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 * Copyright (C) 2010 Google, Inc. 8 * Rewritten by David Rientjes 9 * 10 * The routines in this file are used to kill a process when 11 * we're seriously out of memory. This gets called from __alloc_pages() 12 * in mm/page_alloc.c when we really run out of memory. 13 * 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 20 #include <linux/oom.h> 21 #include <linux/mm.h> 22 #include <linux/err.h> 23 #include <linux/gfp.h> 24 #include <linux/sched.h> 25 #include <linux/swap.h> 26 #include <linux/timex.h> 27 #include <linux/jiffies.h> 28 #include <linux/cpuset.h> 29 #include <linux/export.h> 30 #include <linux/notifier.h> 31 #include <linux/memcontrol.h> 32 #include <linux/mempolicy.h> 33 #include <linux/security.h> 34 #include <linux/ptrace.h> 35 #include <linux/freezer.h> 36 #include <linux/ftrace.h> 37 #include <linux/ratelimit.h> 38 39 #define CREATE_TRACE_POINTS 40 #include <trace/events/oom.h> 41 42 int sysctl_panic_on_oom; 43 int sysctl_oom_kill_allocating_task; 44 int sysctl_oom_dump_tasks = 1; 45 static DEFINE_SPINLOCK(zone_scan_lock); 46 47 #ifdef CONFIG_NUMA 48 /** 49 * has_intersects_mems_allowed() - check task eligiblity for kill 50 * @start: task struct of which task to consider 51 * @mask: nodemask passed to page allocator for mempolicy ooms 52 * 53 * Task eligibility is determined by whether or not a candidate task, @tsk, 54 * shares the same mempolicy nodes as current if it is bound by such a policy 55 * and whether or not it has the same set of allowed cpuset nodes. 56 */ 57 static bool has_intersects_mems_allowed(struct task_struct *start, 58 const nodemask_t *mask) 59 { 60 struct task_struct *tsk; 61 bool ret = false; 62 63 rcu_read_lock(); 64 for_each_thread(start, tsk) { 65 if (mask) { 66 /* 67 * If this is a mempolicy constrained oom, tsk's 68 * cpuset is irrelevant. Only return true if its 69 * mempolicy intersects current, otherwise it may be 70 * needlessly killed. 71 */ 72 ret = mempolicy_nodemask_intersects(tsk, mask); 73 } else { 74 /* 75 * This is not a mempolicy constrained oom, so only 76 * check the mems of tsk's cpuset. 77 */ 78 ret = cpuset_mems_allowed_intersects(current, tsk); 79 } 80 if (ret) 81 break; 82 } 83 rcu_read_unlock(); 84 85 return ret; 86 } 87 #else 88 static bool has_intersects_mems_allowed(struct task_struct *tsk, 89 const nodemask_t *mask) 90 { 91 return true; 92 } 93 #endif /* CONFIG_NUMA */ 94 95 /* 96 * The process p may have detached its own ->mm while exiting or through 97 * use_mm(), but one or more of its subthreads may still have a valid 98 * pointer. Return p, or any of its subthreads with a valid ->mm, with 99 * task_lock() held. 100 */ 101 struct task_struct *find_lock_task_mm(struct task_struct *p) 102 { 103 struct task_struct *t; 104 105 rcu_read_lock(); 106 107 for_each_thread(p, t) { 108 task_lock(t); 109 if (likely(t->mm)) 110 goto found; 111 task_unlock(t); 112 } 113 t = NULL; 114 found: 115 rcu_read_unlock(); 116 117 return t; 118 } 119 120 /* return true if the task is not adequate as candidate victim task. */ 121 static bool oom_unkillable_task(struct task_struct *p, 122 struct mem_cgroup *memcg, const nodemask_t *nodemask) 123 { 124 if (is_global_init(p)) 125 return true; 126 if (p->flags & PF_KTHREAD) 127 return true; 128 129 /* When mem_cgroup_out_of_memory() and p is not member of the group */ 130 if (memcg && !task_in_mem_cgroup(p, memcg)) 131 return true; 132 133 /* p may not have freeable memory in nodemask */ 134 if (!has_intersects_mems_allowed(p, nodemask)) 135 return true; 136 137 return false; 138 } 139 140 /** 141 * oom_badness - heuristic function to determine which candidate task to kill 142 * @p: task struct of which task we should calculate 143 * @totalpages: total present RAM allowed for page allocation 144 * 145 * The heuristic for determining which task to kill is made to be as simple and 146 * predictable as possible. The goal is to return the highest value for the 147 * task consuming the most memory to avoid subsequent oom failures. 148 */ 149 unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, 150 const nodemask_t *nodemask, unsigned long totalpages) 151 { 152 long points; 153 long adj; 154 155 if (oom_unkillable_task(p, memcg, nodemask)) 156 return 0; 157 158 p = find_lock_task_mm(p); 159 if (!p) 160 return 0; 161 162 adj = (long)p->signal->oom_score_adj; 163 if (adj == OOM_SCORE_ADJ_MIN) { 164 task_unlock(p); 165 return 0; 166 } 167 168 /* 169 * The baseline for the badness score is the proportion of RAM that each 170 * task's rss, pagetable and swap space use. 171 */ 172 points = get_mm_rss(p->mm) + atomic_long_read(&p->mm->nr_ptes) + 173 get_mm_counter(p->mm, MM_SWAPENTS); 174 task_unlock(p); 175 176 /* 177 * Root processes get 3% bonus, just like the __vm_enough_memory() 178 * implementation used by LSMs. 179 */ 180 if (has_capability_noaudit(p, CAP_SYS_ADMIN)) 181 points -= (points * 3) / 100; 182 183 /* Normalize to oom_score_adj units */ 184 adj *= totalpages / 1000; 185 points += adj; 186 187 /* 188 * Never return 0 for an eligible task regardless of the root bonus and 189 * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here). 190 */ 191 return points > 0 ? points : 1; 192 } 193 194 /* 195 * Determine the type of allocation constraint. 196 */ 197 #ifdef CONFIG_NUMA 198 static enum oom_constraint constrained_alloc(struct zonelist *zonelist, 199 gfp_t gfp_mask, nodemask_t *nodemask, 200 unsigned long *totalpages) 201 { 202 struct zone *zone; 203 struct zoneref *z; 204 enum zone_type high_zoneidx = gfp_zone(gfp_mask); 205 bool cpuset_limited = false; 206 int nid; 207 208 /* Default to all available memory */ 209 *totalpages = totalram_pages + total_swap_pages; 210 211 if (!zonelist) 212 return CONSTRAINT_NONE; 213 /* 214 * Reach here only when __GFP_NOFAIL is used. So, we should avoid 215 * to kill current.We have to random task kill in this case. 216 * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. 217 */ 218 if (gfp_mask & __GFP_THISNODE) 219 return CONSTRAINT_NONE; 220 221 /* 222 * This is not a __GFP_THISNODE allocation, so a truncated nodemask in 223 * the page allocator means a mempolicy is in effect. Cpuset policy 224 * is enforced in get_page_from_freelist(). 225 */ 226 if (nodemask && !nodes_subset(node_states[N_MEMORY], *nodemask)) { 227 *totalpages = total_swap_pages; 228 for_each_node_mask(nid, *nodemask) 229 *totalpages += node_spanned_pages(nid); 230 return CONSTRAINT_MEMORY_POLICY; 231 } 232 233 /* Check this allocation failure is caused by cpuset's wall function */ 234 for_each_zone_zonelist_nodemask(zone, z, zonelist, 235 high_zoneidx, nodemask) 236 if (!cpuset_zone_allowed(zone, gfp_mask)) 237 cpuset_limited = true; 238 239 if (cpuset_limited) { 240 *totalpages = total_swap_pages; 241 for_each_node_mask(nid, cpuset_current_mems_allowed) 242 *totalpages += node_spanned_pages(nid); 243 return CONSTRAINT_CPUSET; 244 } 245 return CONSTRAINT_NONE; 246 } 247 #else 248 static enum oom_constraint constrained_alloc(struct zonelist *zonelist, 249 gfp_t gfp_mask, nodemask_t *nodemask, 250 unsigned long *totalpages) 251 { 252 *totalpages = totalram_pages + total_swap_pages; 253 return CONSTRAINT_NONE; 254 } 255 #endif 256 257 enum oom_scan_t oom_scan_process_thread(struct task_struct *task, 258 unsigned long totalpages, const nodemask_t *nodemask, 259 bool force_kill) 260 { 261 if (oom_unkillable_task(task, NULL, nodemask)) 262 return OOM_SCAN_CONTINUE; 263 264 /* 265 * This task already has access to memory reserves and is being killed. 266 * Don't allow any other task to have access to the reserves. 267 */ 268 if (test_tsk_thread_flag(task, TIF_MEMDIE)) { 269 if (unlikely(frozen(task))) 270 __thaw_task(task); 271 if (!force_kill) 272 return OOM_SCAN_ABORT; 273 } 274 if (!task->mm) 275 return OOM_SCAN_CONTINUE; 276 277 /* 278 * If task is allocating a lot of memory and has been marked to be 279 * killed first if it triggers an oom, then select it. 280 */ 281 if (oom_task_origin(task)) 282 return OOM_SCAN_SELECT; 283 284 if (task_will_free_mem(task) && !force_kill) 285 return OOM_SCAN_ABORT; 286 287 return OOM_SCAN_OK; 288 } 289 290 /* 291 * Simple selection loop. We chose the process with the highest 292 * number of 'points'. Returns -1 on scan abort. 293 * 294 * (not docbooked, we don't want this one cluttering up the manual) 295 */ 296 static struct task_struct *select_bad_process(unsigned int *ppoints, 297 unsigned long totalpages, const nodemask_t *nodemask, 298 bool force_kill) 299 { 300 struct task_struct *g, *p; 301 struct task_struct *chosen = NULL; 302 unsigned long chosen_points = 0; 303 304 rcu_read_lock(); 305 for_each_process_thread(g, p) { 306 unsigned int points; 307 308 switch (oom_scan_process_thread(p, totalpages, nodemask, 309 force_kill)) { 310 case OOM_SCAN_SELECT: 311 chosen = p; 312 chosen_points = ULONG_MAX; 313 /* fall through */ 314 case OOM_SCAN_CONTINUE: 315 continue; 316 case OOM_SCAN_ABORT: 317 rcu_read_unlock(); 318 return (struct task_struct *)(-1UL); 319 case OOM_SCAN_OK: 320 break; 321 }; 322 points = oom_badness(p, NULL, nodemask, totalpages); 323 if (!points || points < chosen_points) 324 continue; 325 /* Prefer thread group leaders for display purposes */ 326 if (points == chosen_points && thread_group_leader(chosen)) 327 continue; 328 329 chosen = p; 330 chosen_points = points; 331 } 332 if (chosen) 333 get_task_struct(chosen); 334 rcu_read_unlock(); 335 336 *ppoints = chosen_points * 1000 / totalpages; 337 return chosen; 338 } 339 340 /** 341 * dump_tasks - dump current memory state of all system tasks 342 * @memcg: current's memory controller, if constrained 343 * @nodemask: nodemask passed to page allocator for mempolicy ooms 344 * 345 * Dumps the current memory state of all eligible tasks. Tasks not in the same 346 * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes 347 * are not shown. 348 * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes, 349 * swapents, oom_score_adj value, and name. 350 */ 351 static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask) 352 { 353 struct task_struct *p; 354 struct task_struct *task; 355 356 pr_info("[ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name\n"); 357 rcu_read_lock(); 358 for_each_process(p) { 359 if (oom_unkillable_task(p, memcg, nodemask)) 360 continue; 361 362 task = find_lock_task_mm(p); 363 if (!task) { 364 /* 365 * This is a kthread or all of p's threads have already 366 * detached their mm's. There's no need to report 367 * them; they can't be oom killed anyway. 368 */ 369 continue; 370 } 371 372 pr_info("[%5d] %5d %5d %8lu %8lu %7ld %8lu %5hd %s\n", 373 task->pid, from_kuid(&init_user_ns, task_uid(task)), 374 task->tgid, task->mm->total_vm, get_mm_rss(task->mm), 375 atomic_long_read(&task->mm->nr_ptes), 376 get_mm_counter(task->mm, MM_SWAPENTS), 377 task->signal->oom_score_adj, task->comm); 378 task_unlock(task); 379 } 380 rcu_read_unlock(); 381 } 382 383 static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, 384 struct mem_cgroup *memcg, const nodemask_t *nodemask) 385 { 386 task_lock(current); 387 pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " 388 "oom_score_adj=%hd\n", 389 current->comm, gfp_mask, order, 390 current->signal->oom_score_adj); 391 cpuset_print_task_mems_allowed(current); 392 task_unlock(current); 393 dump_stack(); 394 if (memcg) 395 mem_cgroup_print_oom_info(memcg, p); 396 else 397 show_mem(SHOW_MEM_FILTER_NODES); 398 if (sysctl_oom_dump_tasks) 399 dump_tasks(memcg, nodemask); 400 } 401 402 /* 403 * Number of OOM killer invocations (including memcg OOM killer). 404 * Primarily used by PM freezer to check for potential races with 405 * OOM killed frozen task. 406 */ 407 static atomic_t oom_kills = ATOMIC_INIT(0); 408 409 int oom_kills_count(void) 410 { 411 return atomic_read(&oom_kills); 412 } 413 414 void note_oom_kill(void) 415 { 416 atomic_inc(&oom_kills); 417 } 418 419 #define K(x) ((x) << (PAGE_SHIFT-10)) 420 /* 421 * Must be called while holding a reference to p, which will be released upon 422 * returning. 423 */ 424 void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 425 unsigned int points, unsigned long totalpages, 426 struct mem_cgroup *memcg, nodemask_t *nodemask, 427 const char *message) 428 { 429 struct task_struct *victim = p; 430 struct task_struct *child; 431 struct task_struct *t; 432 struct mm_struct *mm; 433 unsigned int victim_points = 0; 434 static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, 435 DEFAULT_RATELIMIT_BURST); 436 437 /* 438 * If the task is already exiting, don't alarm the sysadmin or kill 439 * its children or threads, just set TIF_MEMDIE so it can die quickly 440 */ 441 if (task_will_free_mem(p)) { 442 set_tsk_thread_flag(p, TIF_MEMDIE); 443 put_task_struct(p); 444 return; 445 } 446 447 if (__ratelimit(&oom_rs)) 448 dump_header(p, gfp_mask, order, memcg, nodemask); 449 450 task_lock(p); 451 pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n", 452 message, task_pid_nr(p), p->comm, points); 453 task_unlock(p); 454 455 /* 456 * If any of p's children has a different mm and is eligible for kill, 457 * the one with the highest oom_badness() score is sacrificed for its 458 * parent. This attempts to lose the minimal amount of work done while 459 * still freeing memory. 460 */ 461 read_lock(&tasklist_lock); 462 for_each_thread(p, t) { 463 list_for_each_entry(child, &t->children, sibling) { 464 unsigned int child_points; 465 466 if (child->mm == p->mm) 467 continue; 468 /* 469 * oom_badness() returns 0 if the thread is unkillable 470 */ 471 child_points = oom_badness(child, memcg, nodemask, 472 totalpages); 473 if (child_points > victim_points) { 474 put_task_struct(victim); 475 victim = child; 476 victim_points = child_points; 477 get_task_struct(victim); 478 } 479 } 480 } 481 read_unlock(&tasklist_lock); 482 483 p = find_lock_task_mm(victim); 484 if (!p) { 485 put_task_struct(victim); 486 return; 487 } else if (victim != p) { 488 get_task_struct(p); 489 put_task_struct(victim); 490 victim = p; 491 } 492 493 /* mm cannot safely be dereferenced after task_unlock(victim) */ 494 mm = victim->mm; 495 pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n", 496 task_pid_nr(victim), victim->comm, K(victim->mm->total_vm), 497 K(get_mm_counter(victim->mm, MM_ANONPAGES)), 498 K(get_mm_counter(victim->mm, MM_FILEPAGES))); 499 task_unlock(victim); 500 501 /* 502 * Kill all user processes sharing victim->mm in other thread groups, if 503 * any. They don't get access to memory reserves, though, to avoid 504 * depletion of all memory. This prevents mm->mmap_sem livelock when an 505 * oom killed thread cannot exit because it requires the semaphore and 506 * its contended by another thread trying to allocate memory itself. 507 * That thread will now get access to memory reserves since it has a 508 * pending fatal signal. 509 */ 510 rcu_read_lock(); 511 for_each_process(p) 512 if (p->mm == mm && !same_thread_group(p, victim) && 513 !(p->flags & PF_KTHREAD)) { 514 if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) 515 continue; 516 517 task_lock(p); /* Protect ->comm from prctl() */ 518 pr_err("Kill process %d (%s) sharing same memory\n", 519 task_pid_nr(p), p->comm); 520 task_unlock(p); 521 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); 522 } 523 rcu_read_unlock(); 524 525 set_tsk_thread_flag(victim, TIF_MEMDIE); 526 do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); 527 put_task_struct(victim); 528 } 529 #undef K 530 531 /* 532 * Determines whether the kernel must panic because of the panic_on_oom sysctl. 533 */ 534 void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, 535 int order, const nodemask_t *nodemask) 536 { 537 if (likely(!sysctl_panic_on_oom)) 538 return; 539 if (sysctl_panic_on_oom != 2) { 540 /* 541 * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel 542 * does not panic for cpuset, mempolicy, or memcg allocation 543 * failures. 544 */ 545 if (constraint != CONSTRAINT_NONE) 546 return; 547 } 548 dump_header(NULL, gfp_mask, order, NULL, nodemask); 549 panic("Out of memory: %s panic_on_oom is enabled\n", 550 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); 551 } 552 553 static BLOCKING_NOTIFIER_HEAD(oom_notify_list); 554 555 int register_oom_notifier(struct notifier_block *nb) 556 { 557 return blocking_notifier_chain_register(&oom_notify_list, nb); 558 } 559 EXPORT_SYMBOL_GPL(register_oom_notifier); 560 561 int unregister_oom_notifier(struct notifier_block *nb) 562 { 563 return blocking_notifier_chain_unregister(&oom_notify_list, nb); 564 } 565 EXPORT_SYMBOL_GPL(unregister_oom_notifier); 566 567 /* 568 * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero 569 * if a parallel OOM killing is already taking place that includes a zone in 570 * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. 571 */ 572 bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_mask) 573 { 574 struct zoneref *z; 575 struct zone *zone; 576 bool ret = true; 577 578 spin_lock(&zone_scan_lock); 579 for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) 580 if (test_bit(ZONE_OOM_LOCKED, &zone->flags)) { 581 ret = false; 582 goto out; 583 } 584 585 /* 586 * Lock each zone in the zonelist under zone_scan_lock so a parallel 587 * call to oom_zonelist_trylock() doesn't succeed when it shouldn't. 588 */ 589 for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) 590 set_bit(ZONE_OOM_LOCKED, &zone->flags); 591 592 out: 593 spin_unlock(&zone_scan_lock); 594 return ret; 595 } 596 597 /* 598 * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed 599 * allocation attempts with zonelists containing them may now recall the OOM 600 * killer, if necessary. 601 */ 602 void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_mask) 603 { 604 struct zoneref *z; 605 struct zone *zone; 606 607 spin_lock(&zone_scan_lock); 608 for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) 609 clear_bit(ZONE_OOM_LOCKED, &zone->flags); 610 spin_unlock(&zone_scan_lock); 611 } 612 613 /** 614 * out_of_memory - kill the "best" process when we run out of memory 615 * @zonelist: zonelist pointer 616 * @gfp_mask: memory allocation flags 617 * @order: amount of memory being requested as a power of 2 618 * @nodemask: nodemask passed to page allocator 619 * @force_kill: true if a task must be killed, even if others are exiting 620 * 621 * If we run out of memory, we have the choice between either 622 * killing a random task (bad), letting the system crash (worse) 623 * OR try to be smart about which process to kill. Note that we 624 * don't have to be perfect here, we just have to be good. 625 */ 626 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, 627 int order, nodemask_t *nodemask, bool force_kill) 628 { 629 const nodemask_t *mpol_mask; 630 struct task_struct *p; 631 unsigned long totalpages; 632 unsigned long freed = 0; 633 unsigned int uninitialized_var(points); 634 enum oom_constraint constraint = CONSTRAINT_NONE; 635 int killed = 0; 636 637 blocking_notifier_call_chain(&oom_notify_list, 0, &freed); 638 if (freed > 0) 639 /* Got some memory back in the last second. */ 640 return; 641 642 /* 643 * If current has a pending SIGKILL or is exiting, then automatically 644 * select it. The goal is to allow it to allocate so that it may 645 * quickly exit and free its memory. 646 */ 647 if (fatal_signal_pending(current) || task_will_free_mem(current)) { 648 set_thread_flag(TIF_MEMDIE); 649 return; 650 } 651 652 /* 653 * Check if there were limitations on the allocation (only relevant for 654 * NUMA) that may require different handling. 655 */ 656 constraint = constrained_alloc(zonelist, gfp_mask, nodemask, 657 &totalpages); 658 mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL; 659 check_panic_on_oom(constraint, gfp_mask, order, mpol_mask); 660 661 if (sysctl_oom_kill_allocating_task && current->mm && 662 !oom_unkillable_task(current, NULL, nodemask) && 663 current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) { 664 get_task_struct(current); 665 oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL, 666 nodemask, 667 "Out of memory (oom_kill_allocating_task)"); 668 goto out; 669 } 670 671 p = select_bad_process(&points, totalpages, mpol_mask, force_kill); 672 /* Found nothing?!?! Either we hang forever, or we panic. */ 673 if (!p) { 674 dump_header(NULL, gfp_mask, order, NULL, mpol_mask); 675 panic("Out of memory and no killable processes...\n"); 676 } 677 if (p != (void *)-1UL) { 678 oom_kill_process(p, gfp_mask, order, points, totalpages, NULL, 679 nodemask, "Out of memory"); 680 killed = 1; 681 } 682 out: 683 /* 684 * Give the killed threads a good chance of exiting before trying to 685 * allocate memory again. 686 */ 687 if (killed) 688 schedule_timeout_killable(1); 689 } 690 691 /* 692 * The pagefault handler calls here because it is out of memory, so kill a 693 * memory-hogging task. If any populated zone has ZONE_OOM_LOCKED set, a 694 * parallel oom killing is already in progress so do nothing. 695 */ 696 void pagefault_out_of_memory(void) 697 { 698 struct zonelist *zonelist; 699 700 if (mem_cgroup_oom_synchronize(true)) 701 return; 702 703 zonelist = node_zonelist(first_memory_node, GFP_KERNEL); 704 if (oom_zonelist_trylock(zonelist, GFP_KERNEL)) { 705 out_of_memory(NULL, 0, 0, NULL, false); 706 oom_zonelist_unlock(zonelist, GFP_KERNEL); 707 } 708 } 709