Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/oom_kill.c | |
3 | * | |
4 | * Copyright (C) 1998,2000 Rik van Riel | |
5 | * Thanks go out to Claus Fischer for some serious inspiration and | |
6 | * for goading me into coding this file... | |
7 | * | |
8 | * The routines in this file are used to kill a process when | |
a49335cc PJ |
9 | * 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. | |
1da177e4 LT |
11 | * |
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 | ||
8ac773b4 | 18 | #include <linux/oom.h> |
1da177e4 | 19 | #include <linux/mm.h> |
4e950f6f | 20 | #include <linux/err.h> |
1da177e4 LT |
21 | #include <linux/sched.h> |
22 | #include <linux/swap.h> | |
23 | #include <linux/timex.h> | |
24 | #include <linux/jiffies.h> | |
ef08e3b4 | 25 | #include <linux/cpuset.h> |
8bc719d3 MS |
26 | #include <linux/module.h> |
27 | #include <linux/notifier.h> | |
c7ba5c9e | 28 | #include <linux/memcontrol.h> |
5cd9c58f | 29 | #include <linux/security.h> |
1da177e4 | 30 | |
fadd8fbd | 31 | int sysctl_panic_on_oom; |
fe071d7e | 32 | int sysctl_oom_kill_allocating_task; |
fef1bdd6 | 33 | int sysctl_oom_dump_tasks; |
c7d4caeb | 34 | static DEFINE_SPINLOCK(zone_scan_lock); |
1da177e4 LT |
35 | /* #define DEBUG */ |
36 | ||
37 | /** | |
6937a25c | 38 | * badness - calculate a numeric value for how bad this task has been |
1da177e4 | 39 | * @p: task struct of which task we should calculate |
a49335cc | 40 | * @uptime: current uptime in seconds |
1da177e4 LT |
41 | * |
42 | * The formula used is relatively simple and documented inline in the | |
43 | * function. The main rationale is that we want to select a good task | |
44 | * to kill when we run out of memory. | |
45 | * | |
46 | * Good in this context means that: | |
47 | * 1) we lose the minimum amount of work done | |
48 | * 2) we recover a large amount of memory | |
49 | * 3) we don't kill anything innocent of eating tons of memory | |
50 | * 4) we want to kill the minimum amount of processes (one) | |
51 | * 5) we try to kill the process the user expects us to kill, this | |
52 | * algorithm has been meticulously tuned to meet the principle | |
53 | * of least surprise ... (be careful when you change it) | |
54 | */ | |
55 | ||
97d87c97 | 56 | unsigned long badness(struct task_struct *p, unsigned long uptime) |
1da177e4 LT |
57 | { |
58 | unsigned long points, cpu_time, run_time, s; | |
97c2c9b8 AM |
59 | struct mm_struct *mm; |
60 | struct task_struct *child; | |
1da177e4 | 61 | |
97c2c9b8 AM |
62 | task_lock(p); |
63 | mm = p->mm; | |
64 | if (!mm) { | |
65 | task_unlock(p); | |
1da177e4 | 66 | return 0; |
97c2c9b8 | 67 | } |
1da177e4 LT |
68 | |
69 | /* | |
70 | * The memory size of the process is the basis for the badness. | |
71 | */ | |
97c2c9b8 AM |
72 | points = mm->total_vm; |
73 | ||
74 | /* | |
75 | * After this unlock we can no longer dereference local variable `mm' | |
76 | */ | |
77 | task_unlock(p); | |
1da177e4 | 78 | |
7ba34859 HD |
79 | /* |
80 | * swapoff can easily use up all memory, so kill those first. | |
81 | */ | |
82 | if (p->flags & PF_SWAPOFF) | |
83 | return ULONG_MAX; | |
84 | ||
1da177e4 LT |
85 | /* |
86 | * Processes which fork a lot of child processes are likely | |
9827b781 | 87 | * a good choice. We add half the vmsize of the children if they |
1da177e4 | 88 | * have an own mm. This prevents forking servers to flood the |
9827b781 KG |
89 | * machine with an endless amount of children. In case a single |
90 | * child is eating the vast majority of memory, adding only half | |
91 | * to the parents will make the child our kill candidate of choice. | |
1da177e4 | 92 | */ |
97c2c9b8 AM |
93 | list_for_each_entry(child, &p->children, sibling) { |
94 | task_lock(child); | |
95 | if (child->mm != mm && child->mm) | |
96 | points += child->mm->total_vm/2 + 1; | |
97 | task_unlock(child); | |
1da177e4 LT |
98 | } |
99 | ||
100 | /* | |
101 | * CPU time is in tens of seconds and run time is in thousands | |
102 | * of seconds. There is no particular reason for this other than | |
103 | * that it turned out to work very well in practice. | |
104 | */ | |
105 | cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime)) | |
106 | >> (SHIFT_HZ + 3); | |
107 | ||
108 | if (uptime >= p->start_time.tv_sec) | |
109 | run_time = (uptime - p->start_time.tv_sec) >> 10; | |
110 | else | |
111 | run_time = 0; | |
112 | ||
113 | s = int_sqrt(cpu_time); | |
114 | if (s) | |
115 | points /= s; | |
116 | s = int_sqrt(int_sqrt(run_time)); | |
117 | if (s) | |
118 | points /= s; | |
119 | ||
120 | /* | |
121 | * Niced processes are most likely less important, so double | |
122 | * their badness points. | |
123 | */ | |
124 | if (task_nice(p) > 0) | |
125 | points *= 2; | |
126 | ||
127 | /* | |
128 | * Superuser processes are usually more important, so we make it | |
129 | * less likely that we kill those. | |
130 | */ | |
a2f2945a EP |
131 | if (has_capability_noaudit(p, CAP_SYS_ADMIN) || |
132 | has_capability_noaudit(p, CAP_SYS_RESOURCE)) | |
1da177e4 LT |
133 | points /= 4; |
134 | ||
135 | /* | |
136 | * We don't want to kill a process with direct hardware access. | |
137 | * Not only could that mess up the hardware, but usually users | |
138 | * tend to only have this flag set on applications they think | |
139 | * of as important. | |
140 | */ | |
a2f2945a | 141 | if (has_capability_noaudit(p, CAP_SYS_RAWIO)) |
1da177e4 LT |
142 | points /= 4; |
143 | ||
7887a3da NP |
144 | /* |
145 | * If p's nodes don't overlap ours, it may still help to kill p | |
146 | * because p may have allocated or otherwise mapped memory on | |
147 | * this node before. However it will be less likely. | |
148 | */ | |
bbe373f2 | 149 | if (!cpuset_mems_allowed_intersects(current, p)) |
7887a3da NP |
150 | points /= 8; |
151 | ||
1da177e4 LT |
152 | /* |
153 | * Adjust the score by oomkilladj. | |
154 | */ | |
155 | if (p->oomkilladj) { | |
9a82782f JP |
156 | if (p->oomkilladj > 0) { |
157 | if (!points) | |
158 | points = 1; | |
1da177e4 | 159 | points <<= p->oomkilladj; |
9a82782f | 160 | } else |
1da177e4 LT |
161 | points >>= -(p->oomkilladj); |
162 | } | |
163 | ||
164 | #ifdef DEBUG | |
a5e58a61 | 165 | printk(KERN_DEBUG "OOMkill: task %d (%s) got %lu points\n", |
1da177e4 LT |
166 | p->pid, p->comm, points); |
167 | #endif | |
168 | return points; | |
169 | } | |
170 | ||
9b0f8b04 CL |
171 | /* |
172 | * Determine the type of allocation constraint. | |
173 | */ | |
70e24bdf DR |
174 | static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist, |
175 | gfp_t gfp_mask) | |
9b0f8b04 CL |
176 | { |
177 | #ifdef CONFIG_NUMA | |
54a6eb5c | 178 | struct zone *zone; |
dd1a239f | 179 | struct zoneref *z; |
54a6eb5c | 180 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); |
ee31af5d | 181 | nodemask_t nodes = node_states[N_HIGH_MEMORY]; |
9b0f8b04 | 182 | |
54a6eb5c MG |
183 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) |
184 | if (cpuset_zone_allowed_softwall(zone, gfp_mask)) | |
185 | node_clear(zone_to_nid(zone), nodes); | |
9b0f8b04 CL |
186 | else |
187 | return CONSTRAINT_CPUSET; | |
188 | ||
189 | if (!nodes_empty(nodes)) | |
190 | return CONSTRAINT_MEMORY_POLICY; | |
191 | #endif | |
192 | ||
193 | return CONSTRAINT_NONE; | |
194 | } | |
195 | ||
1da177e4 LT |
196 | /* |
197 | * Simple selection loop. We chose the process with the highest | |
198 | * number of 'points'. We expect the caller will lock the tasklist. | |
199 | * | |
200 | * (not docbooked, we don't want this one cluttering up the manual) | |
201 | */ | |
c7ba5c9e PE |
202 | static struct task_struct *select_bad_process(unsigned long *ppoints, |
203 | struct mem_cgroup *mem) | |
1da177e4 | 204 | { |
1da177e4 LT |
205 | struct task_struct *g, *p; |
206 | struct task_struct *chosen = NULL; | |
207 | struct timespec uptime; | |
9827b781 | 208 | *ppoints = 0; |
1da177e4 LT |
209 | |
210 | do_posix_clock_monotonic_gettime(&uptime); | |
a49335cc PJ |
211 | do_each_thread(g, p) { |
212 | unsigned long points; | |
a49335cc | 213 | |
28324d1d ON |
214 | /* |
215 | * skip kernel threads and tasks which have already released | |
216 | * their mm. | |
217 | */ | |
5081dde3 NP |
218 | if (!p->mm) |
219 | continue; | |
28324d1d | 220 | /* skip the init task */ |
b460cbc5 | 221 | if (is_global_init(p)) |
a49335cc | 222 | continue; |
4c4a2214 DR |
223 | if (mem && !task_in_mem_cgroup(p, mem)) |
224 | continue; | |
ef08e3b4 | 225 | |
b78483a4 NP |
226 | /* |
227 | * This task already has access to memory reserves and is | |
228 | * being killed. Don't allow any other task access to the | |
229 | * memory reserve. | |
230 | * | |
231 | * Note: this may have a chance of deadlock if it gets | |
232 | * blocked waiting for another task which itself is waiting | |
233 | * for memory. Is there a better alternative? | |
234 | */ | |
235 | if (test_tsk_thread_flag(p, TIF_MEMDIE)) | |
236 | return ERR_PTR(-1UL); | |
237 | ||
a49335cc | 238 | /* |
6937a25c | 239 | * This is in the process of releasing memory so wait for it |
a49335cc | 240 | * to finish before killing some other task by mistake. |
50ec3bbf NP |
241 | * |
242 | * However, if p is the current task, we allow the 'kill' to | |
243 | * go ahead if it is exiting: this will simply set TIF_MEMDIE, | |
244 | * which will allow it to gain access to memory reserves in | |
245 | * the process of exiting and releasing its resources. | |
b78483a4 | 246 | * Otherwise we could get an easy OOM deadlock. |
a49335cc | 247 | */ |
b78483a4 NP |
248 | if (p->flags & PF_EXITING) { |
249 | if (p != current) | |
250 | return ERR_PTR(-1UL); | |
251 | ||
972c4ea5 ON |
252 | chosen = p; |
253 | *ppoints = ULONG_MAX; | |
50ec3bbf | 254 | } |
972c4ea5 | 255 | |
4a3ede10 NP |
256 | if (p->oomkilladj == OOM_DISABLE) |
257 | continue; | |
a49335cc | 258 | |
97d87c97 | 259 | points = badness(p, uptime.tv_sec); |
9827b781 | 260 | if (points > *ppoints || !chosen) { |
a49335cc | 261 | chosen = p; |
9827b781 | 262 | *ppoints = points; |
1da177e4 | 263 | } |
a49335cc | 264 | } while_each_thread(g, p); |
972c4ea5 | 265 | |
1da177e4 LT |
266 | return chosen; |
267 | } | |
268 | ||
fef1bdd6 | 269 | /** |
1b578df0 RD |
270 | * dump_tasks - dump current memory state of all system tasks |
271 | * @mem: target memory controller | |
272 | * | |
fef1bdd6 DR |
273 | * Dumps the current memory state of all system tasks, excluding kernel threads. |
274 | * State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj | |
275 | * score, and name. | |
276 | * | |
277 | * If the actual is non-NULL, only tasks that are a member of the mem_cgroup are | |
278 | * shown. | |
279 | * | |
280 | * Call with tasklist_lock read-locked. | |
281 | */ | |
282 | static void dump_tasks(const struct mem_cgroup *mem) | |
283 | { | |
284 | struct task_struct *g, *p; | |
285 | ||
286 | printk(KERN_INFO "[ pid ] uid tgid total_vm rss cpu oom_adj " | |
287 | "name\n"); | |
288 | do_each_thread(g, p) { | |
289 | /* | |
290 | * total_vm and rss sizes do not exist for tasks with a | |
291 | * detached mm so there's no need to report them. | |
292 | */ | |
293 | if (!p->mm) | |
294 | continue; | |
295 | if (mem && !task_in_mem_cgroup(p, mem)) | |
296 | continue; | |
b4416d2b DR |
297 | if (!thread_group_leader(p)) |
298 | continue; | |
fef1bdd6 DR |
299 | |
300 | task_lock(p); | |
301 | printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n", | |
c69e8d9c DH |
302 | p->pid, __task_cred(p)->uid, p->tgid, |
303 | p->mm->total_vm, get_mm_rss(p->mm), (int)task_cpu(p), | |
304 | p->oomkilladj, p->comm); | |
fef1bdd6 DR |
305 | task_unlock(p); |
306 | } while_each_thread(g, p); | |
307 | } | |
308 | ||
1b578df0 | 309 | /* |
5a291b98 RG |
310 | * Send SIGKILL to the selected process irrespective of CAP_SYS_RAW_IO |
311 | * flag though it's unlikely that we select a process with CAP_SYS_RAW_IO | |
312 | * set. | |
1da177e4 | 313 | */ |
f3af38d3 | 314 | static void __oom_kill_task(struct task_struct *p, int verbose) |
1da177e4 | 315 | { |
b460cbc5 | 316 | if (is_global_init(p)) { |
1da177e4 LT |
317 | WARN_ON(1); |
318 | printk(KERN_WARNING "tried to kill init!\n"); | |
319 | return; | |
320 | } | |
321 | ||
01017a22 | 322 | if (!p->mm) { |
1da177e4 LT |
323 | WARN_ON(1); |
324 | printk(KERN_WARNING "tried to kill an mm-less task!\n"); | |
1da177e4 LT |
325 | return; |
326 | } | |
50ec3bbf | 327 | |
f3af38d3 | 328 | if (verbose) |
ba25f9dc PE |
329 | printk(KERN_ERR "Killed process %d (%s)\n", |
330 | task_pid_nr(p), p->comm); | |
1da177e4 LT |
331 | |
332 | /* | |
333 | * We give our sacrificial lamb high priority and access to | |
334 | * all the memory it needs. That way it should be able to | |
335 | * exit() and clear out its resources quickly... | |
336 | */ | |
fa717060 | 337 | p->rt.time_slice = HZ; |
1da177e4 LT |
338 | set_tsk_thread_flag(p, TIF_MEMDIE); |
339 | ||
340 | force_sig(SIGKILL, p); | |
341 | } | |
342 | ||
f3af38d3 | 343 | static int oom_kill_task(struct task_struct *p) |
1da177e4 | 344 | { |
01315922 | 345 | struct mm_struct *mm; |
36c8b586 | 346 | struct task_struct *g, *q; |
1da177e4 | 347 | |
01315922 DP |
348 | mm = p->mm; |
349 | ||
350 | /* WARNING: mm may not be dereferenced since we did not obtain its | |
351 | * value from get_task_mm(p). This is OK since all we need to do is | |
352 | * compare mm to q->mm below. | |
353 | * | |
354 | * Furthermore, even if mm contains a non-NULL value, p->mm may | |
355 | * change to NULL at any time since we do not hold task_lock(p). | |
356 | * However, this is of no concern to us. | |
357 | */ | |
358 | ||
01017a22 | 359 | if (mm == NULL) |
01315922 | 360 | return 1; |
1da177e4 | 361 | |
c33e0fca NP |
362 | /* |
363 | * Don't kill the process if any threads are set to OOM_DISABLE | |
364 | */ | |
365 | do_each_thread(g, q) { | |
35ae834f | 366 | if (q->mm == mm && q->oomkilladj == OOM_DISABLE) |
c33e0fca NP |
367 | return 1; |
368 | } while_each_thread(g, q); | |
369 | ||
f3af38d3 | 370 | __oom_kill_task(p, 1); |
c33e0fca | 371 | |
1da177e4 LT |
372 | /* |
373 | * kill all processes that share the ->mm (i.e. all threads), | |
f2a2a710 NP |
374 | * but are in a different thread group. Don't let them have access |
375 | * to memory reserves though, otherwise we might deplete all memory. | |
1da177e4 | 376 | */ |
c33e0fca | 377 | do_each_thread(g, q) { |
bac0abd6 | 378 | if (q->mm == mm && !same_thread_group(q, p)) |
650a7c97 | 379 | force_sig(SIGKILL, q); |
c33e0fca | 380 | } while_each_thread(g, q); |
1da177e4 | 381 | |
01315922 | 382 | return 0; |
1da177e4 LT |
383 | } |
384 | ||
7213f506 | 385 | static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, |
fef1bdd6 DR |
386 | unsigned long points, struct mem_cgroup *mem, |
387 | const char *message) | |
1da177e4 | 388 | { |
1da177e4 | 389 | struct task_struct *c; |
1da177e4 | 390 | |
7213f506 DR |
391 | if (printk_ratelimit()) { |
392 | printk(KERN_WARNING "%s invoked oom-killer: " | |
393 | "gfp_mask=0x%x, order=%d, oomkilladj=%d\n", | |
394 | current->comm, gfp_mask, order, current->oomkilladj); | |
75aa1994 DR |
395 | task_lock(current); |
396 | cpuset_print_task_mems_allowed(current); | |
397 | task_unlock(current); | |
7213f506 DR |
398 | dump_stack(); |
399 | show_mem(); | |
fef1bdd6 DR |
400 | if (sysctl_oom_dump_tasks) |
401 | dump_tasks(mem); | |
7213f506 DR |
402 | } |
403 | ||
50ec3bbf NP |
404 | /* |
405 | * If the task is already exiting, don't alarm the sysadmin or kill | |
406 | * its children or threads, just set TIF_MEMDIE so it can die quickly | |
407 | */ | |
408 | if (p->flags & PF_EXITING) { | |
f3af38d3 | 409 | __oom_kill_task(p, 0); |
50ec3bbf NP |
410 | return 0; |
411 | } | |
412 | ||
f3af38d3 | 413 | printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n", |
ba25f9dc | 414 | message, task_pid_nr(p), p->comm, points); |
f3af38d3 | 415 | |
1da177e4 | 416 | /* Try to kill a child first */ |
7b1915a9 | 417 | list_for_each_entry(c, &p->children, sibling) { |
1da177e4 LT |
418 | if (c->mm == p->mm) |
419 | continue; | |
f3af38d3 | 420 | if (!oom_kill_task(c)) |
01315922 | 421 | return 0; |
1da177e4 | 422 | } |
f3af38d3 | 423 | return oom_kill_task(p); |
1da177e4 LT |
424 | } |
425 | ||
00f0b825 | 426 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
c7ba5c9e PE |
427 | void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask) |
428 | { | |
429 | unsigned long points = 0; | |
430 | struct task_struct *p; | |
431 | ||
e115f2d8 | 432 | read_lock(&tasklist_lock); |
c7ba5c9e PE |
433 | retry: |
434 | p = select_bad_process(&points, mem); | |
435 | if (PTR_ERR(p) == -1UL) | |
436 | goto out; | |
437 | ||
438 | if (!p) | |
439 | p = current; | |
440 | ||
fef1bdd6 | 441 | if (oom_kill_process(p, gfp_mask, 0, points, mem, |
c7ba5c9e PE |
442 | "Memory cgroup out of memory")) |
443 | goto retry; | |
444 | out: | |
e115f2d8 | 445 | read_unlock(&tasklist_lock); |
c7ba5c9e PE |
446 | } |
447 | #endif | |
448 | ||
8bc719d3 MS |
449 | static BLOCKING_NOTIFIER_HEAD(oom_notify_list); |
450 | ||
451 | int register_oom_notifier(struct notifier_block *nb) | |
452 | { | |
453 | return blocking_notifier_chain_register(&oom_notify_list, nb); | |
454 | } | |
455 | EXPORT_SYMBOL_GPL(register_oom_notifier); | |
456 | ||
457 | int unregister_oom_notifier(struct notifier_block *nb) | |
458 | { | |
459 | return blocking_notifier_chain_unregister(&oom_notify_list, nb); | |
460 | } | |
461 | EXPORT_SYMBOL_GPL(unregister_oom_notifier); | |
462 | ||
098d7f12 DR |
463 | /* |
464 | * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero | |
465 | * if a parallel OOM killing is already taking place that includes a zone in | |
466 | * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. | |
467 | */ | |
dd1a239f | 468 | int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_mask) |
098d7f12 | 469 | { |
dd1a239f MG |
470 | struct zoneref *z; |
471 | struct zone *zone; | |
098d7f12 DR |
472 | int ret = 1; |
473 | ||
c7d4caeb | 474 | spin_lock(&zone_scan_lock); |
dd1a239f MG |
475 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { |
476 | if (zone_is_oom_locked(zone)) { | |
098d7f12 DR |
477 | ret = 0; |
478 | goto out; | |
479 | } | |
dd1a239f MG |
480 | } |
481 | ||
482 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { | |
483 | /* | |
c7d4caeb | 484 | * Lock each zone in the zonelist under zone_scan_lock so a |
dd1a239f MG |
485 | * parallel invocation of try_set_zone_oom() doesn't succeed |
486 | * when it shouldn't. | |
487 | */ | |
488 | zone_set_flag(zone, ZONE_OOM_LOCKED); | |
489 | } | |
098d7f12 | 490 | |
098d7f12 | 491 | out: |
c7d4caeb | 492 | spin_unlock(&zone_scan_lock); |
098d7f12 DR |
493 | return ret; |
494 | } | |
495 | ||
496 | /* | |
497 | * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed | |
498 | * allocation attempts with zonelists containing them may now recall the OOM | |
499 | * killer, if necessary. | |
500 | */ | |
dd1a239f | 501 | void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) |
098d7f12 | 502 | { |
dd1a239f MG |
503 | struct zoneref *z; |
504 | struct zone *zone; | |
098d7f12 | 505 | |
c7d4caeb | 506 | spin_lock(&zone_scan_lock); |
dd1a239f MG |
507 | for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { |
508 | zone_clear_flag(zone, ZONE_OOM_LOCKED); | |
509 | } | |
c7d4caeb | 510 | spin_unlock(&zone_scan_lock); |
098d7f12 DR |
511 | } |
512 | ||
1c0fe6e3 NP |
513 | /* |
514 | * Must be called with tasklist_lock held for read. | |
515 | */ | |
516 | static void __out_of_memory(gfp_t gfp_mask, int order) | |
517 | { | |
518 | if (sysctl_oom_kill_allocating_task) { | |
519 | oom_kill_process(current, gfp_mask, order, 0, NULL, | |
520 | "Out of memory (oom_kill_allocating_task)"); | |
521 | ||
522 | } else { | |
523 | unsigned long points; | |
524 | struct task_struct *p; | |
525 | ||
526 | retry: | |
527 | /* | |
528 | * Rambo mode: Shoot down a process and hope it solves whatever | |
529 | * issues we may have. | |
530 | */ | |
531 | p = select_bad_process(&points, NULL); | |
532 | ||
533 | if (PTR_ERR(p) == -1UL) | |
534 | return; | |
535 | ||
536 | /* Found nothing?!?! Either we hang forever, or we panic. */ | |
537 | if (!p) { | |
538 | read_unlock(&tasklist_lock); | |
539 | panic("Out of memory and no killable processes...\n"); | |
540 | } | |
541 | ||
542 | if (oom_kill_process(p, gfp_mask, order, points, NULL, | |
543 | "Out of memory")) | |
544 | goto retry; | |
545 | } | |
546 | } | |
547 | ||
548 | /* | |
549 | * pagefault handler calls into here because it is out of memory but | |
550 | * doesn't know exactly how or why. | |
551 | */ | |
552 | void pagefault_out_of_memory(void) | |
553 | { | |
554 | unsigned long freed = 0; | |
555 | ||
556 | blocking_notifier_call_chain(&oom_notify_list, 0, &freed); | |
557 | if (freed > 0) | |
558 | /* Got some memory back in the last second. */ | |
559 | return; | |
560 | ||
a636b327 KH |
561 | /* |
562 | * If this is from memcg, oom-killer is already invoked. | |
563 | * and not worth to go system-wide-oom. | |
564 | */ | |
565 | if (mem_cgroup_oom_called(current)) | |
566 | goto rest_and_return; | |
567 | ||
1c0fe6e3 NP |
568 | if (sysctl_panic_on_oom) |
569 | panic("out of memory from page fault. panic_on_oom is selected.\n"); | |
570 | ||
571 | read_lock(&tasklist_lock); | |
572 | __out_of_memory(0, 0); /* unknown gfp_mask and order */ | |
573 | read_unlock(&tasklist_lock); | |
574 | ||
575 | /* | |
576 | * Give "p" a good chance of killing itself before we | |
577 | * retry to allocate memory. | |
578 | */ | |
a636b327 | 579 | rest_and_return: |
1c0fe6e3 NP |
580 | if (!test_thread_flag(TIF_MEMDIE)) |
581 | schedule_timeout_uninterruptible(1); | |
582 | } | |
583 | ||
1da177e4 | 584 | /** |
6937a25c | 585 | * out_of_memory - kill the "best" process when we run out of memory |
1b578df0 RD |
586 | * @zonelist: zonelist pointer |
587 | * @gfp_mask: memory allocation flags | |
588 | * @order: amount of memory being requested as a power of 2 | |
1da177e4 LT |
589 | * |
590 | * If we run out of memory, we have the choice between either | |
591 | * killing a random task (bad), letting the system crash (worse) | |
592 | * OR try to be smart about which process to kill. Note that we | |
593 | * don't have to be perfect here, we just have to be good. | |
594 | */ | |
9b0f8b04 | 595 | void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) |
1da177e4 | 596 | { |
8bc719d3 | 597 | unsigned long freed = 0; |
70e24bdf | 598 | enum oom_constraint constraint; |
8bc719d3 MS |
599 | |
600 | blocking_notifier_call_chain(&oom_notify_list, 0, &freed); | |
601 | if (freed > 0) | |
602 | /* Got some memory back in the last second. */ | |
603 | return; | |
1da177e4 | 604 | |
2b744c01 YG |
605 | if (sysctl_panic_on_oom == 2) |
606 | panic("out of memory. Compulsory panic_on_oom is selected.\n"); | |
607 | ||
9b0f8b04 CL |
608 | /* |
609 | * Check if there were limitations on the allocation (only relevant for | |
610 | * NUMA) that may require different handling. | |
611 | */ | |
2b45ab33 | 612 | constraint = constrained_alloc(zonelist, gfp_mask); |
2b45ab33 DR |
613 | read_lock(&tasklist_lock); |
614 | ||
615 | switch (constraint) { | |
9b0f8b04 | 616 | case CONSTRAINT_MEMORY_POLICY: |
1c0fe6e3 | 617 | oom_kill_process(current, gfp_mask, order, 0, NULL, |
9b0f8b04 CL |
618 | "No available memory (MPOL_BIND)"); |
619 | break; | |
620 | ||
9b0f8b04 | 621 | case CONSTRAINT_NONE: |
fadd8fbd KH |
622 | if (sysctl_panic_on_oom) |
623 | panic("out of memory. panic_on_oom is selected\n"); | |
fe071d7e DR |
624 | /* Fall-through */ |
625 | case CONSTRAINT_CPUSET: | |
1c0fe6e3 | 626 | __out_of_memory(gfp_mask, order); |
9b0f8b04 CL |
627 | break; |
628 | } | |
1da177e4 | 629 | |
140ffcec | 630 | read_unlock(&tasklist_lock); |
1da177e4 LT |
631 | |
632 | /* | |
633 | * Give "p" a good chance of killing itself before we | |
2f659f46 | 634 | * retry to allocate memory unless "p" is current |
1da177e4 | 635 | */ |
2f659f46 | 636 | if (!test_thread_flag(TIF_MEMDIE)) |
140ffcec | 637 | schedule_timeout_uninterruptible(1); |
1da177e4 | 638 | } |