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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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...
David Rientjesa63d83f2010-08-09 17:19:46 -07007 * Copyright (C) 2010 Google, Inc.
8 * Rewritten by David Rientjes
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 *
10 * The routines in this file are used to kill a process when
Paul Jacksona49335c2005-09-06 15:18:09 -070011 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 *
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
Alexey Dobriyan8ac773b2006-10-19 23:28:32 -070020#include <linux/oom.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/mm.h>
Alexey Dobriyan4e950f62007-07-30 02:36:13 +040022#include <linux/err.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090023#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/sched.h>
25#include <linux/swap.h>
26#include <linux/timex.h>
27#include <linux/jiffies.h>
Paul Jacksonef08e3b2005-09-06 15:18:13 -070028#include <linux/cpuset.h>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040029#include <linux/export.h>
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -070030#include <linux/notifier.h>
Pavel Emelianovc7ba5c92008-02-07 00:13:58 -080031#include <linux/memcontrol.h>
David Rientjes6f48d0eb2010-08-09 17:18:52 -070032#include <linux/mempolicy.h>
David Howells5cd9c582008-08-14 11:37:28 +010033#include <linux/security.h>
David Rientjesedd45542011-03-22 16:30:12 -070034#include <linux/ptrace.h>
David Rientjesf660daa2011-10-31 17:07:07 -070035#include <linux/freezer.h>
KAMEZAWA Hiroyuki43d2b112012-01-10 15:08:09 -080036#include <linux/ftrace.h>
David Rientjesdc3f21e2012-03-21 16:33:47 -070037#include <linux/ratelimit.h>
Michal Hockoaac45362016-03-25 14:20:24 -070038#include <linux/kthread.h>
39#include <linux/init.h>
40
41#include <asm/tlb.h>
42#include "internal.h"
KAMEZAWA Hiroyuki43d2b112012-01-10 15:08:09 -080043
44#define CREATE_TRACE_POINTS
45#include <trace/events/oom.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
KAMEZAWA Hiroyukifadd8fb2006-06-23 02:03:13 -070047int sysctl_panic_on_oom;
David Rientjesfe071d72007-10-16 23:25:56 -070048int sysctl_oom_kill_allocating_task;
David Rientjesad915c42010-08-09 17:18:53 -070049int sysctl_oom_dump_tasks = 1;
Johannes Weinerdc564012015-06-24 16:57:19 -070050
51DEFINE_MUTEX(oom_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
David Rientjes6f48d0eb2010-08-09 17:18:52 -070053#ifdef CONFIG_NUMA
54/**
55 * has_intersects_mems_allowed() - check task eligiblity for kill
Oleg Nesterovad962442014-01-21 15:50:00 -080056 * @start: task struct of which task to consider
David Rientjes6f48d0eb2010-08-09 17:18:52 -070057 * @mask: nodemask passed to page allocator for mempolicy ooms
58 *
59 * Task eligibility is determined by whether or not a candidate task, @tsk,
60 * shares the same mempolicy nodes as current if it is bound by such a policy
61 * and whether or not it has the same set of allowed cpuset nodes.
KOSAKI Motohiro495789a2009-09-21 17:03:14 -070062 */
Oleg Nesterovad962442014-01-21 15:50:00 -080063static bool has_intersects_mems_allowed(struct task_struct *start,
David Rientjes6f48d0eb2010-08-09 17:18:52 -070064 const nodemask_t *mask)
KOSAKI Motohiro495789a2009-09-21 17:03:14 -070065{
Oleg Nesterovad962442014-01-21 15:50:00 -080066 struct task_struct *tsk;
67 bool ret = false;
KOSAKI Motohiro495789a2009-09-21 17:03:14 -070068
Oleg Nesterovad962442014-01-21 15:50:00 -080069 rcu_read_lock();
Oleg Nesterov1da4db02014-01-21 15:49:58 -080070 for_each_thread(start, tsk) {
David Rientjes6f48d0eb2010-08-09 17:18:52 -070071 if (mask) {
72 /*
73 * If this is a mempolicy constrained oom, tsk's
74 * cpuset is irrelevant. Only return true if its
75 * mempolicy intersects current, otherwise it may be
76 * needlessly killed.
77 */
Oleg Nesterovad962442014-01-21 15:50:00 -080078 ret = mempolicy_nodemask_intersects(tsk, mask);
David Rientjes6f48d0eb2010-08-09 17:18:52 -070079 } else {
80 /*
81 * This is not a mempolicy constrained oom, so only
82 * check the mems of tsk's cpuset.
83 */
Oleg Nesterovad962442014-01-21 15:50:00 -080084 ret = cpuset_mems_allowed_intersects(current, tsk);
David Rientjes6f48d0eb2010-08-09 17:18:52 -070085 }
Oleg Nesterovad962442014-01-21 15:50:00 -080086 if (ret)
87 break;
Oleg Nesterov1da4db02014-01-21 15:49:58 -080088 }
Oleg Nesterovad962442014-01-21 15:50:00 -080089 rcu_read_unlock();
KOSAKI Motohirodf1090a2010-08-09 17:19:39 -070090
Oleg Nesterovad962442014-01-21 15:50:00 -080091 return ret;
KOSAKI Motohiro495789a2009-09-21 17:03:14 -070092}
David Rientjes6f48d0eb2010-08-09 17:18:52 -070093#else
94static bool has_intersects_mems_allowed(struct task_struct *tsk,
95 const nodemask_t *mask)
96{
97 return true;
98}
99#endif /* CONFIG_NUMA */
KOSAKI Motohiro495789a2009-09-21 17:03:14 -0700100
David Rientjes6f48d0eb2010-08-09 17:18:52 -0700101/*
102 * The process p may have detached its own ->mm while exiting or through
103 * use_mm(), but one or more of its subthreads may still have a valid
104 * pointer. Return p, or any of its subthreads with a valid ->mm, with
105 * task_lock() held.
106 */
KAMEZAWA Hiroyuki158e0a22010-08-10 18:03:00 -0700107struct task_struct *find_lock_task_mm(struct task_struct *p)
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700108{
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800109 struct task_struct *t;
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700110
Oleg Nesterov4d4048b2014-01-21 15:50:01 -0800111 rcu_read_lock();
112
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800113 for_each_thread(p, t) {
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700114 task_lock(t);
115 if (likely(t->mm))
Oleg Nesterov4d4048b2014-01-21 15:50:01 -0800116 goto found;
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700117 task_unlock(t);
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800118 }
Oleg Nesterov4d4048b2014-01-21 15:50:01 -0800119 t = NULL;
120found:
121 rcu_read_unlock();
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700122
Oleg Nesterov4d4048b2014-01-21 15:50:01 -0800123 return t;
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700124}
125
Yaowei Baidb2a0dd2015-11-06 16:28:06 -0800126/*
127 * order == -1 means the oom kill is required by sysrq, otherwise only
128 * for display purposes.
129 */
130static inline bool is_sysrq_oom(struct oom_control *oc)
131{
132 return oc->order == -1;
133}
134
KOSAKI Motohiroab290ad2010-08-09 17:19:35 -0700135/* return true if the task is not adequate as candidate victim task. */
David Rientjese85bfd32010-09-22 13:05:10 -0700136static bool oom_unkillable_task(struct task_struct *p,
Johannes Weiner2314b422014-12-10 15:44:33 -0800137 struct mem_cgroup *memcg, const nodemask_t *nodemask)
KOSAKI Motohiroab290ad2010-08-09 17:19:35 -0700138{
139 if (is_global_init(p))
140 return true;
141 if (p->flags & PF_KTHREAD)
142 return true;
143
144 /* When mem_cgroup_out_of_memory() and p is not member of the group */
Johannes Weiner72835c82012-01-12 17:18:32 -0800145 if (memcg && !task_in_mem_cgroup(p, memcg))
KOSAKI Motohiroab290ad2010-08-09 17:19:35 -0700146 return true;
147
148 /* p may not have freeable memory in nodemask */
149 if (!has_intersects_mems_allowed(p, nodemask))
150 return true;
151
152 return false;
153}
154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155/**
David Rientjesa63d83f2010-08-09 17:19:46 -0700156 * oom_badness - heuristic function to determine which candidate task to kill
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 * @p: task struct of which task we should calculate
David Rientjesa63d83f2010-08-09 17:19:46 -0700158 * @totalpages: total present RAM allowed for page allocation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 *
David Rientjesa63d83f2010-08-09 17:19:46 -0700160 * The heuristic for determining which task to kill is made to be as simple and
161 * predictable as possible. The goal is to return the highest value for the
162 * task consuming the most memory to avoid subsequent oom failures.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 */
David Rientjesa7f638f2012-05-29 15:06:47 -0700164unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
165 const nodemask_t *nodemask, unsigned long totalpages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166{
David Rientjes1e11ad82012-06-08 13:21:26 -0700167 long points;
David Rientjes61eafb02012-06-20 12:52:58 -0700168 long adj;
KOSAKI Motohiro28b83c52009-09-21 17:03:13 -0700169
Johannes Weiner72835c82012-01-12 17:18:32 -0800170 if (oom_unkillable_task(p, memcg, nodemask))
KOSAKI Motohiro26ebc982010-08-09 17:19:37 -0700171 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700173 p = find_lock_task_mm(p);
174 if (!p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 return 0;
176
Michal Hockobb8a4b72016-05-20 16:57:18 -0700177 /*
178 * Do not even consider tasks which are explicitly marked oom
179 * unkillable or have been already oom reaped.
180 */
David Rientjesa9c58b902012-12-11 16:02:54 -0800181 adj = (long)p->signal->oom_score_adj;
Michal Hockobb8a4b72016-05-20 16:57:18 -0700182 if (adj == OOM_SCORE_ADJ_MIN ||
183 test_bit(MMF_OOM_REAPED, &p->mm->flags)) {
Michal Hocko5aecc852011-11-15 14:36:07 -0800184 task_unlock(p);
185 return 0;
186 }
187
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 /*
David Rientjesa63d83f2010-08-09 17:19:46 -0700189 * The baseline for the badness score is the proportion of RAM that each
KOSAKI Motohirof755a042011-04-27 15:26:50 -0700190 * task's rss, pagetable and swap space use.
David Rientjesa63d83f2010-08-09 17:19:46 -0700191 */
Kirill A. Shutemovdc6c9a32015-02-11 15:26:50 -0800192 points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
193 atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm);
Andrew Morton97c2c9b82006-04-18 22:20:38 -0700194 task_unlock(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
196 /*
David Rientjesa63d83f2010-08-09 17:19:46 -0700197 * Root processes get 3% bonus, just like the __vm_enough_memory()
198 * implementation used by LSMs.
Hugh Dickins7ba34852007-01-05 16:37:03 -0800199 */
David Rientjesa63d83f2010-08-09 17:19:46 -0700200 if (has_capability_noaudit(p, CAP_SYS_ADMIN))
David Rientjes778c14a2014-01-30 15:46:11 -0800201 points -= (points * 3) / 100;
Hugh Dickins7ba34852007-01-05 16:37:03 -0800202
David Rientjes61eafb02012-06-20 12:52:58 -0700203 /* Normalize to oom_score_adj units */
204 adj *= totalpages / 1000;
205 points += adj;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206
David Rientjesf19e8aa2010-09-22 13:04:52 -0700207 /*
David Rientjesa7f638f2012-05-29 15:06:47 -0700208 * Never return 0 for an eligible task regardless of the root bonus and
209 * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
David Rientjesf19e8aa2010-09-22 13:04:52 -0700210 */
David Rientjes1e11ad82012-06-08 13:21:26 -0700211 return points > 0 ? points : 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212}
213
214/*
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800215 * Determine the type of allocation constraint.
216 */
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800217#ifdef CONFIG_NUMA
David Rientjes6e0fc462015-09-08 15:00:36 -0700218static enum oom_constraint constrained_alloc(struct oom_control *oc,
219 unsigned long *totalpages)
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800220{
Mel Gorman54a6eb52008-04-28 02:12:16 -0700221 struct zone *zone;
Mel Gormandd1a2392008-04-28 02:12:17 -0700222 struct zoneref *z;
David Rientjes6e0fc462015-09-08 15:00:36 -0700223 enum zone_type high_zoneidx = gfp_zone(oc->gfp_mask);
David Rientjesa63d83f2010-08-09 17:19:46 -0700224 bool cpuset_limited = false;
225 int nid;
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800226
David Rientjesa63d83f2010-08-09 17:19:46 -0700227 /* Default to all available memory */
228 *totalpages = totalram_pages + total_swap_pages;
229
David Rientjes6e0fc462015-09-08 15:00:36 -0700230 if (!oc->zonelist)
David Rientjesa63d83f2010-08-09 17:19:46 -0700231 return CONSTRAINT_NONE;
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800232 /*
233 * Reach here only when __GFP_NOFAIL is used. So, we should avoid
234 * to kill current.We have to random task kill in this case.
235 * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
236 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700237 if (oc->gfp_mask & __GFP_THISNODE)
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800238 return CONSTRAINT_NONE;
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800239
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800240 /*
David Rientjesa63d83f2010-08-09 17:19:46 -0700241 * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
242 * the page allocator means a mempolicy is in effect. Cpuset policy
243 * is enforced in get_page_from_freelist().
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800244 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700245 if (oc->nodemask &&
246 !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
David Rientjesa63d83f2010-08-09 17:19:46 -0700247 *totalpages = total_swap_pages;
David Rientjes6e0fc462015-09-08 15:00:36 -0700248 for_each_node_mask(nid, *oc->nodemask)
David Rientjesa63d83f2010-08-09 17:19:46 -0700249 *totalpages += node_spanned_pages(nid);
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800250 return CONSTRAINT_MEMORY_POLICY;
David Rientjesa63d83f2010-08-09 17:19:46 -0700251 }
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800252
253 /* Check this allocation failure is caused by cpuset's wall function */
David Rientjes6e0fc462015-09-08 15:00:36 -0700254 for_each_zone_zonelist_nodemask(zone, z, oc->zonelist,
255 high_zoneidx, oc->nodemask)
256 if (!cpuset_zone_allowed(zone, oc->gfp_mask))
David Rientjesa63d83f2010-08-09 17:19:46 -0700257 cpuset_limited = true;
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800258
David Rientjesa63d83f2010-08-09 17:19:46 -0700259 if (cpuset_limited) {
260 *totalpages = total_swap_pages;
261 for_each_node_mask(nid, cpuset_current_mems_allowed)
262 *totalpages += node_spanned_pages(nid);
263 return CONSTRAINT_CPUSET;
264 }
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800265 return CONSTRAINT_NONE;
266}
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800267#else
David Rientjes6e0fc462015-09-08 15:00:36 -0700268static enum oom_constraint constrained_alloc(struct oom_control *oc,
269 unsigned long *totalpages)
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800270{
David Rientjesa63d83f2010-08-09 17:19:46 -0700271 *totalpages = totalram_pages + total_swap_pages;
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800272 return CONSTRAINT_NONE;
273}
274#endif
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800275
David Rientjes6e0fc462015-09-08 15:00:36 -0700276enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
277 struct task_struct *task, unsigned long totalpages)
David Rientjes462607e2012-07-31 16:43:40 -0700278{
David Rientjes6e0fc462015-09-08 15:00:36 -0700279 if (oom_unkillable_task(task, NULL, oc->nodemask))
David Rientjes462607e2012-07-31 16:43:40 -0700280 return OOM_SCAN_CONTINUE;
281
282 /*
283 * This task already has access to memory reserves and is being killed.
284 * Don't allow any other task to have access to the reserves.
285 */
Tetsuo Handaf44666b2016-05-20 16:57:27 -0700286 if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims))
287 return OOM_SCAN_ABORT;
David Rientjes462607e2012-07-31 16:43:40 -0700288
David Rientjese1e12d22012-12-11 16:02:56 -0800289 /*
290 * If task is allocating a lot of memory and has been marked to be
291 * killed first if it triggers an oom, then select it.
292 */
293 if (oom_task_origin(task))
294 return OOM_SCAN_SELECT;
295
David Rientjes462607e2012-07-31 16:43:40 -0700296 return OOM_SCAN_OK;
297}
298
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800299/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 * Simple selection loop. We chose the process with the highest
Rusty Russell6b4f2b52013-07-15 11:24:08 +0930301 * number of 'points'. Returns -1 on scan abort.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700303static struct task_struct *select_bad_process(struct oom_control *oc,
304 unsigned int *ppoints, unsigned long totalpages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305{
Tetsuo Handaf44666b2016-05-20 16:57:27 -0700306 struct task_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 struct task_struct *chosen = NULL;
David Rientjesa7f638f2012-05-29 15:06:47 -0700308 unsigned long chosen_points = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309
David Rientjes6b0c81b2012-07-31 16:43:45 -0700310 rcu_read_lock();
Tetsuo Handaf44666b2016-05-20 16:57:27 -0700311 for_each_process(p) {
David Rientjesa63d83f2010-08-09 17:19:46 -0700312 unsigned int points;
Paul Jacksona49335c2005-09-06 15:18:09 -0700313
David Rientjes6e0fc462015-09-08 15:00:36 -0700314 switch (oom_scan_process_thread(oc, p, totalpages)) {
David Rientjes462607e2012-07-31 16:43:40 -0700315 case OOM_SCAN_SELECT:
316 chosen = p;
317 chosen_points = ULONG_MAX;
318 /* fall through */
319 case OOM_SCAN_CONTINUE:
Andrey Vagin30e2b412011-03-22 16:30:11 -0700320 continue;
David Rientjes462607e2012-07-31 16:43:40 -0700321 case OOM_SCAN_ABORT:
David Rientjes6b0c81b2012-07-31 16:43:45 -0700322 rcu_read_unlock();
Rusty Russell6b4f2b52013-07-15 11:24:08 +0930323 return (struct task_struct *)(-1UL);
David Rientjes462607e2012-07-31 16:43:40 -0700324 case OOM_SCAN_OK:
325 break;
326 };
David Rientjes6e0fc462015-09-08 15:00:36 -0700327 points = oom_badness(p, NULL, oc->nodemask, totalpages);
David Rientjesd49ad932014-01-23 15:53:34 -0800328 if (!points || points < chosen_points)
329 continue;
David Rientjesd49ad932014-01-23 15:53:34 -0800330
331 chosen = p;
332 chosen_points = points;
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800333 }
David Rientjes6b0c81b2012-07-31 16:43:45 -0700334 if (chosen)
335 get_task_struct(chosen);
336 rcu_read_unlock();
Oleg Nesterov972c4ea2006-09-29 02:01:12 -0700337
David Rientjesa7f638f2012-05-29 15:06:47 -0700338 *ppoints = chosen_points * 1000 / totalpages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 return chosen;
340}
341
342/**
Randy Dunlap1b578df2008-03-19 17:00:42 -0700343 * dump_tasks - dump current memory state of all system tasks
Wanpeng Lidad75572012-06-20 12:53:01 -0700344 * @memcg: current's memory controller, if constrained
David Rientjese85bfd32010-09-22 13:05:10 -0700345 * @nodemask: nodemask passed to page allocator for mempolicy ooms
Randy Dunlap1b578df2008-03-19 17:00:42 -0700346 *
David Rientjese85bfd32010-09-22 13:05:10 -0700347 * Dumps the current memory state of all eligible tasks. Tasks not in the same
348 * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
349 * are not shown.
David Rientjesde34d962012-07-31 16:42:56 -0700350 * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes,
351 * swapents, oom_score_adj value, and name.
David Rientjesfef1bdd2008-02-07 00:14:07 -0800352 */
Johannes Weiner2314b422014-12-10 15:44:33 -0800353static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
David Rientjesfef1bdd2008-02-07 00:14:07 -0800354{
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700355 struct task_struct *p;
356 struct task_struct *task;
David Rientjesfef1bdd2008-02-07 00:14:07 -0800357
Kirill A. Shutemovdc6c9a32015-02-11 15:26:50 -0800358 pr_info("[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name\n");
David Rientjes6b0c81b2012-07-31 16:43:45 -0700359 rcu_read_lock();
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700360 for_each_process(p) {
Johannes Weiner72835c82012-01-12 17:18:32 -0800361 if (oom_unkillable_task(p, memcg, nodemask))
David Rientjesfef1bdd2008-02-07 00:14:07 -0800362 continue;
363
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700364 task = find_lock_task_mm(p);
365 if (!task) {
David Rientjes6d2661e2009-05-28 14:34:19 -0700366 /*
David Rientjes74ab7f12010-08-09 17:18:46 -0700367 * This is a kthread or all of p's threads have already
368 * detached their mm's. There's no need to report
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700369 * them; they can't be oom killed anyway.
David Rientjes6d2661e2009-05-28 14:34:19 -0700370 */
David Rientjes6d2661e2009-05-28 14:34:19 -0700371 continue;
372 }
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700373
Kirill A. Shutemovdc6c9a32015-02-11 15:26:50 -0800374 pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu %5hd %s\n",
Eric W. Biederman078de5f2012-02-08 07:00:08 -0800375 task->pid, from_kuid(&init_user_ns, task_uid(task)),
376 task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800377 atomic_long_read(&task->mm->nr_ptes),
Kirill A. Shutemovdc6c9a32015-02-11 15:26:50 -0800378 mm_nr_pmds(task->mm),
David Rientjesde34d962012-07-31 16:42:56 -0700379 get_mm_counter(task->mm, MM_SWAPENTS),
David Rientjesa63d83f2010-08-09 17:19:46 -0700380 task->signal->oom_score_adj, task->comm);
KOSAKI Motohiroc55db952010-08-09 17:18:46 -0700381 task_unlock(task);
382 }
David Rientjes6b0c81b2012-07-31 16:43:45 -0700383 rcu_read_unlock();
David Rientjesfef1bdd2008-02-07 00:14:07 -0800384}
385
David Rientjes6e0fc462015-09-08 15:00:36 -0700386static void dump_header(struct oom_control *oc, struct task_struct *p,
387 struct mem_cgroup *memcg)
David Rientjes1b604d72009-12-14 17:57:47 -0800388{
Joe Perches756a025f02016-03-17 14:19:47 -0700389 pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n",
Vlastimil Babkaa0795cd2016-03-15 14:56:05 -0700390 current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order,
David Rientjesa63d83f2010-08-09 17:19:46 -0700391 current->signal->oom_score_adj);
Vlastimil Babkaa0795cd2016-03-15 14:56:05 -0700392
David Rientjesda39da32015-11-05 18:48:05 -0800393 cpuset_print_current_mems_allowed();
David Rientjes1b604d72009-12-14 17:57:47 -0800394 dump_stack();
Sha Zhengju58cf1882013-02-22 16:32:05 -0800395 if (memcg)
396 mem_cgroup_print_oom_info(memcg, p);
397 else
398 show_mem(SHOW_MEM_FILTER_NODES);
David Rientjes1b604d72009-12-14 17:57:47 -0800399 if (sysctl_oom_dump_tasks)
David Rientjes6e0fc462015-09-08 15:00:36 -0700400 dump_tasks(memcg, oc->nodemask);
David Rientjes1b604d72009-12-14 17:57:47 -0800401}
402
Michal Hocko5695be12014-10-20 18:12:32 +0200403/*
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800404 * Number of OOM victims in flight
Michal Hocko5695be12014-10-20 18:12:32 +0200405 */
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800406static atomic_t oom_victims = ATOMIC_INIT(0);
407static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait);
Michal Hocko5695be12014-10-20 18:12:32 +0200408
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800409bool oom_killer_disabled __read_mostly;
Michal Hocko5695be12014-10-20 18:12:32 +0200410
Michal Hockobc448e82016-03-25 14:20:30 -0700411#define K(x) ((x) << (PAGE_SHIFT-10))
412
Michal Hocko3ef22df2016-05-19 17:13:12 -0700413/*
414 * task->mm can be NULL if the task is the exited group leader. So to
415 * determine whether the task is using a particular mm, we examine all the
416 * task's threads: if one of those is using this mm then this task was also
417 * using it.
418 */
419static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
420{
421 struct task_struct *t;
422
423 for_each_thread(p, t) {
424 struct mm_struct *t_mm = READ_ONCE(t->mm);
425 if (t_mm)
426 return t_mm == mm;
427 }
428 return false;
429}
430
431
Michal Hockoaac45362016-03-25 14:20:24 -0700432#ifdef CONFIG_MMU
433/*
434 * OOM Reaper kernel thread which tries to reap the memory used by the OOM
435 * victim (if that is possible) to help the OOM killer to move on.
436 */
437static struct task_struct *oom_reaper_th;
Michal Hockoaac45362016-03-25 14:20:24 -0700438static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
Vladimir Davydov29c696e2016-03-25 14:20:39 -0700439static struct task_struct *oom_reaper_list;
Michal Hocko03049262016-03-25 14:20:33 -0700440static DEFINE_SPINLOCK(oom_reaper_lock);
441
Michal Hocko36324a92016-03-25 14:20:27 -0700442static bool __oom_reap_task(struct task_struct *tsk)
Michal Hockoaac45362016-03-25 14:20:24 -0700443{
444 struct mmu_gather tlb;
445 struct vm_area_struct *vma;
Michal Hockoe2fe1452016-05-27 14:27:35 -0700446 struct mm_struct *mm = NULL;
Michal Hocko36324a92016-03-25 14:20:27 -0700447 struct task_struct *p;
Michal Hockoaac45362016-03-25 14:20:24 -0700448 struct zap_details details = {.check_swap_entries = true,
449 .ignore_dirty = true};
450 bool ret = true;
451
Michal Hocko36324a92016-03-25 14:20:27 -0700452 /*
Michal Hockoe2fe1452016-05-27 14:27:35 -0700453 * We have to make sure to not race with the victim exit path
454 * and cause premature new oom victim selection:
455 * __oom_reap_task exit_mm
456 * atomic_inc_not_zero
457 * mmput
458 * atomic_dec_and_test
459 * exit_oom_victim
460 * [...]
461 * out_of_memory
462 * select_bad_process
463 * # no TIF_MEMDIE task selects new victim
464 * unmap_page_range # frees some memory
465 */
466 mutex_lock(&oom_lock);
467
468 /*
Michal Hocko36324a92016-03-25 14:20:27 -0700469 * Make sure we find the associated mm_struct even when the particular
470 * thread has already terminated and cleared its mm.
471 * We might have race with exit path so consider our work done if there
472 * is no mm.
473 */
474 p = find_lock_task_mm(tsk);
475 if (!p)
Michal Hockoe2fe1452016-05-27 14:27:35 -0700476 goto unlock_oom;
Michal Hockoaac45362016-03-25 14:20:24 -0700477
Michal Hocko36324a92016-03-25 14:20:27 -0700478 mm = p->mm;
479 if (!atomic_inc_not_zero(&mm->mm_users)) {
480 task_unlock(p);
Michal Hockoe2fe1452016-05-27 14:27:35 -0700481 goto unlock_oom;
Michal Hocko36324a92016-03-25 14:20:27 -0700482 }
483
484 task_unlock(p);
485
Michal Hockoaac45362016-03-25 14:20:24 -0700486 if (!down_read_trylock(&mm->mmap_sem)) {
487 ret = false;
Michal Hockoe2fe1452016-05-27 14:27:35 -0700488 goto unlock_oom;
Michal Hockoaac45362016-03-25 14:20:24 -0700489 }
490
491 tlb_gather_mmu(&tlb, mm, 0, -1);
492 for (vma = mm->mmap ; vma; vma = vma->vm_next) {
493 if (is_vm_hugetlb_page(vma))
494 continue;
495
496 /*
497 * mlocked VMAs require explicit munlocking before unmap.
498 * Let's keep it simple here and skip such VMAs.
499 */
500 if (vma->vm_flags & VM_LOCKED)
501 continue;
502
503 /*
504 * Only anonymous pages have a good chance to be dropped
505 * without additional steps which we cannot afford as we
506 * are OOM already.
507 *
508 * We do not even care about fs backed pages because all
509 * which are reclaimable have already been reclaimed and
510 * we do not want to block exit_mmap by keeping mm ref
511 * count elevated without a good reason.
512 */
513 if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED))
514 unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end,
515 &details);
516 }
517 tlb_finish_mmu(&tlb, 0, -1);
Michal Hockobc448e82016-03-25 14:20:30 -0700518 pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
519 task_pid_nr(tsk), tsk->comm,
520 K(get_mm_counter(mm, MM_ANONPAGES)),
521 K(get_mm_counter(mm, MM_FILEPAGES)),
522 K(get_mm_counter(mm, MM_SHMEMPAGES)));
Michal Hockoaac45362016-03-25 14:20:24 -0700523 up_read(&mm->mmap_sem);
Michal Hocko36324a92016-03-25 14:20:27 -0700524
525 /*
Michal Hocko449d7772016-05-19 17:13:15 -0700526 * This task can be safely ignored because we cannot do much more
527 * to release its memory.
Michal Hocko36324a92016-03-25 14:20:27 -0700528 */
Michal Hockobb8a4b72016-05-20 16:57:18 -0700529 set_bit(MMF_OOM_REAPED, &mm->flags);
Michal Hockoe2fe1452016-05-27 14:27:35 -0700530unlock_oom:
531 mutex_unlock(&oom_lock);
Michal Hockoec8d7c12016-05-20 16:57:21 -0700532 /*
533 * Drop our reference but make sure the mmput slow path is called from a
534 * different context because we shouldn't risk we get stuck there and
535 * put the oom_reaper out of the way.
536 */
Michal Hockoe2fe1452016-05-27 14:27:35 -0700537 if (mm)
538 mmput_async(mm);
Michal Hockoaac45362016-03-25 14:20:24 -0700539 return ret;
540}
541
Michal Hockobc448e82016-03-25 14:20:30 -0700542#define MAX_OOM_REAP_RETRIES 10
Michal Hocko36324a92016-03-25 14:20:27 -0700543static void oom_reap_task(struct task_struct *tsk)
Michal Hockoaac45362016-03-25 14:20:24 -0700544{
545 int attempts = 0;
546
547 /* Retry the down_read_trylock(mmap_sem) a few times */
Michal Hockobc448e82016-03-25 14:20:30 -0700548 while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task(tsk))
Michal Hockoaac45362016-03-25 14:20:24 -0700549 schedule_timeout_idle(HZ/10);
550
Michal Hockobc448e82016-03-25 14:20:30 -0700551 if (attempts > MAX_OOM_REAP_RETRIES) {
552 pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
553 task_pid_nr(tsk), tsk->comm);
554 debug_show_all_locks();
555 }
556
Michal Hocko449d7772016-05-19 17:13:15 -0700557 /*
558 * Clear TIF_MEMDIE because the task shouldn't be sitting on a
559 * reasonably reclaimable memory anymore or it is not a good candidate
560 * for the oom victim right now because it cannot release its memory
561 * itself nor by the oom reaper.
562 */
563 tsk->oom_reaper_list = NULL;
564 exit_oom_victim(tsk);
565
Michal Hockoaac45362016-03-25 14:20:24 -0700566 /* Drop a reference taken by wake_oom_reaper */
Michal Hocko36324a92016-03-25 14:20:27 -0700567 put_task_struct(tsk);
Michal Hockoaac45362016-03-25 14:20:24 -0700568}
569
570static int oom_reaper(void *unused)
571{
Michal Hockoe2679602016-03-25 14:20:41 -0700572 set_freezable();
573
Michal Hockoaac45362016-03-25 14:20:24 -0700574 while (true) {
Michal Hocko03049262016-03-25 14:20:33 -0700575 struct task_struct *tsk = NULL;
Michal Hockoaac45362016-03-25 14:20:24 -0700576
Vladimir Davydov29c696e2016-03-25 14:20:39 -0700577 wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
Michal Hocko03049262016-03-25 14:20:33 -0700578 spin_lock(&oom_reaper_lock);
Vladimir Davydov29c696e2016-03-25 14:20:39 -0700579 if (oom_reaper_list != NULL) {
580 tsk = oom_reaper_list;
581 oom_reaper_list = tsk->oom_reaper_list;
Michal Hocko03049262016-03-25 14:20:33 -0700582 }
583 spin_unlock(&oom_reaper_lock);
584
585 if (tsk)
586 oom_reap_task(tsk);
Michal Hockoaac45362016-03-25 14:20:24 -0700587 }
588
589 return 0;
590}
591
Michal Hocko36324a92016-03-25 14:20:27 -0700592static void wake_oom_reaper(struct task_struct *tsk)
Michal Hockoaac45362016-03-25 14:20:24 -0700593{
Michal Hockoaf8e15c2016-04-01 14:31:34 -0700594 if (!oom_reaper_th)
595 return;
596
597 /* tsk is already queued? */
598 if (tsk == oom_reaper_list || tsk->oom_reaper_list)
Michal Hockoaac45362016-03-25 14:20:24 -0700599 return;
600
Michal Hocko36324a92016-03-25 14:20:27 -0700601 get_task_struct(tsk);
Michal Hockoaac45362016-03-25 14:20:24 -0700602
Michal Hocko03049262016-03-25 14:20:33 -0700603 spin_lock(&oom_reaper_lock);
Vladimir Davydov29c696e2016-03-25 14:20:39 -0700604 tsk->oom_reaper_list = oom_reaper_list;
605 oom_reaper_list = tsk;
Michal Hocko03049262016-03-25 14:20:33 -0700606 spin_unlock(&oom_reaper_lock);
607 wake_up(&oom_reaper_wait);
Michal Hockoaac45362016-03-25 14:20:24 -0700608}
609
Michal Hocko3ef22df2016-05-19 17:13:12 -0700610/* Check if we can reap the given task. This has to be called with stable
611 * tsk->mm
612 */
613void try_oom_reaper(struct task_struct *tsk)
614{
615 struct mm_struct *mm = tsk->mm;
616 struct task_struct *p;
617
618 if (!mm)
619 return;
620
621 /*
622 * There might be other threads/processes which are either not
623 * dying or even not killable.
624 */
625 if (atomic_read(&mm->mm_users) > 1) {
626 rcu_read_lock();
627 for_each_process(p) {
628 bool exiting;
629
630 if (!process_shares_mm(p, mm))
631 continue;
Michal Hocko3ef22df2016-05-19 17:13:12 -0700632 if (fatal_signal_pending(p))
633 continue;
634
635 /*
636 * If the task is exiting make sure the whole thread group
637 * is exiting and cannot acces mm anymore.
638 */
639 spin_lock_irq(&p->sighand->siglock);
640 exiting = signal_group_exit(p->signal);
641 spin_unlock_irq(&p->sighand->siglock);
642 if (exiting)
643 continue;
644
645 /* Give up */
646 rcu_read_unlock();
647 return;
648 }
649 rcu_read_unlock();
650 }
651
652 wake_oom_reaper(tsk);
653}
654
Michal Hockoaac45362016-03-25 14:20:24 -0700655static int __init oom_init(void)
656{
657 oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper");
658 if (IS_ERR(oom_reaper_th)) {
659 pr_err("Unable to start OOM reaper %ld. Continuing regardless\n",
660 PTR_ERR(oom_reaper_th));
661 oom_reaper_th = NULL;
662 }
663 return 0;
664}
665subsys_initcall(oom_init)
666#else
Michal Hocko36324a92016-03-25 14:20:27 -0700667static void wake_oom_reaper(struct task_struct *tsk)
Michal Hockoaac45362016-03-25 14:20:24 -0700668{
669}
670#endif
671
Michal Hocko49550b62015-02-11 15:26:12 -0800672/**
Johannes Weiner16e95192015-06-24 16:57:07 -0700673 * mark_oom_victim - mark the given task as OOM victim
Michal Hocko49550b62015-02-11 15:26:12 -0800674 * @tsk: task to mark
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800675 *
Johannes Weinerdc564012015-06-24 16:57:19 -0700676 * Has to be called with oom_lock held and never after
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800677 * oom has been disabled already.
Michal Hocko49550b62015-02-11 15:26:12 -0800678 */
Johannes Weiner16e95192015-06-24 16:57:07 -0700679void mark_oom_victim(struct task_struct *tsk)
Michal Hocko49550b62015-02-11 15:26:12 -0800680{
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800681 WARN_ON(oom_killer_disabled);
682 /* OOM killer might race with memcg OOM */
683 if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
684 return;
Tetsuo Handaf44666b2016-05-20 16:57:27 -0700685 atomic_inc(&tsk->signal->oom_victims);
Michal Hocko63a8ca92015-02-11 15:26:15 -0800686 /*
687 * Make sure that the task is woken up from uninterruptible sleep
688 * if it is frozen because OOM killer wouldn't be able to free
689 * any memory and livelock. freezing_slow_path will tell the freezer
690 * that TIF_MEMDIE tasks should be ignored.
691 */
692 __thaw_task(tsk);
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800693 atomic_inc(&oom_victims);
Michal Hocko49550b62015-02-11 15:26:12 -0800694}
695
696/**
Johannes Weiner16e95192015-06-24 16:57:07 -0700697 * exit_oom_victim - note the exit of an OOM victim
Michal Hocko49550b62015-02-11 15:26:12 -0800698 */
Michal Hocko36324a92016-03-25 14:20:27 -0700699void exit_oom_victim(struct task_struct *tsk)
Michal Hocko49550b62015-02-11 15:26:12 -0800700{
Michal Hocko36324a92016-03-25 14:20:27 -0700701 if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
702 return;
Tetsuo Handaf44666b2016-05-20 16:57:27 -0700703 atomic_dec(&tsk->signal->oom_victims);
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800704
Johannes Weinerc38f1022015-06-24 16:57:13 -0700705 if (!atomic_dec_return(&oom_victims))
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800706 wake_up_all(&oom_victims_wait);
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800707}
708
709/**
710 * oom_killer_disable - disable OOM killer
711 *
712 * Forces all page allocations to fail rather than trigger OOM killer.
713 * Will block and wait until all OOM victims are killed.
714 *
715 * The function cannot be called when there are runnable user tasks because
716 * the userspace would see unexpected allocation failures as a result. Any
717 * new usage of this function should be consulted with MM people.
718 *
719 * Returns true if successful and false if the OOM killer cannot be
720 * disabled.
721 */
722bool oom_killer_disable(void)
723{
724 /*
Tetsuo Handa6afcf282016-03-17 14:20:45 -0700725 * Make sure to not race with an ongoing OOM killer. Check that the
726 * current is not killed (possibly due to sharing the victim's memory).
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800727 */
Tetsuo Handa6afcf282016-03-17 14:20:45 -0700728 if (mutex_lock_killable(&oom_lock))
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800729 return false;
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800730 oom_killer_disabled = true;
Johannes Weinerdc564012015-06-24 16:57:19 -0700731 mutex_unlock(&oom_lock);
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800732
733 wait_event(oom_victims_wait, !atomic_read(&oom_victims));
734
735 return true;
736}
737
738/**
739 * oom_killer_enable - enable OOM killer
740 */
741void oom_killer_enable(void)
742{
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800743 oom_killer_disabled = false;
Michal Hocko49550b62015-02-11 15:26:12 -0800744}
745
Oleg Nesterov4d7b3392015-11-05 18:48:26 -0800746/*
David Rientjes6b0c81b2012-07-31 16:43:45 -0700747 * Must be called while holding a reference to p, which will be released upon
748 * returning.
749 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700750void oom_kill_process(struct oom_control *oc, struct task_struct *p,
David Rientjes9cbb78b2012-07-31 16:43:44 -0700751 unsigned int points, unsigned long totalpages,
David Rientjes6e0fc462015-09-08 15:00:36 -0700752 struct mem_cgroup *memcg, const char *message)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753{
Linus Torvalds52d3c032011-03-14 15:17:07 -0700754 struct task_struct *victim = p;
David Rientjes5e9d8342010-08-09 17:18:51 -0700755 struct task_struct *child;
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800756 struct task_struct *t;
David Rientjes647f2bd2012-03-21 16:33:46 -0700757 struct mm_struct *mm;
Linus Torvalds52d3c032011-03-14 15:17:07 -0700758 unsigned int victim_points = 0;
David Rientjesdc3f21e2012-03-21 16:33:47 -0700759 static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
760 DEFAULT_RATELIMIT_BURST);
Tetsuo Handabb299022016-03-25 14:20:44 -0700761 bool can_oom_reap = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700763 /*
764 * If the task is already exiting, don't alarm the sysadmin or kill
765 * its children or threads, just set TIF_MEMDIE so it can die quickly
766 */
Michal Hocko83363b92015-02-11 15:24:56 -0800767 task_lock(p);
768 if (p->mm && task_will_free_mem(p)) {
Johannes Weiner16e95192015-06-24 16:57:07 -0700769 mark_oom_victim(p);
Michal Hocko3ef22df2016-05-19 17:13:12 -0700770 try_oom_reaper(p);
Michal Hocko83363b92015-02-11 15:24:56 -0800771 task_unlock(p);
David Rientjes6b0c81b2012-07-31 16:43:45 -0700772 put_task_struct(p);
David Rientjes2a1c9b12012-03-21 16:33:46 -0700773 return;
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700774 }
Michal Hocko83363b92015-02-11 15:24:56 -0800775 task_unlock(p);
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700776
David Rientjesdc3f21e2012-03-21 16:33:47 -0700777 if (__ratelimit(&oom_rs))
David Rientjes6e0fc462015-09-08 15:00:36 -0700778 dump_header(oc, p, memcg);
David Rientjes8447d952012-03-21 16:33:47 -0700779
Wang Longf0d66472015-06-24 16:58:01 -0700780 pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
David Rientjes5e9d8342010-08-09 17:18:51 -0700781 message, task_pid_nr(p), p->comm, points);
Nick Pigginf3af38d2006-12-06 20:31:51 -0800782
David Rientjes5e9d8342010-08-09 17:18:51 -0700783 /*
784 * If any of p's children has a different mm and is eligible for kill,
David Rientjes11239832011-07-25 17:12:17 -0700785 * the one with the highest oom_badness() score is sacrificed for its
David Rientjes5e9d8342010-08-09 17:18:51 -0700786 * parent. This attempts to lose the minimal amount of work done while
787 * still freeing memory.
788 */
David Rientjes6b0c81b2012-07-31 16:43:45 -0700789 read_lock(&tasklist_lock);
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800790 for_each_thread(p, t) {
David Rientjes5e9d8342010-08-09 17:18:51 -0700791 list_for_each_entry(child, &t->children, sibling) {
David Rientjesa63d83f2010-08-09 17:19:46 -0700792 unsigned int child_points;
David Rientjes5e9d8342010-08-09 17:18:51 -0700793
Oleg Nesterov4d7b3392015-11-05 18:48:26 -0800794 if (process_shares_mm(child, p->mm))
David Rientjesedd45542011-03-22 16:30:12 -0700795 continue;
David Rientjesa63d83f2010-08-09 17:19:46 -0700796 /*
797 * oom_badness() returns 0 if the thread is unkillable
798 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700799 child_points = oom_badness(child, memcg, oc->nodemask,
David Rientjesa63d83f2010-08-09 17:19:46 -0700800 totalpages);
David Rientjes5e9d8342010-08-09 17:18:51 -0700801 if (child_points > victim_points) {
David Rientjes6b0c81b2012-07-31 16:43:45 -0700802 put_task_struct(victim);
David Rientjes5e9d8342010-08-09 17:18:51 -0700803 victim = child;
804 victim_points = child_points;
David Rientjes6b0c81b2012-07-31 16:43:45 -0700805 get_task_struct(victim);
David Rientjes5e9d8342010-08-09 17:18:51 -0700806 }
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700807 }
Oleg Nesterov1da4db02014-01-21 15:49:58 -0800808 }
David Rientjes6b0c81b2012-07-31 16:43:45 -0700809 read_unlock(&tasklist_lock);
Oleg Nesterovdd8e8f42010-08-09 17:18:45 -0700810
David Rientjes6b0c81b2012-07-31 16:43:45 -0700811 p = find_lock_task_mm(victim);
812 if (!p) {
David Rientjes6b0c81b2012-07-31 16:43:45 -0700813 put_task_struct(victim);
David Rientjes647f2bd2012-03-21 16:33:46 -0700814 return;
David Rientjes6b0c81b2012-07-31 16:43:45 -0700815 } else if (victim != p) {
816 get_task_struct(p);
817 put_task_struct(victim);
818 victim = p;
819 }
David Rientjes647f2bd2012-03-21 16:33:46 -0700820
Tetsuo Handa880b7682015-11-05 18:47:51 -0800821 /* Get a reference to safely compare mm after task_unlock(victim) */
David Rientjes647f2bd2012-03-21 16:33:46 -0700822 mm = victim->mm;
Tetsuo Handa880b7682015-11-05 18:47:51 -0800823 atomic_inc(&mm->mm_count);
Tetsuo Handa426fb5e2015-11-05 18:47:44 -0800824 /*
825 * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
826 * the OOM victim from depleting the memory reserves from the user
827 * space under its control.
828 */
829 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
Johannes Weiner16e95192015-06-24 16:57:07 -0700830 mark_oom_victim(victim);
Jerome Marchandeca56ff2016-01-14 15:19:26 -0800831 pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
David Rientjes647f2bd2012-03-21 16:33:46 -0700832 task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
833 K(get_mm_counter(victim->mm, MM_ANONPAGES)),
Jerome Marchandeca56ff2016-01-14 15:19:26 -0800834 K(get_mm_counter(victim->mm, MM_FILEPAGES)),
835 K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
David Rientjes647f2bd2012-03-21 16:33:46 -0700836 task_unlock(victim);
837
838 /*
839 * Kill all user processes sharing victim->mm in other thread groups, if
840 * any. They don't get access to memory reserves, though, to avoid
841 * depletion of all memory. This prevents mm->mmap_sem livelock when an
842 * oom killed thread cannot exit because it requires the semaphore and
843 * its contended by another thread trying to allocate memory itself.
844 * That thread will now get access to memory reserves since it has a
845 * pending fatal signal.
846 */
Oleg Nesterov4d4048b2014-01-21 15:50:01 -0800847 rcu_read_lock();
Oleg Nesterovc3190252015-11-05 18:48:23 -0800848 for_each_process(p) {
Oleg Nesterov4d7b3392015-11-05 18:48:26 -0800849 if (!process_shares_mm(p, mm))
Oleg Nesterovc3190252015-11-05 18:48:23 -0800850 continue;
851 if (same_thread_group(p, victim))
852 continue;
Michal Hockoaac45362016-03-25 14:20:24 -0700853 if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) ||
854 p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
855 /*
856 * We cannot use oom_reaper for the mm shared by this
857 * process because it wouldn't get killed and so the
858 * memory might be still used.
859 */
860 can_oom_reap = false;
Oleg Nesterovc3190252015-11-05 18:48:23 -0800861 continue;
Michal Hockoaac45362016-03-25 14:20:24 -0700862 }
Oleg Nesterovc3190252015-11-05 18:48:23 -0800863 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
864 }
David Rientjes6b0c81b2012-07-31 16:43:45 -0700865 rcu_read_unlock();
David Rientjes647f2bd2012-03-21 16:33:46 -0700866
Michal Hockoaac45362016-03-25 14:20:24 -0700867 if (can_oom_reap)
Michal Hocko36324a92016-03-25 14:20:27 -0700868 wake_oom_reaper(victim);
Michal Hockoaac45362016-03-25 14:20:24 -0700869
Tetsuo Handa880b7682015-11-05 18:47:51 -0800870 mmdrop(mm);
David Rientjes6b0c81b2012-07-31 16:43:45 -0700871 put_task_struct(victim);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872}
David Rientjes647f2bd2012-03-21 16:33:46 -0700873#undef K
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874
David Rientjes309ed882010-08-09 17:18:54 -0700875/*
876 * Determines whether the kernel must panic because of the panic_on_oom sysctl.
877 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700878void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
Balasubramani Vivekanandan2415b9f2015-04-14 15:48:18 -0700879 struct mem_cgroup *memcg)
David Rientjes309ed882010-08-09 17:18:54 -0700880{
881 if (likely(!sysctl_panic_on_oom))
882 return;
883 if (sysctl_panic_on_oom != 2) {
884 /*
885 * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
886 * does not panic for cpuset, mempolicy, or memcg allocation
887 * failures.
888 */
889 if (constraint != CONSTRAINT_NONE)
890 return;
891 }
David Rientjes071a4be2015-09-08 15:00:42 -0700892 /* Do not panic for oom kills triggered by sysrq */
Yaowei Baidb2a0dd2015-11-06 16:28:06 -0800893 if (is_sysrq_oom(oc))
David Rientjes071a4be2015-09-08 15:00:42 -0700894 return;
David Rientjes6e0fc462015-09-08 15:00:36 -0700895 dump_header(oc, NULL, memcg);
David Rientjes309ed882010-08-09 17:18:54 -0700896 panic("Out of memory: %s panic_on_oom is enabled\n",
897 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
898}
899
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700900static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
901
902int register_oom_notifier(struct notifier_block *nb)
903{
904 return blocking_notifier_chain_register(&oom_notify_list, nb);
905}
906EXPORT_SYMBOL_GPL(register_oom_notifier);
907
908int unregister_oom_notifier(struct notifier_block *nb)
909{
910 return blocking_notifier_chain_unregister(&oom_notify_list, nb);
911}
912EXPORT_SYMBOL_GPL(unregister_oom_notifier);
913
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914/**
David Rientjes6e0fc462015-09-08 15:00:36 -0700915 * out_of_memory - kill the "best" process when we run out of memory
916 * @oc: pointer to struct oom_control
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 *
918 * If we run out of memory, we have the choice between either
919 * killing a random task (bad), letting the system crash (worse)
920 * OR try to be smart about which process to kill. Note that we
921 * don't have to be perfect here, we just have to be good.
922 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700923bool out_of_memory(struct oom_control *oc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924{
David Rientjes0aad4b32010-08-09 17:18:59 -0700925 struct task_struct *p;
David Rientjesa63d83f2010-08-09 17:19:46 -0700926 unsigned long totalpages;
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700927 unsigned long freed = 0;
David Rientjes9cbb78b2012-07-31 16:43:44 -0700928 unsigned int uninitialized_var(points);
David Rientjese3658932010-08-09 17:18:55 -0700929 enum oom_constraint constraint = CONSTRAINT_NONE;
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700930
Johannes Weinerdc564012015-06-24 16:57:19 -0700931 if (oom_killer_disabled)
932 return false;
933
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700934 blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
935 if (freed > 0)
936 /* Got some memory back in the last second. */
David Rientjes75e8f8b2015-09-08 15:00:47 -0700937 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938
David Rientjes7b98c2e2010-08-09 17:18:48 -0700939 /*
David Rientjes9ff48682012-12-11 16:01:30 -0800940 * If current has a pending SIGKILL or is exiting, then automatically
941 * select it. The goal is to allow it to allocate so that it may
942 * quickly exit and free its memory.
Tetsuo Handad7a94e72015-02-11 15:24:54 -0800943 *
944 * But don't select if current has already released its mm and cleared
945 * TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
David Rientjes7b98c2e2010-08-09 17:18:48 -0700946 */
Tetsuo Handad7a94e72015-02-11 15:24:54 -0800947 if (current->mm &&
948 (fatal_signal_pending(current) || task_will_free_mem(current))) {
Johannes Weiner16e95192015-06-24 16:57:07 -0700949 mark_oom_victim(current);
Michal Hocko3ef22df2016-05-19 17:13:12 -0700950 try_oom_reaper(current);
David Rientjes75e8f8b2015-09-08 15:00:47 -0700951 return true;
David Rientjes7b98c2e2010-08-09 17:18:48 -0700952 }
953
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800954 /*
Michal Hocko3da88fb2016-05-19 17:13:09 -0700955 * The OOM killer does not compensate for IO-less reclaim.
956 * pagefault_out_of_memory lost its gfp context so we have to
957 * make sure exclude 0 mask - all other users should have at least
958 * ___GFP_DIRECT_RECLAIM to get here.
959 */
960 if (oc->gfp_mask && !(oc->gfp_mask & (__GFP_FS|__GFP_NOFAIL)))
961 return true;
962
963 /*
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800964 * Check if there were limitations on the allocation (only relevant for
965 * NUMA) that may require different handling.
966 */
David Rientjes6e0fc462015-09-08 15:00:36 -0700967 constraint = constrained_alloc(oc, &totalpages);
968 if (constraint != CONSTRAINT_MEMORY_POLICY)
969 oc->nodemask = NULL;
970 check_panic_on_oom(oc, constraint, NULL);
David Rientjes0aad4b32010-08-09 17:18:59 -0700971
David Rientjes121d1ba2012-07-31 16:42:55 -0700972 if (sysctl_oom_kill_allocating_task && current->mm &&
David Rientjes6e0fc462015-09-08 15:00:36 -0700973 !oom_unkillable_task(current, NULL, oc->nodemask) &&
David Rientjes121d1ba2012-07-31 16:42:55 -0700974 current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
David Rientjes6b0c81b2012-07-31 16:43:45 -0700975 get_task_struct(current);
David Rientjes6e0fc462015-09-08 15:00:36 -0700976 oom_kill_process(oc, current, 0, totalpages, NULL,
David Rientjes2a1c9b12012-03-21 16:33:46 -0700977 "Out of memory (oom_kill_allocating_task)");
David Rientjes75e8f8b2015-09-08 15:00:47 -0700978 return true;
David Rientjes0aad4b32010-08-09 17:18:59 -0700979 }
980
David Rientjes6e0fc462015-09-08 15:00:36 -0700981 p = select_bad_process(oc, &points, totalpages);
David Rientjes0aad4b32010-08-09 17:18:59 -0700982 /* Found nothing?!?! Either we hang forever, or we panic. */
Yaowei Baidb2a0dd2015-11-06 16:28:06 -0800983 if (!p && !is_sysrq_oom(oc)) {
David Rientjes6e0fc462015-09-08 15:00:36 -0700984 dump_header(oc, NULL, NULL);
David Rientjes0aad4b32010-08-09 17:18:59 -0700985 panic("Out of memory and no killable processes...\n");
986 }
David Rientjes071a4be2015-09-08 15:00:42 -0700987 if (p && p != (void *)-1UL) {
David Rientjes6e0fc462015-09-08 15:00:36 -0700988 oom_kill_process(oc, p, points, totalpages, NULL,
989 "Out of memory");
David Rientjes75e8f8b2015-09-08 15:00:47 -0700990 /*
991 * Give the killed process a good chance to exit before trying
992 * to allocate memory again.
993 */
David Rientjes4f774b92012-07-31 16:42:37 -0700994 schedule_timeout_killable(1);
David Rientjes75e8f8b2015-09-08 15:00:47 -0700995 }
Johannes Weinerdc564012015-06-24 16:57:19 -0700996 return true;
Michal Hockoc32b3cb2015-02-11 15:26:24 -0800997}
998
David Rientjese3658932010-08-09 17:18:55 -0700999/*
1000 * The pagefault handler calls here because it is out of memory, so kill a
David Rientjesefacd022012-12-12 13:52:06 -08001001 * memory-hogging task. If any populated zone has ZONE_OOM_LOCKED set, a
1002 * parallel oom killing is already in progress so do nothing.
David Rientjese3658932010-08-09 17:18:55 -07001003 */
1004void pagefault_out_of_memory(void)
1005{
David Rientjes6e0fc462015-09-08 15:00:36 -07001006 struct oom_control oc = {
1007 .zonelist = NULL,
1008 .nodemask = NULL,
1009 .gfp_mask = 0,
1010 .order = 0,
David Rientjes6e0fc462015-09-08 15:00:36 -07001011 };
1012
Johannes Weiner49426422013-10-16 13:46:59 -07001013 if (mem_cgroup_oom_synchronize(true))
Johannes Weinerdc564012015-06-24 16:57:19 -07001014 return;
Johannes Weiner3812c8c2013-09-12 15:13:44 -07001015
Johannes Weinerdc564012015-06-24 16:57:19 -07001016 if (!mutex_trylock(&oom_lock))
1017 return;
Michal Hockoc32b3cb2015-02-11 15:26:24 -08001018
David Rientjes6e0fc462015-09-08 15:00:36 -07001019 if (!out_of_memory(&oc)) {
Johannes Weinerdc564012015-06-24 16:57:19 -07001020 /*
1021 * There shouldn't be any user tasks runnable while the
1022 * OOM killer is disabled, so the current task has to
1023 * be a racing OOM victim for which oom_killer_disable()
1024 * is waiting for.
1025 */
1026 WARN_ON(test_thread_flag(TIF_MEMDIE));
David Rientjese3658932010-08-09 17:18:55 -07001027 }
Johannes Weinerdc564012015-06-24 16:57:19 -07001028
1029 mutex_unlock(&oom_lock);
David Rientjese3658932010-08-09 17:18:55 -07001030}