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1da177e4
LT
1/*
2 * kernel/cpuset.c
3 *
4 * Processor and Memory placement constraints for sets of tasks.
5 *
6 * Copyright (C) 2003 BULL SA.
029190c5 7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8793d854 8 * Copyright (C) 2006 Google, Inc
1da177e4
LT
9 *
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
1da177e4 12 *
825a46af 13 * 2003-10-10 Written by Simon Derr.
1da177e4 14 * 2003-10-22 Updates by Stephen Hemminger.
825a46af 15 * 2004 May-July Rework by Paul Jackson.
8793d854 16 * 2006 Rework by Paul Menage to use generic cgroups
cf417141
MK
17 * 2008 Rework of the scheduler domains and CPU hotplug handling
18 * by Max Krasnyansky
1da177e4
LT
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
1da177e4
LT
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>
68860ec1 37#include <linux/mempolicy.h>
1da177e4 38#include <linux/mm.h>
f481891f 39#include <linux/memory.h>
9984de1a 40#include <linux/export.h>
1da177e4
LT
41#include <linux/mount.h>
42#include <linux/namei.h>
43#include <linux/pagemap.h>
44#include <linux/proc_fs.h>
6b9c2603 45#include <linux/rcupdate.h>
1da177e4
LT
46#include <linux/sched.h>
47#include <linux/seq_file.h>
22fb52dd 48#include <linux/security.h>
1da177e4 49#include <linux/slab.h>
1da177e4
LT
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>
60063497 58#include <linux/atomic.h>
3d3f26a7 59#include <linux/mutex.h>
956db3ca
CW
60#include <linux/workqueue.h>
61#include <linux/cgroup.h>
e44193d3 62#include <linux/wait.h>
1da177e4 63
664eedde 64struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
202f72d5 65
3e0d98b9
PJ
66/* See "Frequency meter" comments, below. */
67
68struct fmeter {
69 int cnt; /* unprocessed events count */
70 int val; /* most recent output value */
71 time_t time; /* clock (secs) when val computed */
72 spinlock_t lock; /* guards read or write of above */
73};
74
1da177e4 75struct cpuset {
8793d854
PM
76 struct cgroup_subsys_state css;
77
1da177e4 78 unsigned long flags; /* "unsigned long" so bitops work */
e2b9a3d7 79
7e88291b
LZ
80 /*
81 * On default hierarchy:
82 *
83 * The user-configured masks can only be changed by writing to
84 * cpuset.cpus and cpuset.mems, and won't be limited by the
85 * parent masks.
86 *
87 * The effective masks is the real masks that apply to the tasks
88 * in the cpuset. They may be changed if the configured masks are
89 * changed or hotplug happens.
90 *
91 * effective_mask == configured_mask & parent's effective_mask,
92 * and if it ends up empty, it will inherit the parent's mask.
93 *
94 *
95 * On legacy hierachy:
96 *
97 * The user-configured masks are always the same with effective masks.
98 */
99
e2b9a3d7
LZ
100 /* user-configured CPUs and Memory Nodes allow to tasks */
101 cpumask_var_t cpus_allowed;
102 nodemask_t mems_allowed;
103
104 /* effective CPUs and Memory Nodes allow to tasks */
105 cpumask_var_t effective_cpus;
106 nodemask_t effective_mems;
1da177e4 107
33ad801d
LZ
108 /*
109 * This is old Memory Nodes tasks took on.
110 *
111 * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
112 * - A new cpuset's old_mems_allowed is initialized when some
113 * task is moved into it.
114 * - old_mems_allowed is used in cpuset_migrate_mm() when we change
115 * cpuset.mems_allowed and have tasks' nodemask updated, and
116 * then old_mems_allowed is updated to mems_allowed.
117 */
118 nodemask_t old_mems_allowed;
119
3e0d98b9 120 struct fmeter fmeter; /* memory_pressure filter */
029190c5 121
452477fa
TH
122 /*
123 * Tasks are being attached to this cpuset. Used to prevent
124 * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
125 */
126 int attach_in_progress;
127
029190c5
PJ
128 /* partition number for rebuild_sched_domains() */
129 int pn;
956db3ca 130
1d3504fc
HS
131 /* for custom sched domain */
132 int relax_domain_level;
1da177e4
LT
133};
134
a7c6d554 135static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
8793d854 136{
a7c6d554 137 return css ? container_of(css, struct cpuset, css) : NULL;
8793d854
PM
138}
139
140/* Retrieve the cpuset for a task */
141static inline struct cpuset *task_cs(struct task_struct *task)
142{
073219e9 143 return css_cs(task_css(task, cpuset_cgrp_id));
8793d854 144}
8793d854 145
c9710d80 146static inline struct cpuset *parent_cs(struct cpuset *cs)
c431069f 147{
5c9d535b 148 return css_cs(cs->css.parent);
c431069f
TH
149}
150
b246272e
DR
151#ifdef CONFIG_NUMA
152static inline bool task_has_mempolicy(struct task_struct *task)
153{
154 return task->mempolicy;
155}
156#else
157static inline bool task_has_mempolicy(struct task_struct *task)
158{
159 return false;
160}
161#endif
162
163
1da177e4
LT
164/* bits in struct cpuset flags field */
165typedef enum {
efeb77b2 166 CS_ONLINE,
1da177e4
LT
167 CS_CPU_EXCLUSIVE,
168 CS_MEM_EXCLUSIVE,
78608366 169 CS_MEM_HARDWALL,
45b07ef3 170 CS_MEMORY_MIGRATE,
029190c5 171 CS_SCHED_LOAD_BALANCE,
825a46af
PJ
172 CS_SPREAD_PAGE,
173 CS_SPREAD_SLAB,
1da177e4
LT
174} cpuset_flagbits_t;
175
176/* convenient tests for these bits */
efeb77b2
TH
177static inline bool is_cpuset_online(const struct cpuset *cs)
178{
179 return test_bit(CS_ONLINE, &cs->flags);
180}
181
1da177e4
LT
182static inline int is_cpu_exclusive(const struct cpuset *cs)
183{
7b5b9ef0 184 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
1da177e4
LT
185}
186
187static inline int is_mem_exclusive(const struct cpuset *cs)
188{
7b5b9ef0 189 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
1da177e4
LT
190}
191
78608366
PM
192static inline int is_mem_hardwall(const struct cpuset *cs)
193{
194 return test_bit(CS_MEM_HARDWALL, &cs->flags);
195}
196
029190c5
PJ
197static inline int is_sched_load_balance(const struct cpuset *cs)
198{
199 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
200}
201
45b07ef3
PJ
202static inline int is_memory_migrate(const struct cpuset *cs)
203{
7b5b9ef0 204 return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
45b07ef3
PJ
205}
206
825a46af
PJ
207static inline int is_spread_page(const struct cpuset *cs)
208{
209 return test_bit(CS_SPREAD_PAGE, &cs->flags);
210}
211
212static inline int is_spread_slab(const struct cpuset *cs)
213{
214 return test_bit(CS_SPREAD_SLAB, &cs->flags);
215}
216
1da177e4 217static struct cpuset top_cpuset = {
efeb77b2
TH
218 .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
219 (1 << CS_MEM_EXCLUSIVE)),
1da177e4
LT
220};
221
ae8086ce
TH
222/**
223 * cpuset_for_each_child - traverse online children of a cpuset
224 * @child_cs: loop cursor pointing to the current child
492eb21b 225 * @pos_css: used for iteration
ae8086ce
TH
226 * @parent_cs: target cpuset to walk children of
227 *
228 * Walk @child_cs through the online children of @parent_cs. Must be used
229 * with RCU read locked.
230 */
492eb21b
TH
231#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
232 css_for_each_child((pos_css), &(parent_cs)->css) \
233 if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
ae8086ce 234
fc560a26
TH
235/**
236 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
237 * @des_cs: loop cursor pointing to the current descendant
492eb21b 238 * @pos_css: used for iteration
fc560a26
TH
239 * @root_cs: target cpuset to walk ancestor of
240 *
241 * Walk @des_cs through the online descendants of @root_cs. Must be used
492eb21b 242 * with RCU read locked. The caller may modify @pos_css by calling
bd8815a6
TH
243 * css_rightmost_descendant() to skip subtree. @root_cs is included in the
244 * iteration and the first node to be visited.
fc560a26 245 */
492eb21b
TH
246#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
247 css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
248 if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
fc560a26 249
1da177e4 250/*
8447a0fe
VD
251 * There are two global locks guarding cpuset structures - cpuset_mutex and
252 * callback_lock. We also require taking task_lock() when dereferencing a
253 * task's cpuset pointer. See "The task_lock() exception", at the end of this
254 * comment.
5d21cc2d 255 *
8447a0fe 256 * A task must hold both locks to modify cpusets. If a task holds
5d21cc2d 257 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
8447a0fe 258 * is the only task able to also acquire callback_lock and be able to
5d21cc2d
TH
259 * modify cpusets. It can perform various checks on the cpuset structure
260 * first, knowing nothing will change. It can also allocate memory while
261 * just holding cpuset_mutex. While it is performing these checks, various
8447a0fe
VD
262 * callback routines can briefly acquire callback_lock to query cpusets.
263 * Once it is ready to make the changes, it takes callback_lock, blocking
5d21cc2d 264 * everyone else.
053199ed
PJ
265 *
266 * Calls to the kernel memory allocator can not be made while holding
8447a0fe 267 * callback_lock, as that would risk double tripping on callback_lock
053199ed
PJ
268 * from one of the callbacks into the cpuset code from within
269 * __alloc_pages().
270 *
8447a0fe 271 * If a task is only holding callback_lock, then it has read-only
053199ed
PJ
272 * access to cpusets.
273 *
58568d2a
MX
274 * Now, the task_struct fields mems_allowed and mempolicy may be changed
275 * by other task, we use alloc_lock in the task_struct fields to protect
276 * them.
053199ed 277 *
8447a0fe 278 * The cpuset_common_file_read() handlers only hold callback_lock across
053199ed
PJ
279 * small pieces of code, such as when reading out possibly multi-word
280 * cpumasks and nodemasks.
281 *
2df167a3
PM
282 * Accessing a task's cpuset should be done in accordance with the
283 * guidelines for accessing subsystem state in kernel/cgroup.c
1da177e4
LT
284 */
285
5d21cc2d 286static DEFINE_MUTEX(cpuset_mutex);
8447a0fe 287static DEFINE_SPINLOCK(callback_lock);
4247bdc6 288
3a5a6d0c
TH
289/*
290 * CPU / memory hotplug is handled asynchronously.
291 */
292static void cpuset_hotplug_workfn(struct work_struct *work);
3a5a6d0c
TH
293static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
294
e44193d3
LZ
295static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
296
cf417141
MK
297/*
298 * This is ugly, but preserves the userspace API for existing cpuset
8793d854 299 * users. If someone tries to mount the "cpuset" filesystem, we
cf417141
MK
300 * silently switch it to mount "cgroup" instead
301 */
f7e83571
AV
302static struct dentry *cpuset_mount(struct file_system_type *fs_type,
303 int flags, const char *unused_dev_name, void *data)
1da177e4 304{
8793d854 305 struct file_system_type *cgroup_fs = get_fs_type("cgroup");
f7e83571 306 struct dentry *ret = ERR_PTR(-ENODEV);
8793d854
PM
307 if (cgroup_fs) {
308 char mountopts[] =
309 "cpuset,noprefix,"
310 "release_agent=/sbin/cpuset_release_agent";
f7e83571
AV
311 ret = cgroup_fs->mount(cgroup_fs, flags,
312 unused_dev_name, mountopts);
8793d854
PM
313 put_filesystem(cgroup_fs);
314 }
315 return ret;
1da177e4
LT
316}
317
318static struct file_system_type cpuset_fs_type = {
319 .name = "cpuset",
f7e83571 320 .mount = cpuset_mount,
1da177e4
LT
321};
322
1da177e4 323/*
300ed6cb 324 * Return in pmask the portion of a cpusets's cpus_allowed that
1da177e4 325 * are online. If none are online, walk up the cpuset hierarchy
40df2deb
LZ
326 * until we find one that does have some online cpus. The top
327 * cpuset always has some cpus online.
1da177e4
LT
328 *
329 * One way or another, we guarantee to return some non-empty subset
5f054e31 330 * of cpu_online_mask.
1da177e4 331 *
8447a0fe 332 * Call with callback_lock or cpuset_mutex held.
1da177e4 333 */
c9710d80 334static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
1da177e4 335{
ae1c8023 336 while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask))
c431069f 337 cs = parent_cs(cs);
ae1c8023 338 cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
1da177e4
LT
339}
340
341/*
342 * Return in *pmask the portion of a cpusets's mems_allowed that
0e1e7c7a
CL
343 * are online, with memory. If none are online with memory, walk
344 * up the cpuset hierarchy until we find one that does have some
40df2deb 345 * online mems. The top cpuset always has some mems online.
1da177e4
LT
346 *
347 * One way or another, we guarantee to return some non-empty subset
38d7bee9 348 * of node_states[N_MEMORY].
1da177e4 349 *
8447a0fe 350 * Call with callback_lock or cpuset_mutex held.
1da177e4 351 */
c9710d80 352static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
1da177e4 353{
ae1c8023 354 while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
c431069f 355 cs = parent_cs(cs);
ae1c8023 356 nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
1da177e4
LT
357}
358
f3b39d47
MX
359/*
360 * update task's spread flag if cpuset's page/slab spread flag is set
361 *
8447a0fe 362 * Call with callback_lock or cpuset_mutex held.
f3b39d47
MX
363 */
364static void cpuset_update_task_spread_flag(struct cpuset *cs,
365 struct task_struct *tsk)
366{
367 if (is_spread_page(cs))
2ad654bc 368 task_set_spread_page(tsk);
f3b39d47 369 else
2ad654bc
ZL
370 task_clear_spread_page(tsk);
371
f3b39d47 372 if (is_spread_slab(cs))
2ad654bc 373 task_set_spread_slab(tsk);
f3b39d47 374 else
2ad654bc 375 task_clear_spread_slab(tsk);
f3b39d47
MX
376}
377
1da177e4
LT
378/*
379 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
380 *
381 * One cpuset is a subset of another if all its allowed CPUs and
382 * Memory Nodes are a subset of the other, and its exclusive flags
5d21cc2d 383 * are only set if the other's are set. Call holding cpuset_mutex.
1da177e4
LT
384 */
385
386static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
387{
300ed6cb 388 return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
1da177e4
LT
389 nodes_subset(p->mems_allowed, q->mems_allowed) &&
390 is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
391 is_mem_exclusive(p) <= is_mem_exclusive(q);
392}
393
645fcc9d
LZ
394/**
395 * alloc_trial_cpuset - allocate a trial cpuset
396 * @cs: the cpuset that the trial cpuset duplicates
397 */
c9710d80 398static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
645fcc9d 399{
300ed6cb
LZ
400 struct cpuset *trial;
401
402 trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
403 if (!trial)
404 return NULL;
405
e2b9a3d7
LZ
406 if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
407 goto free_cs;
408 if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
409 goto free_cpus;
300ed6cb 410
e2b9a3d7
LZ
411 cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
412 cpumask_copy(trial->effective_cpus, cs->effective_cpus);
300ed6cb 413 return trial;
e2b9a3d7
LZ
414
415free_cpus:
416 free_cpumask_var(trial->cpus_allowed);
417free_cs:
418 kfree(trial);
419 return NULL;
645fcc9d
LZ
420}
421
422/**
423 * free_trial_cpuset - free the trial cpuset
424 * @trial: the trial cpuset to be freed
425 */
426static void free_trial_cpuset(struct cpuset *trial)
427{
e2b9a3d7 428 free_cpumask_var(trial->effective_cpus);
300ed6cb 429 free_cpumask_var(trial->cpus_allowed);
645fcc9d
LZ
430 kfree(trial);
431}
432
1da177e4
LT
433/*
434 * validate_change() - Used to validate that any proposed cpuset change
435 * follows the structural rules for cpusets.
436 *
437 * If we replaced the flag and mask values of the current cpuset
438 * (cur) with those values in the trial cpuset (trial), would
439 * our various subset and exclusive rules still be valid? Presumes
5d21cc2d 440 * cpuset_mutex held.
1da177e4
LT
441 *
442 * 'cur' is the address of an actual, in-use cpuset. Operations
443 * such as list traversal that depend on the actual address of the
444 * cpuset in the list must use cur below, not trial.
445 *
446 * 'trial' is the address of bulk structure copy of cur, with
447 * perhaps one or more of the fields cpus_allowed, mems_allowed,
448 * or flags changed to new, trial values.
449 *
450 * Return 0 if valid, -errno if not.
451 */
452
c9710d80 453static int validate_change(struct cpuset *cur, struct cpuset *trial)
1da177e4 454{
492eb21b 455 struct cgroup_subsys_state *css;
1da177e4 456 struct cpuset *c, *par;
ae8086ce
TH
457 int ret;
458
459 rcu_read_lock();
1da177e4
LT
460
461 /* Each of our child cpusets must be a subset of us */
ae8086ce 462 ret = -EBUSY;
492eb21b 463 cpuset_for_each_child(c, css, cur)
ae8086ce
TH
464 if (!is_cpuset_subset(c, trial))
465 goto out;
1da177e4
LT
466
467 /* Remaining checks don't apply to root cpuset */
ae8086ce 468 ret = 0;
69604067 469 if (cur == &top_cpuset)
ae8086ce 470 goto out;
1da177e4 471
c431069f 472 par = parent_cs(cur);
69604067 473
7e88291b 474 /* On legacy hiearchy, we must be a subset of our parent cpuset. */
ae8086ce 475 ret = -EACCES;
7e88291b 476 if (!cgroup_on_dfl(cur->css.cgroup) && !is_cpuset_subset(trial, par))
ae8086ce 477 goto out;
1da177e4 478
2df167a3
PM
479 /*
480 * If either I or some sibling (!= me) is exclusive, we can't
481 * overlap
482 */
ae8086ce 483 ret = -EINVAL;
492eb21b 484 cpuset_for_each_child(c, css, par) {
1da177e4
LT
485 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
486 c != cur &&
300ed6cb 487 cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
ae8086ce 488 goto out;
1da177e4
LT
489 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
490 c != cur &&
491 nodes_intersects(trial->mems_allowed, c->mems_allowed))
ae8086ce 492 goto out;
1da177e4
LT
493 }
494
452477fa
TH
495 /*
496 * Cpusets with tasks - existing or newly being attached - can't
1c09b195 497 * be changed to have empty cpus_allowed or mems_allowed.
452477fa 498 */
ae8086ce 499 ret = -ENOSPC;
07bc356e 500 if ((cgroup_has_tasks(cur->css.cgroup) || cur->attach_in_progress)) {
1c09b195
LZ
501 if (!cpumask_empty(cur->cpus_allowed) &&
502 cpumask_empty(trial->cpus_allowed))
503 goto out;
504 if (!nodes_empty(cur->mems_allowed) &&
505 nodes_empty(trial->mems_allowed))
506 goto out;
507 }
020958b6 508
f82f8042
JL
509 /*
510 * We can't shrink if we won't have enough room for SCHED_DEADLINE
511 * tasks.
512 */
513 ret = -EBUSY;
514 if (is_cpu_exclusive(cur) &&
515 !cpuset_cpumask_can_shrink(cur->cpus_allowed,
516 trial->cpus_allowed))
517 goto out;
518
ae8086ce
TH
519 ret = 0;
520out:
521 rcu_read_unlock();
522 return ret;
1da177e4
LT
523}
524
db7f47cf 525#ifdef CONFIG_SMP
029190c5 526/*
cf417141 527 * Helper routine for generate_sched_domains().
8b5f1c52 528 * Do cpusets a, b have overlapping effective cpus_allowed masks?
029190c5 529 */
029190c5
PJ
530static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
531{
8b5f1c52 532 return cpumask_intersects(a->effective_cpus, b->effective_cpus);
029190c5
PJ
533}
534
1d3504fc
HS
535static void
536update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
537{
1d3504fc
HS
538 if (dattr->relax_domain_level < c->relax_domain_level)
539 dattr->relax_domain_level = c->relax_domain_level;
540 return;
541}
542
fc560a26
TH
543static void update_domain_attr_tree(struct sched_domain_attr *dattr,
544 struct cpuset *root_cs)
f5393693 545{
fc560a26 546 struct cpuset *cp;
492eb21b 547 struct cgroup_subsys_state *pos_css;
f5393693 548
fc560a26 549 rcu_read_lock();
492eb21b 550 cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
fc560a26
TH
551 /* skip the whole subtree if @cp doesn't have any CPU */
552 if (cpumask_empty(cp->cpus_allowed)) {
492eb21b 553 pos_css = css_rightmost_descendant(pos_css);
f5393693 554 continue;
fc560a26 555 }
f5393693
LJ
556
557 if (is_sched_load_balance(cp))
558 update_domain_attr(dattr, cp);
f5393693 559 }
fc560a26 560 rcu_read_unlock();
f5393693
LJ
561}
562
029190c5 563/*
cf417141
MK
564 * generate_sched_domains()
565 *
566 * This function builds a partial partition of the systems CPUs
567 * A 'partial partition' is a set of non-overlapping subsets whose
568 * union is a subset of that set.
0a0fca9d 569 * The output of this function needs to be passed to kernel/sched/core.c
cf417141
MK
570 * partition_sched_domains() routine, which will rebuild the scheduler's
571 * load balancing domains (sched domains) as specified by that partial
572 * partition.
029190c5 573 *
45ce80fb 574 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
029190c5
PJ
575 * for a background explanation of this.
576 *
577 * Does not return errors, on the theory that the callers of this
578 * routine would rather not worry about failures to rebuild sched
579 * domains when operating in the severe memory shortage situations
580 * that could cause allocation failures below.
581 *
5d21cc2d 582 * Must be called with cpuset_mutex held.
029190c5
PJ
583 *
584 * The three key local variables below are:
aeed6824 585 * q - a linked-list queue of cpuset pointers, used to implement a
029190c5
PJ
586 * top-down scan of all cpusets. This scan loads a pointer
587 * to each cpuset marked is_sched_load_balance into the
588 * array 'csa'. For our purposes, rebuilding the schedulers
589 * sched domains, we can ignore !is_sched_load_balance cpusets.
590 * csa - (for CpuSet Array) Array of pointers to all the cpusets
591 * that need to be load balanced, for convenient iterative
592 * access by the subsequent code that finds the best partition,
593 * i.e the set of domains (subsets) of CPUs such that the
594 * cpus_allowed of every cpuset marked is_sched_load_balance
595 * is a subset of one of these domains, while there are as
596 * many such domains as possible, each as small as possible.
597 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
0a0fca9d 598 * the kernel/sched/core.c routine partition_sched_domains() in a
029190c5
PJ
599 * convenient format, that can be easily compared to the prior
600 * value to determine what partition elements (sched domains)
601 * were changed (added or removed.)
602 *
603 * Finding the best partition (set of domains):
604 * The triple nested loops below over i, j, k scan over the
605 * load balanced cpusets (using the array of cpuset pointers in
606 * csa[]) looking for pairs of cpusets that have overlapping
607 * cpus_allowed, but which don't have the same 'pn' partition
608 * number and gives them in the same partition number. It keeps
609 * looping on the 'restart' label until it can no longer find
610 * any such pairs.
611 *
612 * The union of the cpus_allowed masks from the set of
613 * all cpusets having the same 'pn' value then form the one
614 * element of the partition (one sched domain) to be passed to
615 * partition_sched_domains().
616 */
acc3f5d7 617static int generate_sched_domains(cpumask_var_t **domains,
cf417141 618 struct sched_domain_attr **attributes)
029190c5 619{
029190c5
PJ
620 struct cpuset *cp; /* scans q */
621 struct cpuset **csa; /* array of all cpuset ptrs */
622 int csn; /* how many cpuset ptrs in csa so far */
623 int i, j, k; /* indices for partition finding loops */
acc3f5d7 624 cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
47b8ea71 625 cpumask_var_t non_isolated_cpus; /* load balanced CPUs */
1d3504fc 626 struct sched_domain_attr *dattr; /* attributes for custom domains */
1583715d 627 int ndoms = 0; /* number of sched domains in result */
6af866af 628 int nslot; /* next empty doms[] struct cpumask slot */
492eb21b 629 struct cgroup_subsys_state *pos_css;
029190c5 630
029190c5 631 doms = NULL;
1d3504fc 632 dattr = NULL;
cf417141 633 csa = NULL;
029190c5 634
47b8ea71
RR
635 if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
636 goto done;
637 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
638
029190c5
PJ
639 /* Special case for the 99% of systems with one, full, sched domain */
640 if (is_sched_load_balance(&top_cpuset)) {
acc3f5d7
RR
641 ndoms = 1;
642 doms = alloc_sched_domains(ndoms);
029190c5 643 if (!doms)
cf417141
MK
644 goto done;
645
1d3504fc
HS
646 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
647 if (dattr) {
648 *dattr = SD_ATTR_INIT;
93a65575 649 update_domain_attr_tree(dattr, &top_cpuset);
1d3504fc 650 }
47b8ea71
RR
651 cpumask_and(doms[0], top_cpuset.effective_cpus,
652 non_isolated_cpus);
cf417141 653
cf417141 654 goto done;
029190c5
PJ
655 }
656
664eedde 657 csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
029190c5
PJ
658 if (!csa)
659 goto done;
660 csn = 0;
661
fc560a26 662 rcu_read_lock();
492eb21b 663 cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
bd8815a6
TH
664 if (cp == &top_cpuset)
665 continue;
f5393693 666 /*
fc560a26
TH
667 * Continue traversing beyond @cp iff @cp has some CPUs and
668 * isn't load balancing. The former is obvious. The
669 * latter: All child cpusets contain a subset of the
670 * parent's cpus, so just skip them, and then we call
671 * update_domain_attr_tree() to calc relax_domain_level of
672 * the corresponding sched domain.
f5393693 673 */
fc560a26 674 if (!cpumask_empty(cp->cpus_allowed) &&
47b8ea71
RR
675 !(is_sched_load_balance(cp) &&
676 cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
f5393693 677 continue;
489a5393 678
fc560a26
TH
679 if (is_sched_load_balance(cp))
680 csa[csn++] = cp;
681
682 /* skip @cp's subtree */
492eb21b 683 pos_css = css_rightmost_descendant(pos_css);
fc560a26
TH
684 }
685 rcu_read_unlock();
029190c5
PJ
686
687 for (i = 0; i < csn; i++)
688 csa[i]->pn = i;
689 ndoms = csn;
690
691restart:
692 /* Find the best partition (set of sched domains) */
693 for (i = 0; i < csn; i++) {
694 struct cpuset *a = csa[i];
695 int apn = a->pn;
696
697 for (j = 0; j < csn; j++) {
698 struct cpuset *b = csa[j];
699 int bpn = b->pn;
700
701 if (apn != bpn && cpusets_overlap(a, b)) {
702 for (k = 0; k < csn; k++) {
703 struct cpuset *c = csa[k];
704
705 if (c->pn == bpn)
706 c->pn = apn;
707 }
708 ndoms--; /* one less element */
709 goto restart;
710 }
711 }
712 }
713
cf417141
MK
714 /*
715 * Now we know how many domains to create.
716 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
717 */
acc3f5d7 718 doms = alloc_sched_domains(ndoms);
700018e0 719 if (!doms)
cf417141 720 goto done;
cf417141
MK
721
722 /*
723 * The rest of the code, including the scheduler, can deal with
724 * dattr==NULL case. No need to abort if alloc fails.
725 */
1d3504fc 726 dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
029190c5
PJ
727
728 for (nslot = 0, i = 0; i < csn; i++) {
729 struct cpuset *a = csa[i];
6af866af 730 struct cpumask *dp;
029190c5
PJ
731 int apn = a->pn;
732
cf417141
MK
733 if (apn < 0) {
734 /* Skip completed partitions */
735 continue;
736 }
737
acc3f5d7 738 dp = doms[nslot];
cf417141
MK
739
740 if (nslot == ndoms) {
741 static int warnings = 10;
742 if (warnings) {
12d3089c
FF
743 pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
744 nslot, ndoms, csn, i, apn);
cf417141 745 warnings--;
029190c5 746 }
cf417141
MK
747 continue;
748 }
029190c5 749
6af866af 750 cpumask_clear(dp);
cf417141
MK
751 if (dattr)
752 *(dattr + nslot) = SD_ATTR_INIT;
753 for (j = i; j < csn; j++) {
754 struct cpuset *b = csa[j];
755
756 if (apn == b->pn) {
8b5f1c52 757 cpumask_or(dp, dp, b->effective_cpus);
47b8ea71 758 cpumask_and(dp, dp, non_isolated_cpus);
cf417141
MK
759 if (dattr)
760 update_domain_attr_tree(dattr + nslot, b);
761
762 /* Done with this partition */
763 b->pn = -1;
029190c5 764 }
029190c5 765 }
cf417141 766 nslot++;
029190c5
PJ
767 }
768 BUG_ON(nslot != ndoms);
769
cf417141 770done:
47b8ea71 771 free_cpumask_var(non_isolated_cpus);
cf417141
MK
772 kfree(csa);
773
700018e0
LZ
774 /*
775 * Fallback to the default domain if kmalloc() failed.
776 * See comments in partition_sched_domains().
777 */
778 if (doms == NULL)
779 ndoms = 1;
780
cf417141
MK
781 *domains = doms;
782 *attributes = dattr;
783 return ndoms;
784}
785
786/*
787 * Rebuild scheduler domains.
788 *
699140ba
TH
789 * If the flag 'sched_load_balance' of any cpuset with non-empty
790 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
791 * which has that flag enabled, or if any cpuset with a non-empty
792 * 'cpus' is removed, then call this routine to rebuild the
793 * scheduler's dynamic sched domains.
cf417141 794 *
5d21cc2d 795 * Call with cpuset_mutex held. Takes get_online_cpus().
cf417141 796 */
699140ba 797static void rebuild_sched_domains_locked(void)
cf417141
MK
798{
799 struct sched_domain_attr *attr;
acc3f5d7 800 cpumask_var_t *doms;
cf417141
MK
801 int ndoms;
802
5d21cc2d 803 lockdep_assert_held(&cpuset_mutex);
86ef5c9a 804 get_online_cpus();
cf417141 805
5b16c2a4
LZ
806 /*
807 * We have raced with CPU hotplug. Don't do anything to avoid
808 * passing doms with offlined cpu to partition_sched_domains().
809 * Anyways, hotplug work item will rebuild sched domains.
810 */
8b5f1c52 811 if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
5b16c2a4
LZ
812 goto out;
813
cf417141 814 /* Generate domain masks and attrs */
cf417141 815 ndoms = generate_sched_domains(&doms, &attr);
cf417141
MK
816
817 /* Have scheduler rebuild the domains */
818 partition_sched_domains(ndoms, doms, attr);
5b16c2a4 819out:
86ef5c9a 820 put_online_cpus();
cf417141 821}
db7f47cf 822#else /* !CONFIG_SMP */
699140ba 823static void rebuild_sched_domains_locked(void)
db7f47cf
PM
824{
825}
db7f47cf 826#endif /* CONFIG_SMP */
029190c5 827
cf417141
MK
828void rebuild_sched_domains(void)
829{
5d21cc2d 830 mutex_lock(&cpuset_mutex);
699140ba 831 rebuild_sched_domains_locked();
5d21cc2d 832 mutex_unlock(&cpuset_mutex);
029190c5
PJ
833}
834
0b2f630a
MX
835/**
836 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
837 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
0b2f630a 838 *
d66393e5
TH
839 * Iterate through each task of @cs updating its cpus_allowed to the
840 * effective cpuset's. As this function is called with cpuset_mutex held,
841 * cpuset membership stays stable.
0b2f630a 842 */
d66393e5 843static void update_tasks_cpumask(struct cpuset *cs)
0b2f630a 844{
d66393e5
TH
845 struct css_task_iter it;
846 struct task_struct *task;
847
848 css_task_iter_start(&cs->css, &it);
849 while ((task = css_task_iter_next(&it)))
ae1c8023 850 set_cpus_allowed_ptr(task, cs->effective_cpus);
d66393e5 851 css_task_iter_end(&it);
0b2f630a
MX
852}
853
5c5cc623 854/*
734d4513
LZ
855 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
856 * @cs: the cpuset to consider
857 * @new_cpus: temp variable for calculating new effective_cpus
858 *
859 * When congifured cpumask is changed, the effective cpumasks of this cpuset
860 * and all its descendants need to be updated.
5c5cc623 861 *
734d4513 862 * On legacy hierachy, effective_cpus will be the same with cpu_allowed.
5c5cc623
LZ
863 *
864 * Called with cpuset_mutex held
865 */
734d4513 866static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
5c5cc623
LZ
867{
868 struct cpuset *cp;
492eb21b 869 struct cgroup_subsys_state *pos_css;
8b5f1c52 870 bool need_rebuild_sched_domains = false;
5c5cc623
LZ
871
872 rcu_read_lock();
734d4513
LZ
873 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
874 struct cpuset *parent = parent_cs(cp);
875
876 cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
877
554b0d1c
LZ
878 /*
879 * If it becomes empty, inherit the effective mask of the
880 * parent, which is guaranteed to have some CPUs.
881 */
79063bff 882 if (cgroup_on_dfl(cp->css.cgroup) && cpumask_empty(new_cpus))
554b0d1c
LZ
883 cpumask_copy(new_cpus, parent->effective_cpus);
884
734d4513
LZ
885 /* Skip the whole subtree if the cpumask remains the same. */
886 if (cpumask_equal(new_cpus, cp->effective_cpus)) {
887 pos_css = css_rightmost_descendant(pos_css);
888 continue;
5c5cc623 889 }
734d4513 890
ec903c0c 891 if (!css_tryget_online(&cp->css))
5c5cc623
LZ
892 continue;
893 rcu_read_unlock();
894
8447a0fe 895 spin_lock_irq(&callback_lock);
734d4513 896 cpumask_copy(cp->effective_cpus, new_cpus);
8447a0fe 897 spin_unlock_irq(&callback_lock);
734d4513
LZ
898
899 WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
900 !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
901
d66393e5 902 update_tasks_cpumask(cp);
5c5cc623 903
8b5f1c52
LZ
904 /*
905 * If the effective cpumask of any non-empty cpuset is changed,
906 * we need to rebuild sched domains.
907 */
908 if (!cpumask_empty(cp->cpus_allowed) &&
909 is_sched_load_balance(cp))
910 need_rebuild_sched_domains = true;
911
5c5cc623
LZ
912 rcu_read_lock();
913 css_put(&cp->css);
914 }
915 rcu_read_unlock();
8b5f1c52
LZ
916
917 if (need_rebuild_sched_domains)
918 rebuild_sched_domains_locked();
5c5cc623
LZ
919}
920
58f4790b
CW
921/**
922 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
923 * @cs: the cpuset to consider
fc34ac1d 924 * @trialcs: trial cpuset
58f4790b
CW
925 * @buf: buffer of cpu numbers written to this cpuset
926 */
645fcc9d
LZ
927static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
928 const char *buf)
1da177e4 929{
58f4790b 930 int retval;
1da177e4 931
5f054e31 932 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
4c4d50f7
PJ
933 if (cs == &top_cpuset)
934 return -EACCES;
935
6f7f02e7 936 /*
c8d9c90c 937 * An empty cpus_allowed is ok only if the cpuset has no tasks.
020958b6
PJ
938 * Since cpulist_parse() fails on an empty mask, we special case
939 * that parsing. The validate_change() call ensures that cpusets
940 * with tasks have cpus.
6f7f02e7 941 */
020958b6 942 if (!*buf) {
300ed6cb 943 cpumask_clear(trialcs->cpus_allowed);
6f7f02e7 944 } else {
300ed6cb 945 retval = cpulist_parse(buf, trialcs->cpus_allowed);
6f7f02e7
DR
946 if (retval < 0)
947 return retval;
37340746 948
5d8ba82c
LZ
949 if (!cpumask_subset(trialcs->cpus_allowed,
950 top_cpuset.cpus_allowed))
37340746 951 return -EINVAL;
6f7f02e7 952 }
029190c5 953
8707d8b8 954 /* Nothing to do if the cpus didn't change */
300ed6cb 955 if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
8707d8b8 956 return 0;
58f4790b 957
a73456f3
LZ
958 retval = validate_change(cs, trialcs);
959 if (retval < 0)
960 return retval;
961
8447a0fe 962 spin_lock_irq(&callback_lock);
300ed6cb 963 cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
8447a0fe 964 spin_unlock_irq(&callback_lock);
029190c5 965
734d4513
LZ
966 /* use trialcs->cpus_allowed as a temp variable */
967 update_cpumasks_hier(cs, trialcs->cpus_allowed);
85d7b949 968 return 0;
1da177e4
LT
969}
970
e4e364e8
PJ
971/*
972 * cpuset_migrate_mm
973 *
974 * Migrate memory region from one set of nodes to another.
975 *
976 * Temporarilly set tasks mems_allowed to target nodes of migration,
977 * so that the migration code can allocate pages on these nodes.
978 *
e4e364e8
PJ
979 * While the mm_struct we are migrating is typically from some
980 * other task, the task_struct mems_allowed that we are hacking
981 * is for our current task, which must allocate new pages for that
982 * migrating memory region.
e4e364e8
PJ
983 */
984
985static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
986 const nodemask_t *to)
987{
988 struct task_struct *tsk = current;
989
e4e364e8 990 tsk->mems_allowed = *to;
e4e364e8
PJ
991
992 do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
993
47295830 994 rcu_read_lock();
ae1c8023 995 guarantee_online_mems(task_cs(tsk), &tsk->mems_allowed);
47295830 996 rcu_read_unlock();
e4e364e8
PJ
997}
998
3b6766fe 999/*
58568d2a
MX
1000 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
1001 * @tsk: the task to change
1002 * @newmems: new nodes that the task will be set
1003 *
1004 * In order to avoid seeing no nodes if the old and new nodes are disjoint,
1005 * we structure updates as setting all new allowed nodes, then clearing newly
1006 * disallowed ones.
58568d2a
MX
1007 */
1008static void cpuset_change_task_nodemask(struct task_struct *tsk,
1009 nodemask_t *newmems)
1010{
b246272e 1011 bool need_loop;
89e8a244 1012
c0ff7453
MX
1013 /*
1014 * Allow tasks that have access to memory reserves because they have
1015 * been OOM killed to get memory anywhere.
1016 */
1017 if (unlikely(test_thread_flag(TIF_MEMDIE)))
1018 return;
1019 if (current->flags & PF_EXITING) /* Let dying task have memory */
1020 return;
1021
1022 task_lock(tsk);
b246272e
DR
1023 /*
1024 * Determine if a loop is necessary if another thread is doing
d26914d1 1025 * read_mems_allowed_begin(). If at least one node remains unchanged and
b246272e
DR
1026 * tsk does not have a mempolicy, then an empty nodemask will not be
1027 * possible when mems_allowed is larger than a word.
1028 */
1029 need_loop = task_has_mempolicy(tsk) ||
1030 !nodes_intersects(*newmems, tsk->mems_allowed);
c0ff7453 1031
0fc0287c
PZ
1032 if (need_loop) {
1033 local_irq_disable();
cc9a6c87 1034 write_seqcount_begin(&tsk->mems_allowed_seq);
0fc0287c 1035 }
c0ff7453 1036
cc9a6c87
MG
1037 nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
1038 mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
c0ff7453
MX
1039
1040 mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
58568d2a 1041 tsk->mems_allowed = *newmems;
cc9a6c87 1042
0fc0287c 1043 if (need_loop) {
cc9a6c87 1044 write_seqcount_end(&tsk->mems_allowed_seq);
0fc0287c
PZ
1045 local_irq_enable();
1046 }
cc9a6c87 1047
c0ff7453 1048 task_unlock(tsk);
58568d2a
MX
1049}
1050
8793d854
PM
1051static void *cpuset_being_rebound;
1052
0b2f630a
MX
1053/**
1054 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1055 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
0b2f630a 1056 *
d66393e5
TH
1057 * Iterate through each task of @cs updating its mems_allowed to the
1058 * effective cpuset's. As this function is called with cpuset_mutex held,
1059 * cpuset membership stays stable.
0b2f630a 1060 */
d66393e5 1061static void update_tasks_nodemask(struct cpuset *cs)
1da177e4 1062{
33ad801d 1063 static nodemask_t newmems; /* protected by cpuset_mutex */
d66393e5
TH
1064 struct css_task_iter it;
1065 struct task_struct *task;
59dac16f 1066
846a16bf 1067 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
4225399a 1068
ae1c8023 1069 guarantee_online_mems(cs, &newmems);
33ad801d 1070
4225399a 1071 /*
3b6766fe
LZ
1072 * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
1073 * take while holding tasklist_lock. Forks can happen - the
1074 * mpol_dup() cpuset_being_rebound check will catch such forks,
1075 * and rebind their vma mempolicies too. Because we still hold
5d21cc2d 1076 * the global cpuset_mutex, we know that no other rebind effort
3b6766fe 1077 * will be contending for the global variable cpuset_being_rebound.
4225399a 1078 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
04c19fa6 1079 * is idempotent. Also migrate pages in each mm to new nodes.
4225399a 1080 */
d66393e5
TH
1081 css_task_iter_start(&cs->css, &it);
1082 while ((task = css_task_iter_next(&it))) {
1083 struct mm_struct *mm;
1084 bool migrate;
1085
1086 cpuset_change_task_nodemask(task, &newmems);
1087
1088 mm = get_task_mm(task);
1089 if (!mm)
1090 continue;
1091
1092 migrate = is_memory_migrate(cs);
1093
1094 mpol_rebind_mm(mm, &cs->mems_allowed);
1095 if (migrate)
1096 cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
1097 mmput(mm);
1098 }
1099 css_task_iter_end(&it);
4225399a 1100
33ad801d
LZ
1101 /*
1102 * All the tasks' nodemasks have been updated, update
1103 * cs->old_mems_allowed.
1104 */
1105 cs->old_mems_allowed = newmems;
1106
2df167a3 1107 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
8793d854 1108 cpuset_being_rebound = NULL;
1da177e4
LT
1109}
1110
5c5cc623 1111/*
734d4513
LZ
1112 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
1113 * @cs: the cpuset to consider
1114 * @new_mems: a temp variable for calculating new effective_mems
5c5cc623 1115 *
734d4513
LZ
1116 * When configured nodemask is changed, the effective nodemasks of this cpuset
1117 * and all its descendants need to be updated.
5c5cc623 1118 *
734d4513 1119 * On legacy hiearchy, effective_mems will be the same with mems_allowed.
5c5cc623
LZ
1120 *
1121 * Called with cpuset_mutex held
1122 */
734d4513 1123static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
5c5cc623
LZ
1124{
1125 struct cpuset *cp;
492eb21b 1126 struct cgroup_subsys_state *pos_css;
5c5cc623
LZ
1127
1128 rcu_read_lock();
734d4513
LZ
1129 cpuset_for_each_descendant_pre(cp, pos_css, cs) {
1130 struct cpuset *parent = parent_cs(cp);
1131
1132 nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
1133
554b0d1c
LZ
1134 /*
1135 * If it becomes empty, inherit the effective mask of the
1136 * parent, which is guaranteed to have some MEMs.
1137 */
79063bff 1138 if (cgroup_on_dfl(cp->css.cgroup) && nodes_empty(*new_mems))
554b0d1c
LZ
1139 *new_mems = parent->effective_mems;
1140
734d4513
LZ
1141 /* Skip the whole subtree if the nodemask remains the same. */
1142 if (nodes_equal(*new_mems, cp->effective_mems)) {
1143 pos_css = css_rightmost_descendant(pos_css);
1144 continue;
5c5cc623 1145 }
734d4513 1146
ec903c0c 1147 if (!css_tryget_online(&cp->css))
5c5cc623
LZ
1148 continue;
1149 rcu_read_unlock();
1150
8447a0fe 1151 spin_lock_irq(&callback_lock);
734d4513 1152 cp->effective_mems = *new_mems;
8447a0fe 1153 spin_unlock_irq(&callback_lock);
734d4513
LZ
1154
1155 WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
a1381268 1156 !nodes_equal(cp->mems_allowed, cp->effective_mems));
734d4513 1157
d66393e5 1158 update_tasks_nodemask(cp);
5c5cc623
LZ
1159
1160 rcu_read_lock();
1161 css_put(&cp->css);
1162 }
1163 rcu_read_unlock();
1164}
1165
0b2f630a
MX
1166/*
1167 * Handle user request to change the 'mems' memory placement
1168 * of a cpuset. Needs to validate the request, update the
58568d2a
MX
1169 * cpusets mems_allowed, and for each task in the cpuset,
1170 * update mems_allowed and rebind task's mempolicy and any vma
1171 * mempolicies and if the cpuset is marked 'memory_migrate',
1172 * migrate the tasks pages to the new memory.
0b2f630a 1173 *
8447a0fe 1174 * Call with cpuset_mutex held. May take callback_lock during call.
0b2f630a
MX
1175 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1176 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1177 * their mempolicies to the cpusets new mems_allowed.
1178 */
645fcc9d
LZ
1179static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1180 const char *buf)
0b2f630a 1181{
0b2f630a
MX
1182 int retval;
1183
1184 /*
38d7bee9 1185 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
0b2f630a
MX
1186 * it's read-only
1187 */
53feb297
MX
1188 if (cs == &top_cpuset) {
1189 retval = -EACCES;
1190 goto done;
1191 }
0b2f630a 1192
0b2f630a
MX
1193 /*
1194 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1195 * Since nodelist_parse() fails on an empty mask, we special case
1196 * that parsing. The validate_change() call ensures that cpusets
1197 * with tasks have memory.
1198 */
1199 if (!*buf) {
645fcc9d 1200 nodes_clear(trialcs->mems_allowed);
0b2f630a 1201 } else {
645fcc9d 1202 retval = nodelist_parse(buf, trialcs->mems_allowed);
0b2f630a
MX
1203 if (retval < 0)
1204 goto done;
1205
645fcc9d 1206 if (!nodes_subset(trialcs->mems_allowed,
5d8ba82c
LZ
1207 top_cpuset.mems_allowed)) {
1208 retval = -EINVAL;
53feb297
MX
1209 goto done;
1210 }
0b2f630a 1211 }
33ad801d
LZ
1212
1213 if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
0b2f630a
MX
1214 retval = 0; /* Too easy - nothing to do */
1215 goto done;
1216 }
645fcc9d 1217 retval = validate_change(cs, trialcs);
0b2f630a
MX
1218 if (retval < 0)
1219 goto done;
1220
8447a0fe 1221 spin_lock_irq(&callback_lock);
645fcc9d 1222 cs->mems_allowed = trialcs->mems_allowed;
8447a0fe 1223 spin_unlock_irq(&callback_lock);
0b2f630a 1224
734d4513
LZ
1225 /* use trialcs->mems_allowed as a temp variable */
1226 update_nodemasks_hier(cs, &cs->mems_allowed);
0b2f630a
MX
1227done:
1228 return retval;
1229}
1230
8793d854
PM
1231int current_cpuset_is_being_rebound(void)
1232{
391acf97
GZ
1233 int ret;
1234
1235 rcu_read_lock();
1236 ret = task_cs(current) == cpuset_being_rebound;
1237 rcu_read_unlock();
1238
1239 return ret;
8793d854
PM
1240}
1241
5be7a479 1242static int update_relax_domain_level(struct cpuset *cs, s64 val)
1d3504fc 1243{
db7f47cf 1244#ifdef CONFIG_SMP
60495e77 1245 if (val < -1 || val >= sched_domain_level_max)
30e0e178 1246 return -EINVAL;
db7f47cf 1247#endif
1d3504fc
HS
1248
1249 if (val != cs->relax_domain_level) {
1250 cs->relax_domain_level = val;
300ed6cb
LZ
1251 if (!cpumask_empty(cs->cpus_allowed) &&
1252 is_sched_load_balance(cs))
699140ba 1253 rebuild_sched_domains_locked();
1d3504fc
HS
1254 }
1255
1256 return 0;
1257}
1258
72ec7029 1259/**
950592f7
MX
1260 * update_tasks_flags - update the spread flags of tasks in the cpuset.
1261 * @cs: the cpuset in which each task's spread flags needs to be changed
950592f7 1262 *
d66393e5
TH
1263 * Iterate through each task of @cs updating its spread flags. As this
1264 * function is called with cpuset_mutex held, cpuset membership stays
1265 * stable.
950592f7 1266 */
d66393e5 1267static void update_tasks_flags(struct cpuset *cs)
950592f7 1268{
d66393e5
TH
1269 struct css_task_iter it;
1270 struct task_struct *task;
1271
1272 css_task_iter_start(&cs->css, &it);
1273 while ((task = css_task_iter_next(&it)))
1274 cpuset_update_task_spread_flag(cs, task);
1275 css_task_iter_end(&it);
950592f7
MX
1276}
1277
1da177e4
LT
1278/*
1279 * update_flag - read a 0 or a 1 in a file and update associated flag
78608366
PM
1280 * bit: the bit to update (see cpuset_flagbits_t)
1281 * cs: the cpuset to update
1282 * turning_on: whether the flag is being set or cleared
053199ed 1283 *
5d21cc2d 1284 * Call with cpuset_mutex held.
1da177e4
LT
1285 */
1286
700fe1ab
PM
1287static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1288 int turning_on)
1da177e4 1289{
645fcc9d 1290 struct cpuset *trialcs;
40b6a762 1291 int balance_flag_changed;
950592f7 1292 int spread_flag_changed;
950592f7 1293 int err;
1da177e4 1294
645fcc9d
LZ
1295 trialcs = alloc_trial_cpuset(cs);
1296 if (!trialcs)
1297 return -ENOMEM;
1298
1da177e4 1299 if (turning_on)
645fcc9d 1300 set_bit(bit, &trialcs->flags);
1da177e4 1301 else
645fcc9d 1302 clear_bit(bit, &trialcs->flags);
1da177e4 1303
645fcc9d 1304 err = validate_change(cs, trialcs);
85d7b949 1305 if (err < 0)
645fcc9d 1306 goto out;
029190c5 1307
029190c5 1308 balance_flag_changed = (is_sched_load_balance(cs) !=
645fcc9d 1309 is_sched_load_balance(trialcs));
029190c5 1310
950592f7
MX
1311 spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
1312 || (is_spread_page(cs) != is_spread_page(trialcs)));
1313
8447a0fe 1314 spin_lock_irq(&callback_lock);
645fcc9d 1315 cs->flags = trialcs->flags;
8447a0fe 1316 spin_unlock_irq(&callback_lock);
85d7b949 1317
300ed6cb 1318 if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
699140ba 1319 rebuild_sched_domains_locked();
029190c5 1320
950592f7 1321 if (spread_flag_changed)
d66393e5 1322 update_tasks_flags(cs);
645fcc9d
LZ
1323out:
1324 free_trial_cpuset(trialcs);
1325 return err;
1da177e4
LT
1326}
1327
3e0d98b9 1328/*
80f7228b 1329 * Frequency meter - How fast is some event occurring?
3e0d98b9
PJ
1330 *
1331 * These routines manage a digitally filtered, constant time based,
1332 * event frequency meter. There are four routines:
1333 * fmeter_init() - initialize a frequency meter.
1334 * fmeter_markevent() - called each time the event happens.
1335 * fmeter_getrate() - returns the recent rate of such events.
1336 * fmeter_update() - internal routine used to update fmeter.
1337 *
1338 * A common data structure is passed to each of these routines,
1339 * which is used to keep track of the state required to manage the
1340 * frequency meter and its digital filter.
1341 *
1342 * The filter works on the number of events marked per unit time.
1343 * The filter is single-pole low-pass recursive (IIR). The time unit
1344 * is 1 second. Arithmetic is done using 32-bit integers scaled to
1345 * simulate 3 decimal digits of precision (multiplied by 1000).
1346 *
1347 * With an FM_COEF of 933, and a time base of 1 second, the filter
1348 * has a half-life of 10 seconds, meaning that if the events quit
1349 * happening, then the rate returned from the fmeter_getrate()
1350 * will be cut in half each 10 seconds, until it converges to zero.
1351 *
1352 * It is not worth doing a real infinitely recursive filter. If more
1353 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1354 * just compute FM_MAXTICKS ticks worth, by which point the level
1355 * will be stable.
1356 *
1357 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1358 * arithmetic overflow in the fmeter_update() routine.
1359 *
1360 * Given the simple 32 bit integer arithmetic used, this meter works
1361 * best for reporting rates between one per millisecond (msec) and
1362 * one per 32 (approx) seconds. At constant rates faster than one
1363 * per msec it maxes out at values just under 1,000,000. At constant
1364 * rates between one per msec, and one per second it will stabilize
1365 * to a value N*1000, where N is the rate of events per second.
1366 * At constant rates between one per second and one per 32 seconds,
1367 * it will be choppy, moving up on the seconds that have an event,
1368 * and then decaying until the next event. At rates slower than
1369 * about one in 32 seconds, it decays all the way back to zero between
1370 * each event.
1371 */
1372
1373#define FM_COEF 933 /* coefficient for half-life of 10 secs */
1374#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1375#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1376#define FM_SCALE 1000 /* faux fixed point scale */
1377
1378/* Initialize a frequency meter */
1379static void fmeter_init(struct fmeter *fmp)
1380{
1381 fmp->cnt = 0;
1382 fmp->val = 0;
1383 fmp->time = 0;
1384 spin_lock_init(&fmp->lock);
1385}
1386
1387/* Internal meter update - process cnt events and update value */
1388static void fmeter_update(struct fmeter *fmp)
1389{
1390 time_t now = get_seconds();
1391 time_t ticks = now - fmp->time;
1392
1393 if (ticks == 0)
1394 return;
1395
1396 ticks = min(FM_MAXTICKS, ticks);
1397 while (ticks-- > 0)
1398 fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1399 fmp->time = now;
1400
1401 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1402 fmp->cnt = 0;
1403}
1404
1405/* Process any previous ticks, then bump cnt by one (times scale). */
1406static void fmeter_markevent(struct fmeter *fmp)
1407{
1408 spin_lock(&fmp->lock);
1409 fmeter_update(fmp);
1410 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1411 spin_unlock(&fmp->lock);
1412}
1413
1414/* Process any previous ticks, then return current value. */
1415static int fmeter_getrate(struct fmeter *fmp)
1416{
1417 int val;
1418
1419 spin_lock(&fmp->lock);
1420 fmeter_update(fmp);
1421 val = fmp->val;
1422 spin_unlock(&fmp->lock);
1423 return val;
1424}
1425
57fce0a6
TH
1426static struct cpuset *cpuset_attach_old_cs;
1427
5d21cc2d 1428/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
eb95419b
TH
1429static int cpuset_can_attach(struct cgroup_subsys_state *css,
1430 struct cgroup_taskset *tset)
f780bdb7 1431{
eb95419b 1432 struct cpuset *cs = css_cs(css);
bb9d97b6
TH
1433 struct task_struct *task;
1434 int ret;
1da177e4 1435
57fce0a6
TH
1436 /* used later by cpuset_attach() */
1437 cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));
1438
5d21cc2d
TH
1439 mutex_lock(&cpuset_mutex);
1440
aa6ec29b 1441 /* allow moving tasks into an empty cpuset if on default hierarchy */
5d21cc2d 1442 ret = -ENOSPC;
aa6ec29b 1443 if (!cgroup_on_dfl(css->cgroup) &&
88fa523b 1444 (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
5d21cc2d 1445 goto out_unlock;
9985b0ba 1446
924f0d9a 1447 cgroup_taskset_for_each(task, tset) {
7f51412a
JL
1448 ret = task_can_attach(task, cs->cpus_allowed);
1449 if (ret)
5d21cc2d
TH
1450 goto out_unlock;
1451 ret = security_task_setscheduler(task);
1452 if (ret)
1453 goto out_unlock;
bb9d97b6 1454 }
f780bdb7 1455
452477fa
TH
1456 /*
1457 * Mark attach is in progress. This makes validate_change() fail
1458 * changes which zero cpus/mems_allowed.
1459 */
1460 cs->attach_in_progress++;
5d21cc2d
TH
1461 ret = 0;
1462out_unlock:
1463 mutex_unlock(&cpuset_mutex);
1464 return ret;
8793d854 1465}
f780bdb7 1466
eb95419b 1467static void cpuset_cancel_attach(struct cgroup_subsys_state *css,
452477fa
TH
1468 struct cgroup_taskset *tset)
1469{
5d21cc2d 1470 mutex_lock(&cpuset_mutex);
eb95419b 1471 css_cs(css)->attach_in_progress--;
5d21cc2d 1472 mutex_unlock(&cpuset_mutex);
8793d854 1473}
1da177e4 1474
4e4c9a14 1475/*
5d21cc2d 1476 * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
4e4c9a14
TH
1477 * but we can't allocate it dynamically there. Define it global and
1478 * allocate from cpuset_init().
1479 */
1480static cpumask_var_t cpus_attach;
1481
eb95419b
TH
1482static void cpuset_attach(struct cgroup_subsys_state *css,
1483 struct cgroup_taskset *tset)
8793d854 1484{
67bd2c59 1485 /* static buf protected by cpuset_mutex */
4e4c9a14 1486 static nodemask_t cpuset_attach_nodemask_to;
8793d854 1487 struct mm_struct *mm;
bb9d97b6
TH
1488 struct task_struct *task;
1489 struct task_struct *leader = cgroup_taskset_first(tset);
eb95419b 1490 struct cpuset *cs = css_cs(css);
57fce0a6 1491 struct cpuset *oldcs = cpuset_attach_old_cs;
22fb52dd 1492
5d21cc2d
TH
1493 mutex_lock(&cpuset_mutex);
1494
4e4c9a14
TH
1495 /* prepare for attach */
1496 if (cs == &top_cpuset)
1497 cpumask_copy(cpus_attach, cpu_possible_mask);
1498 else
ae1c8023 1499 guarantee_online_cpus(cs, cpus_attach);
4e4c9a14 1500
ae1c8023 1501 guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
4e4c9a14 1502
924f0d9a 1503 cgroup_taskset_for_each(task, tset) {
bb9d97b6
TH
1504 /*
1505 * can_attach beforehand should guarantee that this doesn't
1506 * fail. TODO: have a better way to handle failure here
1507 */
1508 WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
1509
1510 cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
1511 cpuset_update_task_spread_flag(cs, task);
1512 }
22fb52dd 1513
f780bdb7
BB
1514 /*
1515 * Change mm, possibly for multiple threads in a threadgroup. This is
1516 * expensive and may sleep.
1517 */
ae1c8023 1518 cpuset_attach_nodemask_to = cs->effective_mems;
bb9d97b6 1519 mm = get_task_mm(leader);
4225399a 1520 if (mm) {
f780bdb7 1521 mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
f047cecf
LZ
1522
1523 /*
1524 * old_mems_allowed is the same with mems_allowed here, except
1525 * if this task is being moved automatically due to hotplug.
1526 * In that case @mems_allowed has been updated and is empty,
1527 * so @old_mems_allowed is the right nodesets that we migrate
1528 * mm from.
1529 */
1530 if (is_memory_migrate(cs)) {
ae1c8023 1531 cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
f780bdb7 1532 &cpuset_attach_nodemask_to);
f047cecf 1533 }
4225399a
PJ
1534 mmput(mm);
1535 }
452477fa 1536
33ad801d 1537 cs->old_mems_allowed = cpuset_attach_nodemask_to;
02bb5863 1538
452477fa 1539 cs->attach_in_progress--;
e44193d3
LZ
1540 if (!cs->attach_in_progress)
1541 wake_up(&cpuset_attach_wq);
5d21cc2d
TH
1542
1543 mutex_unlock(&cpuset_mutex);
1da177e4
LT
1544}
1545
1546/* The various types of files and directories in a cpuset file system */
1547
1548typedef enum {
45b07ef3 1549 FILE_MEMORY_MIGRATE,
1da177e4
LT
1550 FILE_CPULIST,
1551 FILE_MEMLIST,
afd1a8b3
LZ
1552 FILE_EFFECTIVE_CPULIST,
1553 FILE_EFFECTIVE_MEMLIST,
1da177e4
LT
1554 FILE_CPU_EXCLUSIVE,
1555 FILE_MEM_EXCLUSIVE,
78608366 1556 FILE_MEM_HARDWALL,
029190c5 1557 FILE_SCHED_LOAD_BALANCE,
1d3504fc 1558 FILE_SCHED_RELAX_DOMAIN_LEVEL,
3e0d98b9
PJ
1559 FILE_MEMORY_PRESSURE_ENABLED,
1560 FILE_MEMORY_PRESSURE,
825a46af
PJ
1561 FILE_SPREAD_PAGE,
1562 FILE_SPREAD_SLAB,
1da177e4
LT
1563} cpuset_filetype_t;
1564
182446d0
TH
1565static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
1566 u64 val)
700fe1ab 1567{
182446d0 1568 struct cpuset *cs = css_cs(css);
700fe1ab 1569 cpuset_filetype_t type = cft->private;
a903f086 1570 int retval = 0;
700fe1ab 1571
5d21cc2d 1572 mutex_lock(&cpuset_mutex);
a903f086
LZ
1573 if (!is_cpuset_online(cs)) {
1574 retval = -ENODEV;
5d21cc2d 1575 goto out_unlock;
a903f086 1576 }
700fe1ab
PM
1577
1578 switch (type) {
1da177e4 1579 case FILE_CPU_EXCLUSIVE:
700fe1ab 1580 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1da177e4
LT
1581 break;
1582 case FILE_MEM_EXCLUSIVE:
700fe1ab 1583 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1da177e4 1584 break;
78608366
PM
1585 case FILE_MEM_HARDWALL:
1586 retval = update_flag(CS_MEM_HARDWALL, cs, val);
1587 break;
029190c5 1588 case FILE_SCHED_LOAD_BALANCE:
700fe1ab 1589 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1d3504fc 1590 break;
45b07ef3 1591 case FILE_MEMORY_MIGRATE:
700fe1ab 1592 retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
45b07ef3 1593 break;
3e0d98b9 1594 case FILE_MEMORY_PRESSURE_ENABLED:
700fe1ab 1595 cpuset_memory_pressure_enabled = !!val;
3e0d98b9
PJ
1596 break;
1597 case FILE_MEMORY_PRESSURE:
1598 retval = -EACCES;
1599 break;
825a46af 1600 case FILE_SPREAD_PAGE:
700fe1ab 1601 retval = update_flag(CS_SPREAD_PAGE, cs, val);
825a46af
PJ
1602 break;
1603 case FILE_SPREAD_SLAB:
700fe1ab 1604 retval = update_flag(CS_SPREAD_SLAB, cs, val);
825a46af 1605 break;
1da177e4
LT
1606 default:
1607 retval = -EINVAL;
700fe1ab 1608 break;
1da177e4 1609 }
5d21cc2d
TH
1610out_unlock:
1611 mutex_unlock(&cpuset_mutex);
1da177e4
LT
1612 return retval;
1613}
1614
182446d0
TH
1615static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
1616 s64 val)
5be7a479 1617{
182446d0 1618 struct cpuset *cs = css_cs(css);
5be7a479 1619 cpuset_filetype_t type = cft->private;
5d21cc2d 1620 int retval = -ENODEV;
5be7a479 1621
5d21cc2d
TH
1622 mutex_lock(&cpuset_mutex);
1623 if (!is_cpuset_online(cs))
1624 goto out_unlock;
e3712395 1625
5be7a479
PM
1626 switch (type) {
1627 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1628 retval = update_relax_domain_level(cs, val);
1629 break;
1630 default:
1631 retval = -EINVAL;
1632 break;
1633 }
5d21cc2d
TH
1634out_unlock:
1635 mutex_unlock(&cpuset_mutex);
5be7a479
PM
1636 return retval;
1637}
1638
e3712395
PM
1639/*
1640 * Common handling for a write to a "cpus" or "mems" file.
1641 */
451af504
TH
1642static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
1643 char *buf, size_t nbytes, loff_t off)
e3712395 1644{
451af504 1645 struct cpuset *cs = css_cs(of_css(of));
645fcc9d 1646 struct cpuset *trialcs;
5d21cc2d 1647 int retval = -ENODEV;
e3712395 1648
451af504
TH
1649 buf = strstrip(buf);
1650
3a5a6d0c
TH
1651 /*
1652 * CPU or memory hotunplug may leave @cs w/o any execution
1653 * resources, in which case the hotplug code asynchronously updates
1654 * configuration and transfers all tasks to the nearest ancestor
1655 * which can execute.
1656 *
1657 * As writes to "cpus" or "mems" may restore @cs's execution
1658 * resources, wait for the previously scheduled operations before
1659 * proceeding, so that we don't end up keep removing tasks added
1660 * after execution capability is restored.
76bb5ab8
TH
1661 *
1662 * cpuset_hotplug_work calls back into cgroup core via
1663 * cgroup_transfer_tasks() and waiting for it from a cgroupfs
1664 * operation like this one can lead to a deadlock through kernfs
1665 * active_ref protection. Let's break the protection. Losing the
1666 * protection is okay as we check whether @cs is online after
1667 * grabbing cpuset_mutex anyway. This only happens on the legacy
1668 * hierarchies.
3a5a6d0c 1669 */
76bb5ab8
TH
1670 css_get(&cs->css);
1671 kernfs_break_active_protection(of->kn);
3a5a6d0c
TH
1672 flush_work(&cpuset_hotplug_work);
1673
5d21cc2d
TH
1674 mutex_lock(&cpuset_mutex);
1675 if (!is_cpuset_online(cs))
1676 goto out_unlock;
e3712395 1677
645fcc9d 1678 trialcs = alloc_trial_cpuset(cs);
b75f38d6
LZ
1679 if (!trialcs) {
1680 retval = -ENOMEM;
5d21cc2d 1681 goto out_unlock;
b75f38d6 1682 }
645fcc9d 1683
451af504 1684 switch (of_cft(of)->private) {
e3712395 1685 case FILE_CPULIST:
645fcc9d 1686 retval = update_cpumask(cs, trialcs, buf);
e3712395
PM
1687 break;
1688 case FILE_MEMLIST:
645fcc9d 1689 retval = update_nodemask(cs, trialcs, buf);
e3712395
PM
1690 break;
1691 default:
1692 retval = -EINVAL;
1693 break;
1694 }
645fcc9d
LZ
1695
1696 free_trial_cpuset(trialcs);
5d21cc2d
TH
1697out_unlock:
1698 mutex_unlock(&cpuset_mutex);
76bb5ab8
TH
1699 kernfs_unbreak_active_protection(of->kn);
1700 css_put(&cs->css);
451af504 1701 return retval ?: nbytes;
e3712395
PM
1702}
1703
1da177e4
LT
1704/*
1705 * These ascii lists should be read in a single call, by using a user
1706 * buffer large enough to hold the entire map. If read in smaller
1707 * chunks, there is no guarantee of atomicity. Since the display format
1708 * used, list of ranges of sequential numbers, is variable length,
1709 * and since these maps can change value dynamically, one could read
1710 * gibberish by doing partial reads while a list was changing.
1da177e4 1711 */
2da8ca82 1712static int cpuset_common_seq_show(struct seq_file *sf, void *v)
1da177e4 1713{
2da8ca82
TH
1714 struct cpuset *cs = css_cs(seq_css(sf));
1715 cpuset_filetype_t type = seq_cft(sf)->private;
51ffe411 1716 int ret = 0;
1da177e4 1717
8447a0fe 1718 spin_lock_irq(&callback_lock);
1da177e4
LT
1719
1720 switch (type) {
1721 case FILE_CPULIST:
e8e6d97c 1722 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
1da177e4
LT
1723 break;
1724 case FILE_MEMLIST:
e8e6d97c 1725 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
1da177e4 1726 break;
afd1a8b3 1727 case FILE_EFFECTIVE_CPULIST:
e8e6d97c 1728 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
afd1a8b3
LZ
1729 break;
1730 case FILE_EFFECTIVE_MEMLIST:
e8e6d97c 1731 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
afd1a8b3 1732 break;
1da177e4 1733 default:
51ffe411 1734 ret = -EINVAL;
1da177e4 1735 }
1da177e4 1736
8447a0fe 1737 spin_unlock_irq(&callback_lock);
51ffe411 1738 return ret;
1da177e4
LT
1739}
1740
182446d0 1741static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
700fe1ab 1742{
182446d0 1743 struct cpuset *cs = css_cs(css);
700fe1ab
PM
1744 cpuset_filetype_t type = cft->private;
1745 switch (type) {
1746 case FILE_CPU_EXCLUSIVE:
1747 return is_cpu_exclusive(cs);
1748 case FILE_MEM_EXCLUSIVE:
1749 return is_mem_exclusive(cs);
78608366
PM
1750 case FILE_MEM_HARDWALL:
1751 return is_mem_hardwall(cs);
700fe1ab
PM
1752 case FILE_SCHED_LOAD_BALANCE:
1753 return is_sched_load_balance(cs);
1754 case FILE_MEMORY_MIGRATE:
1755 return is_memory_migrate(cs);
1756 case FILE_MEMORY_PRESSURE_ENABLED:
1757 return cpuset_memory_pressure_enabled;
1758 case FILE_MEMORY_PRESSURE:
1759 return fmeter_getrate(&cs->fmeter);
1760 case FILE_SPREAD_PAGE:
1761 return is_spread_page(cs);
1762 case FILE_SPREAD_SLAB:
1763 return is_spread_slab(cs);
1764 default:
1765 BUG();
1766 }
cf417141
MK
1767
1768 /* Unreachable but makes gcc happy */
1769 return 0;
700fe1ab 1770}
1da177e4 1771
182446d0 1772static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
5be7a479 1773{
182446d0 1774 struct cpuset *cs = css_cs(css);
5be7a479
PM
1775 cpuset_filetype_t type = cft->private;
1776 switch (type) {
1777 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1778 return cs->relax_domain_level;
1779 default:
1780 BUG();
1781 }
cf417141
MK
1782
1783 /* Unrechable but makes gcc happy */
1784 return 0;
5be7a479
PM
1785}
1786
1da177e4
LT
1787
1788/*
1789 * for the common functions, 'private' gives the type of file
1790 */
1791
addf2c73
PM
1792static struct cftype files[] = {
1793 {
1794 .name = "cpus",
2da8ca82 1795 .seq_show = cpuset_common_seq_show,
451af504 1796 .write = cpuset_write_resmask,
e3712395 1797 .max_write_len = (100U + 6 * NR_CPUS),
addf2c73
PM
1798 .private = FILE_CPULIST,
1799 },
1800
1801 {
1802 .name = "mems",
2da8ca82 1803 .seq_show = cpuset_common_seq_show,
451af504 1804 .write = cpuset_write_resmask,
e3712395 1805 .max_write_len = (100U + 6 * MAX_NUMNODES),
addf2c73
PM
1806 .private = FILE_MEMLIST,
1807 },
1808
afd1a8b3
LZ
1809 {
1810 .name = "effective_cpus",
1811 .seq_show = cpuset_common_seq_show,
1812 .private = FILE_EFFECTIVE_CPULIST,
1813 },
1814
1815 {
1816 .name = "effective_mems",
1817 .seq_show = cpuset_common_seq_show,
1818 .private = FILE_EFFECTIVE_MEMLIST,
1819 },
1820
addf2c73
PM
1821 {
1822 .name = "cpu_exclusive",
1823 .read_u64 = cpuset_read_u64,
1824 .write_u64 = cpuset_write_u64,
1825 .private = FILE_CPU_EXCLUSIVE,
1826 },
1827
1828 {
1829 .name = "mem_exclusive",
1830 .read_u64 = cpuset_read_u64,
1831 .write_u64 = cpuset_write_u64,
1832 .private = FILE_MEM_EXCLUSIVE,
1833 },
1834
78608366
PM
1835 {
1836 .name = "mem_hardwall",
1837 .read_u64 = cpuset_read_u64,
1838 .write_u64 = cpuset_write_u64,
1839 .private = FILE_MEM_HARDWALL,
1840 },
1841
addf2c73
PM
1842 {
1843 .name = "sched_load_balance",
1844 .read_u64 = cpuset_read_u64,
1845 .write_u64 = cpuset_write_u64,
1846 .private = FILE_SCHED_LOAD_BALANCE,
1847 },
1848
1849 {
1850 .name = "sched_relax_domain_level",
5be7a479
PM
1851 .read_s64 = cpuset_read_s64,
1852 .write_s64 = cpuset_write_s64,
addf2c73
PM
1853 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1854 },
1855
1856 {
1857 .name = "memory_migrate",
1858 .read_u64 = cpuset_read_u64,
1859 .write_u64 = cpuset_write_u64,
1860 .private = FILE_MEMORY_MIGRATE,
1861 },
1862
1863 {
1864 .name = "memory_pressure",
1865 .read_u64 = cpuset_read_u64,
1866 .write_u64 = cpuset_write_u64,
1867 .private = FILE_MEMORY_PRESSURE,
099fca32 1868 .mode = S_IRUGO,
addf2c73
PM
1869 },
1870
1871 {
1872 .name = "memory_spread_page",
1873 .read_u64 = cpuset_read_u64,
1874 .write_u64 = cpuset_write_u64,
1875 .private = FILE_SPREAD_PAGE,
1876 },
1877
1878 {
1879 .name = "memory_spread_slab",
1880 .read_u64 = cpuset_read_u64,
1881 .write_u64 = cpuset_write_u64,
1882 .private = FILE_SPREAD_SLAB,
1883 },
3e0d98b9 1884
4baf6e33
TH
1885 {
1886 .name = "memory_pressure_enabled",
1887 .flags = CFTYPE_ONLY_ON_ROOT,
1888 .read_u64 = cpuset_read_u64,
1889 .write_u64 = cpuset_write_u64,
1890 .private = FILE_MEMORY_PRESSURE_ENABLED,
1891 },
1da177e4 1892
4baf6e33
TH
1893 { } /* terminate */
1894};
1da177e4
LT
1895
1896/*
92fb9748 1897 * cpuset_css_alloc - allocate a cpuset css
c9e5fe66 1898 * cgrp: control group that the new cpuset will be part of
1da177e4
LT
1899 */
1900
eb95419b
TH
1901static struct cgroup_subsys_state *
1902cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
1da177e4 1903{
c8f699bb 1904 struct cpuset *cs;
1da177e4 1905
eb95419b 1906 if (!parent_css)
8793d854 1907 return &top_cpuset.css;
033fa1c5 1908
c8f699bb 1909 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
1da177e4 1910 if (!cs)
8793d854 1911 return ERR_PTR(-ENOMEM);
e2b9a3d7
LZ
1912 if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
1913 goto free_cs;
1914 if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
1915 goto free_cpus;
1da177e4 1916
029190c5 1917 set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
300ed6cb 1918 cpumask_clear(cs->cpus_allowed);
f9a86fcb 1919 nodes_clear(cs->mems_allowed);
e2b9a3d7
LZ
1920 cpumask_clear(cs->effective_cpus);
1921 nodes_clear(cs->effective_mems);
3e0d98b9 1922 fmeter_init(&cs->fmeter);
1d3504fc 1923 cs->relax_domain_level = -1;
1da177e4 1924
c8f699bb 1925 return &cs->css;
e2b9a3d7
LZ
1926
1927free_cpus:
1928 free_cpumask_var(cs->cpus_allowed);
1929free_cs:
1930 kfree(cs);
1931 return ERR_PTR(-ENOMEM);
c8f699bb
TH
1932}
1933
eb95419b 1934static int cpuset_css_online(struct cgroup_subsys_state *css)
c8f699bb 1935{
eb95419b 1936 struct cpuset *cs = css_cs(css);
c431069f 1937 struct cpuset *parent = parent_cs(cs);
ae8086ce 1938 struct cpuset *tmp_cs;
492eb21b 1939 struct cgroup_subsys_state *pos_css;
c8f699bb
TH
1940
1941 if (!parent)
1942 return 0;
1943
5d21cc2d
TH
1944 mutex_lock(&cpuset_mutex);
1945
efeb77b2 1946 set_bit(CS_ONLINE, &cs->flags);
c8f699bb
TH
1947 if (is_spread_page(parent))
1948 set_bit(CS_SPREAD_PAGE, &cs->flags);
1949 if (is_spread_slab(parent))
1950 set_bit(CS_SPREAD_SLAB, &cs->flags);
1da177e4 1951
664eedde 1952 cpuset_inc();
033fa1c5 1953
8447a0fe 1954 spin_lock_irq(&callback_lock);
e2b9a3d7
LZ
1955 if (cgroup_on_dfl(cs->css.cgroup)) {
1956 cpumask_copy(cs->effective_cpus, parent->effective_cpus);
1957 cs->effective_mems = parent->effective_mems;
1958 }
8447a0fe 1959 spin_unlock_irq(&callback_lock);
e2b9a3d7 1960
eb95419b 1961 if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
5d21cc2d 1962 goto out_unlock;
033fa1c5
TH
1963
1964 /*
1965 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
1966 * set. This flag handling is implemented in cgroup core for
1967 * histrical reasons - the flag may be specified during mount.
1968 *
1969 * Currently, if any sibling cpusets have exclusive cpus or mem, we
1970 * refuse to clone the configuration - thereby refusing the task to
1971 * be entered, and as a result refusing the sys_unshare() or
1972 * clone() which initiated it. If this becomes a problem for some
1973 * users who wish to allow that scenario, then this could be
1974 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1975 * (and likewise for mems) to the new cgroup.
1976 */
ae8086ce 1977 rcu_read_lock();
492eb21b 1978 cpuset_for_each_child(tmp_cs, pos_css, parent) {
ae8086ce
TH
1979 if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
1980 rcu_read_unlock();
5d21cc2d 1981 goto out_unlock;
ae8086ce 1982 }
033fa1c5 1983 }
ae8086ce 1984 rcu_read_unlock();
033fa1c5 1985
8447a0fe 1986 spin_lock_irq(&callback_lock);
033fa1c5 1987 cs->mems_allowed = parent->mems_allowed;
790317e1 1988 cs->effective_mems = parent->mems_allowed;
033fa1c5 1989 cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
790317e1 1990 cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
cea74465 1991 spin_unlock_irq(&callback_lock);
5d21cc2d
TH
1992out_unlock:
1993 mutex_unlock(&cpuset_mutex);
c8f699bb
TH
1994 return 0;
1995}
1996
0b9e6965
ZH
1997/*
1998 * If the cpuset being removed has its flag 'sched_load_balance'
1999 * enabled, then simulate turning sched_load_balance off, which
2000 * will call rebuild_sched_domains_locked().
2001 */
2002
eb95419b 2003static void cpuset_css_offline(struct cgroup_subsys_state *css)
c8f699bb 2004{
eb95419b 2005 struct cpuset *cs = css_cs(css);
c8f699bb 2006
5d21cc2d 2007 mutex_lock(&cpuset_mutex);
c8f699bb
TH
2008
2009 if (is_sched_load_balance(cs))
2010 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
2011
664eedde 2012 cpuset_dec();
efeb77b2 2013 clear_bit(CS_ONLINE, &cs->flags);
c8f699bb 2014
5d21cc2d 2015 mutex_unlock(&cpuset_mutex);
1da177e4
LT
2016}
2017
eb95419b 2018static void cpuset_css_free(struct cgroup_subsys_state *css)
1da177e4 2019{
eb95419b 2020 struct cpuset *cs = css_cs(css);
1da177e4 2021
e2b9a3d7 2022 free_cpumask_var(cs->effective_cpus);
300ed6cb 2023 free_cpumask_var(cs->cpus_allowed);
8793d854 2024 kfree(cs);
1da177e4
LT
2025}
2026
39bd0d15
LZ
2027static void cpuset_bind(struct cgroup_subsys_state *root_css)
2028{
2029 mutex_lock(&cpuset_mutex);
8447a0fe 2030 spin_lock_irq(&callback_lock);
39bd0d15
LZ
2031
2032 if (cgroup_on_dfl(root_css->cgroup)) {
2033 cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
2034 top_cpuset.mems_allowed = node_possible_map;
2035 } else {
2036 cpumask_copy(top_cpuset.cpus_allowed,
2037 top_cpuset.effective_cpus);
2038 top_cpuset.mems_allowed = top_cpuset.effective_mems;
2039 }
2040
8447a0fe 2041 spin_unlock_irq(&callback_lock);
39bd0d15
LZ
2042 mutex_unlock(&cpuset_mutex);
2043}
2044
073219e9 2045struct cgroup_subsys cpuset_cgrp_subsys = {
39bd0d15
LZ
2046 .css_alloc = cpuset_css_alloc,
2047 .css_online = cpuset_css_online,
2048 .css_offline = cpuset_css_offline,
2049 .css_free = cpuset_css_free,
2050 .can_attach = cpuset_can_attach,
2051 .cancel_attach = cpuset_cancel_attach,
2052 .attach = cpuset_attach,
2053 .bind = cpuset_bind,
5577964e 2054 .legacy_cftypes = files,
39bd0d15 2055 .early_init = 1,
8793d854
PM
2056};
2057
1da177e4
LT
2058/**
2059 * cpuset_init - initialize cpusets at system boot
2060 *
2061 * Description: Initialize top_cpuset and the cpuset internal file system,
2062 **/
2063
2064int __init cpuset_init(void)
2065{
8793d854 2066 int err = 0;
1da177e4 2067
58568d2a
MX
2068 if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
2069 BUG();
e2b9a3d7
LZ
2070 if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
2071 BUG();
58568d2a 2072
300ed6cb 2073 cpumask_setall(top_cpuset.cpus_allowed);
f9a86fcb 2074 nodes_setall(top_cpuset.mems_allowed);
e2b9a3d7
LZ
2075 cpumask_setall(top_cpuset.effective_cpus);
2076 nodes_setall(top_cpuset.effective_mems);
1da177e4 2077
3e0d98b9 2078 fmeter_init(&top_cpuset.fmeter);
029190c5 2079 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1d3504fc 2080 top_cpuset.relax_domain_level = -1;
1da177e4 2081
1da177e4
LT
2082 err = register_filesystem(&cpuset_fs_type);
2083 if (err < 0)
8793d854
PM
2084 return err;
2085
2341d1b6
LZ
2086 if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
2087 BUG();
2088
8793d854 2089 return 0;
1da177e4
LT
2090}
2091
b1aac8bb 2092/*
cf417141 2093 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
b1aac8bb
PJ
2094 * or memory nodes, we need to walk over the cpuset hierarchy,
2095 * removing that CPU or node from all cpusets. If this removes the
956db3ca
CW
2096 * last CPU or node from a cpuset, then move the tasks in the empty
2097 * cpuset to its next-highest non-empty parent.
b1aac8bb 2098 */
956db3ca
CW
2099static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
2100{
2101 struct cpuset *parent;
2102
956db3ca
CW
2103 /*
2104 * Find its next-highest non-empty parent, (top cpuset
2105 * has online cpus, so can't be empty).
2106 */
c431069f 2107 parent = parent_cs(cs);
300ed6cb 2108 while (cpumask_empty(parent->cpus_allowed) ||
b4501295 2109 nodes_empty(parent->mems_allowed))
c431069f 2110 parent = parent_cs(parent);
956db3ca 2111
8cc99345 2112 if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
12d3089c 2113 pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
e61734c5
TH
2114 pr_cont_cgroup_name(cs->css.cgroup);
2115 pr_cont("\n");
8cc99345 2116 }
956db3ca
CW
2117}
2118
be4c9dd7
LZ
2119static void
2120hotplug_update_tasks_legacy(struct cpuset *cs,
2121 struct cpumask *new_cpus, nodemask_t *new_mems,
2122 bool cpus_updated, bool mems_updated)
390a36aa
LZ
2123{
2124 bool is_empty;
2125
8447a0fe 2126 spin_lock_irq(&callback_lock);
be4c9dd7
LZ
2127 cpumask_copy(cs->cpus_allowed, new_cpus);
2128 cpumask_copy(cs->effective_cpus, new_cpus);
2129 cs->mems_allowed = *new_mems;
2130 cs->effective_mems = *new_mems;
8447a0fe 2131 spin_unlock_irq(&callback_lock);
390a36aa
LZ
2132
2133 /*
2134 * Don't call update_tasks_cpumask() if the cpuset becomes empty,
2135 * as the tasks will be migratecd to an ancestor.
2136 */
be4c9dd7 2137 if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
390a36aa 2138 update_tasks_cpumask(cs);
be4c9dd7 2139 if (mems_updated && !nodes_empty(cs->mems_allowed))
390a36aa
LZ
2140 update_tasks_nodemask(cs);
2141
2142 is_empty = cpumask_empty(cs->cpus_allowed) ||
2143 nodes_empty(cs->mems_allowed);
2144
2145 mutex_unlock(&cpuset_mutex);
2146
2147 /*
2148 * Move tasks to the nearest ancestor with execution resources,
2149 * This is full cgroup operation which will also call back into
2150 * cpuset. Should be done outside any lock.
2151 */
2152 if (is_empty)
2153 remove_tasks_in_empty_cpuset(cs);
2154
2155 mutex_lock(&cpuset_mutex);
2156}
2157
be4c9dd7
LZ
2158static void
2159hotplug_update_tasks(struct cpuset *cs,
2160 struct cpumask *new_cpus, nodemask_t *new_mems,
2161 bool cpus_updated, bool mems_updated)
390a36aa 2162{
be4c9dd7
LZ
2163 if (cpumask_empty(new_cpus))
2164 cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
2165 if (nodes_empty(*new_mems))
2166 *new_mems = parent_cs(cs)->effective_mems;
2167
8447a0fe 2168 spin_lock_irq(&callback_lock);
be4c9dd7
LZ
2169 cpumask_copy(cs->effective_cpus, new_cpus);
2170 cs->effective_mems = *new_mems;
8447a0fe 2171 spin_unlock_irq(&callback_lock);
390a36aa 2172
be4c9dd7 2173 if (cpus_updated)
390a36aa 2174 update_tasks_cpumask(cs);
be4c9dd7 2175 if (mems_updated)
390a36aa
LZ
2176 update_tasks_nodemask(cs);
2177}
2178
deb7aa30 2179/**
388afd85 2180 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
deb7aa30 2181 * @cs: cpuset in interest
956db3ca 2182 *
deb7aa30
TH
2183 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
2184 * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
2185 * all its tasks are moved to the nearest ancestor with both resources.
80d1fa64 2186 */
388afd85 2187static void cpuset_hotplug_update_tasks(struct cpuset *cs)
80d1fa64 2188{
be4c9dd7
LZ
2189 static cpumask_t new_cpus;
2190 static nodemask_t new_mems;
2191 bool cpus_updated;
2192 bool mems_updated;
e44193d3
LZ
2193retry:
2194 wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
80d1fa64 2195
5d21cc2d 2196 mutex_lock(&cpuset_mutex);
7ddf96b0 2197
e44193d3
LZ
2198 /*
2199 * We have raced with task attaching. We wait until attaching
2200 * is finished, so we won't attach a task to an empty cpuset.
2201 */
2202 if (cs->attach_in_progress) {
2203 mutex_unlock(&cpuset_mutex);
2204 goto retry;
2205 }
2206
be4c9dd7
LZ
2207 cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
2208 nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
80d1fa64 2209
be4c9dd7
LZ
2210 cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
2211 mems_updated = !nodes_equal(new_mems, cs->effective_mems);
deb7aa30 2212
390a36aa 2213 if (cgroup_on_dfl(cs->css.cgroup))
be4c9dd7
LZ
2214 hotplug_update_tasks(cs, &new_cpus, &new_mems,
2215 cpus_updated, mems_updated);
390a36aa 2216 else
be4c9dd7
LZ
2217 hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
2218 cpus_updated, mems_updated);
8d033948 2219
5d21cc2d 2220 mutex_unlock(&cpuset_mutex);
b1aac8bb
PJ
2221}
2222
deb7aa30 2223/**
3a5a6d0c 2224 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
956db3ca 2225 *
deb7aa30
TH
2226 * This function is called after either CPU or memory configuration has
2227 * changed and updates cpuset accordingly. The top_cpuset is always
2228 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
2229 * order to make cpusets transparent (of no affect) on systems that are
2230 * actively using CPU hotplug but making no active use of cpusets.
956db3ca 2231 *
deb7aa30 2232 * Non-root cpusets are only affected by offlining. If any CPUs or memory
388afd85
LZ
2233 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
2234 * all descendants.
956db3ca 2235 *
deb7aa30
TH
2236 * Note that CPU offlining during suspend is ignored. We don't modify
2237 * cpusets across suspend/resume cycles at all.
956db3ca 2238 */
3a5a6d0c 2239static void cpuset_hotplug_workfn(struct work_struct *work)
b1aac8bb 2240{
5c5cc623
LZ
2241 static cpumask_t new_cpus;
2242 static nodemask_t new_mems;
deb7aa30 2243 bool cpus_updated, mems_updated;
7e88291b 2244 bool on_dfl = cgroup_on_dfl(top_cpuset.css.cgroup);
b1aac8bb 2245
5d21cc2d 2246 mutex_lock(&cpuset_mutex);
956db3ca 2247
deb7aa30
TH
2248 /* fetch the available cpus/mems and find out which changed how */
2249 cpumask_copy(&new_cpus, cpu_active_mask);
2250 new_mems = node_states[N_MEMORY];
7ddf96b0 2251
7e88291b
LZ
2252 cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
2253 mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
7ddf96b0 2254
deb7aa30
TH
2255 /* synchronize cpus_allowed to cpu_active_mask */
2256 if (cpus_updated) {
8447a0fe 2257 spin_lock_irq(&callback_lock);
7e88291b
LZ
2258 if (!on_dfl)
2259 cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
1344ab9c 2260 cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
8447a0fe 2261 spin_unlock_irq(&callback_lock);
deb7aa30
TH
2262 /* we don't mess with cpumasks of tasks in top_cpuset */
2263 }
b4501295 2264
deb7aa30
TH
2265 /* synchronize mems_allowed to N_MEMORY */
2266 if (mems_updated) {
8447a0fe 2267 spin_lock_irq(&callback_lock);
7e88291b
LZ
2268 if (!on_dfl)
2269 top_cpuset.mems_allowed = new_mems;
1344ab9c 2270 top_cpuset.effective_mems = new_mems;
8447a0fe 2271 spin_unlock_irq(&callback_lock);
d66393e5 2272 update_tasks_nodemask(&top_cpuset);
deb7aa30 2273 }
b4501295 2274
388afd85
LZ
2275 mutex_unlock(&cpuset_mutex);
2276
5c5cc623
LZ
2277 /* if cpus or mems changed, we need to propagate to descendants */
2278 if (cpus_updated || mems_updated) {
deb7aa30 2279 struct cpuset *cs;
492eb21b 2280 struct cgroup_subsys_state *pos_css;
f9b4fb8d 2281
fc560a26 2282 rcu_read_lock();
492eb21b 2283 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
ec903c0c 2284 if (cs == &top_cpuset || !css_tryget_online(&cs->css))
388afd85
LZ
2285 continue;
2286 rcu_read_unlock();
7ddf96b0 2287
388afd85 2288 cpuset_hotplug_update_tasks(cs);
b4501295 2289
388afd85
LZ
2290 rcu_read_lock();
2291 css_put(&cs->css);
2292 }
2293 rcu_read_unlock();
2294 }
8d033948 2295
deb7aa30 2296 /* rebuild sched domains if cpus_allowed has changed */
e0e80a02
LZ
2297 if (cpus_updated)
2298 rebuild_sched_domains();
b1aac8bb
PJ
2299}
2300
7ddf96b0 2301void cpuset_update_active_cpus(bool cpu_online)
4c4d50f7 2302{
3a5a6d0c
TH
2303 /*
2304 * We're inside cpu hotplug critical region which usually nests
2305 * inside cgroup synchronization. Bounce actual hotplug processing
2306 * to a work item to avoid reverse locking order.
2307 *
2308 * We still need to do partition_sched_domains() synchronously;
2309 * otherwise, the scheduler will get confused and put tasks to the
2310 * dead CPU. Fall back to the default single domain.
2311 * cpuset_hotplug_workfn() will rebuild it as necessary.
2312 */
2313 partition_sched_domains(1, NULL, NULL);
2314 schedule_work(&cpuset_hotplug_work);
4c4d50f7 2315}
4c4d50f7 2316
38837fc7 2317/*
38d7bee9
LJ
2318 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
2319 * Call this routine anytime after node_states[N_MEMORY] changes.
a1cd2b13 2320 * See cpuset_update_active_cpus() for CPU hotplug handling.
38837fc7 2321 */
f481891f
MX
2322static int cpuset_track_online_nodes(struct notifier_block *self,
2323 unsigned long action, void *arg)
38837fc7 2324{
3a5a6d0c 2325 schedule_work(&cpuset_hotplug_work);
f481891f 2326 return NOTIFY_OK;
38837fc7 2327}
d8f10cb3
AM
2328
2329static struct notifier_block cpuset_track_online_nodes_nb = {
2330 .notifier_call = cpuset_track_online_nodes,
2331 .priority = 10, /* ??! */
2332};
38837fc7 2333
1da177e4
LT
2334/**
2335 * cpuset_init_smp - initialize cpus_allowed
2336 *
2337 * Description: Finish top cpuset after cpu, node maps are initialized
d8f10cb3 2338 */
1da177e4
LT
2339void __init cpuset_init_smp(void)
2340{
6ad4c188 2341 cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
38d7bee9 2342 top_cpuset.mems_allowed = node_states[N_MEMORY];
33ad801d 2343 top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
4c4d50f7 2344
e2b9a3d7
LZ
2345 cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
2346 top_cpuset.effective_mems = node_states[N_MEMORY];
2347
d8f10cb3 2348 register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
1da177e4
LT
2349}
2350
2351/**
1da177e4
LT
2352 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2353 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
6af866af 2354 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
1da177e4 2355 *
300ed6cb 2356 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
1da177e4 2357 * attached to the specified @tsk. Guaranteed to return some non-empty
5f054e31 2358 * subset of cpu_online_mask, even if this means going outside the
1da177e4
LT
2359 * tasks cpuset.
2360 **/
2361
6af866af 2362void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
1da177e4 2363{
8447a0fe
VD
2364 unsigned long flags;
2365
2366 spin_lock_irqsave(&callback_lock, flags);
b8dadcb5 2367 rcu_read_lock();
ae1c8023 2368 guarantee_online_cpus(task_cs(tsk), pmask);
b8dadcb5 2369 rcu_read_unlock();
8447a0fe 2370 spin_unlock_irqrestore(&callback_lock, flags);
1da177e4
LT
2371}
2372
2baab4e9 2373void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
9084bb82 2374{
9084bb82 2375 rcu_read_lock();
ae1c8023 2376 do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
9084bb82
ON
2377 rcu_read_unlock();
2378
2379 /*
2380 * We own tsk->cpus_allowed, nobody can change it under us.
2381 *
2382 * But we used cs && cs->cpus_allowed lockless and thus can
2383 * race with cgroup_attach_task() or update_cpumask() and get
2384 * the wrong tsk->cpus_allowed. However, both cases imply the
2385 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
2386 * which takes task_rq_lock().
2387 *
2388 * If we are called after it dropped the lock we must see all
2389 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
2390 * set any mask even if it is not right from task_cs() pov,
2391 * the pending set_cpus_allowed_ptr() will fix things.
2baab4e9
PZ
2392 *
2393 * select_fallback_rq() will fix things ups and set cpu_possible_mask
2394 * if required.
9084bb82 2395 */
9084bb82
ON
2396}
2397
8f4ab07f 2398void __init cpuset_init_current_mems_allowed(void)
1da177e4 2399{
f9a86fcb 2400 nodes_setall(current->mems_allowed);
1da177e4
LT
2401}
2402
909d75a3
PJ
2403/**
2404 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2405 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2406 *
2407 * Description: Returns the nodemask_t mems_allowed of the cpuset
2408 * attached to the specified @tsk. Guaranteed to return some non-empty
38d7bee9 2409 * subset of node_states[N_MEMORY], even if this means going outside the
909d75a3
PJ
2410 * tasks cpuset.
2411 **/
2412
2413nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2414{
2415 nodemask_t mask;
8447a0fe 2416 unsigned long flags;
909d75a3 2417
8447a0fe 2418 spin_lock_irqsave(&callback_lock, flags);
b8dadcb5 2419 rcu_read_lock();
ae1c8023 2420 guarantee_online_mems(task_cs(tsk), &mask);
b8dadcb5 2421 rcu_read_unlock();
8447a0fe 2422 spin_unlock_irqrestore(&callback_lock, flags);
909d75a3
PJ
2423
2424 return mask;
2425}
2426
d9fd8a6d 2427/**
19770b32
MG
2428 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2429 * @nodemask: the nodemask to be checked
d9fd8a6d 2430 *
19770b32 2431 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
1da177e4 2432 */
19770b32 2433int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
1da177e4 2434{
19770b32 2435 return nodes_intersects(*nodemask, current->mems_allowed);
1da177e4
LT
2436}
2437
9bf2229f 2438/*
78608366
PM
2439 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2440 * mem_hardwall ancestor to the specified cpuset. Call holding
8447a0fe 2441 * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
78608366 2442 * (an unusual configuration), then returns the root cpuset.
9bf2229f 2443 */
c9710d80 2444static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
9bf2229f 2445{
c431069f
TH
2446 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
2447 cs = parent_cs(cs);
9bf2229f
PJ
2448 return cs;
2449}
2450
d9fd8a6d 2451/**
344736f2 2452 * cpuset_node_allowed - Can we allocate on a memory node?
a1bc5a4e 2453 * @node: is this an allowed node?
02a0e53d 2454 * @gfp_mask: memory allocation flags
d9fd8a6d 2455 *
6e276d2a
DR
2456 * If we're in interrupt, yes, we can always allocate. If @node is set in
2457 * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
2458 * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
2459 * yes. If current has access to memory reserves due to TIF_MEMDIE, yes.
9bf2229f
PJ
2460 * Otherwise, no.
2461 *
2462 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
c596d9f3
DR
2463 * and do not allow allocations outside the current tasks cpuset
2464 * unless the task has been OOM killed as is marked TIF_MEMDIE.
9bf2229f 2465 * GFP_KERNEL allocations are not so marked, so can escape to the
78608366 2466 * nearest enclosing hardwalled ancestor cpuset.
9bf2229f 2467 *
8447a0fe 2468 * Scanning up parent cpusets requires callback_lock. The
02a0e53d
PJ
2469 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2470 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2471 * current tasks mems_allowed came up empty on the first pass over
2472 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
8447a0fe 2473 * cpuset are short of memory, might require taking the callback_lock.
9bf2229f 2474 *
36be57ff 2475 * The first call here from mm/page_alloc:get_page_from_freelist()
02a0e53d
PJ
2476 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2477 * so no allocation on a node outside the cpuset is allowed (unless
2478 * in interrupt, of course).
36be57ff
PJ
2479 *
2480 * The second pass through get_page_from_freelist() doesn't even call
2481 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2482 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2483 * in alloc_flags. That logic and the checks below have the combined
2484 * affect that:
9bf2229f
PJ
2485 * in_interrupt - any node ok (current task context irrelevant)
2486 * GFP_ATOMIC - any node ok
c596d9f3 2487 * TIF_MEMDIE - any node ok
78608366 2488 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
9bf2229f 2489 * GFP_USER - only nodes in current tasks mems allowed ok.
02a0e53d 2490 */
344736f2 2491int __cpuset_node_allowed(int node, gfp_t gfp_mask)
1da177e4 2492{
c9710d80 2493 struct cpuset *cs; /* current cpuset ancestors */
29afd49b 2494 int allowed; /* is allocation in zone z allowed? */
8447a0fe 2495 unsigned long flags;
9bf2229f 2496
6e276d2a 2497 if (in_interrupt())
9bf2229f 2498 return 1;
9bf2229f
PJ
2499 if (node_isset(node, current->mems_allowed))
2500 return 1;
c596d9f3
DR
2501 /*
2502 * Allow tasks that have access to memory reserves because they have
2503 * been OOM killed to get memory anywhere.
2504 */
2505 if (unlikely(test_thread_flag(TIF_MEMDIE)))
2506 return 1;
9bf2229f
PJ
2507 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
2508 return 0;
2509
5563e770
BP
2510 if (current->flags & PF_EXITING) /* Let dying task have memory */
2511 return 1;
2512
9bf2229f 2513 /* Not hardwall and node outside mems_allowed: scan up cpusets */
8447a0fe 2514 spin_lock_irqsave(&callback_lock, flags);
053199ed 2515
b8dadcb5 2516 rcu_read_lock();
78608366 2517 cs = nearest_hardwall_ancestor(task_cs(current));
99afb0fd 2518 allowed = node_isset(node, cs->mems_allowed);
b8dadcb5 2519 rcu_read_unlock();
053199ed 2520
8447a0fe 2521 spin_unlock_irqrestore(&callback_lock, flags);
9bf2229f 2522 return allowed;
1da177e4
LT
2523}
2524
825a46af 2525/**
6adef3eb
JS
2526 * cpuset_mem_spread_node() - On which node to begin search for a file page
2527 * cpuset_slab_spread_node() - On which node to begin search for a slab page
825a46af
PJ
2528 *
2529 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2530 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2531 * and if the memory allocation used cpuset_mem_spread_node()
2532 * to determine on which node to start looking, as it will for
2533 * certain page cache or slab cache pages such as used for file
2534 * system buffers and inode caches, then instead of starting on the
2535 * local node to look for a free page, rather spread the starting
2536 * node around the tasks mems_allowed nodes.
2537 *
2538 * We don't have to worry about the returned node being offline
2539 * because "it can't happen", and even if it did, it would be ok.
2540 *
2541 * The routines calling guarantee_online_mems() are careful to
2542 * only set nodes in task->mems_allowed that are online. So it
2543 * should not be possible for the following code to return an
2544 * offline node. But if it did, that would be ok, as this routine
2545 * is not returning the node where the allocation must be, only
2546 * the node where the search should start. The zonelist passed to
2547 * __alloc_pages() will include all nodes. If the slab allocator
2548 * is passed an offline node, it will fall back to the local node.
2549 * See kmem_cache_alloc_node().
2550 */
2551
6adef3eb 2552static int cpuset_spread_node(int *rotor)
825a46af
PJ
2553{
2554 int node;
2555
6adef3eb 2556 node = next_node(*rotor, current->mems_allowed);
825a46af
PJ
2557 if (node == MAX_NUMNODES)
2558 node = first_node(current->mems_allowed);
6adef3eb 2559 *rotor = node;
825a46af
PJ
2560 return node;
2561}
6adef3eb
JS
2562
2563int cpuset_mem_spread_node(void)
2564{
778d3b0f
MH
2565 if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
2566 current->cpuset_mem_spread_rotor =
2567 node_random(&current->mems_allowed);
2568
6adef3eb
JS
2569 return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
2570}
2571
2572int cpuset_slab_spread_node(void)
2573{
778d3b0f
MH
2574 if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
2575 current->cpuset_slab_spread_rotor =
2576 node_random(&current->mems_allowed);
2577
6adef3eb
JS
2578 return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
2579}
2580
825a46af
PJ
2581EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2582
ef08e3b4 2583/**
bbe373f2
DR
2584 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2585 * @tsk1: pointer to task_struct of some task.
2586 * @tsk2: pointer to task_struct of some other task.
2587 *
2588 * Description: Return true if @tsk1's mems_allowed intersects the
2589 * mems_allowed of @tsk2. Used by the OOM killer to determine if
2590 * one of the task's memory usage might impact the memory available
2591 * to the other.
ef08e3b4
PJ
2592 **/
2593
bbe373f2
DR
2594int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2595 const struct task_struct *tsk2)
ef08e3b4 2596{
bbe373f2 2597 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
ef08e3b4
PJ
2598}
2599
75aa1994
DR
2600/**
2601 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
fc34ac1d 2602 * @tsk: pointer to task_struct of some task.
75aa1994
DR
2603 *
2604 * Description: Prints @task's name, cpuset name, and cached copy of its
b8dadcb5 2605 * mems_allowed to the kernel log.
75aa1994
DR
2606 */
2607void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2608{
b8dadcb5 2609 struct cgroup *cgrp;
75aa1994 2610
b8dadcb5 2611 rcu_read_lock();
63f43f55 2612
b8dadcb5 2613 cgrp = task_cs(tsk)->css.cgroup;
12d3089c 2614 pr_info("%s cpuset=", tsk->comm);
e61734c5 2615 pr_cont_cgroup_name(cgrp);
e8e6d97c 2616 pr_cont(" mems_allowed=%*pbl\n", nodemask_pr_args(&tsk->mems_allowed));
f440d98f 2617
cfb5966b 2618 rcu_read_unlock();
75aa1994
DR
2619}
2620
3e0d98b9
PJ
2621/*
2622 * Collection of memory_pressure is suppressed unless
2623 * this flag is enabled by writing "1" to the special
2624 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2625 */
2626
c5b2aff8 2627int cpuset_memory_pressure_enabled __read_mostly;
3e0d98b9
PJ
2628
2629/**
2630 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2631 *
2632 * Keep a running average of the rate of synchronous (direct)
2633 * page reclaim efforts initiated by tasks in each cpuset.
2634 *
2635 * This represents the rate at which some task in the cpuset
2636 * ran low on memory on all nodes it was allowed to use, and
2637 * had to enter the kernels page reclaim code in an effort to
2638 * create more free memory by tossing clean pages or swapping
2639 * or writing dirty pages.
2640 *
2641 * Display to user space in the per-cpuset read-only file
2642 * "memory_pressure". Value displayed is an integer
2643 * representing the recent rate of entry into the synchronous
2644 * (direct) page reclaim by any task attached to the cpuset.
2645 **/
2646
2647void __cpuset_memory_pressure_bump(void)
2648{
b8dadcb5 2649 rcu_read_lock();
8793d854 2650 fmeter_markevent(&task_cs(current)->fmeter);
b8dadcb5 2651 rcu_read_unlock();
3e0d98b9
PJ
2652}
2653
8793d854 2654#ifdef CONFIG_PROC_PID_CPUSET
1da177e4
LT
2655/*
2656 * proc_cpuset_show()
2657 * - Print tasks cpuset path into seq_file.
2658 * - Used for /proc/<pid>/cpuset.
053199ed
PJ
2659 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2660 * doesn't really matter if tsk->cpuset changes after we read it,
5d21cc2d 2661 * and we take cpuset_mutex, keeping cpuset_attach() from changing it
2df167a3 2662 * anyway.
1da177e4 2663 */
52de4779
ZL
2664int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
2665 struct pid *pid, struct task_struct *tsk)
1da177e4 2666{
e61734c5 2667 char *buf, *p;
8793d854 2668 struct cgroup_subsys_state *css;
99f89551 2669 int retval;
1da177e4 2670
99f89551 2671 retval = -ENOMEM;
e61734c5 2672 buf = kmalloc(PATH_MAX, GFP_KERNEL);
1da177e4 2673 if (!buf)
99f89551
EB
2674 goto out;
2675
e61734c5 2676 retval = -ENAMETOOLONG;
27e89ae5 2677 rcu_read_lock();
073219e9 2678 css = task_css(tsk, cpuset_cgrp_id);
e61734c5 2679 p = cgroup_path(css->cgroup, buf, PATH_MAX);
27e89ae5 2680 rcu_read_unlock();
e61734c5 2681 if (!p)
52de4779 2682 goto out_free;
e61734c5 2683 seq_puts(m, p);
1da177e4 2684 seq_putc(m, '\n');
e61734c5 2685 retval = 0;
99f89551 2686out_free:
1da177e4 2687 kfree(buf);
99f89551 2688out:
1da177e4
LT
2689 return retval;
2690}
8793d854 2691#endif /* CONFIG_PROC_PID_CPUSET */
1da177e4 2692
d01d4827 2693/* Display task mems_allowed in /proc/<pid>/status file. */
df5f8314
EB
2694void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2695{
e8e6d97c
TH
2696 seq_printf(m, "Mems_allowed:\t%*pb\n",
2697 nodemask_pr_args(&task->mems_allowed));
2698 seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
2699 nodemask_pr_args(&task->mems_allowed));
1da177e4 2700}