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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/export.h> | |
30 | #include <linux/notifier.h> | |
31 | #include <linux/memcontrol.h> | |
32 | #include <linux/mempolicy.h> | |
33 | #include <linux/security.h> | |
34 | #include <linux/ptrace.h> | |
35 | #include <linux/freezer.h> | |
36 | #include <linux/ftrace.h> | |
37 | #include <linux/ratelimit.h> | |
38 | ||
39 | #define CREATE_TRACE_POINTS | |
40 | #include <trace/events/oom.h> | |
41 | ||
42 | int sysctl_panic_on_oom; | |
43 | int sysctl_oom_kill_allocating_task; | |
44 | int sysctl_oom_dump_tasks = 1; | |
45 | ||
46 | DEFINE_MUTEX(oom_lock); | |
47 | ||
48 | #ifdef CONFIG_NUMA | |
49 | /** | |
50 | * has_intersects_mems_allowed() - check task eligiblity for kill | |
51 | * @start: task struct of which task to consider | |
52 | * @mask: nodemask passed to page allocator for mempolicy ooms | |
53 | * | |
54 | * Task eligibility is determined by whether or not a candidate task, @tsk, | |
55 | * shares the same mempolicy nodes as current if it is bound by such a policy | |
56 | * and whether or not it has the same set of allowed cpuset nodes. | |
57 | */ | |
58 | static bool has_intersects_mems_allowed(struct task_struct *start, | |
59 | const nodemask_t *mask) | |
60 | { | |
61 | struct task_struct *tsk; | |
62 | bool ret = false; | |
63 | ||
64 | rcu_read_lock(); | |
65 | for_each_thread(start, tsk) { | |
66 | if (mask) { | |
67 | /* | |
68 | * If this is a mempolicy constrained oom, tsk's | |
69 | * cpuset is irrelevant. Only return true if its | |
70 | * mempolicy intersects current, otherwise it may be | |
71 | * needlessly killed. | |
72 | */ | |
73 | ret = mempolicy_nodemask_intersects(tsk, mask); | |
74 | } else { | |
75 | /* | |
76 | * This is not a mempolicy constrained oom, so only | |
77 | * check the mems of tsk's cpuset. | |
78 | */ | |
79 | ret = cpuset_mems_allowed_intersects(current, tsk); | |
80 | } | |
81 | if (ret) | |
82 | break; | |
83 | } | |
84 | rcu_read_unlock(); | |
85 | ||
86 | return ret; | |
87 | } | |
88 | #else | |
89 | static bool has_intersects_mems_allowed(struct task_struct *tsk, | |
90 | const nodemask_t *mask) | |
91 | { | |
92 | return true; | |
93 | } | |
94 | #endif /* CONFIG_NUMA */ | |
95 | ||
96 | /* | |
97 | * The process p may have detached its own ->mm while exiting or through | |
98 | * use_mm(), but one or more of its subthreads may still have a valid | |
99 | * pointer. Return p, or any of its subthreads with a valid ->mm, with | |
100 | * task_lock() held. | |
101 | */ | |
102 | struct task_struct *find_lock_task_mm(struct task_struct *p) | |
103 | { | |
104 | struct task_struct *t; | |
105 | ||
106 | rcu_read_lock(); | |
107 | ||
108 | for_each_thread(p, t) { | |
109 | task_lock(t); | |
110 | if (likely(t->mm)) | |
111 | goto found; | |
112 | task_unlock(t); | |
113 | } | |
114 | t = NULL; | |
115 | found: | |
116 | rcu_read_unlock(); | |
117 | ||
118 | return t; | |
119 | } | |
120 | ||
121 | /* return true if the task is not adequate as candidate victim task. */ | |
122 | static bool oom_unkillable_task(struct task_struct *p, | |
123 | struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
124 | { | |
125 | if (is_global_init(p)) | |
126 | return true; | |
127 | if (p->flags & PF_KTHREAD) | |
128 | return true; | |
129 | ||
130 | /* When mem_cgroup_out_of_memory() and p is not member of the group */ | |
131 | if (memcg && !task_in_mem_cgroup(p, memcg)) | |
132 | return true; | |
133 | ||
134 | /* p may not have freeable memory in nodemask */ | |
135 | if (!has_intersects_mems_allowed(p, nodemask)) | |
136 | return true; | |
137 | ||
138 | return false; | |
139 | } | |
140 | ||
141 | /** | |
142 | * oom_badness - heuristic function to determine which candidate task to kill | |
143 | * @p: task struct of which task we should calculate | |
144 | * @totalpages: total present RAM allowed for page allocation | |
145 | * | |
146 | * The heuristic for determining which task to kill is made to be as simple and | |
147 | * predictable as possible. The goal is to return the highest value for the | |
148 | * task consuming the most memory to avoid subsequent oom failures. | |
149 | */ | |
150 | unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, | |
151 | const nodemask_t *nodemask, unsigned long totalpages) | |
152 | { | |
153 | long points; | |
154 | long adj; | |
155 | ||
156 | if (oom_unkillable_task(p, memcg, nodemask)) | |
157 | return 0; | |
158 | ||
159 | p = find_lock_task_mm(p); | |
160 | if (!p) | |
161 | return 0; | |
162 | ||
163 | adj = (long)p->signal->oom_score_adj; | |
164 | if (adj == OOM_SCORE_ADJ_MIN) { | |
165 | task_unlock(p); | |
166 | return 0; | |
167 | } | |
168 | ||
169 | /* | |
170 | * The baseline for the badness score is the proportion of RAM that each | |
171 | * task's rss, pagetable and swap space use. | |
172 | */ | |
173 | points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) + | |
174 | atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm); | |
175 | task_unlock(p); | |
176 | ||
177 | /* | |
178 | * Root processes get 3% bonus, just like the __vm_enough_memory() | |
179 | * implementation used by LSMs. | |
180 | */ | |
181 | if (has_capability_noaudit(p, CAP_SYS_ADMIN)) | |
182 | points -= (points * 3) / 100; | |
183 | ||
184 | /* Normalize to oom_score_adj units */ | |
185 | adj *= totalpages / 1000; | |
186 | points += adj; | |
187 | ||
188 | /* | |
189 | * Never return 0 for an eligible task regardless of the root bonus and | |
190 | * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here). | |
191 | */ | |
192 | return points > 0 ? points : 1; | |
193 | } | |
194 | ||
195 | /* | |
196 | * Determine the type of allocation constraint. | |
197 | */ | |
198 | #ifdef CONFIG_NUMA | |
199 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
200 | gfp_t gfp_mask, nodemask_t *nodemask, | |
201 | unsigned long *totalpages) | |
202 | { | |
203 | struct zone *zone; | |
204 | struct zoneref *z; | |
205 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); | |
206 | bool cpuset_limited = false; | |
207 | int nid; | |
208 | ||
209 | /* Default to all available memory */ | |
210 | *totalpages = totalram_pages + total_swap_pages; | |
211 | ||
212 | if (!zonelist) | |
213 | return CONSTRAINT_NONE; | |
214 | /* | |
215 | * Reach here only when __GFP_NOFAIL is used. So, we should avoid | |
216 | * to kill current.We have to random task kill in this case. | |
217 | * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. | |
218 | */ | |
219 | if (gfp_mask & __GFP_THISNODE) | |
220 | return CONSTRAINT_NONE; | |
221 | ||
222 | /* | |
223 | * This is not a __GFP_THISNODE allocation, so a truncated nodemask in | |
224 | * the page allocator means a mempolicy is in effect. Cpuset policy | |
225 | * is enforced in get_page_from_freelist(). | |
226 | */ | |
227 | if (nodemask && !nodes_subset(node_states[N_MEMORY], *nodemask)) { | |
228 | *totalpages = total_swap_pages; | |
229 | for_each_node_mask(nid, *nodemask) | |
230 | *totalpages += node_spanned_pages(nid); | |
231 | return CONSTRAINT_MEMORY_POLICY; | |
232 | } | |
233 | ||
234 | /* Check this allocation failure is caused by cpuset's wall function */ | |
235 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
236 | high_zoneidx, nodemask) | |
237 | if (!cpuset_zone_allowed(zone, gfp_mask)) | |
238 | cpuset_limited = true; | |
239 | ||
240 | if (cpuset_limited) { | |
241 | *totalpages = total_swap_pages; | |
242 | for_each_node_mask(nid, cpuset_current_mems_allowed) | |
243 | *totalpages += node_spanned_pages(nid); | |
244 | return CONSTRAINT_CPUSET; | |
245 | } | |
246 | return CONSTRAINT_NONE; | |
247 | } | |
248 | #else | |
249 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
250 | gfp_t gfp_mask, nodemask_t *nodemask, | |
251 | unsigned long *totalpages) | |
252 | { | |
253 | *totalpages = totalram_pages + total_swap_pages; | |
254 | return CONSTRAINT_NONE; | |
255 | } | |
256 | #endif | |
257 | ||
258 | enum oom_scan_t oom_scan_process_thread(struct task_struct *task, | |
259 | unsigned long totalpages, const nodemask_t *nodemask, | |
260 | bool force_kill) | |
261 | { | |
262 | if (oom_unkillable_task(task, NULL, nodemask)) | |
263 | return OOM_SCAN_CONTINUE; | |
264 | ||
265 | /* | |
266 | * This task already has access to memory reserves and is being killed. | |
267 | * Don't allow any other task to have access to the reserves. | |
268 | */ | |
269 | if (test_tsk_thread_flag(task, TIF_MEMDIE)) { | |
270 | if (!force_kill) | |
271 | return OOM_SCAN_ABORT; | |
272 | } | |
273 | if (!task->mm) | |
274 | return OOM_SCAN_CONTINUE; | |
275 | ||
276 | /* | |
277 | * If task is allocating a lot of memory and has been marked to be | |
278 | * killed first if it triggers an oom, then select it. | |
279 | */ | |
280 | if (oom_task_origin(task)) | |
281 | return OOM_SCAN_SELECT; | |
282 | ||
283 | if (task_will_free_mem(task) && !force_kill) | |
284 | return OOM_SCAN_ABORT; | |
285 | ||
286 | return OOM_SCAN_OK; | |
287 | } | |
288 | ||
289 | /* | |
290 | * Simple selection loop. We chose the process with the highest | |
291 | * number of 'points'. Returns -1 on scan abort. | |
292 | * | |
293 | * (not docbooked, we don't want this one cluttering up the manual) | |
294 | */ | |
295 | static struct task_struct *select_bad_process(unsigned int *ppoints, | |
296 | unsigned long totalpages, const nodemask_t *nodemask, | |
297 | bool force_kill) | |
298 | { | |
299 | struct task_struct *g, *p; | |
300 | struct task_struct *chosen = NULL; | |
301 | unsigned long chosen_points = 0; | |
302 | ||
303 | rcu_read_lock(); | |
304 | for_each_process_thread(g, p) { | |
305 | unsigned int points; | |
306 | ||
307 | switch (oom_scan_process_thread(p, totalpages, nodemask, | |
308 | force_kill)) { | |
309 | case OOM_SCAN_SELECT: | |
310 | chosen = p; | |
311 | chosen_points = ULONG_MAX; | |
312 | /* fall through */ | |
313 | case OOM_SCAN_CONTINUE: | |
314 | continue; | |
315 | case OOM_SCAN_ABORT: | |
316 | rcu_read_unlock(); | |
317 | return (struct task_struct *)(-1UL); | |
318 | case OOM_SCAN_OK: | |
319 | break; | |
320 | }; | |
321 | points = oom_badness(p, NULL, nodemask, totalpages); | |
322 | if (!points || points < chosen_points) | |
323 | continue; | |
324 | /* Prefer thread group leaders for display purposes */ | |
325 | if (points == chosen_points && thread_group_leader(chosen)) | |
326 | continue; | |
327 | ||
328 | chosen = p; | |
329 | chosen_points = points; | |
330 | } | |
331 | if (chosen) | |
332 | get_task_struct(chosen); | |
333 | rcu_read_unlock(); | |
334 | ||
335 | *ppoints = chosen_points * 1000 / totalpages; | |
336 | return chosen; | |
337 | } | |
338 | ||
339 | /** | |
340 | * dump_tasks - dump current memory state of all system tasks | |
341 | * @memcg: current's memory controller, if constrained | |
342 | * @nodemask: nodemask passed to page allocator for mempolicy ooms | |
343 | * | |
344 | * Dumps the current memory state of all eligible tasks. Tasks not in the same | |
345 | * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes | |
346 | * are not shown. | |
347 | * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes, | |
348 | * swapents, oom_score_adj value, and name. | |
349 | */ | |
350 | static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
351 | { | |
352 | struct task_struct *p; | |
353 | struct task_struct *task; | |
354 | ||
355 | pr_info("[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name\n"); | |
356 | rcu_read_lock(); | |
357 | for_each_process(p) { | |
358 | if (oom_unkillable_task(p, memcg, nodemask)) | |
359 | continue; | |
360 | ||
361 | task = find_lock_task_mm(p); | |
362 | if (!task) { | |
363 | /* | |
364 | * This is a kthread or all of p's threads have already | |
365 | * detached their mm's. There's no need to report | |
366 | * them; they can't be oom killed anyway. | |
367 | */ | |
368 | continue; | |
369 | } | |
370 | ||
371 | pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu %5hd %s\n", | |
372 | task->pid, from_kuid(&init_user_ns, task_uid(task)), | |
373 | task->tgid, task->mm->total_vm, get_mm_rss(task->mm), | |
374 | atomic_long_read(&task->mm->nr_ptes), | |
375 | mm_nr_pmds(task->mm), | |
376 | get_mm_counter(task->mm, MM_SWAPENTS), | |
377 | task->signal->oom_score_adj, task->comm); | |
378 | task_unlock(task); | |
379 | } | |
380 | rcu_read_unlock(); | |
381 | } | |
382 | ||
383 | static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, | |
384 | struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
385 | { | |
386 | task_lock(current); | |
387 | pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " | |
388 | "oom_score_adj=%hd\n", | |
389 | current->comm, gfp_mask, order, | |
390 | current->signal->oom_score_adj); | |
391 | cpuset_print_task_mems_allowed(current); | |
392 | task_unlock(current); | |
393 | dump_stack(); | |
394 | if (memcg) | |
395 | mem_cgroup_print_oom_info(memcg, p); | |
396 | else | |
397 | show_mem(SHOW_MEM_FILTER_NODES); | |
398 | if (sysctl_oom_dump_tasks) | |
399 | dump_tasks(memcg, nodemask); | |
400 | } | |
401 | ||
402 | /* | |
403 | * Number of OOM victims in flight | |
404 | */ | |
405 | static atomic_t oom_victims = ATOMIC_INIT(0); | |
406 | static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait); | |
407 | ||
408 | bool oom_killer_disabled __read_mostly; | |
409 | ||
410 | /** | |
411 | * mark_oom_victim - mark the given task as OOM victim | |
412 | * @tsk: task to mark | |
413 | * | |
414 | * Has to be called with oom_lock held and never after | |
415 | * oom has been disabled already. | |
416 | */ | |
417 | void mark_oom_victim(struct task_struct *tsk) | |
418 | { | |
419 | WARN_ON(oom_killer_disabled); | |
420 | /* OOM killer might race with memcg OOM */ | |
421 | if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE)) | |
422 | return; | |
423 | /* | |
424 | * Make sure that the task is woken up from uninterruptible sleep | |
425 | * if it is frozen because OOM killer wouldn't be able to free | |
426 | * any memory and livelock. freezing_slow_path will tell the freezer | |
427 | * that TIF_MEMDIE tasks should be ignored. | |
428 | */ | |
429 | __thaw_task(tsk); | |
430 | atomic_inc(&oom_victims); | |
431 | } | |
432 | ||
433 | /** | |
434 | * exit_oom_victim - note the exit of an OOM victim | |
435 | */ | |
436 | void exit_oom_victim(void) | |
437 | { | |
438 | clear_thread_flag(TIF_MEMDIE); | |
439 | ||
440 | if (!atomic_dec_return(&oom_victims)) | |
441 | wake_up_all(&oom_victims_wait); | |
442 | } | |
443 | ||
444 | /** | |
445 | * oom_killer_disable - disable OOM killer | |
446 | * | |
447 | * Forces all page allocations to fail rather than trigger OOM killer. | |
448 | * Will block and wait until all OOM victims are killed. | |
449 | * | |
450 | * The function cannot be called when there are runnable user tasks because | |
451 | * the userspace would see unexpected allocation failures as a result. Any | |
452 | * new usage of this function should be consulted with MM people. | |
453 | * | |
454 | * Returns true if successful and false if the OOM killer cannot be | |
455 | * disabled. | |
456 | */ | |
457 | bool oom_killer_disable(void) | |
458 | { | |
459 | /* | |
460 | * Make sure to not race with an ongoing OOM killer | |
461 | * and that the current is not the victim. | |
462 | */ | |
463 | mutex_lock(&oom_lock); | |
464 | if (test_thread_flag(TIF_MEMDIE)) { | |
465 | mutex_unlock(&oom_lock); | |
466 | return false; | |
467 | } | |
468 | ||
469 | oom_killer_disabled = true; | |
470 | mutex_unlock(&oom_lock); | |
471 | ||
472 | wait_event(oom_victims_wait, !atomic_read(&oom_victims)); | |
473 | ||
474 | return true; | |
475 | } | |
476 | ||
477 | /** | |
478 | * oom_killer_enable - enable OOM killer | |
479 | */ | |
480 | void oom_killer_enable(void) | |
481 | { | |
482 | oom_killer_disabled = false; | |
483 | } | |
484 | ||
485 | #define K(x) ((x) << (PAGE_SHIFT-10)) | |
486 | /* | |
487 | * Must be called while holding a reference to p, which will be released upon | |
488 | * returning. | |
489 | */ | |
490 | void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, | |
491 | unsigned int points, unsigned long totalpages, | |
492 | struct mem_cgroup *memcg, nodemask_t *nodemask, | |
493 | const char *message) | |
494 | { | |
495 | struct task_struct *victim = p; | |
496 | struct task_struct *child; | |
497 | struct task_struct *t; | |
498 | struct mm_struct *mm; | |
499 | unsigned int victim_points = 0; | |
500 | static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, | |
501 | DEFAULT_RATELIMIT_BURST); | |
502 | ||
503 | /* | |
504 | * If the task is already exiting, don't alarm the sysadmin or kill | |
505 | * its children or threads, just set TIF_MEMDIE so it can die quickly | |
506 | */ | |
507 | task_lock(p); | |
508 | if (p->mm && task_will_free_mem(p)) { | |
509 | mark_oom_victim(p); | |
510 | task_unlock(p); | |
511 | put_task_struct(p); | |
512 | return; | |
513 | } | |
514 | task_unlock(p); | |
515 | ||
516 | if (__ratelimit(&oom_rs)) | |
517 | dump_header(p, gfp_mask, order, memcg, nodemask); | |
518 | ||
519 | task_lock(p); | |
520 | pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n", | |
521 | message, task_pid_nr(p), p->comm, points); | |
522 | task_unlock(p); | |
523 | ||
524 | /* | |
525 | * If any of p's children has a different mm and is eligible for kill, | |
526 | * the one with the highest oom_badness() score is sacrificed for its | |
527 | * parent. This attempts to lose the minimal amount of work done while | |
528 | * still freeing memory. | |
529 | */ | |
530 | read_lock(&tasklist_lock); | |
531 | for_each_thread(p, t) { | |
532 | list_for_each_entry(child, &t->children, sibling) { | |
533 | unsigned int child_points; | |
534 | ||
535 | if (child->mm == p->mm) | |
536 | continue; | |
537 | /* | |
538 | * oom_badness() returns 0 if the thread is unkillable | |
539 | */ | |
540 | child_points = oom_badness(child, memcg, nodemask, | |
541 | totalpages); | |
542 | if (child_points > victim_points) { | |
543 | put_task_struct(victim); | |
544 | victim = child; | |
545 | victim_points = child_points; | |
546 | get_task_struct(victim); | |
547 | } | |
548 | } | |
549 | } | |
550 | read_unlock(&tasklist_lock); | |
551 | ||
552 | p = find_lock_task_mm(victim); | |
553 | if (!p) { | |
554 | put_task_struct(victim); | |
555 | return; | |
556 | } else if (victim != p) { | |
557 | get_task_struct(p); | |
558 | put_task_struct(victim); | |
559 | victim = p; | |
560 | } | |
561 | ||
562 | /* mm cannot safely be dereferenced after task_unlock(victim) */ | |
563 | mm = victim->mm; | |
564 | mark_oom_victim(victim); | |
565 | pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n", | |
566 | task_pid_nr(victim), victim->comm, K(victim->mm->total_vm), | |
567 | K(get_mm_counter(victim->mm, MM_ANONPAGES)), | |
568 | K(get_mm_counter(victim->mm, MM_FILEPAGES))); | |
569 | task_unlock(victim); | |
570 | ||
571 | /* | |
572 | * Kill all user processes sharing victim->mm in other thread groups, if | |
573 | * any. They don't get access to memory reserves, though, to avoid | |
574 | * depletion of all memory. This prevents mm->mmap_sem livelock when an | |
575 | * oom killed thread cannot exit because it requires the semaphore and | |
576 | * its contended by another thread trying to allocate memory itself. | |
577 | * That thread will now get access to memory reserves since it has a | |
578 | * pending fatal signal. | |
579 | */ | |
580 | rcu_read_lock(); | |
581 | for_each_process(p) | |
582 | if (p->mm == mm && !same_thread_group(p, victim) && | |
583 | !(p->flags & PF_KTHREAD)) { | |
584 | if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) | |
585 | continue; | |
586 | ||
587 | task_lock(p); /* Protect ->comm from prctl() */ | |
588 | pr_err("Kill process %d (%s) sharing same memory\n", | |
589 | task_pid_nr(p), p->comm); | |
590 | task_unlock(p); | |
591 | do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); | |
592 | } | |
593 | rcu_read_unlock(); | |
594 | ||
595 | do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); | |
596 | put_task_struct(victim); | |
597 | } | |
598 | #undef K | |
599 | ||
600 | /* | |
601 | * Determines whether the kernel must panic because of the panic_on_oom sysctl. | |
602 | */ | |
603 | void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, | |
604 | int order, const nodemask_t *nodemask, | |
605 | struct mem_cgroup *memcg) | |
606 | { | |
607 | if (likely(!sysctl_panic_on_oom)) | |
608 | return; | |
609 | if (sysctl_panic_on_oom != 2) { | |
610 | /* | |
611 | * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel | |
612 | * does not panic for cpuset, mempolicy, or memcg allocation | |
613 | * failures. | |
614 | */ | |
615 | if (constraint != CONSTRAINT_NONE) | |
616 | return; | |
617 | } | |
618 | dump_header(NULL, gfp_mask, order, memcg, nodemask); | |
619 | panic("Out of memory: %s panic_on_oom is enabled\n", | |
620 | sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); | |
621 | } | |
622 | ||
623 | static BLOCKING_NOTIFIER_HEAD(oom_notify_list); | |
624 | ||
625 | int register_oom_notifier(struct notifier_block *nb) | |
626 | { | |
627 | return blocking_notifier_chain_register(&oom_notify_list, nb); | |
628 | } | |
629 | EXPORT_SYMBOL_GPL(register_oom_notifier); | |
630 | ||
631 | int unregister_oom_notifier(struct notifier_block *nb) | |
632 | { | |
633 | return blocking_notifier_chain_unregister(&oom_notify_list, nb); | |
634 | } | |
635 | EXPORT_SYMBOL_GPL(unregister_oom_notifier); | |
636 | ||
637 | /** | |
638 | * __out_of_memory - kill the "best" process when we run out of memory | |
639 | * @zonelist: zonelist pointer | |
640 | * @gfp_mask: memory allocation flags | |
641 | * @order: amount of memory being requested as a power of 2 | |
642 | * @nodemask: nodemask passed to page allocator | |
643 | * @force_kill: true if a task must be killed, even if others are exiting | |
644 | * | |
645 | * If we run out of memory, we have the choice between either | |
646 | * killing a random task (bad), letting the system crash (worse) | |
647 | * OR try to be smart about which process to kill. Note that we | |
648 | * don't have to be perfect here, we just have to be good. | |
649 | */ | |
650 | bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, | |
651 | int order, nodemask_t *nodemask, bool force_kill) | |
652 | { | |
653 | const nodemask_t *mpol_mask; | |
654 | struct task_struct *p; | |
655 | unsigned long totalpages; | |
656 | unsigned long freed = 0; | |
657 | unsigned int uninitialized_var(points); | |
658 | enum oom_constraint constraint = CONSTRAINT_NONE; | |
659 | int killed = 0; | |
660 | ||
661 | if (oom_killer_disabled) | |
662 | return false; | |
663 | ||
664 | blocking_notifier_call_chain(&oom_notify_list, 0, &freed); | |
665 | if (freed > 0) | |
666 | /* Got some memory back in the last second. */ | |
667 | goto out; | |
668 | ||
669 | /* | |
670 | * If current has a pending SIGKILL or is exiting, then automatically | |
671 | * select it. The goal is to allow it to allocate so that it may | |
672 | * quickly exit and free its memory. | |
673 | * | |
674 | * But don't select if current has already released its mm and cleared | |
675 | * TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur. | |
676 | */ | |
677 | if (current->mm && | |
678 | (fatal_signal_pending(current) || task_will_free_mem(current))) { | |
679 | mark_oom_victim(current); | |
680 | goto out; | |
681 | } | |
682 | ||
683 | /* | |
684 | * Check if there were limitations on the allocation (only relevant for | |
685 | * NUMA) that may require different handling. | |
686 | */ | |
687 | constraint = constrained_alloc(zonelist, gfp_mask, nodemask, | |
688 | &totalpages); | |
689 | mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL; | |
690 | check_panic_on_oom(constraint, gfp_mask, order, mpol_mask, NULL); | |
691 | ||
692 | if (sysctl_oom_kill_allocating_task && current->mm && | |
693 | !oom_unkillable_task(current, NULL, nodemask) && | |
694 | current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) { | |
695 | get_task_struct(current); | |
696 | oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL, | |
697 | nodemask, | |
698 | "Out of memory (oom_kill_allocating_task)"); | |
699 | goto out; | |
700 | } | |
701 | ||
702 | p = select_bad_process(&points, totalpages, mpol_mask, force_kill); | |
703 | /* Found nothing?!?! Either we hang forever, or we panic. */ | |
704 | if (!p) { | |
705 | dump_header(NULL, gfp_mask, order, NULL, mpol_mask); | |
706 | panic("Out of memory and no killable processes...\n"); | |
707 | } | |
708 | if (p != (void *)-1UL) { | |
709 | oom_kill_process(p, gfp_mask, order, points, totalpages, NULL, | |
710 | nodemask, "Out of memory"); | |
711 | killed = 1; | |
712 | } | |
713 | out: | |
714 | /* | |
715 | * Give the killed threads a good chance of exiting before trying to | |
716 | * allocate memory again. | |
717 | */ | |
718 | if (killed) | |
719 | schedule_timeout_killable(1); | |
720 | ||
721 | return true; | |
722 | } | |
723 | ||
724 | /* | |
725 | * The pagefault handler calls here because it is out of memory, so kill a | |
726 | * memory-hogging task. If any populated zone has ZONE_OOM_LOCKED set, a | |
727 | * parallel oom killing is already in progress so do nothing. | |
728 | */ | |
729 | void pagefault_out_of_memory(void) | |
730 | { | |
731 | if (mem_cgroup_oom_synchronize(true)) | |
732 | return; | |
733 | ||
734 | if (!mutex_trylock(&oom_lock)) | |
735 | return; | |
736 | ||
737 | if (!out_of_memory(NULL, 0, 0, NULL, false)) { | |
738 | /* | |
739 | * There shouldn't be any user tasks runnable while the | |
740 | * OOM killer is disabled, so the current task has to | |
741 | * be a racing OOM victim for which oom_killer_disable() | |
742 | * is waiting for. | |
743 | */ | |
744 | WARN_ON(test_thread_flag(TIF_MEMDIE)); | |
745 | } | |
746 | ||
747 | mutex_unlock(&oom_lock); | |
748 | } |