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1 | /* |
2 | * kernel/cpuset.c |
3 | * |
4 | * Processor and Memory placement constraints for sets of tasks. |
5 | * |
6 | * Copyright (C) 2003 BULL SA. |
7 | * Copyright (C) 2004-2007 Silicon Graphics, Inc. |
8 | * Copyright (C) 2006 Google, Inc |
9 | * |
10 | * Portions derived from Patrick Mochel's sysfs code. |
11 | * sysfs is Copyright (c) 2001-3 Patrick Mochel |
12 | * |
13 | * 2003-10-10 Written by Simon Derr. |
14 | * 2003-10-22 Updates by Stephen Hemminger. |
15 | * 2004 May-July Rework by Paul Jackson. |
16 | * 2006 Rework by Paul Menage to use generic cgroups |
17 | * 2008 Rework of the scheduler domains and CPU hotplug handling |
18 | * by Max Krasnyansky |
19 | * |
20 | * This file is subject to the terms and conditions of the GNU General Public |
21 | * License. See the file COPYING in the main directory of the Linux |
22 | * distribution for more details. |
23 | */ |
24 | |
25 | #include <linux/cpu.h> |
26 | #include <linux/cpumask.h> |
27 | #include <linux/cpuset.h> |
28 | #include <linux/err.h> |
29 | #include <linux/errno.h> |
30 | #include <linux/file.h> |
31 | #include <linux/fs.h> |
32 | #include <linux/init.h> |
33 | #include <linux/interrupt.h> |
34 | #include <linux/kernel.h> |
35 | #include <linux/kmod.h> |
36 | #include <linux/list.h> |
37 | #include <linux/mempolicy.h> |
38 | #include <linux/mm.h> |
39 | #include <linux/memory.h> |
40 | #include <linux/module.h> |
41 | #include <linux/mount.h> |
42 | #include <linux/namei.h> |
43 | #include <linux/pagemap.h> |
44 | #include <linux/proc_fs.h> |
45 | #include <linux/rcupdate.h> |
46 | #include <linux/sched.h> |
47 | #include <linux/seq_file.h> |
48 | #include <linux/security.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/spinlock.h> |
51 | #include <linux/stat.h> |
52 | #include <linux/string.h> |
53 | #include <linux/time.h> |
54 | #include <linux/backing-dev.h> |
55 | #include <linux/sort.h> |
56 | |
57 | #include <asm/uaccess.h> |
58 | #include <asm/atomic.h> |
59 | #include <linux/mutex.h> |
60 | #include <linux/workqueue.h> |
61 | #include <linux/cgroup.h> |
62 | |
63 | /* |
64 | * Workqueue for cpuset related tasks. |
65 | * |
66 | * Using kevent workqueue may cause deadlock when memory_migrate |
67 | * is set. So we create a separate workqueue thread for cpuset. |
68 | */ |
69 | static struct workqueue_struct *cpuset_wq; |
70 | |
71 | /* |
72 | * Tracks how many cpusets are currently defined in system. |
73 | * When there is only one cpuset (the root cpuset) we can |
74 | * short circuit some hooks. |
75 | */ |
76 | int number_of_cpusets __read_mostly; |
77 | |
78 | /* Forward declare cgroup structures */ |
79 | struct cgroup_subsys cpuset_subsys; |
80 | struct cpuset; |
81 | |
82 | /* See "Frequency meter" comments, below. */ |
83 | |
84 | struct fmeter { |
85 | int cnt; /* unprocessed events count */ |
86 | int val; /* most recent output value */ |
87 | time_t time; /* clock (secs) when val computed */ |
88 | spinlock_t lock; /* guards read or write of above */ |
89 | }; |
90 | |
91 | struct cpuset { |
92 | struct cgroup_subsys_state css; |
93 | |
94 | unsigned long flags; /* "unsigned long" so bitops work */ |
95 | cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */ |
96 | nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */ |
97 | |
98 | struct cpuset *parent; /* my parent */ |
99 | |
100 | struct fmeter fmeter; /* memory_pressure filter */ |
101 | |
102 | /* partition number for rebuild_sched_domains() */ |
103 | int pn; |
104 | |
105 | /* for custom sched domain */ |
106 | int relax_domain_level; |
107 | |
108 | /* used for walking a cpuset hierarchy */ |
109 | struct list_head stack_list; |
110 | }; |
111 | |
112 | /* Retrieve the cpuset for a cgroup */ |
113 | static inline struct cpuset *cgroup_cs(struct cgroup *cont) |
114 | { |
115 | return container_of(cgroup_subsys_state(cont, cpuset_subsys_id), |
116 | struct cpuset, css); |
117 | } |
118 | |
119 | /* Retrieve the cpuset for a task */ |
120 | static inline struct cpuset *task_cs(struct task_struct *task) |
121 | { |
122 | return container_of(task_subsys_state(task, cpuset_subsys_id), |
123 | struct cpuset, css); |
124 | } |
125 | |
126 | /* bits in struct cpuset flags field */ |
127 | typedef enum { |
128 | CS_CPU_EXCLUSIVE, |
129 | CS_MEM_EXCLUSIVE, |
130 | CS_MEM_HARDWALL, |
131 | CS_MEMORY_MIGRATE, |
132 | CS_SCHED_LOAD_BALANCE, |
133 | CS_SPREAD_PAGE, |
134 | CS_SPREAD_SLAB, |
135 | } cpuset_flagbits_t; |
136 | |
137 | /* convenient tests for these bits */ |
138 | static inline int is_cpu_exclusive(const struct cpuset *cs) |
139 | { |
140 | return test_bit(CS_CPU_EXCLUSIVE, &cs->flags); |
141 | } |
142 | |
143 | static inline int is_mem_exclusive(const struct cpuset *cs) |
144 | { |
145 | return test_bit(CS_MEM_EXCLUSIVE, &cs->flags); |
146 | } |
147 | |
148 | static inline int is_mem_hardwall(const struct cpuset *cs) |
149 | { |
150 | return test_bit(CS_MEM_HARDWALL, &cs->flags); |
151 | } |
152 | |
153 | static inline int is_sched_load_balance(const struct cpuset *cs) |
154 | { |
155 | return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); |
156 | } |
157 | |
158 | static inline int is_memory_migrate(const struct cpuset *cs) |
159 | { |
160 | return test_bit(CS_MEMORY_MIGRATE, &cs->flags); |
161 | } |
162 | |
163 | static inline int is_spread_page(const struct cpuset *cs) |
164 | { |
165 | return test_bit(CS_SPREAD_PAGE, &cs->flags); |
166 | } |
167 | |
168 | static inline int is_spread_slab(const struct cpuset *cs) |
169 | { |
170 | return test_bit(CS_SPREAD_SLAB, &cs->flags); |
171 | } |
172 | |
173 | static struct cpuset top_cpuset = { |
174 | .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), |
175 | }; |
176 | |
177 | /* |
178 | * There are two global mutexes guarding cpuset structures. The first |
179 | * is the main control groups cgroup_mutex, accessed via |
180 | * cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific |
181 | * callback_mutex, below. They can nest. It is ok to first take |
182 | * cgroup_mutex, then nest callback_mutex. We also require taking |
183 | * task_lock() when dereferencing a task's cpuset pointer. See "The |
184 | * task_lock() exception", at the end of this comment. |
185 | * |
186 | * A task must hold both mutexes to modify cpusets. If a task |
187 | * holds cgroup_mutex, then it blocks others wanting that mutex, |
188 | * ensuring that it is the only task able to also acquire callback_mutex |
189 | * and be able to modify cpusets. It can perform various checks on |
190 | * the cpuset structure first, knowing nothing will change. It can |
191 | * also allocate memory while just holding cgroup_mutex. While it is |
192 | * performing these checks, various callback routines can briefly |
193 | * acquire callback_mutex to query cpusets. Once it is ready to make |
194 | * the changes, it takes callback_mutex, blocking everyone else. |
195 | * |
196 | * Calls to the kernel memory allocator can not be made while holding |
197 | * callback_mutex, as that would risk double tripping on callback_mutex |
198 | * from one of the callbacks into the cpuset code from within |
199 | * __alloc_pages(). |
200 | * |
201 | * If a task is only holding callback_mutex, then it has read-only |
202 | * access to cpusets. |
203 | * |
204 | * Now, the task_struct fields mems_allowed and mempolicy may be changed |
205 | * by other task, we use alloc_lock in the task_struct fields to protect |
206 | * them. |
207 | * |
208 | * The cpuset_common_file_read() handlers only hold callback_mutex across |
209 | * small pieces of code, such as when reading out possibly multi-word |
210 | * cpumasks and nodemasks. |
211 | * |
212 | * Accessing a task's cpuset should be done in accordance with the |
213 | * guidelines for accessing subsystem state in kernel/cgroup.c |
214 | */ |
215 | |
216 | static DEFINE_MUTEX(callback_mutex); |
217 | |
218 | /* |
219 | * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist |
220 | * buffers. They are statically allocated to prevent using excess stack |
221 | * when calling cpuset_print_task_mems_allowed(). |
222 | */ |
223 | #define CPUSET_NAME_LEN (128) |
224 | #define CPUSET_NODELIST_LEN (256) |
225 | static char cpuset_name[CPUSET_NAME_LEN]; |
226 | static char cpuset_nodelist[CPUSET_NODELIST_LEN]; |
227 | static DEFINE_SPINLOCK(cpuset_buffer_lock); |
228 | |
229 | /* |
230 | * This is ugly, but preserves the userspace API for existing cpuset |
231 | * users. If someone tries to mount the "cpuset" filesystem, we |
232 | * silently switch it to mount "cgroup" instead |
233 | */ |
234 | static struct dentry *cpuset_mount(struct file_system_type *fs_type, |
235 | int flags, const char *unused_dev_name, void *data) |
236 | { |
237 | struct file_system_type *cgroup_fs = get_fs_type("cgroup"); |
238 | struct dentry *ret = ERR_PTR(-ENODEV); |
239 | if (cgroup_fs) { |
240 | char mountopts[] = |
241 | "cpuset,noprefix," |
242 | "release_agent=/sbin/cpuset_release_agent"; |
243 | ret = cgroup_fs->mount(cgroup_fs, flags, |
244 | unused_dev_name, mountopts); |
245 | put_filesystem(cgroup_fs); |
246 | } |
247 | return ret; |
248 | } |
249 | |
250 | static struct file_system_type cpuset_fs_type = { |
251 | .name = "cpuset", |
252 | .mount = cpuset_mount, |
253 | }; |
254 | |
255 | /* |
256 | * Return in pmask the portion of a cpusets's cpus_allowed that |
257 | * are online. If none are online, walk up the cpuset hierarchy |
258 | * until we find one that does have some online cpus. If we get |
259 | * all the way to the top and still haven't found any online cpus, |
260 | * return cpu_online_map. Or if passed a NULL cs from an exit'ing |
261 | * task, return cpu_online_map. |
262 | * |
263 | * One way or another, we guarantee to return some non-empty subset |
264 | * of cpu_online_map. |
265 | * |
266 | * Call with callback_mutex held. |
267 | */ |
268 | |
269 | static void guarantee_online_cpus(const struct cpuset *cs, |
270 | struct cpumask *pmask) |
271 | { |
272 | while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask)) |
273 | cs = cs->parent; |
274 | if (cs) |
275 | cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask); |
276 | else |
277 | cpumask_copy(pmask, cpu_online_mask); |
278 | BUG_ON(!cpumask_intersects(pmask, cpu_online_mask)); |
279 | } |
280 | |
281 | /* |
282 | * Return in *pmask the portion of a cpusets's mems_allowed that |
283 | * are online, with memory. If none are online with memory, walk |
284 | * up the cpuset hierarchy until we find one that does have some |
285 | * online mems. If we get all the way to the top and still haven't |
286 | * found any online mems, return node_states[N_HIGH_MEMORY]. |
287 | * |
288 | * One way or another, we guarantee to return some non-empty subset |
289 | * of node_states[N_HIGH_MEMORY]. |
290 | * |
291 | * Call with callback_mutex held. |
292 | */ |
293 | |
294 | static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) |
295 | { |
296 | while (cs && !nodes_intersects(cs->mems_allowed, |
297 | node_states[N_HIGH_MEMORY])) |
298 | cs = cs->parent; |
299 | if (cs) |
300 | nodes_and(*pmask, cs->mems_allowed, |
301 | node_states[N_HIGH_MEMORY]); |
302 | else |
303 | *pmask = node_states[N_HIGH_MEMORY]; |
304 | BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY])); |
305 | } |
306 | |
307 | /* |
308 | * update task's spread flag if cpuset's page/slab spread flag is set |
309 | * |
310 | * Called with callback_mutex/cgroup_mutex held |
311 | */ |
312 | static void cpuset_update_task_spread_flag(struct cpuset *cs, |
313 | struct task_struct *tsk) |
314 | { |
315 | if (is_spread_page(cs)) |
316 | tsk->flags |= PF_SPREAD_PAGE; |
317 | else |
318 | tsk->flags &= ~PF_SPREAD_PAGE; |
319 | if (is_spread_slab(cs)) |
320 | tsk->flags |= PF_SPREAD_SLAB; |
321 | else |
322 | tsk->flags &= ~PF_SPREAD_SLAB; |
323 | } |
324 | |
325 | /* |
326 | * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q? |
327 | * |
328 | * One cpuset is a subset of another if all its allowed CPUs and |
329 | * Memory Nodes are a subset of the other, and its exclusive flags |
330 | * are only set if the other's are set. Call holding cgroup_mutex. |
331 | */ |
332 | |
333 | static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) |
334 | { |
335 | return cpumask_subset(p->cpus_allowed, q->cpus_allowed) && |
336 | nodes_subset(p->mems_allowed, q->mems_allowed) && |
337 | is_cpu_exclusive(p) <= is_cpu_exclusive(q) && |
338 | is_mem_exclusive(p) <= is_mem_exclusive(q); |
339 | } |
340 | |
341 | /** |
342 | * alloc_trial_cpuset - allocate a trial cpuset |
343 | * @cs: the cpuset that the trial cpuset duplicates |
344 | */ |
345 | static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs) |
346 | { |
347 | struct cpuset *trial; |
348 | |
349 | trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL); |
350 | if (!trial) |
351 | return NULL; |
352 | |
353 | if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) { |
354 | kfree(trial); |
355 | return NULL; |
356 | } |
357 | cpumask_copy(trial->cpus_allowed, cs->cpus_allowed); |
358 | |
359 | return trial; |
360 | } |
361 | |
362 | /** |
363 | * free_trial_cpuset - free the trial cpuset |
364 | * @trial: the trial cpuset to be freed |
365 | */ |
366 | static void free_trial_cpuset(struct cpuset *trial) |
367 | { |
368 | free_cpumask_var(trial->cpus_allowed); |
369 | kfree(trial); |
370 | } |
371 | |
372 | /* |
373 | * validate_change() - Used to validate that any proposed cpuset change |
374 | * follows the structural rules for cpusets. |
375 | * |
376 | * If we replaced the flag and mask values of the current cpuset |
377 | * (cur) with those values in the trial cpuset (trial), would |
378 | * our various subset and exclusive rules still be valid? Presumes |
379 | * cgroup_mutex held. |
380 | * |
381 | * 'cur' is the address of an actual, in-use cpuset. Operations |
382 | * such as list traversal that depend on the actual address of the |
383 | * cpuset in the list must use cur below, not trial. |
384 | * |
385 | * 'trial' is the address of bulk structure copy of cur, with |
386 | * perhaps one or more of the fields cpus_allowed, mems_allowed, |
387 | * or flags changed to new, trial values. |
388 | * |
389 | * Return 0 if valid, -errno if not. |
390 | */ |
391 | |
392 | static int validate_change(const struct cpuset *cur, const struct cpuset *trial) |
393 | { |
394 | struct cgroup *cont; |
395 | struct cpuset *c, *par; |
396 | |
397 | /* Each of our child cpusets must be a subset of us */ |
398 | list_for_each_entry(cont, &cur->css.cgroup->children, sibling) { |
399 | if (!is_cpuset_subset(cgroup_cs(cont), trial)) |
400 | return -EBUSY; |
401 | } |
402 | |
403 | /* Remaining checks don't apply to root cpuset */ |
404 | if (cur == &top_cpuset) |
405 | return 0; |
406 | |
407 | par = cur->parent; |
408 | |
409 | /* We must be a subset of our parent cpuset */ |
410 | if (!is_cpuset_subset(trial, par)) |
411 | return -EACCES; |
412 | |
413 | /* |
414 | * If either I or some sibling (!= me) is exclusive, we can't |
415 | * overlap |
416 | */ |
417 | list_for_each_entry(cont, &par->css.cgroup->children, sibling) { |
418 | c = cgroup_cs(cont); |
419 | if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && |
420 | c != cur && |
421 | cpumask_intersects(trial->cpus_allowed, c->cpus_allowed)) |
422 | return -EINVAL; |
423 | if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && |
424 | c != cur && |
425 | nodes_intersects(trial->mems_allowed, c->mems_allowed)) |
426 | return -EINVAL; |
427 | } |
428 | |
429 | /* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */ |
430 | if (cgroup_task_count(cur->css.cgroup)) { |
431 | if (cpumask_empty(trial->cpus_allowed) || |
432 | nodes_empty(trial->mems_allowed)) { |
433 | return -ENOSPC; |
434 | } |
435 | } |
436 | |
437 | return 0; |
438 | } |
439 | |
440 | #ifdef CONFIG_SMP |
441 | /* |
442 | * Helper routine for generate_sched_domains(). |
443 | * Do cpusets a, b have overlapping cpus_allowed masks? |
444 | */ |
445 | static int cpusets_overlap(struct cpuset *a, struct cpuset *b) |
446 | { |
447 | return cpumask_intersects(a->cpus_allowed, b->cpus_allowed); |
448 | } |
449 | |
450 | static void |
451 | update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c) |
452 | { |
453 | if (dattr->relax_domain_level < c->relax_domain_level) |
454 | dattr->relax_domain_level = c->relax_domain_level; |
455 | return; |
456 | } |
457 | |
458 | static void |
459 | update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c) |
460 | { |
461 | LIST_HEAD(q); |
462 | |
463 | list_add(&c->stack_list, &q); |
464 | while (!list_empty(&q)) { |
465 | struct cpuset *cp; |
466 | struct cgroup *cont; |
467 | struct cpuset *child; |
468 | |
469 | cp = list_first_entry(&q, struct cpuset, stack_list); |
470 | list_del(q.next); |
471 | |
472 | if (cpumask_empty(cp->cpus_allowed)) |
473 | continue; |
474 | |
475 | if (is_sched_load_balance(cp)) |
476 | update_domain_attr(dattr, cp); |
477 | |
478 | list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { |
479 | child = cgroup_cs(cont); |
480 | list_add_tail(&child->stack_list, &q); |
481 | } |
482 | } |
483 | } |
484 | |
485 | /* |
486 | * generate_sched_domains() |
487 | * |
488 | * This function builds a partial partition of the systems CPUs |
489 | * A 'partial partition' is a set of non-overlapping subsets whose |
490 | * union is a subset of that set. |
491 | * The output of this function needs to be passed to kernel/sched.c |
492 | * partition_sched_domains() routine, which will rebuild the scheduler's |
493 | * load balancing domains (sched domains) as specified by that partial |
494 | * partition. |
495 | * |
496 | * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt |
497 | * for a background explanation of this. |
498 | * |
499 | * Does not return errors, on the theory that the callers of this |
500 | * routine would rather not worry about failures to rebuild sched |
501 | * domains when operating in the severe memory shortage situations |
502 | * that could cause allocation failures below. |
503 | * |
504 | * Must be called with cgroup_lock held. |
505 | * |
506 | * The three key local variables below are: |
507 | * q - a linked-list queue of cpuset pointers, used to implement a |
508 | * top-down scan of all cpusets. This scan loads a pointer |
509 | * to each cpuset marked is_sched_load_balance into the |
510 | * array 'csa'. For our purposes, rebuilding the schedulers |
511 | * sched domains, we can ignore !is_sched_load_balance cpusets. |
512 | * csa - (for CpuSet Array) Array of pointers to all the cpusets |
513 | * that need to be load balanced, for convenient iterative |
514 | * access by the subsequent code that finds the best partition, |
515 | * i.e the set of domains (subsets) of CPUs such that the |
516 | * cpus_allowed of every cpuset marked is_sched_load_balance |
517 | * is a subset of one of these domains, while there are as |
518 | * many such domains as possible, each as small as possible. |
519 | * doms - Conversion of 'csa' to an array of cpumasks, for passing to |
520 | * the kernel/sched.c routine partition_sched_domains() in a |
521 | * convenient format, that can be easily compared to the prior |
522 | * value to determine what partition elements (sched domains) |
523 | * were changed (added or removed.) |
524 | * |
525 | * Finding the best partition (set of domains): |
526 | * The triple nested loops below over i, j, k scan over the |
527 | * load balanced cpusets (using the array of cpuset pointers in |
528 | * csa[]) looking for pairs of cpusets that have overlapping |
529 | * cpus_allowed, but which don't have the same 'pn' partition |
530 | * number and gives them in the same partition number. It keeps |
531 | * looping on the 'restart' label until it can no longer find |
532 | * any such pairs. |
533 | * |
534 | * The union of the cpus_allowed masks from the set of |
535 | * all cpusets having the same 'pn' value then form the one |
536 | * element of the partition (one sched domain) to be passed to |
537 | * partition_sched_domains(). |
538 | */ |
539 | static int generate_sched_domains(cpumask_var_t **domains, |
540 | struct sched_domain_attr **attributes) |
541 | { |
542 | LIST_HEAD(q); /* queue of cpusets to be scanned */ |
543 | struct cpuset *cp; /* scans q */ |
544 | struct cpuset **csa; /* array of all cpuset ptrs */ |
545 | int csn; /* how many cpuset ptrs in csa so far */ |
546 | int i, j, k; /* indices for partition finding loops */ |
547 | cpumask_var_t *doms; /* resulting partition; i.e. sched domains */ |
548 | struct sched_domain_attr *dattr; /* attributes for custom domains */ |
549 | int ndoms = 0; /* number of sched domains in result */ |
550 | int nslot; /* next empty doms[] struct cpumask slot */ |
551 | |
552 | doms = NULL; |
553 | dattr = NULL; |
554 | csa = NULL; |
555 | |
556 | /* Special case for the 99% of systems with one, full, sched domain */ |
557 | if (is_sched_load_balance(&top_cpuset)) { |
558 | ndoms = 1; |
559 | doms = alloc_sched_domains(ndoms); |
560 | if (!doms) |
561 | goto done; |
562 | |
563 | dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL); |
564 | if (dattr) { |
565 | *dattr = SD_ATTR_INIT; |
566 | update_domain_attr_tree(dattr, &top_cpuset); |
567 | } |
568 | cpumask_copy(doms[0], top_cpuset.cpus_allowed); |
569 | |
570 | goto done; |
571 | } |
572 | |
573 | csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL); |
574 | if (!csa) |
575 | goto done; |
576 | csn = 0; |
577 | |
578 | list_add(&top_cpuset.stack_list, &q); |
579 | while (!list_empty(&q)) { |
580 | struct cgroup *cont; |
581 | struct cpuset *child; /* scans child cpusets of cp */ |
582 | |
583 | cp = list_first_entry(&q, struct cpuset, stack_list); |
584 | list_del(q.next); |
585 | |
586 | if (cpumask_empty(cp->cpus_allowed)) |
587 | continue; |
588 | |
589 | /* |
590 | * All child cpusets contain a subset of the parent's cpus, so |
591 | * just skip them, and then we call update_domain_attr_tree() |
592 | * to calc relax_domain_level of the corresponding sched |
593 | * domain. |
594 | */ |
595 | if (is_sched_load_balance(cp)) { |
596 | csa[csn++] = cp; |
597 | continue; |
598 | } |
599 | |
600 | list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { |
601 | child = cgroup_cs(cont); |
602 | list_add_tail(&child->stack_list, &q); |
603 | } |
604 | } |
605 | |
606 | for (i = 0; i < csn; i++) |
607 | csa[i]->pn = i; |
608 | ndoms = csn; |
609 | |
610 | restart: |
611 | /* Find the best partition (set of sched domains) */ |
612 | for (i = 0; i < csn; i++) { |
613 | struct cpuset *a = csa[i]; |
614 | int apn = a->pn; |
615 | |
616 | for (j = 0; j < csn; j++) { |
617 | struct cpuset *b = csa[j]; |
618 | int bpn = b->pn; |
619 | |
620 | if (apn != bpn && cpusets_overlap(a, b)) { |
621 | for (k = 0; k < csn; k++) { |
622 | struct cpuset *c = csa[k]; |
623 | |
624 | if (c->pn == bpn) |
625 | c->pn = apn; |
626 | } |
627 | ndoms--; /* one less element */ |
628 | goto restart; |
629 | } |
630 | } |
631 | } |
632 | |
633 | /* |
634 | * Now we know how many domains to create. |
635 | * Convert <csn, csa> to <ndoms, doms> and populate cpu masks. |
636 | */ |
637 | doms = alloc_sched_domains(ndoms); |
638 | if (!doms) |
639 | goto done; |
640 | |
641 | /* |
642 | * The rest of the code, including the scheduler, can deal with |
643 | * dattr==NULL case. No need to abort if alloc fails. |
644 | */ |
645 | dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL); |
646 | |
647 | for (nslot = 0, i = 0; i < csn; i++) { |
648 | struct cpuset *a = csa[i]; |
649 | struct cpumask *dp; |
650 | int apn = a->pn; |
651 | |
652 | if (apn < 0) { |
653 | /* Skip completed partitions */ |
654 | continue; |
655 | } |
656 | |
657 | dp = doms[nslot]; |
658 | |
659 | if (nslot == ndoms) { |
660 | static int warnings = 10; |
661 | if (warnings) { |
662 | printk(KERN_WARNING |
663 | "rebuild_sched_domains confused:" |
664 | " nslot %d, ndoms %d, csn %d, i %d," |
665 | " apn %d\n", |
666 | nslot, ndoms, csn, i, apn); |
667 | warnings--; |
668 | } |
669 | continue; |
670 | } |
671 | |
672 | cpumask_clear(dp); |
673 | if (dattr) |
674 | *(dattr + nslot) = SD_ATTR_INIT; |
675 | for (j = i; j < csn; j++) { |
676 | struct cpuset *b = csa[j]; |
677 | |
678 | if (apn == b->pn) { |
679 | cpumask_or(dp, dp, b->cpus_allowed); |
680 | if (dattr) |
681 | update_domain_attr_tree(dattr + nslot, b); |
682 | |
683 | /* Done with this partition */ |
684 | b->pn = -1; |
685 | } |
686 | } |
687 | nslot++; |
688 | } |
689 | BUG_ON(nslot != ndoms); |
690 | |
691 | done: |
692 | kfree(csa); |
693 | |
694 | /* |
695 | * Fallback to the default domain if kmalloc() failed. |
696 | * See comments in partition_sched_domains(). |
697 | */ |
698 | if (doms == NULL) |
699 | ndoms = 1; |
700 | |
701 | *domains = doms; |
702 | *attributes = dattr; |
703 | return ndoms; |
704 | } |
705 | |
706 | /* |
707 | * Rebuild scheduler domains. |
708 | * |
709 | * Call with neither cgroup_mutex held nor within get_online_cpus(). |
710 | * Takes both cgroup_mutex and get_online_cpus(). |
711 | * |
712 | * Cannot be directly called from cpuset code handling changes |
713 | * to the cpuset pseudo-filesystem, because it cannot be called |
714 | * from code that already holds cgroup_mutex. |
715 | */ |
716 | static void do_rebuild_sched_domains(struct work_struct *unused) |
717 | { |
718 | struct sched_domain_attr *attr; |
719 | cpumask_var_t *doms; |
720 | int ndoms; |
721 | |
722 | get_online_cpus(); |
723 | |
724 | /* Generate domain masks and attrs */ |
725 | cgroup_lock(); |
726 | ndoms = generate_sched_domains(&doms, &attr); |
727 | cgroup_unlock(); |
728 | |
729 | /* Have scheduler rebuild the domains */ |
730 | partition_sched_domains(ndoms, doms, attr); |
731 | |
732 | put_online_cpus(); |
733 | } |
734 | #else /* !CONFIG_SMP */ |
735 | static void do_rebuild_sched_domains(struct work_struct *unused) |
736 | { |
737 | } |
738 | |
739 | static int generate_sched_domains(cpumask_var_t **domains, |
740 | struct sched_domain_attr **attributes) |
741 | { |
742 | *domains = NULL; |
743 | return 1; |
744 | } |
745 | #endif /* CONFIG_SMP */ |
746 | |
747 | static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains); |
748 | |
749 | /* |
750 | * Rebuild scheduler domains, asynchronously via workqueue. |
751 | * |
752 | * If the flag 'sched_load_balance' of any cpuset with non-empty |
753 | * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset |
754 | * which has that flag enabled, or if any cpuset with a non-empty |
755 | * 'cpus' is removed, then call this routine to rebuild the |
756 | * scheduler's dynamic sched domains. |
757 | * |
758 | * The rebuild_sched_domains() and partition_sched_domains() |
759 | * routines must nest cgroup_lock() inside get_online_cpus(), |
760 | * but such cpuset changes as these must nest that locking the |
761 | * other way, holding cgroup_lock() for much of the code. |
762 | * |
763 | * So in order to avoid an ABBA deadlock, the cpuset code handling |
764 | * these user changes delegates the actual sched domain rebuilding |
765 | * to a separate workqueue thread, which ends up processing the |
766 | * above do_rebuild_sched_domains() function. |
767 | */ |
768 | static void async_rebuild_sched_domains(void) |
769 | { |
770 | queue_work(cpuset_wq, &rebuild_sched_domains_work); |
771 | } |
772 | |
773 | /* |
774 | * Accomplishes the same scheduler domain rebuild as the above |
775 | * async_rebuild_sched_domains(), however it directly calls the |
776 | * rebuild routine synchronously rather than calling it via an |
777 | * asynchronous work thread. |
778 | * |
779 | * This can only be called from code that is not holding |
780 | * cgroup_mutex (not nested in a cgroup_lock() call.) |
781 | */ |
782 | void rebuild_sched_domains(void) |
783 | { |
784 | do_rebuild_sched_domains(NULL); |
785 | } |
786 | |
787 | /** |
788 | * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's |
789 | * @tsk: task to test |
790 | * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner |
791 | * |
792 | * Call with cgroup_mutex held. May take callback_mutex during call. |
793 | * Called for each task in a cgroup by cgroup_scan_tasks(). |
794 | * Return nonzero if this tasks's cpus_allowed mask should be changed (in other |
795 | * words, if its mask is not equal to its cpuset's mask). |
796 | */ |
797 | static int cpuset_test_cpumask(struct task_struct *tsk, |
798 | struct cgroup_scanner *scan) |
799 | { |
800 | return !cpumask_equal(&tsk->cpus_allowed, |
801 | (cgroup_cs(scan->cg))->cpus_allowed); |
802 | } |
803 | |
804 | /** |
805 | * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's |
806 | * @tsk: task to test |
807 | * @scan: struct cgroup_scanner containing the cgroup of the task |
808 | * |
809 | * Called by cgroup_scan_tasks() for each task in a cgroup whose |
810 | * cpus_allowed mask needs to be changed. |
811 | * |
812 | * We don't need to re-check for the cgroup/cpuset membership, since we're |
813 | * holding cgroup_lock() at this point. |
814 | */ |
815 | static void cpuset_change_cpumask(struct task_struct *tsk, |
816 | struct cgroup_scanner *scan) |
817 | { |
818 | set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed)); |
819 | } |
820 | |
821 | /** |
822 | * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset. |
823 | * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed |
824 | * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() |
825 | * |
826 | * Called with cgroup_mutex held |
827 | * |
828 | * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, |
829 | * calling callback functions for each. |
830 | * |
831 | * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0 |
832 | * if @heap != NULL. |
833 | */ |
834 | static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap) |
835 | { |
836 | struct cgroup_scanner scan; |
837 | |
838 | scan.cg = cs->css.cgroup; |
839 | scan.test_task = cpuset_test_cpumask; |
840 | scan.process_task = cpuset_change_cpumask; |
841 | scan.heap = heap; |
842 | cgroup_scan_tasks(&scan); |
843 | } |
844 | |
845 | /** |
846 | * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it |
847 | * @cs: the cpuset to consider |
848 | * @buf: buffer of cpu numbers written to this cpuset |
849 | */ |
850 | static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, |
851 | const char *buf) |
852 | { |
853 | struct ptr_heap heap; |
854 | int retval; |
855 | int is_load_balanced; |
856 | |
857 | /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */ |
858 | if (cs == &top_cpuset) |
859 | return -EACCES; |
860 | |
861 | /* |
862 | * An empty cpus_allowed is ok only if the cpuset has no tasks. |
863 | * Since cpulist_parse() fails on an empty mask, we special case |
864 | * that parsing. The validate_change() call ensures that cpusets |
865 | * with tasks have cpus. |
866 | */ |
867 | if (!*buf) { |
868 | cpumask_clear(trialcs->cpus_allowed); |
869 | } else { |
870 | retval = cpulist_parse(buf, trialcs->cpus_allowed); |
871 | if (retval < 0) |
872 | return retval; |
873 | |
874 | if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask)) |
875 | return -EINVAL; |
876 | } |
877 | retval = validate_change(cs, trialcs); |
878 | if (retval < 0) |
879 | return retval; |
880 | |
881 | /* Nothing to do if the cpus didn't change */ |
882 | if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed)) |
883 | return 0; |
884 | |
885 | retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); |
886 | if (retval) |
887 | return retval; |
888 | |
889 | is_load_balanced = is_sched_load_balance(trialcs); |
890 | |
891 | mutex_lock(&callback_mutex); |
892 | cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); |
893 | mutex_unlock(&callback_mutex); |
894 | |
895 | /* |
896 | * Scan tasks in the cpuset, and update the cpumasks of any |
897 | * that need an update. |
898 | */ |
899 | update_tasks_cpumask(cs, &heap); |
900 | |
901 | heap_free(&heap); |
902 | |
903 | if (is_load_balanced) |
904 | async_rebuild_sched_domains(); |
905 | return 0; |
906 | } |
907 | |
908 | /* |
909 | * cpuset_migrate_mm |
910 | * |
911 | * Migrate memory region from one set of nodes to another. |
912 | * |
913 | * Temporarilly set tasks mems_allowed to target nodes of migration, |
914 | * so that the migration code can allocate pages on these nodes. |
915 | * |
916 | * Call holding cgroup_mutex, so current's cpuset won't change |
917 | * during this call, as manage_mutex holds off any cpuset_attach() |
918 | * calls. Therefore we don't need to take task_lock around the |
919 | * call to guarantee_online_mems(), as we know no one is changing |
920 | * our task's cpuset. |
921 | * |
922 | * While the mm_struct we are migrating is typically from some |
923 | * other task, the task_struct mems_allowed that we are hacking |
924 | * is for our current task, which must allocate new pages for that |
925 | * migrating memory region. |
926 | */ |
927 | |
928 | static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, |
929 | const nodemask_t *to) |
930 | { |
931 | struct task_struct *tsk = current; |
932 | |
933 | tsk->mems_allowed = *to; |
934 | |
935 | do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL); |
936 | |
937 | guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed); |
938 | } |
939 | |
940 | /* |
941 | * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy |
942 | * @tsk: the task to change |
943 | * @newmems: new nodes that the task will be set |
944 | * |
945 | * In order to avoid seeing no nodes if the old and new nodes are disjoint, |
946 | * we structure updates as setting all new allowed nodes, then clearing newly |
947 | * disallowed ones. |
948 | */ |
949 | static void cpuset_change_task_nodemask(struct task_struct *tsk, |
950 | nodemask_t *newmems) |
951 | { |
952 | repeat: |
953 | /* |
954 | * Allow tasks that have access to memory reserves because they have |
955 | * been OOM killed to get memory anywhere. |
956 | */ |
957 | if (unlikely(test_thread_flag(TIF_MEMDIE))) |
958 | return; |
959 | if (current->flags & PF_EXITING) /* Let dying task have memory */ |
960 | return; |
961 | |
962 | task_lock(tsk); |
963 | nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); |
964 | mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1); |
965 | |
966 | |
967 | /* |
968 | * ensure checking ->mems_allowed_change_disable after setting all new |
969 | * allowed nodes. |
970 | * |
971 | * the read-side task can see an nodemask with new allowed nodes and |
972 | * old allowed nodes. and if it allocates page when cpuset clears newly |
973 | * disallowed ones continuous, it can see the new allowed bits. |
974 | * |
975 | * And if setting all new allowed nodes is after the checking, setting |
976 | * all new allowed nodes and clearing newly disallowed ones will be done |
977 | * continuous, and the read-side task may find no node to alloc page. |
978 | */ |
979 | smp_mb(); |
980 | |
981 | /* |
982 | * Allocation of memory is very fast, we needn't sleep when waiting |
983 | * for the read-side. |
984 | */ |
985 | while (ACCESS_ONCE(tsk->mems_allowed_change_disable)) { |
986 | task_unlock(tsk); |
987 | if (!task_curr(tsk)) |
988 | yield(); |
989 | goto repeat; |
990 | } |
991 | |
992 | /* |
993 | * ensure checking ->mems_allowed_change_disable before clearing all new |
994 | * disallowed nodes. |
995 | * |
996 | * if clearing newly disallowed bits before the checking, the read-side |
997 | * task may find no node to alloc page. |
998 | */ |
999 | smp_mb(); |
1000 | |
1001 | mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2); |
1002 | tsk->mems_allowed = *newmems; |
1003 | task_unlock(tsk); |
1004 | } |
1005 | |
1006 | /* |
1007 | * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy |
1008 | * of it to cpuset's new mems_allowed, and migrate pages to new nodes if |
1009 | * memory_migrate flag is set. Called with cgroup_mutex held. |
1010 | */ |
1011 | static void cpuset_change_nodemask(struct task_struct *p, |
1012 | struct cgroup_scanner *scan) |
1013 | { |
1014 | struct mm_struct *mm; |
1015 | struct cpuset *cs; |
1016 | int migrate; |
1017 | const nodemask_t *oldmem = scan->data; |
1018 | static nodemask_t newmems; /* protected by cgroup_mutex */ |
1019 | |
1020 | cs = cgroup_cs(scan->cg); |
1021 | guarantee_online_mems(cs, &newmems); |
1022 | |
1023 | cpuset_change_task_nodemask(p, &newmems); |
1024 | |
1025 | mm = get_task_mm(p); |
1026 | if (!mm) |
1027 | return; |
1028 | |
1029 | migrate = is_memory_migrate(cs); |
1030 | |
1031 | mpol_rebind_mm(mm, &cs->mems_allowed); |
1032 | if (migrate) |
1033 | cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed); |
1034 | mmput(mm); |
1035 | } |
1036 | |
1037 | static void *cpuset_being_rebound; |
1038 | |
1039 | /** |
1040 | * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset. |
1041 | * @cs: the cpuset in which each task's mems_allowed mask needs to be changed |
1042 | * @oldmem: old mems_allowed of cpuset cs |
1043 | * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() |
1044 | * |
1045 | * Called with cgroup_mutex held |
1046 | * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0 |
1047 | * if @heap != NULL. |
1048 | */ |
1049 | static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem, |
1050 | struct ptr_heap *heap) |
1051 | { |
1052 | struct cgroup_scanner scan; |
1053 | |
1054 | cpuset_being_rebound = cs; /* causes mpol_dup() rebind */ |
1055 | |
1056 | scan.cg = cs->css.cgroup; |
1057 | scan.test_task = NULL; |
1058 | scan.process_task = cpuset_change_nodemask; |
1059 | scan.heap = heap; |
1060 | scan.data = (nodemask_t *)oldmem; |
1061 | |
1062 | /* |
1063 | * The mpol_rebind_mm() call takes mmap_sem, which we couldn't |
1064 | * take while holding tasklist_lock. Forks can happen - the |
1065 | * mpol_dup() cpuset_being_rebound check will catch such forks, |
1066 | * and rebind their vma mempolicies too. Because we still hold |
1067 | * the global cgroup_mutex, we know that no other rebind effort |
1068 | * will be contending for the global variable cpuset_being_rebound. |
1069 | * It's ok if we rebind the same mm twice; mpol_rebind_mm() |
1070 | * is idempotent. Also migrate pages in each mm to new nodes. |
1071 | */ |
1072 | cgroup_scan_tasks(&scan); |
1073 | |
1074 | /* We're done rebinding vmas to this cpuset's new mems_allowed. */ |
1075 | cpuset_being_rebound = NULL; |
1076 | } |
1077 | |
1078 | /* |
1079 | * Handle user request to change the 'mems' memory placement |
1080 | * of a cpuset. Needs to validate the request, update the |
1081 | * cpusets mems_allowed, and for each task in the cpuset, |
1082 | * update mems_allowed and rebind task's mempolicy and any vma |
1083 | * mempolicies and if the cpuset is marked 'memory_migrate', |
1084 | * migrate the tasks pages to the new memory. |
1085 | * |
1086 | * Call with cgroup_mutex held. May take callback_mutex during call. |
1087 | * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, |
1088 | * lock each such tasks mm->mmap_sem, scan its vma's and rebind |
1089 | * their mempolicies to the cpusets new mems_allowed. |
1090 | */ |
1091 | static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, |
1092 | const char *buf) |
1093 | { |
1094 | NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL); |
1095 | int retval; |
1096 | struct ptr_heap heap; |
1097 | |
1098 | if (!oldmem) |
1099 | return -ENOMEM; |
1100 | |
1101 | /* |
1102 | * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY]; |
1103 | * it's read-only |
1104 | */ |
1105 | if (cs == &top_cpuset) { |
1106 | retval = -EACCES; |
1107 | goto done; |
1108 | } |
1109 | |
1110 | /* |
1111 | * An empty mems_allowed is ok iff there are no tasks in the cpuset. |
1112 | * Since nodelist_parse() fails on an empty mask, we special case |
1113 | * that parsing. The validate_change() call ensures that cpusets |
1114 | * with tasks have memory. |
1115 | */ |
1116 | if (!*buf) { |
1117 | nodes_clear(trialcs->mems_allowed); |
1118 | } else { |
1119 | retval = nodelist_parse(buf, trialcs->mems_allowed); |
1120 | if (retval < 0) |
1121 | goto done; |
1122 | |
1123 | if (!nodes_subset(trialcs->mems_allowed, |
1124 | node_states[N_HIGH_MEMORY])) { |
1125 | retval = -EINVAL; |
1126 | goto done; |
1127 | } |
1128 | } |
1129 | *oldmem = cs->mems_allowed; |
1130 | if (nodes_equal(*oldmem, trialcs->mems_allowed)) { |
1131 | retval = 0; /* Too easy - nothing to do */ |
1132 | goto done; |
1133 | } |
1134 | retval = validate_change(cs, trialcs); |
1135 | if (retval < 0) |
1136 | goto done; |
1137 | |
1138 | retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); |
1139 | if (retval < 0) |
1140 | goto done; |
1141 | |
1142 | mutex_lock(&callback_mutex); |
1143 | cs->mems_allowed = trialcs->mems_allowed; |
1144 | mutex_unlock(&callback_mutex); |
1145 | |
1146 | update_tasks_nodemask(cs, oldmem, &heap); |
1147 | |
1148 | heap_free(&heap); |
1149 | done: |
1150 | NODEMASK_FREE(oldmem); |
1151 | return retval; |
1152 | } |
1153 | |
1154 | int current_cpuset_is_being_rebound(void) |
1155 | { |
1156 | return task_cs(current) == cpuset_being_rebound; |
1157 | } |
1158 | |
1159 | static int update_relax_domain_level(struct cpuset *cs, s64 val) |
1160 | { |
1161 | #ifdef CONFIG_SMP |
1162 | if (val < -1 || val >= SD_LV_MAX) |
1163 | return -EINVAL; |
1164 | #endif |
1165 | |
1166 | if (val != cs->relax_domain_level) { |
1167 | cs->relax_domain_level = val; |
1168 | if (!cpumask_empty(cs->cpus_allowed) && |
1169 | is_sched_load_balance(cs)) |
1170 | async_rebuild_sched_domains(); |
1171 | } |
1172 | |
1173 | return 0; |
1174 | } |
1175 | |
1176 | /* |
1177 | * cpuset_change_flag - make a task's spread flags the same as its cpuset's |
1178 | * @tsk: task to be updated |
1179 | * @scan: struct cgroup_scanner containing the cgroup of the task |
1180 | * |
1181 | * Called by cgroup_scan_tasks() for each task in a cgroup. |
1182 | * |
1183 | * We don't need to re-check for the cgroup/cpuset membership, since we're |
1184 | * holding cgroup_lock() at this point. |
1185 | */ |
1186 | static void cpuset_change_flag(struct task_struct *tsk, |
1187 | struct cgroup_scanner *scan) |
1188 | { |
1189 | cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk); |
1190 | } |
1191 | |
1192 | /* |
1193 | * update_tasks_flags - update the spread flags of tasks in the cpuset. |
1194 | * @cs: the cpuset in which each task's spread flags needs to be changed |
1195 | * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() |
1196 | * |
1197 | * Called with cgroup_mutex held |
1198 | * |
1199 | * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, |
1200 | * calling callback functions for each. |
1201 | * |
1202 | * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0 |
1203 | * if @heap != NULL. |
1204 | */ |
1205 | static void update_tasks_flags(struct cpuset *cs, struct ptr_heap *heap) |
1206 | { |
1207 | struct cgroup_scanner scan; |
1208 | |
1209 | scan.cg = cs->css.cgroup; |
1210 | scan.test_task = NULL; |
1211 | scan.process_task = cpuset_change_flag; |
1212 | scan.heap = heap; |
1213 | cgroup_scan_tasks(&scan); |
1214 | } |
1215 | |
1216 | /* |
1217 | * update_flag - read a 0 or a 1 in a file and update associated flag |
1218 | * bit: the bit to update (see cpuset_flagbits_t) |
1219 | * cs: the cpuset to update |
1220 | * turning_on: whether the flag is being set or cleared |
1221 | * |
1222 | * Call with cgroup_mutex held. |
1223 | */ |
1224 | |
1225 | static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, |
1226 | int turning_on) |
1227 | { |
1228 | struct cpuset *trialcs; |
1229 | int balance_flag_changed; |
1230 | int spread_flag_changed; |
1231 | struct ptr_heap heap; |
1232 | int err; |
1233 | |
1234 | trialcs = alloc_trial_cpuset(cs); |
1235 | if (!trialcs) |
1236 | return -ENOMEM; |
1237 | |
1238 | if (turning_on) |
1239 | set_bit(bit, &trialcs->flags); |
1240 | else |
1241 | clear_bit(bit, &trialcs->flags); |
1242 | |
1243 | err = validate_change(cs, trialcs); |
1244 | if (err < 0) |
1245 | goto out; |
1246 | |
1247 | err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); |
1248 | if (err < 0) |
1249 | goto out; |
1250 | |
1251 | balance_flag_changed = (is_sched_load_balance(cs) != |
1252 | is_sched_load_balance(trialcs)); |
1253 | |
1254 | spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs)) |
1255 | || (is_spread_page(cs) != is_spread_page(trialcs))); |
1256 | |
1257 | mutex_lock(&callback_mutex); |
1258 | cs->flags = trialcs->flags; |
1259 | mutex_unlock(&callback_mutex); |
1260 | |
1261 | if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) |
1262 | async_rebuild_sched_domains(); |
1263 | |
1264 | if (spread_flag_changed) |
1265 | update_tasks_flags(cs, &heap); |
1266 | heap_free(&heap); |
1267 | out: |
1268 | free_trial_cpuset(trialcs); |
1269 | return err; |
1270 | } |
1271 | |
1272 | /* |
1273 | * Frequency meter - How fast is some event occurring? |
1274 | * |
1275 | * These routines manage a digitally filtered, constant time based, |
1276 | * event frequency meter. There are four routines: |
1277 | * fmeter_init() - initialize a frequency meter. |
1278 | * fmeter_markevent() - called each time the event happens. |
1279 | * fmeter_getrate() - returns the recent rate of such events. |
1280 | * fmeter_update() - internal routine used to update fmeter. |
1281 | * |
1282 | * A common data structure is passed to each of these routines, |
1283 | * which is used to keep track of the state required to manage the |
1284 | * frequency meter and its digital filter. |
1285 | * |
1286 | * The filter works on the number of events marked per unit time. |
1287 | * The filter is single-pole low-pass recursive (IIR). The time unit |
1288 | * is 1 second. Arithmetic is done using 32-bit integers scaled to |
1289 | * simulate 3 decimal digits of precision (multiplied by 1000). |
1290 | * |
1291 | * With an FM_COEF of 933, and a time base of 1 second, the filter |
1292 | * has a half-life of 10 seconds, meaning that if the events quit |
1293 | * happening, then the rate returned from the fmeter_getrate() |
1294 | * will be cut in half each 10 seconds, until it converges to zero. |
1295 | * |
1296 | * It is not worth doing a real infinitely recursive filter. If more |
1297 | * than FM_MAXTICKS ticks have elapsed since the last filter event, |
1298 | * just compute FM_MAXTICKS ticks worth, by which point the level |
1299 | * will be stable. |
1300 | * |
1301 | * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid |
1302 | * arithmetic overflow in the fmeter_update() routine. |
1303 | * |
1304 | * Given the simple 32 bit integer arithmetic used, this meter works |
1305 | * best for reporting rates between one per millisecond (msec) and |
1306 | * one per 32 (approx) seconds. At constant rates faster than one |
1307 | * per msec it maxes out at values just under 1,000,000. At constant |
1308 | * rates between one per msec, and one per second it will stabilize |
1309 | * to a value N*1000, where N is the rate of events per second. |
1310 | * At constant rates between one per second and one per 32 seconds, |
1311 | * it will be choppy, moving up on the seconds that have an event, |
1312 | * and then decaying until the next event. At rates slower than |
1313 | * about one in 32 seconds, it decays all the way back to zero between |
1314 | * each event. |
1315 | */ |
1316 | |
1317 | #define FM_COEF 933 /* coefficient for half-life of 10 secs */ |
1318 | #define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */ |
1319 | #define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */ |
1320 | #define FM_SCALE 1000 /* faux fixed point scale */ |
1321 | |
1322 | /* Initialize a frequency meter */ |
1323 | static void fmeter_init(struct fmeter *fmp) |
1324 | { |
1325 | fmp->cnt = 0; |
1326 | fmp->val = 0; |
1327 | fmp->time = 0; |
1328 | spin_lock_init(&fmp->lock); |
1329 | } |
1330 | |
1331 | /* Internal meter update - process cnt events and update value */ |
1332 | static void fmeter_update(struct fmeter *fmp) |
1333 | { |
1334 | time_t now = get_seconds(); |
1335 | time_t ticks = now - fmp->time; |
1336 | |
1337 | if (ticks == 0) |
1338 | return; |
1339 | |
1340 | ticks = min(FM_MAXTICKS, ticks); |
1341 | while (ticks-- > 0) |
1342 | fmp->val = (FM_COEF * fmp->val) / FM_SCALE; |
1343 | fmp->time = now; |
1344 | |
1345 | fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE; |
1346 | fmp->cnt = 0; |
1347 | } |
1348 | |
1349 | /* Process any previous ticks, then bump cnt by one (times scale). */ |
1350 | static void fmeter_markevent(struct fmeter *fmp) |
1351 | { |
1352 | spin_lock(&fmp->lock); |
1353 | fmeter_update(fmp); |
1354 | fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE); |
1355 | spin_unlock(&fmp->lock); |
1356 | } |
1357 | |
1358 | /* Process any previous ticks, then return current value. */ |
1359 | static int fmeter_getrate(struct fmeter *fmp) |
1360 | { |
1361 | int val; |
1362 | |
1363 | spin_lock(&fmp->lock); |
1364 | fmeter_update(fmp); |
1365 | val = fmp->val; |
1366 | spin_unlock(&fmp->lock); |
1367 | return val; |
1368 | } |
1369 | |
1370 | /* Protected by cgroup_lock */ |
1371 | static cpumask_var_t cpus_attach; |
1372 | |
1373 | /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */ |
1374 | static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont, |
1375 | struct task_struct *tsk, bool threadgroup) |
1376 | { |
1377 | int ret; |
1378 | struct cpuset *cs = cgroup_cs(cont); |
1379 | |
1380 | if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) |
1381 | return -ENOSPC; |
1382 | |
1383 | /* |
1384 | * Kthreads bound to specific cpus cannot be moved to a new cpuset; we |
1385 | * cannot change their cpu affinity and isolating such threads by their |
1386 | * set of allowed nodes is unnecessary. Thus, cpusets are not |
1387 | * applicable for such threads. This prevents checking for success of |
1388 | * set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may |
1389 | * be changed. |
1390 | */ |
1391 | if (tsk->flags & PF_THREAD_BOUND) |
1392 | return -EINVAL; |
1393 | |
1394 | ret = security_task_setscheduler(tsk); |
1395 | if (ret) |
1396 | return ret; |
1397 | if (threadgroup) { |
1398 | struct task_struct *c; |
1399 | |
1400 | rcu_read_lock(); |
1401 | list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { |
1402 | ret = security_task_setscheduler(c); |
1403 | if (ret) { |
1404 | rcu_read_unlock(); |
1405 | return ret; |
1406 | } |
1407 | } |
1408 | rcu_read_unlock(); |
1409 | } |
1410 | return 0; |
1411 | } |
1412 | |
1413 | static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to, |
1414 | struct cpuset *cs) |
1415 | { |
1416 | int err; |
1417 | /* |
1418 | * can_attach beforehand should guarantee that this doesn't fail. |
1419 | * TODO: have a better way to handle failure here |
1420 | */ |
1421 | err = set_cpus_allowed_ptr(tsk, cpus_attach); |
1422 | WARN_ON_ONCE(err); |
1423 | |
1424 | cpuset_change_task_nodemask(tsk, to); |
1425 | cpuset_update_task_spread_flag(cs, tsk); |
1426 | |
1427 | } |
1428 | |
1429 | static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, |
1430 | struct cgroup *oldcont, struct task_struct *tsk, |
1431 | bool threadgroup) |
1432 | { |
1433 | struct mm_struct *mm; |
1434 | struct cpuset *cs = cgroup_cs(cont); |
1435 | struct cpuset *oldcs = cgroup_cs(oldcont); |
1436 | static nodemask_t to; /* protected by cgroup_mutex */ |
1437 | |
1438 | if (cs == &top_cpuset) { |
1439 | cpumask_copy(cpus_attach, cpu_possible_mask); |
1440 | } else { |
1441 | guarantee_online_cpus(cs, cpus_attach); |
1442 | } |
1443 | guarantee_online_mems(cs, &to); |
1444 | |
1445 | /* do per-task migration stuff possibly for each in the threadgroup */ |
1446 | cpuset_attach_task(tsk, &to, cs); |
1447 | if (threadgroup) { |
1448 | struct task_struct *c; |
1449 | rcu_read_lock(); |
1450 | list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { |
1451 | cpuset_attach_task(c, &to, cs); |
1452 | } |
1453 | rcu_read_unlock(); |
1454 | } |
1455 | |
1456 | /* change mm; only needs to be done once even if threadgroup */ |
1457 | to = cs->mems_allowed; |
1458 | mm = get_task_mm(tsk); |
1459 | if (mm) { |
1460 | mpol_rebind_mm(mm, &to); |
1461 | if (is_memory_migrate(cs)) |
1462 | cpuset_migrate_mm(mm, &oldcs->mems_allowed, &to); |
1463 | mmput(mm); |
1464 | } |
1465 | } |
1466 | |
1467 | /* The various types of files and directories in a cpuset file system */ |
1468 | |
1469 | typedef enum { |
1470 | FILE_MEMORY_MIGRATE, |
1471 | FILE_CPULIST, |
1472 | FILE_MEMLIST, |
1473 | FILE_CPU_EXCLUSIVE, |
1474 | FILE_MEM_EXCLUSIVE, |
1475 | FILE_MEM_HARDWALL, |
1476 | FILE_SCHED_LOAD_BALANCE, |
1477 | FILE_SCHED_RELAX_DOMAIN_LEVEL, |
1478 | FILE_MEMORY_PRESSURE_ENABLED, |
1479 | FILE_MEMORY_PRESSURE, |
1480 | FILE_SPREAD_PAGE, |
1481 | FILE_SPREAD_SLAB, |
1482 | } cpuset_filetype_t; |
1483 | |
1484 | static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val) |
1485 | { |
1486 | int retval = 0; |
1487 | struct cpuset *cs = cgroup_cs(cgrp); |
1488 | cpuset_filetype_t type = cft->private; |
1489 | |
1490 | if (!cgroup_lock_live_group(cgrp)) |
1491 | return -ENODEV; |
1492 | |
1493 | switch (type) { |
1494 | case FILE_CPU_EXCLUSIVE: |
1495 | retval = update_flag(CS_CPU_EXCLUSIVE, cs, val); |
1496 | break; |
1497 | case FILE_MEM_EXCLUSIVE: |
1498 | retval = update_flag(CS_MEM_EXCLUSIVE, cs, val); |
1499 | break; |
1500 | case FILE_MEM_HARDWALL: |
1501 | retval = update_flag(CS_MEM_HARDWALL, cs, val); |
1502 | break; |
1503 | case FILE_SCHED_LOAD_BALANCE: |
1504 | retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val); |
1505 | break; |
1506 | case FILE_MEMORY_MIGRATE: |
1507 | retval = update_flag(CS_MEMORY_MIGRATE, cs, val); |
1508 | break; |
1509 | case FILE_MEMORY_PRESSURE_ENABLED: |
1510 | cpuset_memory_pressure_enabled = !!val; |
1511 | break; |
1512 | case FILE_MEMORY_PRESSURE: |
1513 | retval = -EACCES; |
1514 | break; |
1515 | case FILE_SPREAD_PAGE: |
1516 | retval = update_flag(CS_SPREAD_PAGE, cs, val); |
1517 | break; |
1518 | case FILE_SPREAD_SLAB: |
1519 | retval = update_flag(CS_SPREAD_SLAB, cs, val); |
1520 | break; |
1521 | default: |
1522 | retval = -EINVAL; |
1523 | break; |
1524 | } |
1525 | cgroup_unlock(); |
1526 | return retval; |
1527 | } |
1528 | |
1529 | static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val) |
1530 | { |
1531 | int retval = 0; |
1532 | struct cpuset *cs = cgroup_cs(cgrp); |
1533 | cpuset_filetype_t type = cft->private; |
1534 | |
1535 | if (!cgroup_lock_live_group(cgrp)) |
1536 | return -ENODEV; |
1537 | |
1538 | switch (type) { |
1539 | case FILE_SCHED_RELAX_DOMAIN_LEVEL: |
1540 | retval = update_relax_domain_level(cs, val); |
1541 | break; |
1542 | default: |
1543 | retval = -EINVAL; |
1544 | break; |
1545 | } |
1546 | cgroup_unlock(); |
1547 | return retval; |
1548 | } |
1549 | |
1550 | /* |
1551 | * Common handling for a write to a "cpus" or "mems" file. |
1552 | */ |
1553 | static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft, |
1554 | const char *buf) |
1555 | { |
1556 | int retval = 0; |
1557 | struct cpuset *cs = cgroup_cs(cgrp); |
1558 | struct cpuset *trialcs; |
1559 | |
1560 | if (!cgroup_lock_live_group(cgrp)) |
1561 | return -ENODEV; |
1562 | |
1563 | trialcs = alloc_trial_cpuset(cs); |
1564 | if (!trialcs) { |
1565 | retval = -ENOMEM; |
1566 | goto out; |
1567 | } |
1568 | |
1569 | switch (cft->private) { |
1570 | case FILE_CPULIST: |
1571 | retval = update_cpumask(cs, trialcs, buf); |
1572 | break; |
1573 | case FILE_MEMLIST: |
1574 | retval = update_nodemask(cs, trialcs, buf); |
1575 | break; |
1576 | default: |
1577 | retval = -EINVAL; |
1578 | break; |
1579 | } |
1580 | |
1581 | free_trial_cpuset(trialcs); |
1582 | out: |
1583 | cgroup_unlock(); |
1584 | return retval; |
1585 | } |
1586 | |
1587 | /* |
1588 | * These ascii lists should be read in a single call, by using a user |
1589 | * buffer large enough to hold the entire map. If read in smaller |
1590 | * chunks, there is no guarantee of atomicity. Since the display format |
1591 | * used, list of ranges of sequential numbers, is variable length, |
1592 | * and since these maps can change value dynamically, one could read |
1593 | * gibberish by doing partial reads while a list was changing. |
1594 | * A single large read to a buffer that crosses a page boundary is |
1595 | * ok, because the result being copied to user land is not recomputed |
1596 | * across a page fault. |
1597 | */ |
1598 | |
1599 | static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs) |
1600 | { |
1601 | size_t count; |
1602 | |
1603 | mutex_lock(&callback_mutex); |
1604 | count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed); |
1605 | mutex_unlock(&callback_mutex); |
1606 | |
1607 | return count; |
1608 | } |
1609 | |
1610 | static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs) |
1611 | { |
1612 | size_t count; |
1613 | |
1614 | mutex_lock(&callback_mutex); |
1615 | count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed); |
1616 | mutex_unlock(&callback_mutex); |
1617 | |
1618 | return count; |
1619 | } |
1620 | |
1621 | static ssize_t cpuset_common_file_read(struct cgroup *cont, |
1622 | struct cftype *cft, |
1623 | struct file *file, |
1624 | char __user *buf, |
1625 | size_t nbytes, loff_t *ppos) |
1626 | { |
1627 | struct cpuset *cs = cgroup_cs(cont); |
1628 | cpuset_filetype_t type = cft->private; |
1629 | char *page; |
1630 | ssize_t retval = 0; |
1631 | char *s; |
1632 | |
1633 | if (!(page = (char *)__get_free_page(GFP_TEMPORARY))) |
1634 | return -ENOMEM; |
1635 | |
1636 | s = page; |
1637 | |
1638 | switch (type) { |
1639 | case FILE_CPULIST: |
1640 | s += cpuset_sprintf_cpulist(s, cs); |
1641 | break; |
1642 | case FILE_MEMLIST: |
1643 | s += cpuset_sprintf_memlist(s, cs); |
1644 | break; |
1645 | default: |
1646 | retval = -EINVAL; |
1647 | goto out; |
1648 | } |
1649 | *s++ = '\n'; |
1650 | |
1651 | retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page); |
1652 | out: |
1653 | free_page((unsigned long)page); |
1654 | return retval; |
1655 | } |
1656 | |
1657 | static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft) |
1658 | { |
1659 | struct cpuset *cs = cgroup_cs(cont); |
1660 | cpuset_filetype_t type = cft->private; |
1661 | switch (type) { |
1662 | case FILE_CPU_EXCLUSIVE: |
1663 | return is_cpu_exclusive(cs); |
1664 | case FILE_MEM_EXCLUSIVE: |
1665 | return is_mem_exclusive(cs); |
1666 | case FILE_MEM_HARDWALL: |
1667 | return is_mem_hardwall(cs); |
1668 | case FILE_SCHED_LOAD_BALANCE: |
1669 | return is_sched_load_balance(cs); |
1670 | case FILE_MEMORY_MIGRATE: |
1671 | return is_memory_migrate(cs); |
1672 | case FILE_MEMORY_PRESSURE_ENABLED: |
1673 | return cpuset_memory_pressure_enabled; |
1674 | case FILE_MEMORY_PRESSURE: |
1675 | return fmeter_getrate(&cs->fmeter); |
1676 | case FILE_SPREAD_PAGE: |
1677 | return is_spread_page(cs); |
1678 | case FILE_SPREAD_SLAB: |
1679 | return is_spread_slab(cs); |
1680 | default: |
1681 | BUG(); |
1682 | } |
1683 | |
1684 | /* Unreachable but makes gcc happy */ |
1685 | return 0; |
1686 | } |
1687 | |
1688 | static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft) |
1689 | { |
1690 | struct cpuset *cs = cgroup_cs(cont); |
1691 | cpuset_filetype_t type = cft->private; |
1692 | switch (type) { |
1693 | case FILE_SCHED_RELAX_DOMAIN_LEVEL: |
1694 | return cs->relax_domain_level; |
1695 | default: |
1696 | BUG(); |
1697 | } |
1698 | |
1699 | /* Unrechable but makes gcc happy */ |
1700 | return 0; |
1701 | } |
1702 | |
1703 | |
1704 | /* |
1705 | * for the common functions, 'private' gives the type of file |
1706 | */ |
1707 | |
1708 | static struct cftype files[] = { |
1709 | { |
1710 | .name = "cpus", |
1711 | .read = cpuset_common_file_read, |
1712 | .write_string = cpuset_write_resmask, |
1713 | .max_write_len = (100U + 6 * NR_CPUS), |
1714 | .private = FILE_CPULIST, |
1715 | }, |
1716 | |
1717 | { |
1718 | .name = "mems", |
1719 | .read = cpuset_common_file_read, |
1720 | .write_string = cpuset_write_resmask, |
1721 | .max_write_len = (100U + 6 * MAX_NUMNODES), |
1722 | .private = FILE_MEMLIST, |
1723 | }, |
1724 | |
1725 | { |
1726 | .name = "cpu_exclusive", |
1727 | .read_u64 = cpuset_read_u64, |
1728 | .write_u64 = cpuset_write_u64, |
1729 | .private = FILE_CPU_EXCLUSIVE, |
1730 | }, |
1731 | |
1732 | { |
1733 | .name = "mem_exclusive", |
1734 | .read_u64 = cpuset_read_u64, |
1735 | .write_u64 = cpuset_write_u64, |
1736 | .private = FILE_MEM_EXCLUSIVE, |
1737 | }, |
1738 | |
1739 | { |
1740 | .name = "mem_hardwall", |
1741 | .read_u64 = cpuset_read_u64, |
1742 | .write_u64 = cpuset_write_u64, |
1743 | .private = FILE_MEM_HARDWALL, |
1744 | }, |
1745 | |
1746 | { |
1747 | .name = "sched_load_balance", |
1748 | .read_u64 = cpuset_read_u64, |
1749 | .write_u64 = cpuset_write_u64, |
1750 | .private = FILE_SCHED_LOAD_BALANCE, |
1751 | }, |
1752 | |
1753 | { |
1754 | .name = "sched_relax_domain_level", |
1755 | .read_s64 = cpuset_read_s64, |
1756 | .write_s64 = cpuset_write_s64, |
1757 | .private = FILE_SCHED_RELAX_DOMAIN_LEVEL, |
1758 | }, |
1759 | |
1760 | { |
1761 | .name = "memory_migrate", |
1762 | .read_u64 = cpuset_read_u64, |
1763 | .write_u64 = cpuset_write_u64, |
1764 | .private = FILE_MEMORY_MIGRATE, |
1765 | }, |
1766 | |
1767 | { |
1768 | .name = "memory_pressure", |
1769 | .read_u64 = cpuset_read_u64, |
1770 | .write_u64 = cpuset_write_u64, |
1771 | .private = FILE_MEMORY_PRESSURE, |
1772 | .mode = S_IRUGO, |
1773 | }, |
1774 | |
1775 | { |
1776 | .name = "memory_spread_page", |
1777 | .read_u64 = cpuset_read_u64, |
1778 | .write_u64 = cpuset_write_u64, |
1779 | .private = FILE_SPREAD_PAGE, |
1780 | }, |
1781 | |
1782 | { |
1783 | .name = "memory_spread_slab", |
1784 | .read_u64 = cpuset_read_u64, |
1785 | .write_u64 = cpuset_write_u64, |
1786 | .private = FILE_SPREAD_SLAB, |
1787 | }, |
1788 | }; |
1789 | |
1790 | static struct cftype cft_memory_pressure_enabled = { |
1791 | .name = "memory_pressure_enabled", |
1792 | .read_u64 = cpuset_read_u64, |
1793 | .write_u64 = cpuset_write_u64, |
1794 | .private = FILE_MEMORY_PRESSURE_ENABLED, |
1795 | }; |
1796 | |
1797 | static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont) |
1798 | { |
1799 | int err; |
1800 | |
1801 | err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files)); |
1802 | if (err) |
1803 | return err; |
1804 | /* memory_pressure_enabled is in root cpuset only */ |
1805 | if (!cont->parent) |
1806 | err = cgroup_add_file(cont, ss, |
1807 | &cft_memory_pressure_enabled); |
1808 | return err; |
1809 | } |
1810 | |
1811 | /* |
1812 | * post_clone() is called at the end of cgroup_clone(). |
1813 | * 'cgroup' was just created automatically as a result of |
1814 | * a cgroup_clone(), and the current task is about to |
1815 | * be moved into 'cgroup'. |
1816 | * |
1817 | * Currently we refuse to set up the cgroup - thereby |
1818 | * refusing the task to be entered, and as a result refusing |
1819 | * the sys_unshare() or clone() which initiated it - if any |
1820 | * sibling cpusets have exclusive cpus or mem. |
1821 | * |
1822 | * If this becomes a problem for some users who wish to |
1823 | * allow that scenario, then cpuset_post_clone() could be |
1824 | * changed to grant parent->cpus_allowed-sibling_cpus_exclusive |
1825 | * (and likewise for mems) to the new cgroup. Called with cgroup_mutex |
1826 | * held. |
1827 | */ |
1828 | static void cpuset_post_clone(struct cgroup_subsys *ss, |
1829 | struct cgroup *cgroup) |
1830 | { |
1831 | struct cgroup *parent, *child; |
1832 | struct cpuset *cs, *parent_cs; |
1833 | |
1834 | parent = cgroup->parent; |
1835 | list_for_each_entry(child, &parent->children, sibling) { |
1836 | cs = cgroup_cs(child); |
1837 | if (is_mem_exclusive(cs) || is_cpu_exclusive(cs)) |
1838 | return; |
1839 | } |
1840 | cs = cgroup_cs(cgroup); |
1841 | parent_cs = cgroup_cs(parent); |
1842 | |
1843 | mutex_lock(&callback_mutex); |
1844 | cs->mems_allowed = parent_cs->mems_allowed; |
1845 | cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed); |
1846 | mutex_unlock(&callback_mutex); |
1847 | return; |
1848 | } |
1849 | |
1850 | /* |
1851 | * cpuset_create - create a cpuset |
1852 | * ss: cpuset cgroup subsystem |
1853 | * cont: control group that the new cpuset will be part of |
1854 | */ |
1855 | |
1856 | static struct cgroup_subsys_state *cpuset_create( |
1857 | struct cgroup_subsys *ss, |
1858 | struct cgroup *cont) |
1859 | { |
1860 | struct cpuset *cs; |
1861 | struct cpuset *parent; |
1862 | |
1863 | if (!cont->parent) { |
1864 | return &top_cpuset.css; |
1865 | } |
1866 | parent = cgroup_cs(cont->parent); |
1867 | cs = kmalloc(sizeof(*cs), GFP_KERNEL); |
1868 | if (!cs) |
1869 | return ERR_PTR(-ENOMEM); |
1870 | if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) { |
1871 | kfree(cs); |
1872 | return ERR_PTR(-ENOMEM); |
1873 | } |
1874 | |
1875 | cs->flags = 0; |
1876 | if (is_spread_page(parent)) |
1877 | set_bit(CS_SPREAD_PAGE, &cs->flags); |
1878 | if (is_spread_slab(parent)) |
1879 | set_bit(CS_SPREAD_SLAB, &cs->flags); |
1880 | set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); |
1881 | cpumask_clear(cs->cpus_allowed); |
1882 | nodes_clear(cs->mems_allowed); |
1883 | fmeter_init(&cs->fmeter); |
1884 | cs->relax_domain_level = -1; |
1885 | |
1886 | cs->parent = parent; |
1887 | number_of_cpusets++; |
1888 | return &cs->css ; |
1889 | } |
1890 | |
1891 | /* |
1892 | * If the cpuset being removed has its flag 'sched_load_balance' |
1893 | * enabled, then simulate turning sched_load_balance off, which |
1894 | * will call async_rebuild_sched_domains(). |
1895 | */ |
1896 | |
1897 | static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont) |
1898 | { |
1899 | struct cpuset *cs = cgroup_cs(cont); |
1900 | |
1901 | if (is_sched_load_balance(cs)) |
1902 | update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); |
1903 | |
1904 | number_of_cpusets--; |
1905 | free_cpumask_var(cs->cpus_allowed); |
1906 | kfree(cs); |
1907 | } |
1908 | |
1909 | struct cgroup_subsys cpuset_subsys = { |
1910 | .name = "cpuset", |
1911 | .create = cpuset_create, |
1912 | .destroy = cpuset_destroy, |
1913 | .can_attach = cpuset_can_attach, |
1914 | .attach = cpuset_attach, |
1915 | .populate = cpuset_populate, |
1916 | .post_clone = cpuset_post_clone, |
1917 | .subsys_id = cpuset_subsys_id, |
1918 | .early_init = 1, |
1919 | }; |
1920 | |
1921 | /** |
1922 | * cpuset_init - initialize cpusets at system boot |
1923 | * |
1924 | * Description: Initialize top_cpuset and the cpuset internal file system, |
1925 | **/ |
1926 | |
1927 | int __init cpuset_init(void) |
1928 | { |
1929 | int err = 0; |
1930 | |
1931 | if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL)) |
1932 | BUG(); |
1933 | |
1934 | cpumask_setall(top_cpuset.cpus_allowed); |
1935 | nodes_setall(top_cpuset.mems_allowed); |
1936 | |
1937 | fmeter_init(&top_cpuset.fmeter); |
1938 | set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags); |
1939 | top_cpuset.relax_domain_level = -1; |
1940 | |
1941 | err = register_filesystem(&cpuset_fs_type); |
1942 | if (err < 0) |
1943 | return err; |
1944 | |
1945 | if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL)) |
1946 | BUG(); |
1947 | |
1948 | number_of_cpusets = 1; |
1949 | return 0; |
1950 | } |
1951 | |
1952 | /** |
1953 | * cpuset_do_move_task - move a given task to another cpuset |
1954 | * @tsk: pointer to task_struct the task to move |
1955 | * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner |
1956 | * |
1957 | * Called by cgroup_scan_tasks() for each task in a cgroup. |
1958 | * Return nonzero to stop the walk through the tasks. |
1959 | */ |
1960 | static void cpuset_do_move_task(struct task_struct *tsk, |
1961 | struct cgroup_scanner *scan) |
1962 | { |
1963 | struct cgroup *new_cgroup = scan->data; |
1964 | |
1965 | cgroup_attach_task(new_cgroup, tsk); |
1966 | } |
1967 | |
1968 | /** |
1969 | * move_member_tasks_to_cpuset - move tasks from one cpuset to another |
1970 | * @from: cpuset in which the tasks currently reside |
1971 | * @to: cpuset to which the tasks will be moved |
1972 | * |
1973 | * Called with cgroup_mutex held |
1974 | * callback_mutex must not be held, as cpuset_attach() will take it. |
1975 | * |
1976 | * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, |
1977 | * calling callback functions for each. |
1978 | */ |
1979 | static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to) |
1980 | { |
1981 | struct cgroup_scanner scan; |
1982 | |
1983 | scan.cg = from->css.cgroup; |
1984 | scan.test_task = NULL; /* select all tasks in cgroup */ |
1985 | scan.process_task = cpuset_do_move_task; |
1986 | scan.heap = NULL; |
1987 | scan.data = to->css.cgroup; |
1988 | |
1989 | if (cgroup_scan_tasks(&scan)) |
1990 | printk(KERN_ERR "move_member_tasks_to_cpuset: " |
1991 | "cgroup_scan_tasks failed\n"); |
1992 | } |
1993 | |
1994 | /* |
1995 | * If CPU and/or memory hotplug handlers, below, unplug any CPUs |
1996 | * or memory nodes, we need to walk over the cpuset hierarchy, |
1997 | * removing that CPU or node from all cpusets. If this removes the |
1998 | * last CPU or node from a cpuset, then move the tasks in the empty |
1999 | * cpuset to its next-highest non-empty parent. |
2000 | * |
2001 | * Called with cgroup_mutex held |
2002 | * callback_mutex must not be held, as cpuset_attach() will take it. |
2003 | */ |
2004 | static void remove_tasks_in_empty_cpuset(struct cpuset *cs) |
2005 | { |
2006 | struct cpuset *parent; |
2007 | |
2008 | /* |
2009 | * The cgroup's css_sets list is in use if there are tasks |
2010 | * in the cpuset; the list is empty if there are none; |
2011 | * the cs->css.refcnt seems always 0. |
2012 | */ |
2013 | if (list_empty(&cs->css.cgroup->css_sets)) |
2014 | return; |
2015 | |
2016 | /* |
2017 | * Find its next-highest non-empty parent, (top cpuset |
2018 | * has online cpus, so can't be empty). |
2019 | */ |
2020 | parent = cs->parent; |
2021 | while (cpumask_empty(parent->cpus_allowed) || |
2022 | nodes_empty(parent->mems_allowed)) |
2023 | parent = parent->parent; |
2024 | |
2025 | move_member_tasks_to_cpuset(cs, parent); |
2026 | } |
2027 | |
2028 | /* |
2029 | * Walk the specified cpuset subtree and look for empty cpusets. |
2030 | * The tasks of such cpuset must be moved to a parent cpuset. |
2031 | * |
2032 | * Called with cgroup_mutex held. We take callback_mutex to modify |
2033 | * cpus_allowed and mems_allowed. |
2034 | * |
2035 | * This walk processes the tree from top to bottom, completing one layer |
2036 | * before dropping down to the next. It always processes a node before |
2037 | * any of its children. |
2038 | * |
2039 | * For now, since we lack memory hot unplug, we'll never see a cpuset |
2040 | * that has tasks along with an empty 'mems'. But if we did see such |
2041 | * a cpuset, we'd handle it just like we do if its 'cpus' was empty. |
2042 | */ |
2043 | static void scan_for_empty_cpusets(struct cpuset *root) |
2044 | { |
2045 | LIST_HEAD(queue); |
2046 | struct cpuset *cp; /* scans cpusets being updated */ |
2047 | struct cpuset *child; /* scans child cpusets of cp */ |
2048 | struct cgroup *cont; |
2049 | static nodemask_t oldmems; /* protected by cgroup_mutex */ |
2050 | |
2051 | list_add_tail((struct list_head *)&root->stack_list, &queue); |
2052 | |
2053 | while (!list_empty(&queue)) { |
2054 | cp = list_first_entry(&queue, struct cpuset, stack_list); |
2055 | list_del(queue.next); |
2056 | list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { |
2057 | child = cgroup_cs(cont); |
2058 | list_add_tail(&child->stack_list, &queue); |
2059 | } |
2060 | |
2061 | /* Continue past cpusets with all cpus, mems online */ |
2062 | if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) && |
2063 | nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) |
2064 | continue; |
2065 | |
2066 | oldmems = cp->mems_allowed; |
2067 | |
2068 | /* Remove offline cpus and mems from this cpuset. */ |
2069 | mutex_lock(&callback_mutex); |
2070 | cpumask_and(cp->cpus_allowed, cp->cpus_allowed, |
2071 | cpu_active_mask); |
2072 | nodes_and(cp->mems_allowed, cp->mems_allowed, |
2073 | node_states[N_HIGH_MEMORY]); |
2074 | mutex_unlock(&callback_mutex); |
2075 | |
2076 | /* Move tasks from the empty cpuset to a parent */ |
2077 | if (cpumask_empty(cp->cpus_allowed) || |
2078 | nodes_empty(cp->mems_allowed)) |
2079 | remove_tasks_in_empty_cpuset(cp); |
2080 | else { |
2081 | update_tasks_cpumask(cp, NULL); |
2082 | update_tasks_nodemask(cp, &oldmems, NULL); |
2083 | } |
2084 | } |
2085 | } |
2086 | |
2087 | /* |
2088 | * The top_cpuset tracks what CPUs and Memory Nodes are online, |
2089 | * period. This is necessary in order to make cpusets transparent |
2090 | * (of no affect) on systems that are actively using CPU hotplug |
2091 | * but making no active use of cpusets. |
2092 | * |
2093 | * This routine ensures that top_cpuset.cpus_allowed tracks |
2094 | * cpu_active_mask on each CPU hotplug (cpuhp) event. |
2095 | * |
2096 | * Called within get_online_cpus(). Needs to call cgroup_lock() |
2097 | * before calling generate_sched_domains(). |
2098 | */ |
2099 | void cpuset_update_active_cpus(void) |
2100 | { |
2101 | struct sched_domain_attr *attr; |
2102 | cpumask_var_t *doms; |
2103 | int ndoms; |
2104 | |
2105 | cgroup_lock(); |
2106 | mutex_lock(&callback_mutex); |
2107 | cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); |
2108 | mutex_unlock(&callback_mutex); |
2109 | scan_for_empty_cpusets(&top_cpuset); |
2110 | ndoms = generate_sched_domains(&doms, &attr); |
2111 | cgroup_unlock(); |
2112 | |
2113 | /* Have scheduler rebuild the domains */ |
2114 | partition_sched_domains(ndoms, doms, attr); |
2115 | } |
2116 | |
2117 | #ifdef CONFIG_MEMORY_HOTPLUG |
2118 | /* |
2119 | * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY]. |
2120 | * Call this routine anytime after node_states[N_HIGH_MEMORY] changes. |
2121 | * See also the previous routine cpuset_track_online_cpus(). |
2122 | */ |
2123 | static int cpuset_track_online_nodes(struct notifier_block *self, |
2124 | unsigned long action, void *arg) |
2125 | { |
2126 | static nodemask_t oldmems; /* protected by cgroup_mutex */ |
2127 | |
2128 | cgroup_lock(); |
2129 | switch (action) { |
2130 | case MEM_ONLINE: |
2131 | oldmems = top_cpuset.mems_allowed; |
2132 | mutex_lock(&callback_mutex); |
2133 | top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; |
2134 | mutex_unlock(&callback_mutex); |
2135 | update_tasks_nodemask(&top_cpuset, &oldmems, NULL); |
2136 | break; |
2137 | case MEM_OFFLINE: |
2138 | /* |
2139 | * needn't update top_cpuset.mems_allowed explicitly because |
2140 | * scan_for_empty_cpusets() will update it. |
2141 | */ |
2142 | scan_for_empty_cpusets(&top_cpuset); |
2143 | break; |
2144 | default: |
2145 | break; |
2146 | } |
2147 | cgroup_unlock(); |
2148 | |
2149 | return NOTIFY_OK; |
2150 | } |
2151 | #endif |
2152 | |
2153 | /** |
2154 | * cpuset_init_smp - initialize cpus_allowed |
2155 | * |
2156 | * Description: Finish top cpuset after cpu, node maps are initialized |
2157 | **/ |
2158 | |
2159 | void __init cpuset_init_smp(void) |
2160 | { |
2161 | cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); |
2162 | top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; |
2163 | |
2164 | hotplug_memory_notifier(cpuset_track_online_nodes, 10); |
2165 | |
2166 | cpuset_wq = create_singlethread_workqueue("cpuset"); |
2167 | BUG_ON(!cpuset_wq); |
2168 | } |
2169 | |
2170 | /** |
2171 | * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. |
2172 | * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. |
2173 | * @pmask: pointer to struct cpumask variable to receive cpus_allowed set. |
2174 | * |
2175 | * Description: Returns the cpumask_var_t cpus_allowed of the cpuset |
2176 | * attached to the specified @tsk. Guaranteed to return some non-empty |
2177 | * subset of cpu_online_map, even if this means going outside the |
2178 | * tasks cpuset. |
2179 | **/ |
2180 | |
2181 | void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) |
2182 | { |
2183 | mutex_lock(&callback_mutex); |
2184 | task_lock(tsk); |
2185 | guarantee_online_cpus(task_cs(tsk), pmask); |
2186 | task_unlock(tsk); |
2187 | mutex_unlock(&callback_mutex); |
2188 | } |
2189 | |
2190 | int cpuset_cpus_allowed_fallback(struct task_struct *tsk) |
2191 | { |
2192 | const struct cpuset *cs; |
2193 | int cpu; |
2194 | |
2195 | rcu_read_lock(); |
2196 | cs = task_cs(tsk); |
2197 | if (cs) |
2198 | cpumask_copy(&tsk->cpus_allowed, cs->cpus_allowed); |
2199 | rcu_read_unlock(); |
2200 | |
2201 | /* |
2202 | * We own tsk->cpus_allowed, nobody can change it under us. |
2203 | * |
2204 | * But we used cs && cs->cpus_allowed lockless and thus can |
2205 | * race with cgroup_attach_task() or update_cpumask() and get |
2206 | * the wrong tsk->cpus_allowed. However, both cases imply the |
2207 | * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr() |
2208 | * which takes task_rq_lock(). |
2209 | * |
2210 | * If we are called after it dropped the lock we must see all |
2211 | * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary |
2212 | * set any mask even if it is not right from task_cs() pov, |
2213 | * the pending set_cpus_allowed_ptr() will fix things. |
2214 | */ |
2215 | |
2216 | cpu = cpumask_any_and(&tsk->cpus_allowed, cpu_active_mask); |
2217 | if (cpu >= nr_cpu_ids) { |
2218 | /* |
2219 | * Either tsk->cpus_allowed is wrong (see above) or it |
2220 | * is actually empty. The latter case is only possible |
2221 | * if we are racing with remove_tasks_in_empty_cpuset(). |
2222 | * Like above we can temporary set any mask and rely on |
2223 | * set_cpus_allowed_ptr() as synchronization point. |
2224 | */ |
2225 | cpumask_copy(&tsk->cpus_allowed, cpu_possible_mask); |
2226 | cpu = cpumask_any(cpu_active_mask); |
2227 | } |
2228 | |
2229 | return cpu; |
2230 | } |
2231 | |
2232 | void cpuset_init_current_mems_allowed(void) |
2233 | { |
2234 | nodes_setall(current->mems_allowed); |
2235 | } |
2236 | |
2237 | /** |
2238 | * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset. |
2239 | * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed. |
2240 | * |
2241 | * Description: Returns the nodemask_t mems_allowed of the cpuset |
2242 | * attached to the specified @tsk. Guaranteed to return some non-empty |
2243 | * subset of node_states[N_HIGH_MEMORY], even if this means going outside the |
2244 | * tasks cpuset. |
2245 | **/ |
2246 | |
2247 | nodemask_t cpuset_mems_allowed(struct task_struct *tsk) |
2248 | { |
2249 | nodemask_t mask; |
2250 | |
2251 | mutex_lock(&callback_mutex); |
2252 | task_lock(tsk); |
2253 | guarantee_online_mems(task_cs(tsk), &mask); |
2254 | task_unlock(tsk); |
2255 | mutex_unlock(&callback_mutex); |
2256 | |
2257 | return mask; |
2258 | } |
2259 | |
2260 | /** |
2261 | * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed |
2262 | * @nodemask: the nodemask to be checked |
2263 | * |
2264 | * Are any of the nodes in the nodemask allowed in current->mems_allowed? |
2265 | */ |
2266 | int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask) |
2267 | { |
2268 | return nodes_intersects(*nodemask, current->mems_allowed); |
2269 | } |
2270 | |
2271 | /* |
2272 | * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or |
2273 | * mem_hardwall ancestor to the specified cpuset. Call holding |
2274 | * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall |
2275 | * (an unusual configuration), then returns the root cpuset. |
2276 | */ |
2277 | static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs) |
2278 | { |
2279 | while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent) |
2280 | cs = cs->parent; |
2281 | return cs; |
2282 | } |
2283 | |
2284 | /** |
2285 | * cpuset_node_allowed_softwall - Can we allocate on a memory node? |
2286 | * @node: is this an allowed node? |
2287 | * @gfp_mask: memory allocation flags |
2288 | * |
2289 | * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is |
2290 | * set, yes, we can always allocate. If node is in our task's mems_allowed, |
2291 | * yes. If it's not a __GFP_HARDWALL request and this node is in the nearest |
2292 | * hardwalled cpuset ancestor to this task's cpuset, yes. If the task has been |
2293 | * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE |
2294 | * flag, yes. |
2295 | * Otherwise, no. |
2296 | * |
2297 | * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to |
2298 | * cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall() |
2299 | * might sleep, and might allow a node from an enclosing cpuset. |
2300 | * |
2301 | * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall |
2302 | * cpusets, and never sleeps. |
2303 | * |
2304 | * The __GFP_THISNODE placement logic is really handled elsewhere, |
2305 | * by forcibly using a zonelist starting at a specified node, and by |
2306 | * (in get_page_from_freelist()) refusing to consider the zones for |
2307 | * any node on the zonelist except the first. By the time any such |
2308 | * calls get to this routine, we should just shut up and say 'yes'. |
2309 | * |
2310 | * GFP_USER allocations are marked with the __GFP_HARDWALL bit, |
2311 | * and do not allow allocations outside the current tasks cpuset |
2312 | * unless the task has been OOM killed as is marked TIF_MEMDIE. |
2313 | * GFP_KERNEL allocations are not so marked, so can escape to the |
2314 | * nearest enclosing hardwalled ancestor cpuset. |
2315 | * |
2316 | * Scanning up parent cpusets requires callback_mutex. The |
2317 | * __alloc_pages() routine only calls here with __GFP_HARDWALL bit |
2318 | * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the |
2319 | * current tasks mems_allowed came up empty on the first pass over |
2320 | * the zonelist. So only GFP_KERNEL allocations, if all nodes in the |
2321 | * cpuset are short of memory, might require taking the callback_mutex |
2322 | * mutex. |
2323 | * |
2324 | * The first call here from mm/page_alloc:get_page_from_freelist() |
2325 | * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, |
2326 | * so no allocation on a node outside the cpuset is allowed (unless |
2327 | * in interrupt, of course). |
2328 | * |
2329 | * The second pass through get_page_from_freelist() doesn't even call |
2330 | * here for GFP_ATOMIC calls. For those calls, the __alloc_pages() |
2331 | * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set |
2332 | * in alloc_flags. That logic and the checks below have the combined |
2333 | * affect that: |
2334 | * in_interrupt - any node ok (current task context irrelevant) |
2335 | * GFP_ATOMIC - any node ok |
2336 | * TIF_MEMDIE - any node ok |
2337 | * GFP_KERNEL - any node in enclosing hardwalled cpuset ok |
2338 | * GFP_USER - only nodes in current tasks mems allowed ok. |
2339 | * |
2340 | * Rule: |
2341 | * Don't call cpuset_node_allowed_softwall if you can't sleep, unless you |
2342 | * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables |
2343 | * the code that might scan up ancestor cpusets and sleep. |
2344 | */ |
2345 | int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask) |
2346 | { |
2347 | const struct cpuset *cs; /* current cpuset ancestors */ |
2348 | int allowed; /* is allocation in zone z allowed? */ |
2349 | |
2350 | if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) |
2351 | return 1; |
2352 | might_sleep_if(!(gfp_mask & __GFP_HARDWALL)); |
2353 | if (node_isset(node, current->mems_allowed)) |
2354 | return 1; |
2355 | /* |
2356 | * Allow tasks that have access to memory reserves because they have |
2357 | * been OOM killed to get memory anywhere. |
2358 | */ |
2359 | if (unlikely(test_thread_flag(TIF_MEMDIE))) |
2360 | return 1; |
2361 | if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */ |
2362 | return 0; |
2363 | |
2364 | if (current->flags & PF_EXITING) /* Let dying task have memory */ |
2365 | return 1; |
2366 | |
2367 | /* Not hardwall and node outside mems_allowed: scan up cpusets */ |
2368 | mutex_lock(&callback_mutex); |
2369 | |
2370 | task_lock(current); |
2371 | cs = nearest_hardwall_ancestor(task_cs(current)); |
2372 | task_unlock(current); |
2373 | |
2374 | allowed = node_isset(node, cs->mems_allowed); |
2375 | mutex_unlock(&callback_mutex); |
2376 | return allowed; |
2377 | } |
2378 | |
2379 | /* |
2380 | * cpuset_node_allowed_hardwall - Can we allocate on a memory node? |
2381 | * @node: is this an allowed node? |
2382 | * @gfp_mask: memory allocation flags |
2383 | * |
2384 | * If we're in interrupt, yes, we can always allocate. If __GFP_THISNODE is |
2385 | * set, yes, we can always allocate. If node is in our task's mems_allowed, |
2386 | * yes. If the task has been OOM killed and has access to memory reserves as |
2387 | * specified by the TIF_MEMDIE flag, yes. |
2388 | * Otherwise, no. |
2389 | * |
2390 | * The __GFP_THISNODE placement logic is really handled elsewhere, |
2391 | * by forcibly using a zonelist starting at a specified node, and by |
2392 | * (in get_page_from_freelist()) refusing to consider the zones for |
2393 | * any node on the zonelist except the first. By the time any such |
2394 | * calls get to this routine, we should just shut up and say 'yes'. |
2395 | * |
2396 | * Unlike the cpuset_node_allowed_softwall() variant, above, |
2397 | * this variant requires that the node be in the current task's |
2398 | * mems_allowed or that we're in interrupt. It does not scan up the |
2399 | * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset. |
2400 | * It never sleeps. |
2401 | */ |
2402 | int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask) |
2403 | { |
2404 | if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) |
2405 | return 1; |
2406 | if (node_isset(node, current->mems_allowed)) |
2407 | return 1; |
2408 | /* |
2409 | * Allow tasks that have access to memory reserves because they have |
2410 | * been OOM killed to get memory anywhere. |
2411 | */ |
2412 | if (unlikely(test_thread_flag(TIF_MEMDIE))) |
2413 | return 1; |
2414 | return 0; |
2415 | } |
2416 | |
2417 | /** |
2418 | * cpuset_unlock - release lock on cpuset changes |
2419 | * |
2420 | * Undo the lock taken in a previous cpuset_lock() call. |
2421 | */ |
2422 | |
2423 | void cpuset_unlock(void) |
2424 | { |
2425 | mutex_unlock(&callback_mutex); |
2426 | } |
2427 | |
2428 | /** |
2429 | * cpuset_mem_spread_node() - On which node to begin search for a file page |
2430 | * cpuset_slab_spread_node() - On which node to begin search for a slab page |
2431 | * |
2432 | * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for |
2433 | * tasks in a cpuset with is_spread_page or is_spread_slab set), |
2434 | * and if the memory allocation used cpuset_mem_spread_node() |
2435 | * to determine on which node to start looking, as it will for |
2436 | * certain page cache or slab cache pages such as used for file |
2437 | * system buffers and inode caches, then instead of starting on the |
2438 | * local node to look for a free page, rather spread the starting |
2439 | * node around the tasks mems_allowed nodes. |
2440 | * |
2441 | * We don't have to worry about the returned node being offline |
2442 | * because "it can't happen", and even if it did, it would be ok. |
2443 | * |
2444 | * The routines calling guarantee_online_mems() are careful to |
2445 | * only set nodes in task->mems_allowed that are online. So it |
2446 | * should not be possible for the following code to return an |
2447 | * offline node. But if it did, that would be ok, as this routine |
2448 | * is not returning the node where the allocation must be, only |
2449 | * the node where the search should start. The zonelist passed to |
2450 | * __alloc_pages() will include all nodes. If the slab allocator |
2451 | * is passed an offline node, it will fall back to the local node. |
2452 | * See kmem_cache_alloc_node(). |
2453 | */ |
2454 | |
2455 | static int cpuset_spread_node(int *rotor) |
2456 | { |
2457 | int node; |
2458 | |
2459 | node = next_node(*rotor, current->mems_allowed); |
2460 | if (node == MAX_NUMNODES) |
2461 | node = first_node(current->mems_allowed); |
2462 | *rotor = node; |
2463 | return node; |
2464 | } |
2465 | |
2466 | int cpuset_mem_spread_node(void) |
2467 | { |
2468 | return cpuset_spread_node(¤t->cpuset_mem_spread_rotor); |
2469 | } |
2470 | |
2471 | int cpuset_slab_spread_node(void) |
2472 | { |
2473 | return cpuset_spread_node(¤t->cpuset_slab_spread_rotor); |
2474 | } |
2475 | |
2476 | EXPORT_SYMBOL_GPL(cpuset_mem_spread_node); |
2477 | |
2478 | /** |
2479 | * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's? |
2480 | * @tsk1: pointer to task_struct of some task. |
2481 | * @tsk2: pointer to task_struct of some other task. |
2482 | * |
2483 | * Description: Return true if @tsk1's mems_allowed intersects the |
2484 | * mems_allowed of @tsk2. Used by the OOM killer to determine if |
2485 | * one of the task's memory usage might impact the memory available |
2486 | * to the other. |
2487 | **/ |
2488 | |
2489 | int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, |
2490 | const struct task_struct *tsk2) |
2491 | { |
2492 | return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed); |
2493 | } |
2494 | |
2495 | /** |
2496 | * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed |
2497 | * @task: pointer to task_struct of some task. |
2498 | * |
2499 | * Description: Prints @task's name, cpuset name, and cached copy of its |
2500 | * mems_allowed to the kernel log. Must hold task_lock(task) to allow |
2501 | * dereferencing task_cs(task). |
2502 | */ |
2503 | void cpuset_print_task_mems_allowed(struct task_struct *tsk) |
2504 | { |
2505 | struct dentry *dentry; |
2506 | |
2507 | dentry = task_cs(tsk)->css.cgroup->dentry; |
2508 | spin_lock(&cpuset_buffer_lock); |
2509 | snprintf(cpuset_name, CPUSET_NAME_LEN, |
2510 | dentry ? (const char *)dentry->d_name.name : "/"); |
2511 | nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, |
2512 | tsk->mems_allowed); |
2513 | printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", |
2514 | tsk->comm, cpuset_name, cpuset_nodelist); |
2515 | spin_unlock(&cpuset_buffer_lock); |
2516 | } |
2517 | |
2518 | /* |
2519 | * Collection of memory_pressure is suppressed unless |
2520 | * this flag is enabled by writing "1" to the special |
2521 | * cpuset file 'memory_pressure_enabled' in the root cpuset. |
2522 | */ |
2523 | |
2524 | int cpuset_memory_pressure_enabled __read_mostly; |
2525 | |
2526 | /** |
2527 | * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims. |
2528 | * |
2529 | * Keep a running average of the rate of synchronous (direct) |
2530 | * page reclaim efforts initiated by tasks in each cpuset. |
2531 | * |
2532 | * This represents the rate at which some task in the cpuset |
2533 | * ran low on memory on all nodes it was allowed to use, and |
2534 | * had to enter the kernels page reclaim code in an effort to |
2535 | * create more free memory by tossing clean pages or swapping |
2536 | * or writing dirty pages. |
2537 | * |
2538 | * Display to user space in the per-cpuset read-only file |
2539 | * "memory_pressure". Value displayed is an integer |
2540 | * representing the recent rate of entry into the synchronous |
2541 | * (direct) page reclaim by any task attached to the cpuset. |
2542 | **/ |
2543 | |
2544 | void __cpuset_memory_pressure_bump(void) |
2545 | { |
2546 | task_lock(current); |
2547 | fmeter_markevent(&task_cs(current)->fmeter); |
2548 | task_unlock(current); |
2549 | } |
2550 | |
2551 | #ifdef CONFIG_PROC_PID_CPUSET |
2552 | /* |
2553 | * proc_cpuset_show() |
2554 | * - Print tasks cpuset path into seq_file. |
2555 | * - Used for /proc/<pid>/cpuset. |
2556 | * - No need to task_lock(tsk) on this tsk->cpuset reference, as it |
2557 | * doesn't really matter if tsk->cpuset changes after we read it, |
2558 | * and we take cgroup_mutex, keeping cpuset_attach() from changing it |
2559 | * anyway. |
2560 | */ |
2561 | static int proc_cpuset_show(struct seq_file *m, void *unused_v) |
2562 | { |
2563 | struct pid *pid; |
2564 | struct task_struct *tsk; |
2565 | char *buf; |
2566 | struct cgroup_subsys_state *css; |
2567 | int retval; |
2568 | |
2569 | retval = -ENOMEM; |
2570 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
2571 | if (!buf) |
2572 | goto out; |
2573 | |
2574 | retval = -ESRCH; |
2575 | pid = m->private; |
2576 | tsk = get_pid_task(pid, PIDTYPE_PID); |
2577 | if (!tsk) |
2578 | goto out_free; |
2579 | |
2580 | retval = -EINVAL; |
2581 | cgroup_lock(); |
2582 | css = task_subsys_state(tsk, cpuset_subsys_id); |
2583 | retval = cgroup_path(css->cgroup, buf, PAGE_SIZE); |
2584 | if (retval < 0) |
2585 | goto out_unlock; |
2586 | seq_puts(m, buf); |
2587 | seq_putc(m, '\n'); |
2588 | out_unlock: |
2589 | cgroup_unlock(); |
2590 | put_task_struct(tsk); |
2591 | out_free: |
2592 | kfree(buf); |
2593 | out: |
2594 | return retval; |
2595 | } |
2596 | |
2597 | static int cpuset_open(struct inode *inode, struct file *file) |
2598 | { |
2599 | struct pid *pid = PROC_I(inode)->pid; |
2600 | return single_open(file, proc_cpuset_show, pid); |
2601 | } |
2602 | |
2603 | const struct file_operations proc_cpuset_operations = { |
2604 | .open = cpuset_open, |
2605 | .read = seq_read, |
2606 | .llseek = seq_lseek, |
2607 | .release = single_release, |
2608 | }; |
2609 | #endif /* CONFIG_PROC_PID_CPUSET */ |
2610 | |
2611 | /* Display task mems_allowed in /proc/<pid>/status file. */ |
2612 | void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) |
2613 | { |
2614 | seq_printf(m, "Mems_allowed:\t"); |
2615 | seq_nodemask(m, &task->mems_allowed); |
2616 | seq_printf(m, "\n"); |
2617 | seq_printf(m, "Mems_allowed_list:\t"); |
2618 | seq_nodemask_list(m, &task->mems_allowed); |
2619 | seq_printf(m, "\n"); |
2620 | } |
2621 |
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