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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 | ||
38 | #define CREATE_TRACE_POINTS | |
39 | #include <trace/events/oom.h> | |
40 | ||
41 | int sysctl_panic_on_oom; | |
42 | int sysctl_oom_kill_allocating_task; | |
43 | int sysctl_oom_dump_tasks = 1; | |
44 | static DEFINE_SPINLOCK(zone_scan_lock); | |
45 | ||
46 | /* | |
47 | * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj | |
48 | * @old_val: old oom_score_adj for compare | |
49 | * @new_val: new oom_score_adj for swap | |
50 | * | |
51 | * Sets the oom_score_adj value for current to @new_val iff its present value is | |
52 | * @old_val. Usually used to reinstate a previous value to prevent racing with | |
53 | * userspacing tuning the value in the interim. | |
54 | */ | |
55 | void compare_swap_oom_score_adj(int old_val, int new_val) | |
56 | { | |
57 | struct sighand_struct *sighand = current->sighand; | |
58 | ||
59 | spin_lock_irq(&sighand->siglock); | |
60 | if (current->signal->oom_score_adj == old_val) | |
61 | current->signal->oom_score_adj = new_val; | |
62 | trace_oom_score_adj_update(current); | |
63 | spin_unlock_irq(&sighand->siglock); | |
64 | } | |
65 | ||
66 | /** | |
67 | * test_set_oom_score_adj() - set current's oom_score_adj and return old value | |
68 | * @new_val: new oom_score_adj value | |
69 | * | |
70 | * Sets the oom_score_adj value for current to @new_val with proper | |
71 | * synchronization and returns the old value. Usually used to temporarily | |
72 | * set a value, save the old value in the caller, and then reinstate it later. | |
73 | */ | |
74 | int test_set_oom_score_adj(int new_val) | |
75 | { | |
76 | struct sighand_struct *sighand = current->sighand; | |
77 | int old_val; | |
78 | ||
79 | spin_lock_irq(&sighand->siglock); | |
80 | old_val = current->signal->oom_score_adj; | |
81 | current->signal->oom_score_adj = new_val; | |
82 | trace_oom_score_adj_update(current); | |
83 | spin_unlock_irq(&sighand->siglock); | |
84 | ||
85 | return old_val; | |
86 | } | |
87 | ||
88 | #ifdef CONFIG_NUMA | |
89 | /** | |
90 | * has_intersects_mems_allowed() - check task eligiblity for kill | |
91 | * @tsk: task struct of which task to consider | |
92 | * @mask: nodemask passed to page allocator for mempolicy ooms | |
93 | * | |
94 | * Task eligibility is determined by whether or not a candidate task, @tsk, | |
95 | * shares the same mempolicy nodes as current if it is bound by such a policy | |
96 | * and whether or not it has the same set of allowed cpuset nodes. | |
97 | */ | |
98 | static bool has_intersects_mems_allowed(struct task_struct *tsk, | |
99 | const nodemask_t *mask) | |
100 | { | |
101 | struct task_struct *start = tsk; | |
102 | ||
103 | do { | |
104 | if (mask) { | |
105 | /* | |
106 | * If this is a mempolicy constrained oom, tsk's | |
107 | * cpuset is irrelevant. Only return true if its | |
108 | * mempolicy intersects current, otherwise it may be | |
109 | * needlessly killed. | |
110 | */ | |
111 | if (mempolicy_nodemask_intersects(tsk, mask)) | |
112 | return true; | |
113 | } else { | |
114 | /* | |
115 | * This is not a mempolicy constrained oom, so only | |
116 | * check the mems of tsk's cpuset. | |
117 | */ | |
118 | if (cpuset_mems_allowed_intersects(current, tsk)) | |
119 | return true; | |
120 | } | |
121 | } while_each_thread(start, tsk); | |
122 | ||
123 | return false; | |
124 | } | |
125 | #else | |
126 | static bool has_intersects_mems_allowed(struct task_struct *tsk, | |
127 | const nodemask_t *mask) | |
128 | { | |
129 | return true; | |
130 | } | |
131 | #endif /* CONFIG_NUMA */ | |
132 | ||
133 | /* | |
134 | * The process p may have detached its own ->mm while exiting or through | |
135 | * use_mm(), but one or more of its subthreads may still have a valid | |
136 | * pointer. Return p, or any of its subthreads with a valid ->mm, with | |
137 | * task_lock() held. | |
138 | */ | |
139 | struct task_struct *find_lock_task_mm(struct task_struct *p) | |
140 | { | |
141 | struct task_struct *t = p; | |
142 | ||
143 | do { | |
144 | task_lock(t); | |
145 | if (likely(t->mm)) | |
146 | return t; | |
147 | task_unlock(t); | |
148 | } while_each_thread(p, t); | |
149 | ||
150 | return NULL; | |
151 | } | |
152 | ||
153 | /* return true if the task is not adequate as candidate victim task. */ | |
154 | static bool oom_unkillable_task(struct task_struct *p, | |
155 | const struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
156 | { | |
157 | if (is_global_init(p)) | |
158 | return true; | |
159 | if (p->flags & PF_KTHREAD) | |
160 | return true; | |
161 | ||
162 | /* When mem_cgroup_out_of_memory() and p is not member of the group */ | |
163 | if (memcg && !task_in_mem_cgroup(p, memcg)) | |
164 | return true; | |
165 | ||
166 | /* p may not have freeable memory in nodemask */ | |
167 | if (!has_intersects_mems_allowed(p, nodemask)) | |
168 | return true; | |
169 | ||
170 | return false; | |
171 | } | |
172 | ||
173 | /** | |
174 | * oom_badness - heuristic function to determine which candidate task to kill | |
175 | * @p: task struct of which task we should calculate | |
176 | * @totalpages: total present RAM allowed for page allocation | |
177 | * | |
178 | * The heuristic for determining which task to kill is made to be as simple and | |
179 | * predictable as possible. The goal is to return the highest value for the | |
180 | * task consuming the most memory to avoid subsequent oom failures. | |
181 | */ | |
182 | unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg, | |
183 | const nodemask_t *nodemask, unsigned long totalpages) | |
184 | { | |
185 | long points; | |
186 | ||
187 | if (oom_unkillable_task(p, memcg, nodemask)) | |
188 | return 0; | |
189 | ||
190 | p = find_lock_task_mm(p); | |
191 | if (!p) | |
192 | return 0; | |
193 | ||
194 | if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { | |
195 | task_unlock(p); | |
196 | return 0; | |
197 | } | |
198 | ||
199 | /* | |
200 | * The memory controller may have a limit of 0 bytes, so avoid a divide | |
201 | * by zero, if necessary. | |
202 | */ | |
203 | if (!totalpages) | |
204 | totalpages = 1; | |
205 | ||
206 | /* | |
207 | * The baseline for the badness score is the proportion of RAM that each | |
208 | * task's rss, pagetable and swap space use. | |
209 | */ | |
210 | points = get_mm_rss(p->mm) + p->mm->nr_ptes; | |
211 | points += get_mm_counter(p->mm, MM_SWAPENTS); | |
212 | ||
213 | points *= 1000; | |
214 | points /= totalpages; | |
215 | task_unlock(p); | |
216 | ||
217 | /* | |
218 | * Root processes get 3% bonus, just like the __vm_enough_memory() | |
219 | * implementation used by LSMs. | |
220 | */ | |
221 | if (has_capability_noaudit(p, CAP_SYS_ADMIN)) | |
222 | points -= 30; | |
223 | ||
224 | /* | |
225 | * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may | |
226 | * either completely disable oom killing or always prefer a certain | |
227 | * task. | |
228 | */ | |
229 | points += p->signal->oom_score_adj; | |
230 | ||
231 | /* | |
232 | * Never return 0 for an eligible task that may be killed since it's | |
233 | * possible that no single user task uses more than 0.1% of memory and | |
234 | * no single admin tasks uses more than 3.0%. | |
235 | */ | |
236 | if (points <= 0) | |
237 | return 1; | |
238 | return (points < 1000) ? points : 1000; | |
239 | } | |
240 | ||
241 | /* | |
242 | * Determine the type of allocation constraint. | |
243 | */ | |
244 | #ifdef CONFIG_NUMA | |
245 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
246 | gfp_t gfp_mask, nodemask_t *nodemask, | |
247 | unsigned long *totalpages) | |
248 | { | |
249 | struct zone *zone; | |
250 | struct zoneref *z; | |
251 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); | |
252 | bool cpuset_limited = false; | |
253 | int nid; | |
254 | ||
255 | /* Default to all available memory */ | |
256 | *totalpages = totalram_pages + total_swap_pages; | |
257 | ||
258 | if (!zonelist) | |
259 | return CONSTRAINT_NONE; | |
260 | /* | |
261 | * Reach here only when __GFP_NOFAIL is used. So, we should avoid | |
262 | * to kill current.We have to random task kill in this case. | |
263 | * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. | |
264 | */ | |
265 | if (gfp_mask & __GFP_THISNODE) | |
266 | return CONSTRAINT_NONE; | |
267 | ||
268 | /* | |
269 | * This is not a __GFP_THISNODE allocation, so a truncated nodemask in | |
270 | * the page allocator means a mempolicy is in effect. Cpuset policy | |
271 | * is enforced in get_page_from_freelist(). | |
272 | */ | |
273 | if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask)) { | |
274 | *totalpages = total_swap_pages; | |
275 | for_each_node_mask(nid, *nodemask) | |
276 | *totalpages += node_spanned_pages(nid); | |
277 | return CONSTRAINT_MEMORY_POLICY; | |
278 | } | |
279 | ||
280 | /* Check this allocation failure is caused by cpuset's wall function */ | |
281 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
282 | high_zoneidx, nodemask) | |
283 | if (!cpuset_zone_allowed_softwall(zone, gfp_mask)) | |
284 | cpuset_limited = true; | |
285 | ||
286 | if (cpuset_limited) { | |
287 | *totalpages = total_swap_pages; | |
288 | for_each_node_mask(nid, cpuset_current_mems_allowed) | |
289 | *totalpages += node_spanned_pages(nid); | |
290 | return CONSTRAINT_CPUSET; | |
291 | } | |
292 | return CONSTRAINT_NONE; | |
293 | } | |
294 | #else | |
295 | static enum oom_constraint constrained_alloc(struct zonelist *zonelist, | |
296 | gfp_t gfp_mask, nodemask_t *nodemask, | |
297 | unsigned long *totalpages) | |
298 | { | |
299 | *totalpages = totalram_pages + total_swap_pages; | |
300 | return CONSTRAINT_NONE; | |
301 | } | |
302 | #endif | |
303 | ||
304 | /* | |
305 | * Simple selection loop. We chose the process with the highest | |
306 | * number of 'points'. We expect the caller will lock the tasklist. | |
307 | * | |
308 | * (not docbooked, we don't want this one cluttering up the manual) | |
309 | */ | |
310 | static struct task_struct *select_bad_process(unsigned int *ppoints, | |
311 | unsigned long totalpages, struct mem_cgroup *memcg, | |
312 | const nodemask_t *nodemask) | |
313 | { | |
314 | struct task_struct *g, *p; | |
315 | struct task_struct *chosen = NULL; | |
316 | *ppoints = 0; | |
317 | ||
318 | do_each_thread(g, p) { | |
319 | unsigned int points; | |
320 | ||
321 | if (p->exit_state) | |
322 | continue; | |
323 | if (oom_unkillable_task(p, memcg, nodemask)) | |
324 | continue; | |
325 | ||
326 | /* | |
327 | * This task already has access to memory reserves and is | |
328 | * being killed. Don't allow any other task access to the | |
329 | * memory reserve. | |
330 | * | |
331 | * Note: this may have a chance of deadlock if it gets | |
332 | * blocked waiting for another task which itself is waiting | |
333 | * for memory. Is there a better alternative? | |
334 | */ | |
335 | if (test_tsk_thread_flag(p, TIF_MEMDIE)) { | |
336 | if (unlikely(frozen(p))) | |
337 | __thaw_task(p); | |
338 | return ERR_PTR(-1UL); | |
339 | } | |
340 | if (!p->mm) | |
341 | continue; | |
342 | ||
343 | if (p->flags & PF_EXITING) { | |
344 | /* | |
345 | * If p is the current task and is in the process of | |
346 | * releasing memory, we allow the "kill" to set | |
347 | * TIF_MEMDIE, which will allow it to gain access to | |
348 | * memory reserves. Otherwise, it may stall forever. | |
349 | * | |
350 | * The loop isn't broken here, however, in case other | |
351 | * threads are found to have already been oom killed. | |
352 | */ | |
353 | if (p == current) { | |
354 | chosen = p; | |
355 | *ppoints = 1000; | |
356 | } else { | |
357 | /* | |
358 | * If this task is not being ptraced on exit, | |
359 | * then wait for it to finish before killing | |
360 | * some other task unnecessarily. | |
361 | */ | |
362 | if (!(p->group_leader->ptrace & PT_TRACE_EXIT)) | |
363 | return ERR_PTR(-1UL); | |
364 | } | |
365 | } | |
366 | ||
367 | points = oom_badness(p, memcg, nodemask, totalpages); | |
368 | if (points > *ppoints) { | |
369 | chosen = p; | |
370 | *ppoints = points; | |
371 | } | |
372 | } while_each_thread(g, p); | |
373 | ||
374 | return chosen; | |
375 | } | |
376 | ||
377 | /** | |
378 | * dump_tasks - dump current memory state of all system tasks | |
379 | * @mem: current's memory controller, if constrained | |
380 | * @nodemask: nodemask passed to page allocator for mempolicy ooms | |
381 | * | |
382 | * Dumps the current memory state of all eligible tasks. Tasks not in the same | |
383 | * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes | |
384 | * are not shown. | |
385 | * State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj | |
386 | * value, oom_score_adj value, and name. | |
387 | * | |
388 | * Call with tasklist_lock read-locked. | |
389 | */ | |
390 | static void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
391 | { | |
392 | struct task_struct *p; | |
393 | struct task_struct *task; | |
394 | ||
395 | pr_info("[ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name\n"); | |
396 | for_each_process(p) { | |
397 | if (oom_unkillable_task(p, memcg, nodemask)) | |
398 | continue; | |
399 | ||
400 | task = find_lock_task_mm(p); | |
401 | if (!task) { | |
402 | /* | |
403 | * This is a kthread or all of p's threads have already | |
404 | * detached their mm's. There's no need to report | |
405 | * them; they can't be oom killed anyway. | |
406 | */ | |
407 | continue; | |
408 | } | |
409 | ||
410 | pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n", | |
411 | task->pid, task_uid(task), task->tgid, | |
412 | task->mm->total_vm, get_mm_rss(task->mm), | |
413 | task_cpu(task), task->signal->oom_adj, | |
414 | task->signal->oom_score_adj, task->comm); | |
415 | task_unlock(task); | |
416 | } | |
417 | } | |
418 | ||
419 | static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, | |
420 | struct mem_cgroup *memcg, const nodemask_t *nodemask) | |
421 | { | |
422 | task_lock(current); | |
423 | pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " | |
424 | "oom_adj=%d, oom_score_adj=%d\n", | |
425 | current->comm, gfp_mask, order, current->signal->oom_adj, | |
426 | current->signal->oom_score_adj); | |
427 | cpuset_print_task_mems_allowed(current); | |
428 | task_unlock(current); | |
429 | dump_stack(); | |
430 | mem_cgroup_print_oom_info(memcg, p); | |
431 | show_mem(SHOW_MEM_FILTER_NODES); | |
432 | if (sysctl_oom_dump_tasks) | |
433 | dump_tasks(memcg, nodemask); | |
434 | } | |
435 | ||
436 | #define K(x) ((x) << (PAGE_SHIFT-10)) | |
437 | static int oom_kill_task(struct task_struct *p) | |
438 | { | |
439 | struct task_struct *q; | |
440 | struct mm_struct *mm; | |
441 | ||
442 | p = find_lock_task_mm(p); | |
443 | if (!p) | |
444 | return 1; | |
445 | ||
446 | /* mm cannot be safely dereferenced after task_unlock(p) */ | |
447 | mm = p->mm; | |
448 | ||
449 | pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n", | |
450 | task_pid_nr(p), p->comm, K(p->mm->total_vm), | |
451 | K(get_mm_counter(p->mm, MM_ANONPAGES)), | |
452 | K(get_mm_counter(p->mm, MM_FILEPAGES))); | |
453 | task_unlock(p); | |
454 | ||
455 | /* | |
456 | * Kill all user processes sharing p->mm in other thread groups, if any. | |
457 | * They don't get access to memory reserves or a higher scheduler | |
458 | * priority, though, to avoid depletion of all memory or task | |
459 | * starvation. This prevents mm->mmap_sem livelock when an oom killed | |
460 | * task cannot exit because it requires the semaphore and its contended | |
461 | * by another thread trying to allocate memory itself. That thread will | |
462 | * now get access to memory reserves since it has a pending fatal | |
463 | * signal. | |
464 | */ | |
465 | for_each_process(q) | |
466 | if (q->mm == mm && !same_thread_group(q, p) && | |
467 | !(q->flags & PF_KTHREAD)) { | |
468 | if (q->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) | |
469 | continue; | |
470 | ||
471 | task_lock(q); /* Protect ->comm from prctl() */ | |
472 | pr_err("Kill process %d (%s) sharing same memory\n", | |
473 | task_pid_nr(q), q->comm); | |
474 | task_unlock(q); | |
475 | force_sig(SIGKILL, q); | |
476 | } | |
477 | ||
478 | set_tsk_thread_flag(p, TIF_MEMDIE); | |
479 | force_sig(SIGKILL, p); | |
480 | ||
481 | return 0; | |
482 | } | |
483 | #undef K | |
484 | ||
485 | static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, | |
486 | unsigned int points, unsigned long totalpages, | |
487 | struct mem_cgroup *memcg, nodemask_t *nodemask, | |
488 | const char *message) | |
489 | { | |
490 | struct task_struct *victim = p; | |
491 | struct task_struct *child; | |
492 | struct task_struct *t = p; | |
493 | unsigned int victim_points = 0; | |
494 | ||
495 | if (printk_ratelimit()) | |
496 | dump_header(p, gfp_mask, order, memcg, nodemask); | |
497 | ||
498 | /* | |
499 | * If the task is already exiting, don't alarm the sysadmin or kill | |
500 | * its children or threads, just set TIF_MEMDIE so it can die quickly | |
501 | */ | |
502 | if (p->flags & PF_EXITING) { | |
503 | set_tsk_thread_flag(p, TIF_MEMDIE); | |
504 | return 0; | |
505 | } | |
506 | ||
507 | task_lock(p); | |
508 | pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n", | |
509 | message, task_pid_nr(p), p->comm, points); | |
510 | task_unlock(p); | |
511 | ||
512 | /* | |
513 | * If any of p's children has a different mm and is eligible for kill, | |
514 | * the one with the highest oom_badness() score is sacrificed for its | |
515 | * parent. This attempts to lose the minimal amount of work done while | |
516 | * still freeing memory. | |
517 | */ | |
518 | do { | |
519 | list_for_each_entry(child, &t->children, sibling) { | |
520 | unsigned int child_points; | |
521 | ||
522 | if (child->mm == p->mm) | |
523 | continue; | |
524 | /* | |
525 | * oom_badness() returns 0 if the thread is unkillable | |
526 | */ | |
527 | child_points = oom_badness(child, memcg, nodemask, | |
528 | totalpages); | |
529 | if (child_points > victim_points) { | |
530 | victim = child; | |
531 | victim_points = child_points; | |
532 | } | |
533 | } | |
534 | } while_each_thread(p, t); | |
535 | ||
536 | return oom_kill_task(victim); | |
537 | } | |
538 | ||
539 | /* | |
540 | * Determines whether the kernel must panic because of the panic_on_oom sysctl. | |
541 | */ | |
542 | static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, | |
543 | int order, const nodemask_t *nodemask) | |
544 | { | |
545 | if (likely(!sysctl_panic_on_oom)) | |
546 | return; | |
547 | if (sysctl_panic_on_oom != 2) { | |
548 | /* | |
549 | * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel | |
550 | * does not panic for cpuset, mempolicy, or memcg allocation | |
551 | * failures. | |
552 | */ | |
553 | if (constraint != CONSTRAINT_NONE) | |
554 | return; | |
555 | } | |
556 | read_lock(&tasklist_lock); | |
557 | dump_header(NULL, gfp_mask, order, NULL, nodemask); | |
558 | read_unlock(&tasklist_lock); | |
559 | panic("Out of memory: %s panic_on_oom is enabled\n", | |
560 | sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); | |
561 | } | |
562 | ||
563 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR | |
564 | void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask) | |
565 | { | |
566 | unsigned long limit; | |
567 | unsigned int points = 0; | |
568 | struct task_struct *p; | |
569 | ||
570 | /* | |
571 | * If current has a pending SIGKILL, then automatically select it. The | |
572 | * goal is to allow it to allocate so that it may quickly exit and free | |
573 | * its memory. | |
574 | */ | |
575 | if (fatal_signal_pending(current)) { | |
576 | set_thread_flag(TIF_MEMDIE); | |
577 | return; | |
578 | } | |
579 | ||
580 | check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL); | |
581 | limit = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT; | |
582 | read_lock(&tasklist_lock); | |
583 | retry: | |
584 | p = select_bad_process(&points, limit, memcg, NULL); | |
585 | if (!p || PTR_ERR(p) == -1UL) | |
586 | goto out; | |
587 | ||
588 | if (oom_kill_process(p, gfp_mask, 0, points, limit, memcg, NULL, | |
589 | "Memory cgroup out of memory")) | |
590 | goto retry; | |
591 | out: | |
592 | read_unlock(&tasklist_lock); | |
593 | } | |
594 | #endif | |
595 | ||
596 | static BLOCKING_NOTIFIER_HEAD(oom_notify_list); | |
597 | ||
598 | int register_oom_notifier(struct notifier_block *nb) | |
599 | { | |
600 | return blocking_notifier_chain_register(&oom_notify_list, nb); | |
601 | } | |
602 | EXPORT_SYMBOL_GPL(register_oom_notifier); | |
603 | ||
604 | int unregister_oom_notifier(struct notifier_block *nb) | |
605 | { | |
606 | return blocking_notifier_chain_unregister(&oom_notify_list, nb); | |
607 | } | |
608 | EXPORT_SYMBOL_GPL(unregister_oom_notifier); | |
609 | ||
610 | /* | |
611 | * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero | |
612 | * if a parallel OOM killing is already taking place that includes a zone in | |
613 | * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. | |
614 | */ | |
615 | int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) | |
616 | { | |
617 | struct zoneref *z; | |
618 | struct zone *zone; | |
619 | int ret = 1; | |
620 | ||
621 | spin_lock(&zone_scan_lock); | |
622 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
623 | if (zone_is_oom_locked(zone)) { | |
624 | ret = 0; | |
625 | goto out; | |
626 | } | |
627 | } | |
628 | ||
629 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
630 | /* | |
631 | * Lock each zone in the zonelist under zone_scan_lock so a | |
632 | * parallel invocation of try_set_zonelist_oom() doesn't succeed | |
633 | * when it shouldn't. | |
634 | */ | |
635 | zone_set_flag(zone, ZONE_OOM_LOCKED); | |
636 | } | |
637 | ||
638 | out: | |
639 | spin_unlock(&zone_scan_lock); | |
640 | return ret; | |
641 | } | |
642 | ||
643 | /* | |
644 | * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed | |
645 | * allocation attempts with zonelists containing them may now recall the OOM | |
646 | * killer, if necessary. | |
647 | */ | |
648 | void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) | |
649 | { | |
650 | struct zoneref *z; | |
651 | struct zone *zone; | |
652 | ||
653 | spin_lock(&zone_scan_lock); | |
654 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
655 | zone_clear_flag(zone, ZONE_OOM_LOCKED); | |
656 | } | |
657 | spin_unlock(&zone_scan_lock); | |
658 | } | |
659 | ||
660 | /* | |
661 | * Try to acquire the oom killer lock for all system zones. Returns zero if a | |
662 | * parallel oom killing is taking place, otherwise locks all zones and returns | |
663 | * non-zero. | |
664 | */ | |
665 | static int try_set_system_oom(void) | |
666 | { | |
667 | struct zone *zone; | |
668 | int ret = 1; | |
669 | ||
670 | spin_lock(&zone_scan_lock); | |
671 | for_each_populated_zone(zone) | |
672 | if (zone_is_oom_locked(zone)) { | |
673 | ret = 0; | |
674 | goto out; | |
675 | } | |
676 | for_each_populated_zone(zone) | |
677 | zone_set_flag(zone, ZONE_OOM_LOCKED); | |
678 | out: | |
679 | spin_unlock(&zone_scan_lock); | |
680 | return ret; | |
681 | } | |
682 | ||
683 | /* | |
684 | * Clears ZONE_OOM_LOCKED for all system zones so that failed allocation | |
685 | * attempts or page faults may now recall the oom killer, if necessary. | |
686 | */ | |
687 | static void clear_system_oom(void) | |
688 | { | |
689 | struct zone *zone; | |
690 | ||
691 | spin_lock(&zone_scan_lock); | |
692 | for_each_populated_zone(zone) | |
693 | zone_clear_flag(zone, ZONE_OOM_LOCKED); | |
694 | spin_unlock(&zone_scan_lock); | |
695 | } | |
696 | ||
697 | /** | |
698 | * out_of_memory - kill the "best" process when we run out of memory | |
699 | * @zonelist: zonelist pointer | |
700 | * @gfp_mask: memory allocation flags | |
701 | * @order: amount of memory being requested as a power of 2 | |
702 | * @nodemask: nodemask passed to page allocator | |
703 | * | |
704 | * If we run out of memory, we have the choice between either | |
705 | * killing a random task (bad), letting the system crash (worse) | |
706 | * OR try to be smart about which process to kill. Note that we | |
707 | * don't have to be perfect here, we just have to be good. | |
708 | */ | |
709 | void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, | |
710 | int order, nodemask_t *nodemask) | |
711 | { | |
712 | const nodemask_t *mpol_mask; | |
713 | struct task_struct *p; | |
714 | unsigned long totalpages; | |
715 | unsigned long freed = 0; | |
716 | unsigned int points; | |
717 | enum oom_constraint constraint = CONSTRAINT_NONE; | |
718 | int killed = 0; | |
719 | ||
720 | blocking_notifier_call_chain(&oom_notify_list, 0, &freed); | |
721 | if (freed > 0) | |
722 | /* Got some memory back in the last second. */ | |
723 | return; | |
724 | ||
725 | /* | |
726 | * If current has a pending SIGKILL, then automatically select it. The | |
727 | * goal is to allow it to allocate so that it may quickly exit and free | |
728 | * its memory. | |
729 | */ | |
730 | if (fatal_signal_pending(current)) { | |
731 | set_thread_flag(TIF_MEMDIE); | |
732 | return; | |
733 | } | |
734 | ||
735 | /* | |
736 | * Check if there were limitations on the allocation (only relevant for | |
737 | * NUMA) that may require different handling. | |
738 | */ | |
739 | constraint = constrained_alloc(zonelist, gfp_mask, nodemask, | |
740 | &totalpages); | |
741 | mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL; | |
742 | check_panic_on_oom(constraint, gfp_mask, order, mpol_mask); | |
743 | ||
744 | read_lock(&tasklist_lock); | |
745 | if (sysctl_oom_kill_allocating_task && | |
746 | !oom_unkillable_task(current, NULL, nodemask) && | |
747 | current->mm) { | |
748 | /* | |
749 | * oom_kill_process() needs tasklist_lock held. If it returns | |
750 | * non-zero, current could not be killed so we must fallback to | |
751 | * the tasklist scan. | |
752 | */ | |
753 | if (!oom_kill_process(current, gfp_mask, order, 0, totalpages, | |
754 | NULL, nodemask, | |
755 | "Out of memory (oom_kill_allocating_task)")) | |
756 | goto out; | |
757 | } | |
758 | ||
759 | retry: | |
760 | p = select_bad_process(&points, totalpages, NULL, mpol_mask); | |
761 | if (PTR_ERR(p) == -1UL) | |
762 | goto out; | |
763 | ||
764 | /* Found nothing?!?! Either we hang forever, or we panic. */ | |
765 | if (!p) { | |
766 | dump_header(NULL, gfp_mask, order, NULL, mpol_mask); | |
767 | read_unlock(&tasklist_lock); | |
768 | panic("Out of memory and no killable processes...\n"); | |
769 | } | |
770 | ||
771 | if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL, | |
772 | nodemask, "Out of memory")) | |
773 | goto retry; | |
774 | killed = 1; | |
775 | out: | |
776 | read_unlock(&tasklist_lock); | |
777 | ||
778 | /* | |
779 | * Give "p" a good chance of killing itself before we | |
780 | * retry to allocate memory unless "p" is current | |
781 | */ | |
782 | if (killed && !test_thread_flag(TIF_MEMDIE)) | |
783 | schedule_timeout_uninterruptible(1); | |
784 | } | |
785 | ||
786 | /* | |
787 | * The pagefault handler calls here because it is out of memory, so kill a | |
788 | * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel | |
789 | * oom killing is already in progress so do nothing. If a task is found with | |
790 | * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit. | |
791 | */ | |
792 | void pagefault_out_of_memory(void) | |
793 | { | |
794 | if (try_set_system_oom()) { | |
795 | out_of_memory(NULL, 0, 0, NULL); | |
796 | clear_system_oom(); | |
797 | } | |
798 | if (!test_thread_flag(TIF_MEMDIE)) | |
799 | schedule_timeout_uninterruptible(1); | |
800 | } |