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1 | /* | |
2 | * linux/mm/oom_kill.c | |
3 | * | |
4 | * Copyright (C) 1998,2000 Rik van Riel | |
5 | * Thanks go out to Claus Fischer for some serious inspiration and | |
6 | * for goading me into coding this file... | |
7 | * Copyright (C) 2010 Google, Inc. | |
8 | * Rewritten by David Rientjes | |
9 | * | |
10 | * The routines in this file are used to kill a process when | |
11 | * we're seriously out of memory. This gets called from __alloc_pages() | |
12 | * in mm/page_alloc.c when we really run out of memory. | |
13 | * | |
14 | * Since we won't call these routines often (on a well-configured | |
15 | * machine) this file will double as a 'coding guide' and a signpost | |
16 | * for newbie kernel hackers. It features several pointers to major | |
17 | * kernel subsystems and hints as to where to find out what things do. | |
18 | */ | |
19 | ||
20 | #include <linux/oom.h> | |
21 | #include <linux/mm.h> | |
22 | #include <linux/err.h> | |
23 | #include <linux/gfp.h> | |
24 | #include <linux/sched.h> | |
25 | #include <linux/swap.h> | |
26 | #include <linux/timex.h> | |
27 | #include <linux/jiffies.h> | |
28 | #include <linux/cpuset.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/notifier.h> | |
31 | #include <linux/memcontrol.h> | |
32 | #include <linux/mempolicy.h> | |
33 | #include <linux/security.h> | |
34 | ||
35 | int sysctl_panic_on_oom; | |
36 | int sysctl_oom_kill_allocating_task; | |
37 | int sysctl_oom_dump_tasks = 1; | |
38 | static DEFINE_SPINLOCK(zone_scan_lock); | |
39 | ||
40 | #ifdef CONFIG_NUMA | |
41 | /** | |
42 | * has_intersects_mems_allowed() - check task eligiblity for kill | |
43 | * @tsk: task struct of which task to consider | |
44 | * @mask: nodemask passed to page allocator for mempolicy ooms | |
45 | * | |
46 | * Task eligibility is determined by whether or not a candidate task, @tsk, | |
47 | * shares the same mempolicy nodes as current if it is bound by such a policy | |
48 | * and whether or not it has the same set of allowed cpuset nodes. | |
49 | */ | |
50 | static bool has_intersects_mems_allowed(struct task_struct *tsk, | |
51 | const nodemask_t *mask) | |
52 | { | |
53 | struct task_struct *start = tsk; | |
54 | ||
55 | do { | |
56 | if (mask) { | |
57 | /* | |
58 | * If this is a mempolicy constrained oom, tsk's | |
59 | * cpuset is irrelevant. Only return true if its | |
60 | * mempolicy intersects current, otherwise it may be | |
61 | * needlessly killed. | |
62 | */ | |
63 | if (mempolicy_nodemask_intersects(tsk, mask)) | |
64 | return true; | |
65 | } else { | |
66 | /* | |
67 | * This is not a mempolicy constrained oom, so only | |
68 | * check the mems of tsk's cpuset. | |
69 | */ | |
70 | if (cpuset_mems_allowed_intersects(current, tsk)) | |
71 | return true; | |
72 | } | |
73 | } while_each_thread(start, tsk); | |
74 | ||
75 | return false; | |
76 | } | |
77 | #else | |
78 | static bool has_intersects_mems_allowed(struct task_struct *tsk, | |
79 | const nodemask_t *mask) | |
80 | { | |
81 | return true; | |
82 | } | |
83 | #endif /* CONFIG_NUMA */ | |
84 | ||
85 | /* | |
86 | * If this is a system OOM (not a memcg OOM) and the task selected to be | |
87 | * killed is not already running at high (RT) priorities, speed up the | |
88 | * recovery by boosting the dying task to the lowest FIFO priority. | |
89 | * That helps with the recovery and avoids interfering with RT tasks. | |
90 | */ | |
91 | static void boost_dying_task_prio(struct task_struct *p, | |
92 | struct mem_cgroup *mem) | |
93 | { | |
94 | struct sched_param param = { .sched_priority = 1 }; | |
95 | ||
96 | if (mem) | |
97 | return; | |
98 | ||
99 | if (!rt_task(p)) | |
100 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); | |
101 | } | |
102 | ||
103 | /* | |
104 | * The process p may have detached its own ->mm while exiting or through | |
105 | * use_mm(), but one or more of its subthreads may still have a valid | |
106 | * pointer. Return p, or any of its subthreads with a valid ->mm, with | |
107 | * task_lock() held. | |
108 | */ | |
109 | struct task_struct *find_lock_task_mm(struct task_struct *p) | |
110 | { | |
111 | struct task_struct *t = p; | |
112 | ||
113 | do { | |
114 | task_lock(t); | |
115 | if (likely(t->mm)) | |
116 | return t; | |
117 | task_unlock(t); | |
118 | } while_each_thread(p, t); | |
119 | ||
120 | return NULL; | |
121 | } | |
122 | ||
123 | /* return true if the task is not adequate as candidate victim task. */ | |
124 | static bool oom_unkillable_task(struct task_struct *p, struct mem_cgroup *mem, | |
125 | const nodemask_t *nodemask) | |
126 | { | |
127 | if (is_global_init(p)) | |
128 | return true; | |
129 | if (p->flags & PF_KTHREAD) | |
130 | return true; | |
131 | ||
132 | /* When mem_cgroup_out_of_memory() and p is not member of the group */ | |
133 | if (mem && !task_in_mem_cgroup(p, mem)) | |
134 | return true; | |
135 | ||
136 | /* p may not have freeable memory in nodemask */ | |
137 | if (!has_intersects_mems_allowed(p, nodemask)) | |
138 | return true; | |
139 | ||
140 | return false; | |
141 | } | |
142 | ||
143 | /** | |
144 | * oom_badness - heuristic function to determine which candidate task to kill | |
145 | * @p: task struct of which task we should calculate | |
146 | * @totalpages: total present RAM allowed for page allocation | |
147 | * | |
148 | * The heuristic for determining which task to kill is made to be as simple and | |
149 | * predictable as possible. The goal is to return the highest value for the | |
150 | * task consuming the most memory to avoid subsequent oom failures. | |
151 | */ | |
152 | unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, | |
153 | const nodemask_t *nodemask, unsigned long totalpages) | |
154 | { | |
155 | int points; | |
156 | ||
157 | if (oom_unkillable_task(p, mem, nodemask)) | |
158 | return 0; | |
159 | ||
160 | p = find_lock_task_mm(p); | |
161 | if (!p) | |
162 | return 0; | |
163 | ||
164 | /* | |
165 | * Shortcut check for OOM_SCORE_ADJ_MIN so the entire heuristic doesn't | |
166 | * need to be executed for something that cannot be killed. | |
167 | */ | |
168 | if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { | |
169 | task_unlock(p); | |
170 | return 0; | |
171 | } | |
172 | ||
173 | /* | |
174 | * When the PF_OOM_ORIGIN bit is set, it indicates the task should have | |
175 | * priority for oom killing. | |
176 | */ | |
177 | if (p->flags & PF_OOM_ORIGIN) { | |
178 | task_unlock(p); | |
179 | return 1000; | |
180 | } | |
181 | ||
182 | /* | |
183 | * The memory controller may have a limit of 0 bytes, so avoid a divide | |
184 | * by zero, if necessary. | |
185 | */ | |
186 | if (!totalpages) | |
187 | totalpages = 1; | |
188 | ||
189 | /* | |
190 | * The baseline for the badness score is the proportion of RAM that each | |
191 | * task's rss and swap space use. | |
192 | */ | |
193 | points = (get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS)) * 1000 / | |
194 | totalpages; | |
195 | task_unlock(p); | |
196 | ||
197 | /* | |
198 | * Root processes get 3% bonus, just like the __vm_enough_memory() | |
199 | * implementation used by LSMs. | |
200 | */ | |
201 | if (has_capability_noaudit(p, CAP_SYS_ADMIN)) | |
202 | points -= 30; | |
203 | ||
204 | /* | |
205 | * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may | |
206 | * either completely disable oom killing or always prefer a certain | |
207 | * task. | |
208 | */ | |
209 | points += p->signal->oom_score_adj; | |
210 | ||
211 | if (points < 0) | |
212 | return 0; | |
213 | return (points < 1000) ? points : 1000; | |
214 | } | |
215 | ||
216 | /* | |
217 | * Determine the type of allocation constraint. | |
218 | */ | |
219 | #ifdef CONFIG_NUMA | |
220 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
221 | gfp_t gfp_mask, nodemask_t *nodemask, | |
222 | unsigned long *totalpages) | |
223 | { | |
224 | struct zone *zone; | |
225 | struct zoneref *z; | |
226 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); | |
227 | bool cpuset_limited = false; | |
228 | int nid; | |
229 | ||
230 | /* Default to all available memory */ | |
231 | *totalpages = totalram_pages + total_swap_pages; | |
232 | ||
233 | if (!zonelist) | |
234 | return CONSTRAINT_NONE; | |
235 | /* | |
236 | * Reach here only when __GFP_NOFAIL is used. So, we should avoid | |
237 | * to kill current.We have to random task kill in this case. | |
238 | * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. | |
239 | */ | |
240 | if (gfp_mask & __GFP_THISNODE) | |
241 | return CONSTRAINT_NONE; | |
242 | ||
243 | /* | |
244 | * This is not a __GFP_THISNODE allocation, so a truncated nodemask in | |
245 | * the page allocator means a mempolicy is in effect. Cpuset policy | |
246 | * is enforced in get_page_from_freelist(). | |
247 | */ | |
248 | if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask)) { | |
249 | *totalpages = total_swap_pages; | |
250 | for_each_node_mask(nid, *nodemask) | |
251 | *totalpages += node_spanned_pages(nid); | |
252 | return CONSTRAINT_MEMORY_POLICY; | |
253 | } | |
254 | ||
255 | /* Check this allocation failure is caused by cpuset's wall function */ | |
256 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
257 | high_zoneidx, nodemask) | |
258 | if (!cpuset_zone_allowed_softwall(zone, gfp_mask)) | |
259 | cpuset_limited = true; | |
260 | ||
261 | if (cpuset_limited) { | |
262 | *totalpages = total_swap_pages; | |
263 | for_each_node_mask(nid, cpuset_current_mems_allowed) | |
264 | *totalpages += node_spanned_pages(nid); | |
265 | return CONSTRAINT_CPUSET; | |
266 | } | |
267 | return CONSTRAINT_NONE; | |
268 | } | |
269 | #else | |
270 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
271 | gfp_t gfp_mask, nodemask_t *nodemask, | |
272 | unsigned long *totalpages) | |
273 | { | |
274 | *totalpages = totalram_pages + total_swap_pages; | |
275 | return CONSTRAINT_NONE; | |
276 | } | |
277 | #endif | |
278 | ||
279 | /* | |
280 | * Simple selection loop. We chose the process with the highest | |
281 | * number of 'points'. We expect the caller will lock the tasklist. | |
282 | * | |
283 | * (not docbooked, we don't want this one cluttering up the manual) | |
284 | */ | |
285 | static struct task_struct *select_bad_process(unsigned int *ppoints, | |
286 | unsigned long totalpages, struct mem_cgroup *mem, | |
287 | const nodemask_t *nodemask) | |
288 | { | |
289 | struct task_struct *p; | |
290 | struct task_struct *chosen = NULL; | |
291 | *ppoints = 0; | |
292 | ||
293 | for_each_process(p) { | |
294 | unsigned int points; | |
295 | ||
296 | if (oom_unkillable_task(p, mem, nodemask)) | |
297 | continue; | |
298 | ||
299 | /* | |
300 | * This task already has access to memory reserves and is | |
301 | * being killed. Don't allow any other task access to the | |
302 | * memory reserve. | |
303 | * | |
304 | * Note: this may have a chance of deadlock if it gets | |
305 | * blocked waiting for another task which itself is waiting | |
306 | * for memory. Is there a better alternative? | |
307 | */ | |
308 | if (test_tsk_thread_flag(p, TIF_MEMDIE)) | |
309 | return ERR_PTR(-1UL); | |
310 | ||
311 | /* | |
312 | * This is in the process of releasing memory so wait for it | |
313 | * to finish before killing some other task by mistake. | |
314 | * | |
315 | * However, if p is the current task, we allow the 'kill' to | |
316 | * go ahead if it is exiting: this will simply set TIF_MEMDIE, | |
317 | * which will allow it to gain access to memory reserves in | |
318 | * the process of exiting and releasing its resources. | |
319 | * Otherwise we could get an easy OOM deadlock. | |
320 | */ | |
321 | if (thread_group_empty(p) && (p->flags & PF_EXITING) && p->mm) { | |
322 | if (p != current) | |
323 | return ERR_PTR(-1UL); | |
324 | ||
325 | chosen = p; | |
326 | *ppoints = 1000; | |
327 | } | |
328 | ||
329 | points = oom_badness(p, mem, nodemask, totalpages); | |
330 | if (points > *ppoints) { | |
331 | chosen = p; | |
332 | *ppoints = points; | |
333 | } | |
334 | } | |
335 | ||
336 | return chosen; | |
337 | } | |
338 | ||
339 | /** | |
340 | * dump_tasks - dump current memory state of all system tasks | |
341 | * @mem: current's memory controller, if constrained | |
342 | * | |
343 | * Dumps the current memory state of all system tasks, excluding kernel threads. | |
344 | * State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj | |
345 | * value, oom_score_adj value, and name. | |
346 | * | |
347 | * If the actual is non-NULL, only tasks that are a member of the mem_cgroup are | |
348 | * shown. | |
349 | * | |
350 | * Call with tasklist_lock read-locked. | |
351 | */ | |
352 | static void dump_tasks(const struct mem_cgroup *mem) | |
353 | { | |
354 | struct task_struct *p; | |
355 | struct task_struct *task; | |
356 | ||
357 | pr_info("[ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name\n"); | |
358 | for_each_process(p) { | |
359 | if (p->flags & PF_KTHREAD) | |
360 | continue; | |
361 | if (mem && !task_in_mem_cgroup(p, mem)) | |
362 | continue; | |
363 | ||
364 | task = find_lock_task_mm(p); | |
365 | if (!task) { | |
366 | /* | |
367 | * This is a kthread or all of p's threads have already | |
368 | * detached their mm's. There's no need to report | |
369 | * them; they can't be oom killed anyway. | |
370 | */ | |
371 | continue; | |
372 | } | |
373 | ||
374 | pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n", | |
375 | task->pid, task_uid(task), task->tgid, | |
376 | task->mm->total_vm, get_mm_rss(task->mm), | |
377 | task_cpu(task), task->signal->oom_adj, | |
378 | task->signal->oom_score_adj, task->comm); | |
379 | task_unlock(task); | |
380 | } | |
381 | } | |
382 | ||
383 | static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, | |
384 | struct mem_cgroup *mem) | |
385 | { | |
386 | task_lock(current); | |
387 | pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " | |
388 | "oom_adj=%d, oom_score_adj=%d\n", | |
389 | current->comm, gfp_mask, order, current->signal->oom_adj, | |
390 | current->signal->oom_score_adj); | |
391 | cpuset_print_task_mems_allowed(current); | |
392 | task_unlock(current); | |
393 | dump_stack(); | |
394 | mem_cgroup_print_oom_info(mem, p); | |
395 | show_mem(); | |
396 | if (sysctl_oom_dump_tasks) | |
397 | dump_tasks(mem); | |
398 | } | |
399 | ||
400 | #define K(x) ((x) << (PAGE_SHIFT-10)) | |
401 | static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem) | |
402 | { | |
403 | p = find_lock_task_mm(p); | |
404 | if (!p) | |
405 | return 1; | |
406 | ||
407 | pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n", | |
408 | task_pid_nr(p), p->comm, K(p->mm->total_vm), | |
409 | K(get_mm_counter(p->mm, MM_ANONPAGES)), | |
410 | K(get_mm_counter(p->mm, MM_FILEPAGES))); | |
411 | task_unlock(p); | |
412 | ||
413 | ||
414 | set_tsk_thread_flag(p, TIF_MEMDIE); | |
415 | force_sig(SIGKILL, p); | |
416 | ||
417 | /* | |
418 | * We give our sacrificial lamb high priority and access to | |
419 | * all the memory it needs. That way it should be able to | |
420 | * exit() and clear out its resources quickly... | |
421 | */ | |
422 | boost_dying_task_prio(p, mem); | |
423 | ||
424 | return 0; | |
425 | } | |
426 | #undef K | |
427 | ||
428 | static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, | |
429 | unsigned int points, unsigned long totalpages, | |
430 | struct mem_cgroup *mem, nodemask_t *nodemask, | |
431 | const char *message) | |
432 | { | |
433 | struct task_struct *victim = p; | |
434 | struct task_struct *child; | |
435 | struct task_struct *t = p; | |
436 | unsigned int victim_points = 0; | |
437 | ||
438 | if (printk_ratelimit()) | |
439 | dump_header(p, gfp_mask, order, mem); | |
440 | ||
441 | /* | |
442 | * If the task is already exiting, don't alarm the sysadmin or kill | |
443 | * its children or threads, just set TIF_MEMDIE so it can die quickly | |
444 | */ | |
445 | if (p->flags & PF_EXITING) { | |
446 | set_tsk_thread_flag(p, TIF_MEMDIE); | |
447 | boost_dying_task_prio(p, mem); | |
448 | return 0; | |
449 | } | |
450 | ||
451 | task_lock(p); | |
452 | pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n", | |
453 | message, task_pid_nr(p), p->comm, points); | |
454 | task_unlock(p); | |
455 | ||
456 | /* | |
457 | * If any of p's children has a different mm and is eligible for kill, | |
458 | * the one with the highest badness() score is sacrificed for its | |
459 | * parent. This attempts to lose the minimal amount of work done while | |
460 | * still freeing memory. | |
461 | */ | |
462 | do { | |
463 | list_for_each_entry(child, &t->children, sibling) { | |
464 | unsigned int child_points; | |
465 | ||
466 | /* | |
467 | * oom_badness() returns 0 if the thread is unkillable | |
468 | */ | |
469 | child_points = oom_badness(child, mem, nodemask, | |
470 | totalpages); | |
471 | if (child_points > victim_points) { | |
472 | victim = child; | |
473 | victim_points = child_points; | |
474 | } | |
475 | } | |
476 | } while_each_thread(p, t); | |
477 | ||
478 | return oom_kill_task(victim, mem); | |
479 | } | |
480 | ||
481 | /* | |
482 | * Determines whether the kernel must panic because of the panic_on_oom sysctl. | |
483 | */ | |
484 | static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, | |
485 | int order) | |
486 | { | |
487 | if (likely(!sysctl_panic_on_oom)) | |
488 | return; | |
489 | if (sysctl_panic_on_oom != 2) { | |
490 | /* | |
491 | * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel | |
492 | * does not panic for cpuset, mempolicy, or memcg allocation | |
493 | * failures. | |
494 | */ | |
495 | if (constraint != CONSTRAINT_NONE) | |
496 | return; | |
497 | } | |
498 | read_lock(&tasklist_lock); | |
499 | dump_header(NULL, gfp_mask, order, NULL); | |
500 | read_unlock(&tasklist_lock); | |
501 | panic("Out of memory: %s panic_on_oom is enabled\n", | |
502 | sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); | |
503 | } | |
504 | ||
505 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR | |
506 | void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask) | |
507 | { | |
508 | unsigned long limit; | |
509 | unsigned int points = 0; | |
510 | struct task_struct *p; | |
511 | ||
512 | check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0); | |
513 | limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT; | |
514 | read_lock(&tasklist_lock); | |
515 | retry: | |
516 | p = select_bad_process(&points, limit, mem, NULL); | |
517 | if (!p || PTR_ERR(p) == -1UL) | |
518 | goto out; | |
519 | ||
520 | if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, NULL, | |
521 | "Memory cgroup out of memory")) | |
522 | goto retry; | |
523 | out: | |
524 | read_unlock(&tasklist_lock); | |
525 | } | |
526 | #endif | |
527 | ||
528 | static BLOCKING_NOTIFIER_HEAD(oom_notify_list); | |
529 | ||
530 | int register_oom_notifier(struct notifier_block *nb) | |
531 | { | |
532 | return blocking_notifier_chain_register(&oom_notify_list, nb); | |
533 | } | |
534 | EXPORT_SYMBOL_GPL(register_oom_notifier); | |
535 | ||
536 | int unregister_oom_notifier(struct notifier_block *nb) | |
537 | { | |
538 | return blocking_notifier_chain_unregister(&oom_notify_list, nb); | |
539 | } | |
540 | EXPORT_SYMBOL_GPL(unregister_oom_notifier); | |
541 | ||
542 | /* | |
543 | * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero | |
544 | * if a parallel OOM killing is already taking place that includes a zone in | |
545 | * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. | |
546 | */ | |
547 | int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) | |
548 | { | |
549 | struct zoneref *z; | |
550 | struct zone *zone; | |
551 | int ret = 1; | |
552 | ||
553 | spin_lock(&zone_scan_lock); | |
554 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
555 | if (zone_is_oom_locked(zone)) { | |
556 | ret = 0; | |
557 | goto out; | |
558 | } | |
559 | } | |
560 | ||
561 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
562 | /* | |
563 | * Lock each zone in the zonelist under zone_scan_lock so a | |
564 | * parallel invocation of try_set_zonelist_oom() doesn't succeed | |
565 | * when it shouldn't. | |
566 | */ | |
567 | zone_set_flag(zone, ZONE_OOM_LOCKED); | |
568 | } | |
569 | ||
570 | out: | |
571 | spin_unlock(&zone_scan_lock); | |
572 | return ret; | |
573 | } | |
574 | ||
575 | /* | |
576 | * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed | |
577 | * allocation attempts with zonelists containing them may now recall the OOM | |
578 | * killer, if necessary. | |
579 | */ | |
580 | void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) | |
581 | { | |
582 | struct zoneref *z; | |
583 | struct zone *zone; | |
584 | ||
585 | spin_lock(&zone_scan_lock); | |
586 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
587 | zone_clear_flag(zone, ZONE_OOM_LOCKED); | |
588 | } | |
589 | spin_unlock(&zone_scan_lock); | |
590 | } | |
591 | ||
592 | /* | |
593 | * Try to acquire the oom killer lock for all system zones. Returns zero if a | |
594 | * parallel oom killing is taking place, otherwise locks all zones and returns | |
595 | * non-zero. | |
596 | */ | |
597 | static int try_set_system_oom(void) | |
598 | { | |
599 | struct zone *zone; | |
600 | int ret = 1; | |
601 | ||
602 | spin_lock(&zone_scan_lock); | |
603 | for_each_populated_zone(zone) | |
604 | if (zone_is_oom_locked(zone)) { | |
605 | ret = 0; | |
606 | goto out; | |
607 | } | |
608 | for_each_populated_zone(zone) | |
609 | zone_set_flag(zone, ZONE_OOM_LOCKED); | |
610 | out: | |
611 | spin_unlock(&zone_scan_lock); | |
612 | return ret; | |
613 | } | |
614 | ||
615 | /* | |
616 | * Clears ZONE_OOM_LOCKED for all system zones so that failed allocation | |
617 | * attempts or page faults may now recall the oom killer, if necessary. | |
618 | */ | |
619 | static void clear_system_oom(void) | |
620 | { | |
621 | struct zone *zone; | |
622 | ||
623 | spin_lock(&zone_scan_lock); | |
624 | for_each_populated_zone(zone) | |
625 | zone_clear_flag(zone, ZONE_OOM_LOCKED); | |
626 | spin_unlock(&zone_scan_lock); | |
627 | } | |
628 | ||
629 | /** | |
630 | * out_of_memory - kill the "best" process when we run out of memory | |
631 | * @zonelist: zonelist pointer | |
632 | * @gfp_mask: memory allocation flags | |
633 | * @order: amount of memory being requested as a power of 2 | |
634 | * @nodemask: nodemask passed to page allocator | |
635 | * | |
636 | * If we run out of memory, we have the choice between either | |
637 | * killing a random task (bad), letting the system crash (worse) | |
638 | * OR try to be smart about which process to kill. Note that we | |
639 | * don't have to be perfect here, we just have to be good. | |
640 | */ | |
641 | void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, | |
642 | int order, nodemask_t *nodemask) | |
643 | { | |
644 | struct task_struct *p; | |
645 | unsigned long totalpages; | |
646 | unsigned long freed = 0; | |
647 | unsigned int points; | |
648 | enum oom_constraint constraint = CONSTRAINT_NONE; | |
649 | int killed = 0; | |
650 | ||
651 | blocking_notifier_call_chain(&oom_notify_list, 0, &freed); | |
652 | if (freed > 0) | |
653 | /* Got some memory back in the last second. */ | |
654 | return; | |
655 | ||
656 | /* | |
657 | * If current has a pending SIGKILL, then automatically select it. The | |
658 | * goal is to allow it to allocate so that it may quickly exit and free | |
659 | * its memory. | |
660 | */ | |
661 | if (fatal_signal_pending(current)) { | |
662 | set_thread_flag(TIF_MEMDIE); | |
663 | boost_dying_task_prio(current, NULL); | |
664 | return; | |
665 | } | |
666 | ||
667 | /* | |
668 | * Check if there were limitations on the allocation (only relevant for | |
669 | * NUMA) that may require different handling. | |
670 | */ | |
671 | constraint = constrained_alloc(zonelist, gfp_mask, nodemask, | |
672 | &totalpages); | |
673 | check_panic_on_oom(constraint, gfp_mask, order); | |
674 | ||
675 | read_lock(&tasklist_lock); | |
676 | if (sysctl_oom_kill_allocating_task && | |
677 | !oom_unkillable_task(current, NULL, nodemask) && | |
678 | (current->signal->oom_adj != OOM_DISABLE)) { | |
679 | /* | |
680 | * oom_kill_process() needs tasklist_lock held. If it returns | |
681 | * non-zero, current could not be killed so we must fallback to | |
682 | * the tasklist scan. | |
683 | */ | |
684 | if (!oom_kill_process(current, gfp_mask, order, 0, totalpages, | |
685 | NULL, nodemask, | |
686 | "Out of memory (oom_kill_allocating_task)")) | |
687 | goto out; | |
688 | } | |
689 | ||
690 | retry: | |
691 | p = select_bad_process(&points, totalpages, NULL, | |
692 | constraint == CONSTRAINT_MEMORY_POLICY ? nodemask : | |
693 | NULL); | |
694 | if (PTR_ERR(p) == -1UL) | |
695 | goto out; | |
696 | ||
697 | /* Found nothing?!?! Either we hang forever, or we panic. */ | |
698 | if (!p) { | |
699 | dump_header(NULL, gfp_mask, order, NULL); | |
700 | read_unlock(&tasklist_lock); | |
701 | panic("Out of memory and no killable processes...\n"); | |
702 | } | |
703 | ||
704 | if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL, | |
705 | nodemask, "Out of memory")) | |
706 | goto retry; | |
707 | killed = 1; | |
708 | out: | |
709 | read_unlock(&tasklist_lock); | |
710 | ||
711 | /* | |
712 | * Give "p" a good chance of killing itself before we | |
713 | * retry to allocate memory unless "p" is current | |
714 | */ | |
715 | if (killed && !test_thread_flag(TIF_MEMDIE)) | |
716 | schedule_timeout_uninterruptible(1); | |
717 | } | |
718 | ||
719 | /* | |
720 | * The pagefault handler calls here because it is out of memory, so kill a | |
721 | * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel | |
722 | * oom killing is already in progress so do nothing. If a task is found with | |
723 | * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit. | |
724 | */ | |
725 | void pagefault_out_of_memory(void) | |
726 | { | |
727 | if (try_set_system_oom()) { | |
728 | out_of_memory(NULL, 0, 0, NULL); | |
729 | clear_system_oom(); | |
730 | } | |
731 | if (!test_thread_flag(TIF_MEMDIE)) | |
732 | schedule_timeout_uninterruptible(1); | |
733 | } |