linux - kernel/cpuset.c

2633 lines · 74.0 KiB

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