.name = "memory_spread_slab",
1806	.read_u64 = cpuset_read_u64,
1807	.write_u64 = cpuset_write_u64,
1808	.private = FILE_SPREAD_SLAB,
1809	},
1810	};
1811
1812	static struct cftype cft_memory_pressure_enabled = {
1813	.name = "memory_pressure_enabled",
1814	.read_u64 = cpuset_read_u64,
1815	.write_u64 = cpuset_write_u64,
1816	.private = FILE_MEMORY_PRESSURE_ENABLED,
1817	};
1818
1819	static int cpuset_populate(struct cgroup_subsys ss, struct cgroup cont)
1820	{
1821	int err;
1822
1823	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
1824	if (err)
1825	return err;
1826	/* memory_pressure_enabled is in root cpuset only */
1827	if (!cont->parent)
1828	err = cgroup_add_file(cont, ss,
1829	&cft_memory_pressure_enabled);
1830	return err;
1831	}
1832
1833	/*
1834	* post_clone() is called at the end of cgroup_clone().
1835	* 'cgroup' was just created automatically as a result of
1836	* a cgroup_clone(), and the current task is about to
1837	* be moved into 'cgroup'.
1838	*
1839	* Currently we refuse to set up the cgroup - thereby
1840	* refusing the task to be entered, and as a result refusing
1841	* the sys_unshare() or clone() which initiated it - if any
1842	* sibling cpusets have exclusive cpus or mem.
1843	*
1844	* If this becomes a problem for some users who wish to
1845	* allow that scenario, then cpuset_post_clone() could be
1846	* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1847	* (and likewise for mems) to the new cgroup. Called with cgroup_mutex
1848	* held.
1849	*/
1850	static void cpuset_post_clone(struct cgroup_subsys *ss,
1851	struct cgroup *cgroup)
1852	{
1853	struct cgroup parent, child;
1854	struct cpuset cs, parent_cs;
1855
1856	parent = cgroup->parent;
1857	list_for_each_entry(child, &parent->children, sibling) {
1858	cs = cgroup_cs(child);
1859	if (is_mem_exclusive(cs) \|\| is_cpu_exclusive(cs))
1860	return;
1861	}
1862	cs = cgroup_cs(cgroup);
1863	parent_cs = cgroup_cs(parent);
1864
1865	cs->mems_allowed = parent_cs->mems_allowed;
1866	cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
1867	return;
1868	}
1869
1870	/*
1871	* cpuset_create - create a cpuset
1872	* ss: cpuset cgroup subsystem
1873	* cont: control group that the new cpuset will be part of
1874	*/
1875
1876	static struct cgroup_subsys_state *cpuset_create(
1877	struct cgroup_subsys *ss,
1878	struct cgroup *cont)
1879	{
1880	struct cpuset *cs;
1881	struct cpuset *parent;
1882
1883	if (!cont->parent) {
1884	return &top_cpuset.css;
1885	}
1886	parent = cgroup_cs(cont->parent);
1887	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
1888	if (!cs)
1889	return ERR_PTR(-ENOMEM);
1890	if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
1891	kfree(cs);
1892	return ERR_PTR(-ENOMEM);
1893	}
1894
1895	cs->flags = 0;
1896	if (is_spread_page(parent))
1897	set_bit(CS_SPREAD_PAGE, &cs->flags);
1898	if (is_spread_slab(parent))
1899	set_bit(CS_SPREAD_SLAB, &cs->flags);
1900	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1901	cpumask_clear(cs->cpus_allowed);
1902	nodes_clear(cs->mems_allowed);
1903	fmeter_init(&cs->fmeter);
1904	cs->relax_domain_level = -1;
1905
1906	cs->parent = parent;
1907	number_of_cpusets++;
1908	return &cs->css ;
1909	}
1910
1911	/*
1912	* If the cpuset being removed has its flag 'sched_load_balance'
1913	* enabled, then simulate turning sched_load_balance off, which
1914	* will call async_rebuild_sched_domains().
1915	*/
1916
1917	static void cpuset_destroy(struct cgroup_subsys ss, struct cgroup cont)
1918	{
1919	struct cpuset *cs = cgroup_cs(cont);
1920
1921	if (is_sched_load_balance(cs))
1922	update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1923
1924	number_of_cpusets--;
1925	free_cpumask_var(cs->cpus_allowed);
1926	kfree(cs);
1927	}
1928
1929	struct cgroup_subsys cpuset_subsys = {
1930	.name = "cpuset",
1931	.create = cpuset_create,
1932	.destroy = cpuset_destroy,
1933	.can_attach = cpuset_can_attach,
1934	.attach = cpuset_attach,
1935	.populate = cpuset_populate,
1936	.post_clone = cpuset_post_clone,
1937	.subsys_id = cpuset_subsys_id,
1938	.early_init = 1,
1939	};
1940
1941	/**
1942	* cpuset_init - initialize cpusets at system boot
1943	*
1944	* Description: Initialize top_cpuset and the cpuset internal file system,
1945	**/
1946
1947	int __init cpuset_init(void)
1948	{
1949	int err = 0;
1950
1951	if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
1952	BUG();
1953
1954	cpumask_setall(top_cpuset.cpus_allowed);
1955	nodes_setall(top_cpuset.mems_allowed);
1956
1957	fmeter_init(&top_cpuset.fmeter);
1958	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1959	top_cpuset.relax_domain_level = -1;
1960
1961	err = register_filesystem(&cpuset_fs_type);
1962	if (err < 0)
1963	return err;
1964
1965	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
1966	BUG();
1967
1968	number_of_cpusets = 1;
1969	return 0;
1970	}
1971
1972	/**
1973	* cpuset_do_move_task - move a given task to another cpuset
1974	* @tsk: pointer to task_struct the task to move
1975	* @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
1976	*
1977	* Called by cgroup_scan_tasks() for each task in a cgroup.
1978	* Return nonzero to stop the walk through the tasks.
1979	*/
1980	static void cpuset_do_move_task(struct task_struct *tsk,
1981	struct cgroup_scanner *scan)
1982	{
1983	struct cgroup *new_cgroup = scan->data;
1984
1985	cgroup_attach_task(new_cgroup, tsk);
1986	}
1987
1988	/**
1989	* move_member_tasks_to_cpuset - move tasks from one cpuset to another
1990	* @from: cpuset in which the tasks currently reside
1991	* @to: cpuset to which the tasks will be moved
1992	*
1993	* Called with cgroup_mutex held
1994	* callback_mutex must not be held, as cpuset_attach() will take it.
1995	*
1996	* The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1997	* calling callback functions for each.
1998	*/
1999	static void move_member_tasks_to_cpuset(struct cpuset from, struct cpuset to)
2000	{
2001	struct cgroup_scanner scan;
2002
2003	scan.cg = from->css.cgroup;
2004	scan.test_task = NULL; /* select all tasks in cgroup */
2005	scan.process_task = cpuset_do_move_task;
2006	scan.heap = NULL;
2007	scan.data = to->css.cgroup;
2008
2009	if (cgroup_scan_tasks(&scan))
2010	printk(KERN_ERR "move_member_tasks_to_cpuset: "
2011	"cgroup_scan_tasks failed\n");
2012	}
2013
2014	/*
2015	* If CPU and/or memory hotplug handlers, below, unplug any CPUs
2016	* or memory nodes, we need to walk over the cpuset hierarchy,
2017	* removing that CPU or node from all cpusets. If this removes the
2018	* last CPU or node from a cpuset, then move the tasks in the empty
2019	* cpuset to its next-highest non-empty parent.
2020	*
2021	* Called with cgroup_mutex held
2022	* callback_mutex must not be held, as cpuset_attach() will take it.
2023	*/
2024	static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2025	{
2026	struct cpuset *parent;
2027
2028	/*
2029	* The cgroup's css_sets list is in use if there are tasks
2030	* in the cpuset; the list is empty if there are none;
2031	* the cs->css.refcnt seems always 0.
2032	*/
2033	if (list_empty(&cs->css.cgroup->css_sets))
2034	return;
2035
2036	/*
2037	* Find its next-highest non-empty parent, (top cpuset
2038	* has online cpus, so can't be empty).
2039	*/
2040	parent = cs->parent;
2041	while (cpumask_empty(parent->cpus_allowed) \|\|
2042	nodes_empty(parent->mems_allowed))
2043	parent = parent->parent;
2044
2045	move_member_tasks_to_cpuset(cs, parent);
2046	}
2047
2048	/*
2049	* Walk the specified cpuset subtree and look for empty cpusets.
2050	* The tasks of such cpuset must be moved to a parent cpuset.
2051	*
2052	* Called with cgroup_mutex held. We take callback_mutex to modify
2053	* cpus_allowed and mems_allowed.
2054	*
2055	* This walk processes the tree from top to bottom, completing one layer
2056	* before dropping down to the next. It always processes a node before
2057	* any of its children.
2058	*
2059	* For now, since we lack memory hot unplug, we'll never see a cpuset
2060	* that has tasks along with an empty 'mems'. But if we did see such
2061	* a cpuset, we'd handle it just like we do if its 'cpus' was empty.
2062	*/
2063	static void scan_for_empty_cpusets(struct cpuset *root)
2064	{
2065	LIST_HEAD(queue);
2066	struct cpuset cp; / scans cpusets being updated */
2067	struct cpuset child; / scans child cpusets of cp */
2068	struct cgroup *cont;
2069	NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL);
2070
2071	if (oldmems == NULL)
2072	return;
2073
2074	list_add_tail((struct list_head *)&root->stack_list, &queue);
2075
2076	while (!list_empty(&queue)) {
2077	cp = list_first_entry(&queue, struct cpuset, stack_list);
2078	list_del(queue.next);
2079	list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
2080	child = cgroup_cs(cont);
2081	list_add_tail(&child->stack_list, &queue);
2082	}
2083
2084	/* Continue past cpusets with all cpus, mems online */
2085	if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&
2086	nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
2087	continue;
2088
2089	*oldmems = cp->mems_allowed;
2090
2091	/* Remove offline cpus and mems from this cpuset. */
2092	mutex_lock(&callback_mutex);
2093	cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
2094	cpu_active_mask);
2095	nodes_and(cp->mems_allowed, cp->mems_allowed,
2096	node_states[N_HIGH_MEMORY]);
2097	mutex_unlock(&callback_mutex);
2098
2099	/* Move tasks from the empty cpuset to a parent */
2100	if (cpumask_empty(cp->cpus_allowed) \|\|
2101	nodes_empty(cp->mems_allowed))
2102	remove_tasks_in_empty_cpuset(cp);
2103	else {
2104	update_tasks_cpumask(cp, NULL);
2105	update_tasks_nodemask(cp, oldmems, NULL);
2106	}
2107	}
2108	NODEMASK_FREE(oldmems);
2109	}
2110
2111	/*
2112	* The top_cpuset tracks what CPUs and Memory Nodes are online,
2113	* period. This is necessary in order to make cpusets transparent
2114	* (of no affect) on systems that are actively using CPU hotplug
2115	* but making no active use of cpusets.
2116	*
2117	* This routine ensures that top_cpuset.cpus_allowed tracks
2118	* cpu_active_mask on each CPU hotplug (cpuhp) event.
2119	*
2120	* Called within get_online_cpus(). Needs to call cgroup_lock()
2121	* before calling generate_sched_domains().
2122	*/
2123	void cpuset_update_active_cpus(void)
2124	{
2125	struct sched_domain_attr *attr;
2126	cpumask_var_t *doms;
2127	int ndoms;
2128
2129	cgroup_lock();
2130	mutex_lock(&callback_mutex);
2131	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2132	mutex_unlock(&callback_mutex);
2133	scan_for_empty_cpusets(&top_cpuset);
2134	ndoms = generate_sched_domains(&doms, &attr);
2135	cgroup_unlock();
2136
2137	/* Have scheduler rebuild the domains */
2138	partition_sched_domains(ndoms, doms, attr);
2139	}
2140
2141	#ifdef CONFIG_MEMORY_HOTPLUG
2142	/*
2143	* Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2144	* Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
2145	* See also the previous routine cpuset_track_online_cpus().
2146	*/
2147	static int cpuset_track_online_nodes(struct notifier_block *self,
2148	unsigned long action, void *arg)
2149	{
2150	NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL);
2151
2152	if (oldmems == NULL)
2153	return NOTIFY_DONE;
2154
2155	cgroup_lock();
2156	switch (action) {
2157	case MEM_ONLINE:
2158	*oldmems = top_cpuset.mems_allowed;
2159	mutex_lock(&callback_mutex);
2160	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2161	mutex_unlock(&callback_mutex);
2162	update_tasks_nodemask(&top_cpuset, oldmems, NULL);
2163	break;
2164	case MEM_OFFLINE:
2165	/*
2166	* needn't update top_cpuset.mems_allowed explicitly because
2167	* scan_for_empty_cpusets() will update it.
2168	*/
2169	scan_for_empty_cpusets(&top_cpuset);
2170	break;
2171	default:
2172	break;
2173	}
2174	cgroup_unlock();
2175
2176	NODEMASK_FREE(oldmems);
2177	return NOTIFY_OK;
2178	}
2179	#endif
2180
2181	/**
2182	* cpuset_init_smp - initialize cpus_allowed
2183	*
2184	* Description: Finish top cpuset after cpu, node maps are initialized
2185	**/
2186
2187	void __init cpuset_init_smp(void)
2188	{
2189	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
2190	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2191
2192	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2193
2194	cpuset_wq = create_singlethread_workqueue("cpuset");
2195	BUG_ON(!cpuset_wq);
2196	}
2197
2198	/**
2199	* cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2200	* @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2201	* @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
2202	*
2203	* Description: Returns the cpumask_var_t cpus_allowed of the cpuset
2204	* attached to the specified @tsk. Guaranteed to return some non-empty
2205	* subset of cpu_online_map, even if this means going outside the
2206	* tasks cpuset.
2207	**/
2208
2209	void cpuset_cpus_allowed(struct task_struct tsk, struct cpumask pmask)
2210	{
2211	mutex_lock(&callback_mutex);
2212	task_lock(tsk);
2213	guarantee_online_cpus(task_cs(tsk), pmask);
2214	task_unlock(tsk);
2215	mutex_unlock(&callback_mutex);
2216	}
2217
2218	int cpuset_cpus_allowed_fallback(struct task_struct *tsk)
2219	{
2220	const struct cpuset *cs;
2221	int cpu;
2222
2223	rcu_read_lock();
2224	cs = task_cs(tsk);
2225	if (cs)
2226	cpumask_copy(&tsk->cpus_allowed, cs->cpus_allowed);
2227	rcu_read_unlock();
2228
2229	/*
2230	* We own tsk->cpus_allowed, nobody can change it under us.
2231	*
2232	* But we used cs && cs->cpus_allowed lockless and thus can
2233	* race with cgroup_attach_task() or update_cpumask() and get
2234	* the wrong tsk->cpus_allowed. However, both cases imply the
2235	* subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2236	* which takes task_rq_lock().
2237	*
2238	* If we are called after it dropped the lock we must see all
2239	* changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2240	* set any mask even if it is not right from task_cs() pov,
2241	* the pending set_cpus_allowed_ptr() will fix things.
2242	*/
2243
2244	cpu = cpumask_any_and(&tsk->cpus_allowed, cpu_active_mask);
2245	if (cpu >= nr_cpu_ids) {
2246	/*
2247	* Either tsk->cpus_allowed is wrong (see above) or it
2248	* is actually empty. The latter case is only possible
2249	* if we are racing with remove_tasks_in_empty_cpuset().
2250	* Like above we can temporary set any mask and rely on
2251	* set_cpus_allowed_ptr() as synchronization point.
2252	*/
2253	cpumask_copy(&tsk->cpus_allowed, cpu_possible_mask);
2254	cpu = cpumask_any(cpu_active_mask);
2255	}
2256
2257	return cpu;
2258	}
2259
2260	void cpuset_init_current_mems_allowed(void)
2261	{
2262	nodes_setall(current->mems_allowed);
2263	}
2264
2265	/**
2266	* cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2267	* @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2268	*
2269	* Description: Returns the nodemask_t mems_allowed of the cpuset
2270	* attached to the specified @tsk. Guaranteed to return some non-empty
2271	* subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2272	* tasks cpuset.
2273	**/
2274
2275	nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2276	{
2277	nodemask_t mask;
2278
2279	mutex_lock(&callback_mutex);
2280	task_lock(tsk);
2281	guarantee_online_mems(task_cs(tsk), &mask);
2282	task_unlock(tsk);
2283	mutex_unlock(&callback_mutex);
2284
2285	return mask;
2286	}
2287
2288	/**
2289	* cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2290	* @nodemask: the nodemask to be checked
2291	*
2292	* Are any of the nodes in the nodemask allowed in current->mems_allowed?
2293	*/
2294	int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2295	{
2296	return nodes_intersects(*nodemask, current->mems_allowed);
2297	}
2298
2299	/*
2300	* nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2301	* mem_hardwall ancestor to the specified cpuset. Call holding
2302	* callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
2303	* (an unusual configuration), then returns the root cpuset.
2304	*/
2305	static const struct cpuset nearest_hardwall_ancestor(const struct cpuset cs)
2306	{
2307	while (!(is_mem_exclusive(cs) \|\| is_mem_hardwall(cs)) && cs->parent)
2308	cs = cs->parent;
2309	return cs;
2310	}
2311
2312	/**
2313	* cpuset_node_allowed_softwall - Can we allocate on a memory node?
2314	* @node: is this an allowed node?
2315	* @gfp_mask: memory allocation flags
2316	*
2317	* If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2318	* set, yes, we can always allocate. If node is in our task's mems_allowed,
2319	* yes. If it's not a __GFP_HARDWALL request and this node is in the nearest
2320	* hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been
2321	* OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
2322	* flag, yes.
2323	* Otherwise, no.
2324	*
2325	* If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
2326	* cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall()
2327	* might sleep, and might allow a node from an enclosing cpuset.
2328	*
2329	* cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
2330	* cpusets, and never sleeps.
2331	*
2332	* The __GFP_THISNODE placement logic is really handled elsewhere,
2333	* by forcibly using a zonelist starting at a specified node, and by
2334	* (in get_page_from_freelist()) refusing to consider the zones for
2335	* any node on the zonelist except the first. By the time any such
2336	* calls get to this routine, we should just shut up and say 'yes'.
2337	*
2338	* GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2339	* and do not allow allocations outside the current tasks cpuset
2340	* unless the task has been OOM killed as is marked TIF_MEMDIE.
2341	* GFP_KERNEL allocations are not so marked, so can escape to the
2342	* nearest enclosing hardwalled ancestor cpuset.
2343	*
2344	* Scanning up parent cpusets requires callback_mutex. The
2345	* __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2346	* _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2347	* current tasks mems_allowed came up empty on the first pass over
2348	* the zonelist. So only GFP_KERNEL allocations, if all nodes in the
2349	* cpuset are short of memory, might require taking the callback_mutex
2350	* mutex.
2351	*
2352	* The first call here from mm/page_alloc:get_page_from_freelist()
2353	* has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2354	* so no allocation on a node outside the cpuset is allowed (unless
2355	* in interrupt, of course).
2356	*
2357	* The second pass through get_page_from_freelist() doesn't even call
2358	* here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2359	* variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2360	* in alloc_flags. That logic and the checks below have the combined
2361	* affect that:
2362	* in_interrupt - any node ok (current task context irrelevant)
2363	* GFP_ATOMIC - any node ok
2364	* TIF_MEMDIE - any node ok
2365	* GFP_KERNEL - any node in enclosing hardwalled cpuset ok
2366	* GFP_USER - only nodes in current tasks mems allowed ok.
2367	*
2368	* Rule:
2369	* Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
2370	* pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2371	* the code that might scan up ancestor cpusets and sleep.
2372	*/
2373	int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
2374	{
2375	const struct cpuset cs; / current cpuset ancestors */
2376	int allowed; /* is allocation in zone z allowed? */
2377
2378	if (in_interrupt() \|\| (gfp_mask & __GFP_THISNODE))
2379	return 1;
2380	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2381	if (node_isset(node, current->mems_allowed))
2382	return 1;
2383	/*
2384	* Allow tasks that have access to memory reserves because they have
2385	* been OOM killed to get memory anywhere.
2386	*/
2387	if (unlikely(test_thread_flag(TIF_MEMDIE)))
2388	return 1;
2389	if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
2390	return 0;
2391
2392	if (current->flags & PF_EXITING) /* Let dying task have memory */
2393	return 1;
2394
2395	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2396	mutex_lock(&callback_mutex);
2397
2398	task_lock(current);
2399	cs = nearest_hardwall_ancestor(task_cs(current));
2400	task_unlock(current);
2401
2402	allowed = node_isset(node, cs->mems_allowed);
2403	mutex_unlock(&callback_mutex);
2404	return allowed;
2405	}
2406
2407	/*
2408	* cpuset_node_allowed_hardwall - Can we allocate on a memory node?
2409	* @node: is this an allowed node?
2410	* @gfp_mask: memory allocation flags
2411	*
2412	* If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is
2413	* set, yes, we can always allocate. If node is in our task's mems_allowed,
2414	* yes. If the task has been OOM killed and has access to memory reserves as
2415	* specified by the TIF_MEMDIE flag, yes.
2416	* Otherwise, no.
2417	*
2418	* The __GFP_THISNODE placement logic is really handled elsewhere,
2419	* by forcibly using a zonelist starting at a specified node, and by
2420	* (in get_page_from_freelist()) refusing to consider the zones for
2421	* any node on the zonelist except the first. By the time any such
2422	* calls get to this routine, we should just shut up and say 'yes'.
2423	*
2424	* Unlike the cpuset_node_allowed_softwall() variant, above,
2425	* this variant requires that the node be in the current task's
2426	* mems_allowed or that we're in interrupt. It does not scan up the
2427	* cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2428	* It never sleeps.
2429	*/
2430	int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
2431	{
2432	if (in_interrupt() \|\| (gfp_mask & __GFP_THISNODE))
2433	return 1;
2434	if (node_isset(node, current->mems_allowed))
2435	return 1;
2436	/*
2437	* Allow tasks that have access to memory reserves because they have
2438	* been OOM killed to get memory anywhere.
2439	*/
2440	if (unlikely(test_thread_flag(TIF_MEMDIE)))
2441	return 1;
2442	return 0;
2443	}
2444
2445	/**
2446	* cpuset_unlock - release lock on cpuset changes
2447	*
2448	* Undo the lock taken in a previous cpuset_lock() call.
2449	*/
2450
2451	void cpuset_unlock(void)
2452	{
2453	mutex_unlock(&callback_mutex);
2454	}
2455
2456	/**
2457	* cpuset_mem_spread_node() - On which node to begin search for a file page
2458	* cpuset_slab_spread_node() - On which node to begin search for a slab page
2459	*
2460	* If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2461	* tasks in a cpuset with is_spread_page or is_spread_slab set),
2462	* and if the memory allocation used cpuset_mem_spread_node()
2463	* to determine on which node to start looking, as it will for
2464	* certain page cache or slab cache pages such as used for file
2465	* system buffers and inode caches, then instead of starting on the
2466	* local node to look for a free page, rather spread the starting
2467	* node around the tasks mems_allowed nodes.
2468	*
2469	* We don't have to worry about the returned node being offline
2470	* because "it can't happen", and even if it did, it would be ok.
2471	*
2472	* The routines calling guarantee_online_mems() are careful to
2473	* only set nodes in task->mems_allowed that are online. So it
2474	* should not be possible for the following code to return an
2475	* offline node. But if it did, that would be ok, as this routine
2476	* is not returning the node where the allocation must be, only
2477	* the node where the search should start. The zonelist passed to
2478	* __alloc_pages() will include all nodes. If the slab allocator
2479	* is passed an offline node, it will fall back to the local node.
2480	* See kmem_cache_alloc_node().
2481	*/
2482
2483	static int cpuset_spread_node(int *rotor)
2484	{
2485	int node;
2486
2487	node = next_node(*rotor, current->mems_allowed);
2488	if (node == MAX_NUMNODES)
2489	node = first_node(current->mems_allowed);
2490	*rotor = node;
2491	return node;
2492	}
2493
2494	int cpuset_mem_spread_node(void)
2495	{
2496	return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
2497	}
2498
2499	int cpuset_slab_spread_node(void)
2500	{
2501	return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
2502	}
2503
2504	EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2505
2506	/**
2507	* cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2508	* @tsk1: pointer to task_struct of some task.
2509	* @tsk2: pointer to task_struct of some other task.
2510	*
2511	* Description: Return true if @tsk1's mems_allowed intersects the
2512	* mems_allowed of @tsk2. Used by the OOM killer to determine if
2513	* one of the task's memory usage might impact the memory available
2514	* to the other.
2515	**/
2516
2517	int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2518	const struct task_struct *tsk2)
2519	{
2520	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2521	}
2522
2523	/**
2524	* cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2525	* @task: pointer to task_struct of some task.
2526	*
2527	* Description: Prints @task's name, cpuset name, and cached copy of its
2528	* mems_allowed to the kernel log. Must hold task_lock(task) to allow
2529	* dereferencing task_cs(task).
2530	*/
2531	void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2532	{
2533	struct dentry *dentry;
2534
2535	dentry = task_cs(tsk)->css.cgroup->dentry;
2536	spin_lock(&cpuset_buffer_lock);
2537	snprintf(cpuset_name, CPUSET_NAME_LEN,
2538	dentry ? (const char *)dentry->d_name.name : "/");
2539	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2540	tsk->mems_allowed);
2541	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
2542	tsk->comm, cpuset_name, cpuset_nodelist);
2543	spin_unlock(&cpuset_buffer_lock);
2544	}
2545
2546	/*
2547	* Collection of memory_pressure is suppressed unless
2548	* this flag is enabled by writing "1" to the special
2549	* cpuset file 'memory_pressure_enabled' in the root cpuset.
2550	*/
2551
2552	int cpuset_memory_pressure_enabled __read_mostly;
2553
2554	/**
2555	* cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2556	*
2557	* Keep a running average of the rate of synchronous (direct)
2558	* page reclaim efforts initiated by tasks in each cpuset.
2559	*
2560	* This represents the rate at which some task in the cpuset
2561	* ran low on memory on all nodes it was allowed to use, and
2562	* had to enter the kernels page reclaim code in an effort to
2563	* create more free memory by tossing clean pages or swapping
2564	* or writing dirty pages.
2565	*
2566	* Display to user space in the per-cpuset read-only file
2567	* "memory_pressure". Value displayed is an integer
2568	* representing the recent rate of entry into the synchronous
2569	* (direct) page reclaim by any task attached to the cpuset.
2570	**/
2571
2572	void __cpuset_memory_pressure_bump(void)
2573	{
2574	task_lock(current);
2575	fmeter_markevent(&task_cs(current)->fmeter);
2576	task_unlock(current);
2577	}
2578
2579	#ifdef CONFIG_PROC_PID_CPUSET
2580	/*
2581	* proc_cpuset_show()
2582	* - Print tasks cpuset path into seq_file.
2583	* - Used for /proc/<pid>/cpuset.
2584	* - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2585	* doesn't really matter if tsk->cpuset changes after we read it,
2586	* and we take cgroup_mutex, keeping cpuset_attach() from changing it
2587	* anyway.
2588	*/
2589	static int proc_cpuset_show(struct seq_file m, void unused_v)
2590	{
2591	struct pid *pid;
2592	struct task_struct *tsk;
2593	char *buf;
2594	struct cgroup_subsys_state *css;
2595	int retval;
2596
2597	retval = -ENOMEM;
2598	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
2599	if (!buf)
2600	goto out;
2601
2602	retval = -ESRCH;
2603	pid = m->private;
2604	tsk = get_pid_task(pid, PIDTYPE_PID);
2605	if (!tsk)
2606	goto out_free;
2607
2608	retval = -EINVAL;
2609	cgroup_lock();
2610	css = task_subsys_state(tsk, cpuset_subsys_id);
2611	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
2612	if (retval < 0)
2613	goto out_unlock;
2614	seq_puts(m, buf);
2615	seq_putc(m, '\n');
2616	out_unlock:
2617	cgroup_unlock();
2618	put_task_struct(tsk);
2619	out_free:
2620	kfree(buf);
2621	out:
2622	return retval;
2623	}
2624
2625	static int cpuset_open(struct inode inode, struct file file)
2626	{
2627	struct pid *pid = PROC_I(inode)->pid;
2628	return single_open(file, proc_cpuset_show, pid);
2629	}
2630
2631	const struct file_operations proc_cpuset_operations = {
2632	.open = cpuset_open,
2633	.read = seq_read,
2634	.llseek = seq_lseek,
2635	.release = single_release,
2636	};
2637	#endif /* CONFIG_PROC_PID_CPUSET */
2638
2639	/* Display task mems_allowed in /proc/<pid>/status file. */
2640	void cpuset_task_status_allowed(struct seq_file m, struct task_struct task)
2641	{
2642	seq_printf(m, "Mems_allowed:\t");
2643	seq_nodemask(m, &task->mems_allowed);
2644	seq_printf(m, "\n");
2645	seq_printf(m, "Mems_allowed_list:\t");
2646	seq_nodemask_list(m, &task->mems_allowed);
2647	seq_printf(m, "\n");
2648	}
2649

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