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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#include <linux/kthread.h>
39#include <linux/init.h>
40
41#include <asm/tlb.h>
42#include "internal.h"
43
44#define CREATE_TRACE_POINTS
45#include <trace/events/oom.h>
46
47int sysctl_panic_on_oom;
48int sysctl_oom_kill_allocating_task;
49int sysctl_oom_dump_tasks = 1;
50
51DEFINE_MUTEX(oom_lock);
52
53#ifdef CONFIG_NUMA
54
55
56
57
58
59
60
61
62
63static bool has_intersects_mems_allowed(struct task_struct *start,
64 const nodemask_t *mask)
65{
66 struct task_struct *tsk;
67 bool ret = false;
68
69 rcu_read_lock();
70 for_each_thread(start, tsk) {
71 if (mask) {
72
73
74
75
76
77
78 ret = mempolicy_nodemask_intersects(tsk, mask);
79 } else {
80
81
82
83
84 ret = cpuset_mems_allowed_intersects(current, tsk);
85 }
86 if (ret)
87 break;
88 }
89 rcu_read_unlock();
90
91 return ret;
92}
93#else
94static bool has_intersects_mems_allowed(struct task_struct *tsk,
95 const nodemask_t *mask)
96{
97 return true;
98}
99#endif
100
101
102
103
104
105
106
107struct task_struct *find_lock_task_mm(struct task_struct *p)
108{
109 struct task_struct *t;
110
111 rcu_read_lock();
112
113 for_each_thread(p, t) {
114 task_lock(t);
115 if (likely(t->mm))
116 goto found;
117 task_unlock(t);
118 }
119 t = NULL;
120found:
121 rcu_read_unlock();
122
123 return t;
124}
125
126
127
128
129
130static inline bool is_sysrq_oom(struct oom_control *oc)
131{
132 return oc->order == -1;
133}
134
135
136static bool oom_unkillable_task(struct task_struct *p,
137 struct mem_cgroup *memcg, const nodemask_t *nodemask)
138{
139 if (is_global_init(p))
140 return true;
141 if (p->flags & PF_KTHREAD)
142 return true;
143
144
145 if (memcg && !task_in_mem_cgroup(p, memcg))
146 return true;
147
148
149 if (!has_intersects_mems_allowed(p, nodemask))
150 return true;
151
152 return false;
153}
154
155
156
157
158
159
160
161
162
163
164unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
165 const nodemask_t *nodemask, unsigned long totalpages)
166{
167 long points;
168 long adj;
169
170 if (oom_unkillable_task(p, memcg, nodemask))
171 return 0;
172
173 p = find_lock_task_mm(p);
174 if (!p)
175 return 0;
176
177 adj = (long)p->signal->oom_score_adj;
178 if (adj == OOM_SCORE_ADJ_MIN) {
179 task_unlock(p);
180 return 0;
181 }
182
183
184
185
186
187 points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
188 atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm);
189 task_unlock(p);
190
191
192
193
194
195 if (has_capability_noaudit(p, CAP_SYS_ADMIN))
196 points -= (points * 3) / 100;
197
198
199 adj *= totalpages / 1000;
200 points += adj;
201
202
203
204
205
206 return points > 0 ? points : 1;
207}
208
209
210
211
212#ifdef CONFIG_NUMA
213static enum oom_constraint constrained_alloc(struct oom_control *oc,
214 unsigned long *totalpages)
215{
216 struct zone *zone;
217 struct zoneref *z;
218 enum zone_type high_zoneidx = gfp_zone(oc->gfp_mask);
219 bool cpuset_limited = false;
220 int nid;
221
222
223 *totalpages = totalram_pages + total_swap_pages;
224
225 if (!oc->zonelist)
226 return CONSTRAINT_NONE;
227
228
229
230
231
232 if (oc->gfp_mask & __GFP_THISNODE)
233 return CONSTRAINT_NONE;
234
235
236
237
238
239
240 if (oc->nodemask &&
241 !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
242 *totalpages = total_swap_pages;
243 for_each_node_mask(nid, *oc->nodemask)
244 *totalpages += node_spanned_pages(nid);
245 return CONSTRAINT_MEMORY_POLICY;
246 }
247
248
249 for_each_zone_zonelist_nodemask(zone, z, oc->zonelist,
250 high_zoneidx, oc->nodemask)
251 if (!cpuset_zone_allowed(zone, oc->gfp_mask))
252 cpuset_limited = true;
253
254 if (cpuset_limited) {
255 *totalpages = total_swap_pages;
256 for_each_node_mask(nid, cpuset_current_mems_allowed)
257 *totalpages += node_spanned_pages(nid);
258 return CONSTRAINT_CPUSET;
259 }
260 return CONSTRAINT_NONE;
261}
262#else
263static enum oom_constraint constrained_alloc(struct oom_control *oc,
264 unsigned long *totalpages)
265{
266 *totalpages = totalram_pages + total_swap_pages;
267 return CONSTRAINT_NONE;
268}
269#endif
270
271enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
272 struct task_struct *task, unsigned long totalpages)
273{
274 if (oom_unkillable_task(task, NULL, oc->nodemask))
275 return OOM_SCAN_CONTINUE;
276
277
278
279
280
281 if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
282 if (!is_sysrq_oom(oc))
283 return OOM_SCAN_ABORT;
284 }
285 if (!task->mm)
286 return OOM_SCAN_CONTINUE;
287
288
289
290
291
292 if (oom_task_origin(task))
293 return OOM_SCAN_SELECT;
294
295 return OOM_SCAN_OK;
296}
297
298
299
300
301
302static struct task_struct *select_bad_process(struct oom_control *oc,
303 unsigned int *ppoints, unsigned long totalpages)
304{
305 struct task_struct *g, *p;
306 struct task_struct *chosen = NULL;
307 unsigned long chosen_points = 0;
308
309 rcu_read_lock();
310 for_each_process_thread(g, p) {
311 unsigned int points;
312
313 switch (oom_scan_process_thread(oc, p, totalpages)) {
314 case OOM_SCAN_SELECT:
315 chosen = p;
316 chosen_points = ULONG_MAX;
317
318 case OOM_SCAN_CONTINUE:
319 continue;
320 case OOM_SCAN_ABORT:
321 rcu_read_unlock();
322 return (struct task_struct *)(-1UL);
323 case OOM_SCAN_OK:
324 break;
325 };
326 points = oom_badness(p, NULL, oc->nodemask, totalpages);
327 if (!points || points < chosen_points)
328 continue;
329
330 if (points == chosen_points && thread_group_leader(chosen))
331 continue;
332
333 chosen = p;
334 chosen_points = points;
335 }
336 if (chosen)
337 get_task_struct(chosen);
338 rcu_read_unlock();
339
340 *ppoints = chosen_points * 1000 / totalpages;
341 return chosen;
342}
343
344
345
346
347
348
349
350
351
352
353
354
355static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
356{
357 struct task_struct *p;
358 struct task_struct *task;
359
360 pr_info("[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name\n");
361 rcu_read_lock();
362 for_each_process(p) {
363 if (oom_unkillable_task(p, memcg, nodemask))
364 continue;
365
366 task = find_lock_task_mm(p);
367 if (!task) {
368
369
370
371
372
373 continue;
374 }
375
376 pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu %5hd %s\n",
377 task->pid, from_kuid(&init_user_ns, task_uid(task)),
378 task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
379 atomic_long_read(&task->mm->nr_ptes),
380 mm_nr_pmds(task->mm),
381 get_mm_counter(task->mm, MM_SWAPENTS),
382 task->signal->oom_score_adj, task->comm);
383 task_unlock(task);
384 }
385 rcu_read_unlock();
386}
387
388static void dump_header(struct oom_control *oc, struct task_struct *p,
389 struct mem_cgroup *memcg)
390{
391 pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n",
392 current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order,
393 current->signal->oom_score_adj);
394
395 cpuset_print_current_mems_allowed();
396 dump_stack();
397 if (memcg)
398 mem_cgroup_print_oom_info(memcg, p);
399 else
400 show_mem(SHOW_MEM_FILTER_NODES);
401 if (sysctl_oom_dump_tasks)
402 dump_tasks(memcg, oc->nodemask);
403}
404
405
406
407
408static atomic_t oom_victims = ATOMIC_INIT(0);
409static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait);
410
411bool oom_killer_disabled __read_mostly;
412
413#define K(x) ((x) << (PAGE_SHIFT-10))
414
415#ifdef CONFIG_MMU
416
417
418
419
420static struct task_struct *oom_reaper_th;
421static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
422static struct task_struct *oom_reaper_list;
423static DEFINE_SPINLOCK(oom_reaper_lock);
424
425
426static bool __oom_reap_task(struct task_struct *tsk)
427{
428 struct mmu_gather tlb;
429 struct vm_area_struct *vma;
430 struct mm_struct *mm;
431 struct task_struct *p;
432 struct zap_details details = {.check_swap_entries = true,
433 .ignore_dirty = true};
434 bool ret = true;
435
436
437
438
439
440
441
442 p = find_lock_task_mm(tsk);
443 if (!p)
444 return true;
445
446 mm = p->mm;
447 if (!atomic_inc_not_zero(&mm->mm_users)) {
448 task_unlock(p);
449 return true;
450 }
451
452 task_unlock(p);
453
454 if (!down_read_trylock(&mm->mmap_sem)) {
455 ret = false;
456 goto out;
457 }
458
459 tlb_gather_mmu(&tlb, mm, 0, -1);
460 for (vma = mm->mmap ; vma; vma = vma->vm_next) {
461 if (is_vm_hugetlb_page(vma))
462 continue;
463
464
465
466
467
468 if (vma->vm_flags & VM_LOCKED)
469 continue;
470
471
472
473
474
475
476
477
478
479
480
481 if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED))
482 unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end,
483 &details);
484 }
485 tlb_finish_mmu(&tlb, 0, -1);
486 pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
487 task_pid_nr(tsk), tsk->comm,
488 K(get_mm_counter(mm, MM_ANONPAGES)),
489 K(get_mm_counter(mm, MM_FILEPAGES)),
490 K(get_mm_counter(mm, MM_SHMEMPAGES)));
491 up_read(&mm->mmap_sem);
492
493
494
495
496
497
498
499
500 tsk->signal->oom_score_adj = OOM_SCORE_ADJ_MIN;
501 exit_oom_victim(tsk);
502out:
503 mmput(mm);
504 return ret;
505}
506
507#define MAX_OOM_REAP_RETRIES 10
508static void oom_reap_task(struct task_struct *tsk)
509{
510 int attempts = 0;
511
512
513 while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task(tsk))
514 schedule_timeout_idle(HZ/10);
515
516 if (attempts > MAX_OOM_REAP_RETRIES) {
517 pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
518 task_pid_nr(tsk), tsk->comm);
519 debug_show_all_locks();
520 }
521
522
523 put_task_struct(tsk);
524}
525
526static int oom_reaper(void *unused)
527{
528 set_freezable();
529
530 while (true) {
531 struct task_struct *tsk = NULL;
532
533 wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
534 spin_lock(&oom_reaper_lock);
535 if (oom_reaper_list != NULL) {
536 tsk = oom_reaper_list;
537 oom_reaper_list = tsk->oom_reaper_list;
538 }
539 spin_unlock(&oom_reaper_lock);
540
541 if (tsk)
542 oom_reap_task(tsk);
543 }
544
545 return 0;
546}
547
548static void wake_oom_reaper(struct task_struct *tsk)
549{
550 if (!oom_reaper_th)
551 return;
552
553
554 if (tsk == oom_reaper_list || tsk->oom_reaper_list)
555 return;
556
557 get_task_struct(tsk);
558
559 spin_lock(&oom_reaper_lock);
560 tsk->oom_reaper_list = oom_reaper_list;
561 oom_reaper_list = tsk;
562 spin_unlock(&oom_reaper_lock);
563 wake_up(&oom_reaper_wait);
564}
565
566static int __init oom_init(void)
567{
568 oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper");
569 if (IS_ERR(oom_reaper_th)) {
570 pr_err("Unable to start OOM reaper %ld. Continuing regardless\n",
571 PTR_ERR(oom_reaper_th));
572 oom_reaper_th = NULL;
573 }
574 return 0;
575}
576subsys_initcall(oom_init)
577#else
578static void wake_oom_reaper(struct task_struct *tsk)
579{
580}
581#endif
582
583
584
585
586
587
588
589
590void mark_oom_victim(struct task_struct *tsk)
591{
592 WARN_ON(oom_killer_disabled);
593
594 if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
595 return;
596
597
598
599
600
601
602 __thaw_task(tsk);
603 atomic_inc(&oom_victims);
604}
605
606
607
608
609void exit_oom_victim(struct task_struct *tsk)
610{
611 if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
612 return;
613
614 if (!atomic_dec_return(&oom_victims))
615 wake_up_all(&oom_victims_wait);
616}
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631bool oom_killer_disable(void)
632{
633
634
635
636
637 if (mutex_lock_killable(&oom_lock))
638 return false;
639 oom_killer_disabled = true;
640 mutex_unlock(&oom_lock);
641
642 wait_event(oom_victims_wait, !atomic_read(&oom_victims));
643
644 return true;
645}
646
647
648
649
650void oom_killer_enable(void)
651{
652 oom_killer_disabled = false;
653}
654
655
656
657
658
659
660
661static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
662{
663 struct task_struct *t;
664
665 for_each_thread(p, t) {
666 struct mm_struct *t_mm = READ_ONCE(t->mm);
667 if (t_mm)
668 return t_mm == mm;
669 }
670 return false;
671}
672
673
674
675
676
677void oom_kill_process(struct oom_control *oc, struct task_struct *p,
678 unsigned int points, unsigned long totalpages,
679 struct mem_cgroup *memcg, const char *message)
680{
681 struct task_struct *victim = p;
682 struct task_struct *child;
683 struct task_struct *t;
684 struct mm_struct *mm;
685 unsigned int victim_points = 0;
686 static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
687 DEFAULT_RATELIMIT_BURST);
688 bool can_oom_reap = true;
689
690
691
692
693
694 task_lock(p);
695 if (p->mm && task_will_free_mem(p)) {
696 mark_oom_victim(p);
697 task_unlock(p);
698 put_task_struct(p);
699 return;
700 }
701 task_unlock(p);
702
703 if (__ratelimit(&oom_rs))
704 dump_header(oc, p, memcg);
705
706 pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
707 message, task_pid_nr(p), p->comm, points);
708
709
710
711
712
713
714
715 read_lock(&tasklist_lock);
716 for_each_thread(p, t) {
717 list_for_each_entry(child, &t->children, sibling) {
718 unsigned int child_points;
719
720 if (process_shares_mm(child, p->mm))
721 continue;
722
723
724
725 child_points = oom_badness(child, memcg, oc->nodemask,
726 totalpages);
727 if (child_points > victim_points) {
728 put_task_struct(victim);
729 victim = child;
730 victim_points = child_points;
731 get_task_struct(victim);
732 }
733 }
734 }
735 read_unlock(&tasklist_lock);
736
737 p = find_lock_task_mm(victim);
738 if (!p) {
739 put_task_struct(victim);
740 return;
741 } else if (victim != p) {
742 get_task_struct(p);
743 put_task_struct(victim);
744 victim = p;
745 }
746
747
748 mm = victim->mm;
749 atomic_inc(&mm->mm_count);
750
751
752
753
754
755 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
756 mark_oom_victim(victim);
757 pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
758 task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
759 K(get_mm_counter(victim->mm, MM_ANONPAGES)),
760 K(get_mm_counter(victim->mm, MM_FILEPAGES)),
761 K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
762 task_unlock(victim);
763
764
765
766
767
768
769
770
771
772
773 rcu_read_lock();
774 for_each_process(p) {
775 if (!process_shares_mm(p, mm))
776 continue;
777 if (same_thread_group(p, victim))
778 continue;
779 if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) ||
780 p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
781
782
783
784
785
786 can_oom_reap = false;
787 continue;
788 }
789 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
790 }
791 rcu_read_unlock();
792
793 if (can_oom_reap)
794 wake_oom_reaper(victim);
795
796 mmdrop(mm);
797 put_task_struct(victim);
798}
799#undef K
800
801
802
803
804void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
805 struct mem_cgroup *memcg)
806{
807 if (likely(!sysctl_panic_on_oom))
808 return;
809 if (sysctl_panic_on_oom != 2) {
810
811
812
813
814
815 if (constraint != CONSTRAINT_NONE)
816 return;
817 }
818
819 if (is_sysrq_oom(oc))
820 return;
821 dump_header(oc, NULL, memcg);
822 panic("Out of memory: %s panic_on_oom is enabled\n",
823 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
824}
825
826static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
827
828int register_oom_notifier(struct notifier_block *nb)
829{
830 return blocking_notifier_chain_register(&oom_notify_list, nb);
831}
832EXPORT_SYMBOL_GPL(register_oom_notifier);
833
834int unregister_oom_notifier(struct notifier_block *nb)
835{
836 return blocking_notifier_chain_unregister(&oom_notify_list, nb);
837}
838EXPORT_SYMBOL_GPL(unregister_oom_notifier);
839
840
841
842
843
844
845
846
847
848
849bool out_of_memory(struct oom_control *oc)
850{
851 struct task_struct *p;
852 unsigned long totalpages;
853 unsigned long freed = 0;
854 unsigned int uninitialized_var(points);
855 enum oom_constraint constraint = CONSTRAINT_NONE;
856
857 if (oom_killer_disabled)
858 return false;
859
860 blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
861 if (freed > 0)
862
863 return true;
864
865
866
867
868
869
870
871
872
873 if (current->mm &&
874 (fatal_signal_pending(current) || task_will_free_mem(current))) {
875 mark_oom_victim(current);
876 return true;
877 }
878
879
880
881
882
883 constraint = constrained_alloc(oc, &totalpages);
884 if (constraint != CONSTRAINT_MEMORY_POLICY)
885 oc->nodemask = NULL;
886 check_panic_on_oom(oc, constraint, NULL);
887
888 if (sysctl_oom_kill_allocating_task && current->mm &&
889 !oom_unkillable_task(current, NULL, oc->nodemask) &&
890 current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
891 get_task_struct(current);
892 oom_kill_process(oc, current, 0, totalpages, NULL,
893 "Out of memory (oom_kill_allocating_task)");
894 return true;
895 }
896
897 p = select_bad_process(oc, &points, totalpages);
898
899 if (!p && !is_sysrq_oom(oc)) {
900 dump_header(oc, NULL, NULL);
901 panic("Out of memory and no killable processes...\n");
902 }
903 if (p && p != (void *)-1UL) {
904 oom_kill_process(oc, p, points, totalpages, NULL,
905 "Out of memory");
906
907
908
909
910 schedule_timeout_killable(1);
911 }
912 return true;
913}
914
915
916
917
918
919
920void pagefault_out_of_memory(void)
921{
922 struct oom_control oc = {
923 .zonelist = NULL,
924 .nodemask = NULL,
925 .gfp_mask = 0,
926 .order = 0,
927 };
928
929 if (mem_cgroup_oom_synchronize(true))
930 return;
931
932 if (!mutex_trylock(&oom_lock))
933 return;
934
935 if (!out_of_memory(&oc)) {
936
937
938
939
940
941
942 WARN_ON(test_thread_flag(TIF_MEMDIE));
943 }
944
945 mutex_unlock(&oom_lock);
946}
947