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
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.
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.
20 #include <linux/oom.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 #include <linux/mmu_notifier.h>
45 #define CREATE_TRACE_POINTS
46 #include <trace/events/oom.h>
48 int sysctl_panic_on_oom;
49 int sysctl_oom_kill_allocating_task;
50 int sysctl_oom_dump_tasks = 1;
52 DEFINE_MUTEX(oom_lock);
56 * has_intersects_mems_allowed() - check task eligiblity for kill
57 * @start: task struct of which task to consider
58 * @mask: nodemask passed to page allocator for mempolicy ooms
60 * Task eligibility is determined by whether or not a candidate task, @tsk,
61 * shares the same mempolicy nodes as current if it is bound by such a policy
62 * and whether or not it has the same set of allowed cpuset nodes.
64 static bool has_intersects_mems_allowed(struct task_struct *start,
65 const nodemask_t *mask)
67 struct task_struct *tsk;
71 for_each_thread(start, tsk) {
74 * If this is a mempolicy constrained oom, tsk's
75 * cpuset is irrelevant. Only return true if its
76 * mempolicy intersects current, otherwise it may be
79 ret = mempolicy_nodemask_intersects(tsk, mask);
82 * This is not a mempolicy constrained oom, so only
83 * check the mems of tsk's cpuset.
85 ret = cpuset_mems_allowed_intersects(current, tsk);
95 static bool has_intersects_mems_allowed(struct task_struct *tsk,
96 const nodemask_t *mask)
100 #endif /* CONFIG_NUMA */
103 * The process p may have detached its own ->mm while exiting or through
104 * use_mm(), but one or more of its subthreads may still have a valid
105 * pointer. Return p, or any of its subthreads with a valid ->mm, with
108 struct task_struct *find_lock_task_mm(struct task_struct *p)
110 struct task_struct *t;
114 for_each_thread(p, t) {
128 * order == -1 means the oom kill is required by sysrq, otherwise only
129 * for display purposes.
131 static inline bool is_sysrq_oom(struct oom_control *oc)
133 return oc->order == -1;
136 static inline bool is_memcg_oom(struct oom_control *oc)
138 return oc->memcg != NULL;
141 /* return true if the task is not adequate as candidate victim task. */
142 static bool oom_unkillable_task(struct task_struct *p,
143 struct mem_cgroup *memcg, const nodemask_t *nodemask)
145 if (is_global_init(p))
147 if (p->flags & PF_KTHREAD)
150 /* When mem_cgroup_out_of_memory() and p is not member of the group */
151 if (memcg && !task_in_mem_cgroup(p, memcg))
154 /* p may not have freeable memory in nodemask */
155 if (!has_intersects_mems_allowed(p, nodemask))
162 * oom_badness - heuristic function to determine which candidate task to kill
163 * @p: task struct of which task we should calculate
164 * @totalpages: total present RAM allowed for page allocation
166 * The heuristic for determining which task to kill is made to be as simple and
167 * predictable as possible. The goal is to return the highest value for the
168 * task consuming the most memory to avoid subsequent oom failures.
170 unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
171 const nodemask_t *nodemask, unsigned long totalpages)
176 if (oom_unkillable_task(p, memcg, nodemask))
179 p = find_lock_task_mm(p);
184 * Do not even consider tasks which are explicitly marked oom
185 * unkillable or have been already oom reaped or the are in
186 * the middle of vfork
188 adj = (long)p->signal->oom_score_adj;
189 if (adj == OOM_SCORE_ADJ_MIN ||
190 test_bit(MMF_OOM_SKIP, &p->mm->flags) ||
197 * The baseline for the badness score is the proportion of RAM that each
198 * task's rss, pagetable and swap space use.
200 points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
201 atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm);
205 * Root processes get 3% bonus, just like the __vm_enough_memory()
206 * implementation used by LSMs.
208 if (has_capability_noaudit(p, CAP_SYS_ADMIN))
209 points -= (points * 3) / 100;
211 /* Normalize to oom_score_adj units */
212 adj *= totalpages / 1000;
216 * Never return 0 for an eligible task regardless of the root bonus and
217 * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
219 return points > 0 ? points : 1;
222 enum oom_constraint {
225 CONSTRAINT_MEMORY_POLICY,
230 * Determine the type of allocation constraint.
232 static enum oom_constraint constrained_alloc(struct oom_control *oc)
236 enum zone_type high_zoneidx = gfp_zone(oc->gfp_mask);
237 bool cpuset_limited = false;
240 if (is_memcg_oom(oc)) {
241 oc->totalpages = mem_cgroup_get_limit(oc->memcg) ?: 1;
242 return CONSTRAINT_MEMCG;
245 /* Default to all available memory */
246 oc->totalpages = totalram_pages + total_swap_pages;
248 if (!IS_ENABLED(CONFIG_NUMA))
249 return CONSTRAINT_NONE;
252 return CONSTRAINT_NONE;
254 * Reach here only when __GFP_NOFAIL is used. So, we should avoid
255 * to kill current.We have to random task kill in this case.
256 * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
258 if (oc->gfp_mask & __GFP_THISNODE)
259 return CONSTRAINT_NONE;
262 * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
263 * the page allocator means a mempolicy is in effect. Cpuset policy
264 * is enforced in get_page_from_freelist().
267 !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
268 oc->totalpages = total_swap_pages;
269 for_each_node_mask(nid, *oc->nodemask)
270 oc->totalpages += node_spanned_pages(nid);
271 return CONSTRAINT_MEMORY_POLICY;
274 /* Check this allocation failure is caused by cpuset's wall function */
275 for_each_zone_zonelist_nodemask(zone, z, oc->zonelist,
276 high_zoneidx, oc->nodemask)
277 if (!cpuset_zone_allowed(zone, oc->gfp_mask))
278 cpuset_limited = true;
280 if (cpuset_limited) {
281 oc->totalpages = total_swap_pages;
282 for_each_node_mask(nid, cpuset_current_mems_allowed)
283 oc->totalpages += node_spanned_pages(nid);
284 return CONSTRAINT_CPUSET;
286 return CONSTRAINT_NONE;
289 static int oom_evaluate_task(struct task_struct *task, void *arg)
291 struct oom_control *oc = arg;
292 unsigned long points;
294 if (oom_unkillable_task(task, NULL, oc->nodemask))
298 * This task already has access to memory reserves and is being killed.
299 * Don't allow any other task to have access to the reserves unless
300 * the task has MMF_OOM_SKIP because chances that it would release
301 * any memory is quite low.
303 if (!is_sysrq_oom(oc) && tsk_is_oom_victim(task)) {
304 if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags))
310 * If task is allocating a lot of memory and has been marked to be
311 * killed first if it triggers an oom, then select it.
313 if (oom_task_origin(task)) {
318 points = oom_badness(task, NULL, oc->nodemask, oc->totalpages);
319 if (!points || points < oc->chosen_points)
322 /* Prefer thread group leaders for display purposes */
323 if (points == oc->chosen_points && thread_group_leader(oc->chosen))
327 put_task_struct(oc->chosen);
328 get_task_struct(task);
330 oc->chosen_points = points;
335 put_task_struct(oc->chosen);
336 oc->chosen = (void *)-1UL;
341 * Simple selection loop. We choose the process with the highest number of
342 * 'points'. In case scan was aborted, oc->chosen is set to -1.
344 static void select_bad_process(struct oom_control *oc)
346 if (is_memcg_oom(oc))
347 mem_cgroup_scan_tasks(oc->memcg, oom_evaluate_task, oc);
349 struct task_struct *p;
353 if (oom_evaluate_task(p, oc))
358 oc->chosen_points = oc->chosen_points * 1000 / oc->totalpages;
362 * dump_tasks - dump current memory state of all system tasks
363 * @memcg: current's memory controller, if constrained
364 * @nodemask: nodemask passed to page allocator for mempolicy ooms
366 * Dumps the current memory state of all eligible tasks. Tasks not in the same
367 * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
369 * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes,
370 * swapents, oom_score_adj value, and name.
372 static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
374 struct task_struct *p;
375 struct task_struct *task;
377 pr_info("[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name\n");
379 for_each_process(p) {
380 if (oom_unkillable_task(p, memcg, nodemask))
383 task = find_lock_task_mm(p);
386 * This is a kthread or all of p's threads have already
387 * detached their mm's. There's no need to report
388 * them; they can't be oom killed anyway.
393 pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu %5hd %s\n",
394 task->pid, from_kuid(&init_user_ns, task_uid(task)),
395 task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
396 atomic_long_read(&task->mm->nr_ptes),
397 mm_nr_pmds(task->mm),
398 get_mm_counter(task->mm, MM_SWAPENTS),
399 task->signal->oom_score_adj, task->comm);
405 static void dump_header(struct oom_control *oc, struct task_struct *p)
407 nodemask_t *nm = (oc->nodemask) ? oc->nodemask : &cpuset_current_mems_allowed;
409 pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n",
410 current->comm, oc->gfp_mask, &oc->gfp_mask,
411 nodemask_pr_args(nm), oc->order,
412 current->signal->oom_score_adj);
413 if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
414 pr_warn("COMPACTION is disabled!!!\n");
416 cpuset_print_current_mems_allowed();
419 mem_cgroup_print_oom_info(oc->memcg, p);
421 show_mem(SHOW_MEM_FILTER_NODES);
422 if (sysctl_oom_dump_tasks)
423 dump_tasks(oc->memcg, oc->nodemask);
427 * Number of OOM victims in flight
429 static atomic_t oom_victims = ATOMIC_INIT(0);
430 static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait);
432 static bool oom_killer_disabled __read_mostly;
434 #define K(x) ((x) << (PAGE_SHIFT-10))
437 * task->mm can be NULL if the task is the exited group leader. So to
438 * determine whether the task is using a particular mm, we examine all the
439 * task's threads: if one of those is using this mm then this task was also
442 bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
444 struct task_struct *t;
446 for_each_thread(p, t) {
447 struct mm_struct *t_mm = READ_ONCE(t->mm);
457 * OOM Reaper kernel thread which tries to reap the memory used by the OOM
458 * victim (if that is possible) to help the OOM killer to move on.
460 static struct task_struct *oom_reaper_th;
461 static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
462 static struct task_struct *oom_reaper_list;
463 static DEFINE_SPINLOCK(oom_reaper_lock);
465 static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
467 struct mmu_gather tlb;
468 struct vm_area_struct *vma;
469 struct zap_details details = {.check_swap_entries = true,
470 .ignore_dirty = true};
474 * We have to make sure to not race with the victim exit path
475 * and cause premature new oom victim selection:
476 * __oom_reap_task_mm exit_mm
479 * atomic_dec_and_test
484 * # no TIF_MEMDIE task selects new victim
485 * unmap_page_range # frees some memory
487 mutex_lock(&oom_lock);
489 if (!down_read_trylock(&mm->mmap_sem)) {
495 * If the mm has notifiers then we would need to invalidate them around
496 * unmap_page_range and that is risky because notifiers can sleep and
497 * what they do is basically undeterministic. So let's have a short
498 * sleep to give the oom victim some more time.
499 * TODO: we really want to get rid of this ugly hack and make sure that
500 * notifiers cannot block for unbounded amount of time and add
501 * mmu_notifier_invalidate_range_{start,end} around unmap_page_range
503 if (mm_has_notifiers(mm)) {
504 up_read(&mm->mmap_sem);
505 schedule_timeout_idle(HZ);
510 * increase mm_users only after we know we will reap something so
511 * that the mmput_async is called only when we have reaped something
512 * and delayed __mmput doesn't matter that much
514 if (!mmget_not_zero(mm)) {
515 up_read(&mm->mmap_sem);
520 * Tell all users of get_user/copy_from_user etc... that the content
521 * is no longer stable. No barriers really needed because unmapping
522 * should imply barriers already and the reader would hit a page fault
523 * if it stumbled over a reaped memory.
525 set_bit(MMF_UNSTABLE, &mm->flags);
527 for (vma = mm->mmap ; vma; vma = vma->vm_next) {
528 if (is_vm_hugetlb_page(vma))
532 * mlocked VMAs require explicit munlocking before unmap.
533 * Let's keep it simple here and skip such VMAs.
535 if (vma->vm_flags & VM_LOCKED)
539 * Only anonymous pages have a good chance to be dropped
540 * without additional steps which we cannot afford as we
543 * We do not even care about fs backed pages because all
544 * which are reclaimable have already been reclaimed and
545 * we do not want to block exit_mmap by keeping mm ref
546 * count elevated without a good reason.
548 if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) {
549 tlb_gather_mmu(&tlb, mm, vma->vm_start, vma->vm_end);
550 unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end,
552 tlb_finish_mmu(&tlb, vma->vm_start, vma->vm_end);
555 pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
556 task_pid_nr(tsk), tsk->comm,
557 K(get_mm_counter(mm, MM_ANONPAGES)),
558 K(get_mm_counter(mm, MM_FILEPAGES)),
559 K(get_mm_counter(mm, MM_SHMEMPAGES)));
560 up_read(&mm->mmap_sem);
563 * Drop our reference but make sure the mmput slow path is called from a
564 * different context because we shouldn't risk we get stuck there and
565 * put the oom_reaper out of the way.
569 mutex_unlock(&oom_lock);
573 #define MAX_OOM_REAP_RETRIES 10
574 static void oom_reap_task(struct task_struct *tsk)
577 struct mm_struct *mm = tsk->signal->oom_mm;
579 /* Retry the down_read_trylock(mmap_sem) a few times */
580 while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task_mm(tsk, mm))
581 schedule_timeout_idle(HZ/10);
583 if (attempts <= MAX_OOM_REAP_RETRIES)
587 pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
588 task_pid_nr(tsk), tsk->comm);
589 debug_show_all_locks();
592 tsk->oom_reaper_list = NULL;
595 * Hide this mm from OOM killer because it has been either reaped or
596 * somebody can't call up_write(mmap_sem).
598 set_bit(MMF_OOM_SKIP, &mm->flags);
600 /* Drop a reference taken by wake_oom_reaper */
601 put_task_struct(tsk);
604 static int oom_reaper(void *unused)
607 struct task_struct *tsk = NULL;
609 wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
610 spin_lock(&oom_reaper_lock);
611 if (oom_reaper_list != NULL) {
612 tsk = oom_reaper_list;
613 oom_reaper_list = tsk->oom_reaper_list;
615 spin_unlock(&oom_reaper_lock);
624 static void wake_oom_reaper(struct task_struct *tsk)
629 /* mm is already queued? */
630 if (test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags))
633 get_task_struct(tsk);
635 spin_lock(&oom_reaper_lock);
636 tsk->oom_reaper_list = oom_reaper_list;
637 oom_reaper_list = tsk;
638 spin_unlock(&oom_reaper_lock);
639 wake_up(&oom_reaper_wait);
642 static int __init oom_init(void)
644 oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper");
645 if (IS_ERR(oom_reaper_th)) {
646 pr_err("Unable to start OOM reaper %ld. Continuing regardless\n",
647 PTR_ERR(oom_reaper_th));
648 oom_reaper_th = NULL;
652 subsys_initcall(oom_init)
654 static inline void wake_oom_reaper(struct task_struct *tsk)
657 #endif /* CONFIG_MMU */
660 * mark_oom_victim - mark the given task as OOM victim
663 * Has to be called with oom_lock held and never after
664 * oom has been disabled already.
666 * tsk->mm has to be non NULL and caller has to guarantee it is stable (either
667 * under task_lock or operate on the current).
669 static void mark_oom_victim(struct task_struct *tsk)
671 struct mm_struct *mm = tsk->mm;
673 WARN_ON(oom_killer_disabled);
674 /* OOM killer might race with memcg OOM */
675 if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
678 /* oom_mm is bound to the signal struct life time. */
679 if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm))
680 atomic_inc(&tsk->signal->oom_mm->mm_count);
683 * Make sure that the task is woken up from uninterruptible sleep
684 * if it is frozen because OOM killer wouldn't be able to free
685 * any memory and livelock. freezing_slow_path will tell the freezer
686 * that TIF_MEMDIE tasks should be ignored.
689 atomic_inc(&oom_victims);
693 * exit_oom_victim - note the exit of an OOM victim
695 void exit_oom_victim(void)
697 clear_thread_flag(TIF_MEMDIE);
699 if (!atomic_dec_return(&oom_victims))
700 wake_up_all(&oom_victims_wait);
704 * oom_killer_enable - enable OOM killer
706 void oom_killer_enable(void)
708 oom_killer_disabled = false;
712 * oom_killer_disable - disable OOM killer
713 * @timeout: maximum timeout to wait for oom victims in jiffies
715 * Forces all page allocations to fail rather than trigger OOM killer.
716 * Will block and wait until all OOM victims are killed or the given
719 * The function cannot be called when there are runnable user tasks because
720 * the userspace would see unexpected allocation failures as a result. Any
721 * new usage of this function should be consulted with MM people.
723 * Returns true if successful and false if the OOM killer cannot be
726 bool oom_killer_disable(signed long timeout)
731 * Make sure to not race with an ongoing OOM killer. Check that the
732 * current is not killed (possibly due to sharing the victim's memory).
734 if (mutex_lock_killable(&oom_lock))
736 oom_killer_disabled = true;
737 mutex_unlock(&oom_lock);
739 ret = wait_event_interruptible_timeout(oom_victims_wait,
740 !atomic_read(&oom_victims), timeout);
749 static inline bool __task_will_free_mem(struct task_struct *task)
751 struct signal_struct *sig = task->signal;
754 * A coredumping process may sleep for an extended period in exit_mm(),
755 * so the oom killer cannot assume that the process will promptly exit
756 * and release memory.
758 if (sig->flags & SIGNAL_GROUP_COREDUMP)
761 if (sig->flags & SIGNAL_GROUP_EXIT)
764 if (thread_group_empty(task) && (task->flags & PF_EXITING))
771 * Checks whether the given task is dying or exiting and likely to
772 * release its address space. This means that all threads and processes
773 * sharing the same mm have to be killed or exiting.
774 * Caller has to make sure that task->mm is stable (hold task_lock or
775 * it operates on the current).
777 static bool task_will_free_mem(struct task_struct *task)
779 struct mm_struct *mm = task->mm;
780 struct task_struct *p;
784 * Skip tasks without mm because it might have passed its exit_mm and
785 * exit_oom_victim. oom_reaper could have rescued that but do not rely
786 * on that for now. We can consider find_lock_task_mm in future.
791 if (!__task_will_free_mem(task))
795 * This task has already been drained by the oom reaper so there are
796 * only small chances it will free some more
798 if (test_bit(MMF_OOM_SKIP, &mm->flags))
801 if (atomic_read(&mm->mm_users) <= 1)
805 * Make sure that all tasks which share the mm with the given tasks
806 * are dying as well to make sure that a) nobody pins its mm and
807 * b) the task is also reapable by the oom reaper.
810 for_each_process(p) {
811 if (!process_shares_mm(p, mm))
813 if (same_thread_group(task, p))
815 ret = __task_will_free_mem(p);
824 static void oom_kill_process(struct oom_control *oc, const char *message)
826 struct task_struct *p = oc->chosen;
827 unsigned int points = oc->chosen_points;
828 struct task_struct *victim = p;
829 struct task_struct *child;
830 struct task_struct *t;
831 struct mm_struct *mm;
832 unsigned int victim_points = 0;
833 static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
834 DEFAULT_RATELIMIT_BURST);
835 bool can_oom_reap = true;
838 * If the task is already exiting, don't alarm the sysadmin or kill
839 * its children or threads, just set TIF_MEMDIE so it can die quickly
842 if (task_will_free_mem(p)) {
851 if (__ratelimit(&oom_rs))
854 pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
855 message, task_pid_nr(p), p->comm, points);
858 * If any of p's children has a different mm and is eligible for kill,
859 * the one with the highest oom_badness() score is sacrificed for its
860 * parent. This attempts to lose the minimal amount of work done while
861 * still freeing memory.
863 read_lock(&tasklist_lock);
866 * The task 'p' might have already exited before reaching here. The
867 * put_task_struct() will free task_struct 'p' while the loop still try
868 * to access the field of 'p', so, get an extra reference.
871 for_each_thread(p, t) {
872 list_for_each_entry(child, &t->children, sibling) {
873 unsigned int child_points;
875 if (process_shares_mm(child, p->mm))
878 * oom_badness() returns 0 if the thread is unkillable
880 child_points = oom_badness(child,
881 oc->memcg, oc->nodemask, oc->totalpages);
882 if (child_points > victim_points) {
883 put_task_struct(victim);
885 victim_points = child_points;
886 get_task_struct(victim);
891 read_unlock(&tasklist_lock);
893 p = find_lock_task_mm(victim);
895 put_task_struct(victim);
897 } else if (victim != p) {
899 put_task_struct(victim);
903 /* Get a reference to safely compare mm after task_unlock(victim) */
905 atomic_inc(&mm->mm_count);
907 * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
908 * the OOM victim from depleting the memory reserves from the user
909 * space under its control.
911 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
912 mark_oom_victim(victim);
913 pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
914 task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
915 K(get_mm_counter(victim->mm, MM_ANONPAGES)),
916 K(get_mm_counter(victim->mm, MM_FILEPAGES)),
917 K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
921 * Kill all user processes sharing victim->mm in other thread groups, if
922 * any. They don't get access to memory reserves, though, to avoid
923 * depletion of all memory. This prevents mm->mmap_sem livelock when an
924 * oom killed thread cannot exit because it requires the semaphore and
925 * its contended by another thread trying to allocate memory itself.
926 * That thread will now get access to memory reserves since it has a
927 * pending fatal signal.
930 for_each_process(p) {
931 if (!process_shares_mm(p, mm))
933 if (same_thread_group(p, victim))
935 if (is_global_init(p)) {
936 can_oom_reap = false;
937 set_bit(MMF_OOM_SKIP, &mm->flags);
938 pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n",
939 task_pid_nr(victim), victim->comm,
940 task_pid_nr(p), p->comm);
944 * No use_mm() user needs to read from the userspace so we are
947 if (unlikely(p->flags & PF_KTHREAD))
949 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
954 wake_oom_reaper(victim);
957 put_task_struct(victim);
962 * Determines whether the kernel must panic because of the panic_on_oom sysctl.
964 static void check_panic_on_oom(struct oom_control *oc,
965 enum oom_constraint constraint)
967 if (likely(!sysctl_panic_on_oom))
969 if (sysctl_panic_on_oom != 2) {
971 * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
972 * does not panic for cpuset, mempolicy, or memcg allocation
975 if (constraint != CONSTRAINT_NONE)
978 /* Do not panic for oom kills triggered by sysrq */
979 if (is_sysrq_oom(oc))
981 dump_header(oc, NULL);
982 panic("Out of memory: %s panic_on_oom is enabled\n",
983 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
986 static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
988 int register_oom_notifier(struct notifier_block *nb)
990 return blocking_notifier_chain_register(&oom_notify_list, nb);
992 EXPORT_SYMBOL_GPL(register_oom_notifier);
994 int unregister_oom_notifier(struct notifier_block *nb)
996 return blocking_notifier_chain_unregister(&oom_notify_list, nb);
998 EXPORT_SYMBOL_GPL(unregister_oom_notifier);
1001 * out_of_memory - kill the "best" process when we run out of memory
1002 * @oc: pointer to struct oom_control
1004 * If we run out of memory, we have the choice between either
1005 * killing a random task (bad), letting the system crash (worse)
1006 * OR try to be smart about which process to kill. Note that we
1007 * don't have to be perfect here, we just have to be good.
1009 bool out_of_memory(struct oom_control *oc)
1011 unsigned long freed = 0;
1012 enum oom_constraint constraint = CONSTRAINT_NONE;
1014 if (oom_killer_disabled)
1017 if (!is_memcg_oom(oc)) {
1018 blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
1020 /* Got some memory back in the last second. */
1025 * If current has a pending SIGKILL or is exiting, then automatically
1026 * select it. The goal is to allow it to allocate so that it may
1027 * quickly exit and free its memory.
1029 if (task_will_free_mem(current)) {
1030 mark_oom_victim(current);
1031 wake_oom_reaper(current);
1036 * The OOM killer does not compensate for IO-less reclaim.
1037 * pagefault_out_of_memory lost its gfp context so we have to
1038 * make sure exclude 0 mask - all other users should have at least
1039 * ___GFP_DIRECT_RECLAIM to get here.
1041 if (oc->gfp_mask && !(oc->gfp_mask & (__GFP_FS|__GFP_NOFAIL)))
1045 * Check if there were limitations on the allocation (only relevant for
1046 * NUMA and memcg) that may require different handling.
1048 constraint = constrained_alloc(oc);
1049 if (constraint != CONSTRAINT_MEMORY_POLICY)
1050 oc->nodemask = NULL;
1051 check_panic_on_oom(oc, constraint);
1053 if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
1054 current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
1055 current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
1056 get_task_struct(current);
1057 oc->chosen = current;
1058 oom_kill_process(oc, "Out of memory (oom_kill_allocating_task)");
1062 select_bad_process(oc);
1063 /* Found nothing?!?! Either we hang forever, or we panic. */
1064 if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
1065 dump_header(oc, NULL);
1066 panic("Out of memory and no killable processes...\n");
1068 if (oc->chosen && oc->chosen != (void *)-1UL) {
1069 oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" :
1070 "Memory cgroup out of memory");
1072 * Give the killed process a good chance to exit before trying
1073 * to allocate memory again.
1075 schedule_timeout_killable(1);
1077 return !!oc->chosen;
1081 * The pagefault handler calls here because some allocation has failed. We have
1082 * to take care of the memcg OOM here because this is the only safe context without
1083 * any locks held but let the oom killer triggered from the allocation context care
1084 * about the global OOM.
1086 void pagefault_out_of_memory(void)
1088 static DEFINE_RATELIMIT_STATE(pfoom_rs, DEFAULT_RATELIMIT_INTERVAL,
1089 DEFAULT_RATELIMIT_BURST);
1091 if (mem_cgroup_oom_synchronize(true))
1094 if (fatal_signal_pending(current))
1097 if (__ratelimit(&pfoom_rs))
1098 pr_warn("Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF\n");