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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...
7 *
8 * The routines in this file are used to kill a process when
Paul Jacksona49335c2005-09-06 15:18:09 -07009 * we're seriously out of memory. This gets called from __alloc_pages()
10 * in mm/page_alloc.c when we really run out of memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 *
12 * Since we won't call these routines often (on a well-configured
13 * machine) this file will double as a 'coding guide' and a signpost
14 * for newbie kernel hackers. It features several pointers to major
15 * kernel subsystems and hints as to where to find out what things do.
16 */
17
Alexey Dobriyan8ac773b2006-10-19 23:28:32 -070018#include <linux/oom.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/mm.h>
Alexey Dobriyan4e950f62007-07-30 02:36:13 +040020#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/sched.h>
22#include <linux/swap.h>
23#include <linux/timex.h>
24#include <linux/jiffies.h>
Paul Jacksonef08e3b2005-09-06 15:18:13 -070025#include <linux/cpuset.h>
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -070026#include <linux/module.h>
27#include <linux/notifier.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
KAMEZAWA Hiroyukifadd8fb2006-06-23 02:03:13 -070029int sysctl_panic_on_oom;
David Rientjesfe071d72007-10-16 23:25:56 -070030int sysctl_oom_kill_allocating_task;
David Rientjes098d7f12007-10-16 23:25:55 -070031static DEFINE_MUTEX(zone_scan_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/* #define DEBUG */
33
34/**
Dave Peterson6937a252006-06-23 02:03:13 -070035 * badness - calculate a numeric value for how bad this task has been
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 * @p: task struct of which task we should calculate
Paul Jacksona49335c2005-09-06 15:18:09 -070037 * @uptime: current uptime in seconds
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 *
39 * The formula used is relatively simple and documented inline in the
40 * function. The main rationale is that we want to select a good task
41 * to kill when we run out of memory.
42 *
43 * Good in this context means that:
44 * 1) we lose the minimum amount of work done
45 * 2) we recover a large amount of memory
46 * 3) we don't kill anything innocent of eating tons of memory
47 * 4) we want to kill the minimum amount of processes (one)
48 * 5) we try to kill the process the user expects us to kill, this
49 * algorithm has been meticulously tuned to meet the principle
50 * of least surprise ... (be careful when you change it)
51 */
52
53unsigned long badness(struct task_struct *p, unsigned long uptime)
54{
55 unsigned long points, cpu_time, run_time, s;
Andrew Morton97c2c9b82006-04-18 22:20:38 -070056 struct mm_struct *mm;
57 struct task_struct *child;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
Andrew Morton97c2c9b82006-04-18 22:20:38 -070059 task_lock(p);
60 mm = p->mm;
61 if (!mm) {
62 task_unlock(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 return 0;
Andrew Morton97c2c9b82006-04-18 22:20:38 -070064 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
66 /*
67 * The memory size of the process is the basis for the badness.
68 */
Andrew Morton97c2c9b82006-04-18 22:20:38 -070069 points = mm->total_vm;
70
71 /*
72 * After this unlock we can no longer dereference local variable `mm'
73 */
74 task_unlock(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
76 /*
Hugh Dickins7ba34852007-01-05 16:37:03 -080077 * swapoff can easily use up all memory, so kill those first.
78 */
79 if (p->flags & PF_SWAPOFF)
80 return ULONG_MAX;
81
82 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 * Processes which fork a lot of child processes are likely
Kurt Garloff9827b782006-02-20 18:27:51 -080084 * a good choice. We add half the vmsize of the children if they
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 * have an own mm. This prevents forking servers to flood the
Kurt Garloff9827b782006-02-20 18:27:51 -080086 * machine with an endless amount of children. In case a single
87 * child is eating the vast majority of memory, adding only half
88 * to the parents will make the child our kill candidate of choice.
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 */
Andrew Morton97c2c9b82006-04-18 22:20:38 -070090 list_for_each_entry(child, &p->children, sibling) {
91 task_lock(child);
92 if (child->mm != mm && child->mm)
93 points += child->mm->total_vm/2 + 1;
94 task_unlock(child);
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 }
96
97 /*
98 * CPU time is in tens of seconds and run time is in thousands
99 * of seconds. There is no particular reason for this other than
100 * that it turned out to work very well in practice.
101 */
102 cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
103 >> (SHIFT_HZ + 3);
104
105 if (uptime >= p->start_time.tv_sec)
106 run_time = (uptime - p->start_time.tv_sec) >> 10;
107 else
108 run_time = 0;
109
110 s = int_sqrt(cpu_time);
111 if (s)
112 points /= s;
113 s = int_sqrt(int_sqrt(run_time));
114 if (s)
115 points /= s;
116
117 /*
118 * Niced processes are most likely less important, so double
119 * their badness points.
120 */
121 if (task_nice(p) > 0)
122 points *= 2;
123
124 /*
125 * Superuser processes are usually more important, so we make it
126 * less likely that we kill those.
127 */
128 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_ADMIN) ||
129 p->uid == 0 || p->euid == 0)
130 points /= 4;
131
132 /*
133 * We don't want to kill a process with direct hardware access.
134 * Not only could that mess up the hardware, but usually users
135 * tend to only have this flag set on applications they think
136 * of as important.
137 */
138 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
139 points /= 4;
140
141 /*
Nick Piggin7887a3d2006-09-25 23:31:29 -0700142 * If p's nodes don't overlap ours, it may still help to kill p
143 * because p may have allocated or otherwise mapped memory on
144 * this node before. However it will be less likely.
145 */
146 if (!cpuset_excl_nodes_overlap(p))
147 points /= 8;
148
149 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 * Adjust the score by oomkilladj.
151 */
152 if (p->oomkilladj) {
Joshua N Pritikin9a827822007-05-06 14:49:07 -0700153 if (p->oomkilladj > 0) {
154 if (!points)
155 points = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 points <<= p->oomkilladj;
Joshua N Pritikin9a827822007-05-06 14:49:07 -0700157 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 points >>= -(p->oomkilladj);
159 }
160
161#ifdef DEBUG
David Rientjesa5e58a62007-07-31 00:37:32 -0700162 printk(KERN_DEBUG "OOMkill: task %d (%s) got %lu points\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 p->pid, p->comm, points);
164#endif
165 return points;
166}
167
168/*
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800169 * Determine the type of allocation constraint.
170 */
David Rientjes70e24bd2007-10-16 23:25:53 -0700171static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
172 gfp_t gfp_mask)
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800173{
174#ifdef CONFIG_NUMA
175 struct zone **z;
Christoph Lameteree31af52007-10-16 01:25:30 -0700176 nodemask_t nodes = node_states[N_HIGH_MEMORY];
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800177
178 for (z = zonelist->zones; *z; z++)
Paul Jackson02a0e532006-12-13 00:34:25 -0800179 if (cpuset_zone_allowed_softwall(*z, gfp_mask))
Christoph Lameter89fa3022006-09-25 23:31:55 -0700180 node_clear(zone_to_nid(*z), nodes);
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800181 else
182 return CONSTRAINT_CPUSET;
183
184 if (!nodes_empty(nodes))
185 return CONSTRAINT_MEMORY_POLICY;
186#endif
187
188 return CONSTRAINT_NONE;
189}
190
191/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 * Simple selection loop. We chose the process with the highest
193 * number of 'points'. We expect the caller will lock the tasklist.
194 *
195 * (not docbooked, we don't want this one cluttering up the manual)
196 */
Kurt Garloff9827b782006-02-20 18:27:51 -0800197static struct task_struct *select_bad_process(unsigned long *ppoints)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 struct task_struct *g, *p;
200 struct task_struct *chosen = NULL;
201 struct timespec uptime;
Kurt Garloff9827b782006-02-20 18:27:51 -0800202 *ppoints = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
204 do_posix_clock_monotonic_gettime(&uptime);
Paul Jacksona49335c2005-09-06 15:18:09 -0700205 do_each_thread(g, p) {
206 unsigned long points;
Paul Jacksona49335c2005-09-06 15:18:09 -0700207
Oleg Nesterov28324d12006-09-29 02:01:12 -0700208 /*
209 * skip kernel threads and tasks which have already released
210 * their mm.
211 */
Nick Piggin5081dde2006-09-25 23:31:32 -0700212 if (!p->mm)
213 continue;
Oleg Nesterov28324d12006-09-29 02:01:12 -0700214 /* skip the init task */
215 if (is_init(p))
Paul Jacksona49335c2005-09-06 15:18:09 -0700216 continue;
Paul Jacksonef08e3b2005-09-06 15:18:13 -0700217
Paul Jacksona49335c2005-09-06 15:18:09 -0700218 /*
Nick Pigginb78483a2006-09-29 02:01:14 -0700219 * This task already has access to memory reserves and is
220 * being killed. Don't allow any other task access to the
221 * memory reserve.
222 *
223 * Note: this may have a chance of deadlock if it gets
224 * blocked waiting for another task which itself is waiting
225 * for memory. Is there a better alternative?
226 */
227 if (test_tsk_thread_flag(p, TIF_MEMDIE))
228 return ERR_PTR(-1UL);
229
230 /*
Dave Peterson6937a252006-06-23 02:03:13 -0700231 * This is in the process of releasing memory so wait for it
Paul Jacksona49335c2005-09-06 15:18:09 -0700232 * to finish before killing some other task by mistake.
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700233 *
234 * However, if p is the current task, we allow the 'kill' to
235 * go ahead if it is exiting: this will simply set TIF_MEMDIE,
236 * which will allow it to gain access to memory reserves in
237 * the process of exiting and releasing its resources.
Nick Pigginb78483a2006-09-29 02:01:14 -0700238 * Otherwise we could get an easy OOM deadlock.
Paul Jacksona49335c2005-09-06 15:18:09 -0700239 */
Nick Pigginb78483a2006-09-29 02:01:14 -0700240 if (p->flags & PF_EXITING) {
241 if (p != current)
242 return ERR_PTR(-1UL);
243
Oleg Nesterov972c4ea2006-09-29 02:01:12 -0700244 chosen = p;
245 *ppoints = ULONG_MAX;
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700246 }
Oleg Nesterov972c4ea2006-09-29 02:01:12 -0700247
Nick Piggin4a3ede12006-09-25 23:31:30 -0700248 if (p->oomkilladj == OOM_DISABLE)
249 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250
Paul Jacksona49335c2005-09-06 15:18:09 -0700251 points = badness(p, uptime.tv_sec);
Kurt Garloff9827b782006-02-20 18:27:51 -0800252 if (points > *ppoints || !chosen) {
Paul Jacksona49335c2005-09-06 15:18:09 -0700253 chosen = p;
Kurt Garloff9827b782006-02-20 18:27:51 -0800254 *ppoints = points;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 }
Paul Jacksona49335c2005-09-06 15:18:09 -0700256 } while_each_thread(g, p);
Oleg Nesterov972c4ea2006-09-29 02:01:12 -0700257
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 return chosen;
259}
260
261/**
Ram Gupta5a291b982006-09-25 23:31:54 -0700262 * Send SIGKILL to the selected process irrespective of CAP_SYS_RAW_IO
263 * flag though it's unlikely that we select a process with CAP_SYS_RAW_IO
264 * set.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 */
Nick Pigginf3af38d2006-12-06 20:31:51 -0800266static void __oom_kill_task(struct task_struct *p, int verbose)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
Sukadev Bhattiproluf400e192006-09-29 02:00:07 -0700268 if (is_init(p)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 WARN_ON(1);
270 printk(KERN_WARNING "tried to kill init!\n");
271 return;
272 }
273
Oleg Nesterov01017a22006-09-29 02:01:13 -0700274 if (!p->mm) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 WARN_ON(1);
276 printk(KERN_WARNING "tried to kill an mm-less task!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 return;
278 }
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700279
Nick Pigginf3af38d2006-12-06 20:31:51 -0800280 if (verbose)
281 printk(KERN_ERR "Killed process %d (%s)\n", p->pid, p->comm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
283 /*
284 * We give our sacrificial lamb high priority and access to
285 * all the memory it needs. That way it should be able to
286 * exit() and clear out its resources quickly...
287 */
288 p->time_slice = HZ;
289 set_tsk_thread_flag(p, TIF_MEMDIE);
290
291 force_sig(SIGKILL, p);
292}
293
Nick Pigginf3af38d2006-12-06 20:31:51 -0800294static int oom_kill_task(struct task_struct *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295{
Dave Peterson01315922006-04-18 22:20:44 -0700296 struct mm_struct *mm;
Ingo Molnar36c8b582006-07-03 00:25:41 -0700297 struct task_struct *g, *q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298
Dave Peterson01315922006-04-18 22:20:44 -0700299 mm = p->mm;
300
301 /* WARNING: mm may not be dereferenced since we did not obtain its
302 * value from get_task_mm(p). This is OK since all we need to do is
303 * compare mm to q->mm below.
304 *
305 * Furthermore, even if mm contains a non-NULL value, p->mm may
306 * change to NULL at any time since we do not hold task_lock(p).
307 * However, this is of no concern to us.
308 */
309
Oleg Nesterov01017a22006-09-29 02:01:13 -0700310 if (mm == NULL)
Dave Peterson01315922006-04-18 22:20:44 -0700311 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312
Nick Pigginc33e0fc2006-12-06 20:31:50 -0800313 /*
314 * Don't kill the process if any threads are set to OOM_DISABLE
315 */
316 do_each_thread(g, q) {
Ankita Garg35ae8342007-03-16 13:38:33 -0800317 if (q->mm == mm && q->oomkilladj == OOM_DISABLE)
Nick Pigginc33e0fc2006-12-06 20:31:50 -0800318 return 1;
319 } while_each_thread(g, q);
320
Nick Pigginf3af38d2006-12-06 20:31:51 -0800321 __oom_kill_task(p, 1);
Nick Pigginc33e0fc2006-12-06 20:31:50 -0800322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 /*
324 * kill all processes that share the ->mm (i.e. all threads),
Nick Pigginf2a2a712006-12-06 20:31:52 -0800325 * but are in a different thread group. Don't let them have access
326 * to memory reserves though, otherwise we might deplete all memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 */
Nick Pigginc33e0fc2006-12-06 20:31:50 -0800328 do_each_thread(g, q) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 if (q->mm == mm && q->tgid != p->tgid)
David Rientjes650a7c92007-04-23 21:36:13 -0700330 force_sig(SIGKILL, q);
Nick Pigginc33e0fc2006-12-06 20:31:50 -0800331 } while_each_thread(g, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332
Dave Peterson01315922006-04-18 22:20:44 -0700333 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334}
335
Dave Peterson01315922006-04-18 22:20:44 -0700336static int oom_kill_process(struct task_struct *p, unsigned long points,
337 const char *message)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 struct task_struct *c;
340 struct list_head *tsk;
341
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700342 /*
343 * If the task is already exiting, don't alarm the sysadmin or kill
344 * its children or threads, just set TIF_MEMDIE so it can die quickly
345 */
346 if (p->flags & PF_EXITING) {
Nick Pigginf3af38d2006-12-06 20:31:51 -0800347 __oom_kill_task(p, 0);
Nick Piggin50ec3bb2006-09-25 23:31:29 -0700348 return 0;
349 }
350
Nick Pigginf3af38d2006-12-06 20:31:51 -0800351 printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
352 message, p->pid, p->comm, points);
353
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 /* Try to kill a child first */
355 list_for_each(tsk, &p->children) {
356 c = list_entry(tsk, struct task_struct, sibling);
357 if (c->mm == p->mm)
358 continue;
Nick Pigginf3af38d2006-12-06 20:31:51 -0800359 if (!oom_kill_task(c))
Dave Peterson01315922006-04-18 22:20:44 -0700360 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 }
Nick Pigginf3af38d2006-12-06 20:31:51 -0800362 return oom_kill_task(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363}
364
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700365static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
366
367int register_oom_notifier(struct notifier_block *nb)
368{
369 return blocking_notifier_chain_register(&oom_notify_list, nb);
370}
371EXPORT_SYMBOL_GPL(register_oom_notifier);
372
373int unregister_oom_notifier(struct notifier_block *nb)
374{
375 return blocking_notifier_chain_unregister(&oom_notify_list, nb);
376}
377EXPORT_SYMBOL_GPL(unregister_oom_notifier);
378
David Rientjes098d7f12007-10-16 23:25:55 -0700379/*
380 * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero
381 * if a parallel OOM killing is already taking place that includes a zone in
382 * the zonelist. Otherwise, locks all zones in the zonelist and returns 1.
383 */
384int try_set_zone_oom(struct zonelist *zonelist)
385{
386 struct zone **z;
387 int ret = 1;
388
389 z = zonelist->zones;
390
391 mutex_lock(&zone_scan_mutex);
392 do {
393 if (zone_is_oom_locked(*z)) {
394 ret = 0;
395 goto out;
396 }
397 } while (*(++z) != NULL);
398
399 /*
400 * Lock each zone in the zonelist under zone_scan_mutex so a parallel
401 * invocation of try_set_zone_oom() doesn't succeed when it shouldn't.
402 */
403 z = zonelist->zones;
404 do {
405 zone_set_flag(*z, ZONE_OOM_LOCKED);
406 } while (*(++z) != NULL);
407out:
408 mutex_unlock(&zone_scan_mutex);
409 return ret;
410}
411
412/*
413 * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed
414 * allocation attempts with zonelists containing them may now recall the OOM
415 * killer, if necessary.
416 */
417void clear_zonelist_oom(struct zonelist *zonelist)
418{
419 struct zone **z;
420
421 z = zonelist->zones;
422
423 mutex_lock(&zone_scan_mutex);
424 do {
425 zone_clear_flag(*z, ZONE_OOM_LOCKED);
426 } while (*(++z) != NULL);
427 mutex_unlock(&zone_scan_mutex);
428}
429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430/**
Dave Peterson6937a252006-06-23 02:03:13 -0700431 * out_of_memory - kill the "best" process when we run out of memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 *
433 * If we run out of memory, we have the choice between either
434 * killing a random task (bad), letting the system crash (worse)
435 * OR try to be smart about which process to kill. Note that we
436 * don't have to be perfect here, we just have to be good.
437 */
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800438void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439{
Ingo Molnar36c8b582006-07-03 00:25:41 -0700440 struct task_struct *p;
Andrew Mortond6713e02006-02-28 16:59:19 -0800441 unsigned long points = 0;
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700442 unsigned long freed = 0;
David Rientjes70e24bd2007-10-16 23:25:53 -0700443 enum oom_constraint constraint;
Martin Schwidefsky8bc719d2006-09-25 23:31:20 -0700444
445 blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
446 if (freed > 0)
447 /* Got some memory back in the last second. */
448 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449
Anton Blanchard42639262005-07-07 17:56:06 -0700450 if (printk_ratelimit()) {
Nick Pigginb72f1602006-09-25 23:31:32 -0700451 printk(KERN_WARNING "%s invoked oom-killer: "
452 "gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
453 current->comm, gfp_mask, order, current->oomkilladj);
Andrew Mortonb958f7d2006-02-01 03:05:51 -0800454 dump_stack();
Anton Blanchard42639262005-07-07 17:56:06 -0700455 show_mem();
456 }
Janet Morgan578c2fd2005-06-21 17:14:56 -0700457
Yasunori Goto2b744c02007-05-06 14:49:59 -0700458 if (sysctl_panic_on_oom == 2)
459 panic("out of memory. Compulsory panic_on_oom is selected.\n");
460
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800461 /*
462 * Check if there were limitations on the allocation (only relevant for
463 * NUMA) that may require different handling.
464 */
David Rientjes2b45ab32007-05-06 14:50:00 -0700465 constraint = constrained_alloc(zonelist, gfp_mask);
466 cpuset_lock();
467 read_lock(&tasklist_lock);
468
469 switch (constraint) {
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800470 case CONSTRAINT_MEMORY_POLICY:
Dave Peterson01315922006-04-18 22:20:44 -0700471 oom_kill_process(current, points,
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800472 "No available memory (MPOL_BIND)");
473 break;
474
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800475 case CONSTRAINT_NONE:
KAMEZAWA Hiroyukifadd8fb2006-06-23 02:03:13 -0700476 if (sysctl_panic_on_oom)
477 panic("out of memory. panic_on_oom is selected\n");
David Rientjesfe071d72007-10-16 23:25:56 -0700478 /* Fall-through */
479 case CONSTRAINT_CPUSET:
480 if (sysctl_oom_kill_allocating_task) {
481 oom_kill_process(current, points,
482 "Out of memory (oom_kill_allocating_task)");
483 break;
484 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485retry:
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800486 /*
487 * Rambo mode: Shoot down a process and hope it solves whatever
488 * issues we may have.
489 */
490 p = select_bad_process(&points);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800492 if (PTR_ERR(p) == -1UL)
493 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800495 /* Found nothing?!?! Either we hang forever, or we panic. */
496 if (!p) {
497 read_unlock(&tasklist_lock);
498 cpuset_unlock();
499 panic("Out of memory and no killable processes...\n");
500 }
501
Dave Peterson01315922006-04-18 22:20:44 -0700502 if (oom_kill_process(p, points, "Out of memory"))
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800503 goto retry;
504
505 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 }
507
Christoph Lameter9b0f8b02006-02-20 18:27:52 -0800508out:
Andrew Morton140ffce2006-03-02 02:54:28 -0800509 read_unlock(&tasklist_lock);
Paul Jackson505970b2006-01-14 13:21:06 -0800510 cpuset_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511
512 /*
513 * Give "p" a good chance of killing itself before we
Kirill Korotaev2f659f42006-01-08 01:01:05 -0800514 * retry to allocate memory unless "p" is current
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 */
Kirill Korotaev2f659f42006-01-08 01:01:05 -0800516 if (!test_thread_flag(TIF_MEMDIE))
Andrew Morton140ffce2006-03-02 02:54:28 -0800517 schedule_timeout_uninterruptible(1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518}