| /* |
| * linux/mm/oom_kill.c |
| * |
| * Copyright (C) 1998,2000 Rik van Riel |
| * Thanks go out to Claus Fischer for some serious inspiration and |
| * for goading me into coding this file... |
| * Copyright (C) 2010 Google, Inc. |
| * Rewritten by David Rientjes |
| * |
| * The routines in this file are used to kill a process when |
| * we're seriously out of memory. This gets called from __alloc_pages() |
| * in mm/page_alloc.c when we really run out of memory. |
| * |
| * Since we won't call these routines often (on a well-configured |
| * machine) this file will double as a 'coding guide' and a signpost |
| * for newbie kernel hackers. It features several pointers to major |
| * kernel subsystems and hints as to where to find out what things do. |
| */ |
| |
| #include <linux/oom.h> |
| #include <linux/mm.h> |
| #include <linux/err.h> |
| #include <linux/gfp.h> |
| #include <linux/sched.h> |
| #include <linux/swap.h> |
| #include <linux/timex.h> |
| #include <linux/jiffies.h> |
| #include <linux/cpuset.h> |
| #include <linux/export.h> |
| #include <linux/notifier.h> |
| #include <linux/memcontrol.h> |
| #include <linux/mempolicy.h> |
| #include <linux/security.h> |
| #include <linux/ptrace.h> |
| #include <linux/freezer.h> |
| #include <linux/ftrace.h> |
| #include <linux/ratelimit.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/oom.h> |
| |
| int sysctl_panic_on_oom; |
| int sysctl_oom_kill_allocating_task; |
| int sysctl_oom_dump_tasks = 1; |
| static DEFINE_SPINLOCK(zone_scan_lock); |
| |
| /* |
| * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj |
| * @old_val: old oom_score_adj for compare |
| * @new_val: new oom_score_adj for swap |
| * |
| * Sets the oom_score_adj value for current to @new_val iff its present value is |
| * @old_val. Usually used to reinstate a previous value to prevent racing with |
| * userspacing tuning the value in the interim. |
| */ |
| void compare_swap_oom_score_adj(int old_val, int new_val) |
| { |
| struct sighand_struct *sighand = current->sighand; |
| |
| spin_lock_irq(&sighand->siglock); |
| if (current->signal->oom_score_adj == old_val) |
| current->signal->oom_score_adj = new_val; |
| trace_oom_score_adj_update(current); |
| spin_unlock_irq(&sighand->siglock); |
| } |
| |
| /** |
| * test_set_oom_score_adj() - set current's oom_score_adj and return old value |
| * @new_val: new oom_score_adj value |
| * |
| * Sets the oom_score_adj value for current to @new_val with proper |
| * synchronization and returns the old value. Usually used to temporarily |
| * set a value, save the old value in the caller, and then reinstate it later. |
| */ |
| int test_set_oom_score_adj(int new_val) |
| { |
| struct sighand_struct *sighand = current->sighand; |
| int old_val; |
| |
| spin_lock_irq(&sighand->siglock); |
| old_val = current->signal->oom_score_adj; |
| current->signal->oom_score_adj = new_val; |
| trace_oom_score_adj_update(current); |
| spin_unlock_irq(&sighand->siglock); |
| |
| return old_val; |
| } |
| |
| #ifdef CONFIG_NUMA |
| /** |
| * has_intersects_mems_allowed() - check task eligiblity for kill |
| * @tsk: task struct of which task to consider |
| * @mask: nodemask passed to page allocator for mempolicy ooms |
| * |
| * Task eligibility is determined by whether or not a candidate task, @tsk, |
| * shares the same mempolicy nodes as current if it is bound by such a policy |
| * and whether or not it has the same set of allowed cpuset nodes. |
| */ |
| static bool has_intersects_mems_allowed(struct task_struct *tsk, |
| const nodemask_t *mask) |
| { |
| struct task_struct *start = tsk; |
| |
| do { |
| if (mask) { |
| /* |
| * If this is a mempolicy constrained oom, tsk's |
| * cpuset is irrelevant. Only return true if its |
| * mempolicy intersects current, otherwise it may be |
| * needlessly killed. |
| */ |
| if (mempolicy_nodemask_intersects(tsk, mask)) |
| return true; |
| } else { |
| /* |
| * This is not a mempolicy constrained oom, so only |
| * check the mems of tsk's cpuset. |
| */ |
| if (cpuset_mems_allowed_intersects(current, tsk)) |
| return true; |
| } |
| } while_each_thread(start, tsk); |
| |
| return false; |
| } |
| #else |
| static bool has_intersects_mems_allowed(struct task_struct *tsk, |
| const nodemask_t *mask) |
| { |
| return true; |
| } |
| #endif /* CONFIG_NUMA */ |
| |
| /* |
| * The process p may have detached its own ->mm while exiting or through |
| * use_mm(), but one or more of its subthreads may still have a valid |
| * pointer. Return p, or any of its subthreads with a valid ->mm, with |
| * task_lock() held. |
| */ |
| struct task_struct *find_lock_task_mm(struct task_struct *p) |
| { |
| struct task_struct *t = p; |
| |
| do { |
| task_lock(t); |
| if (likely(t->mm)) |
| return t; |
| task_unlock(t); |
| } while_each_thread(p, t); |
| |
| return NULL; |
| } |
| |
| /* return true if the task is not adequate as candidate victim task. */ |
| static bool oom_unkillable_task(struct task_struct *p, |
| const struct mem_cgroup *memcg, const nodemask_t *nodemask) |
| { |
| if (is_global_init(p)) |
| return true; |
| if (p->flags & PF_KTHREAD) |
| return true; |
| |
| /* When mem_cgroup_out_of_memory() and p is not member of the group */ |
| if (memcg && !task_in_mem_cgroup(p, memcg)) |
| return true; |
| |
| /* p may not have freeable memory in nodemask */ |
| if (!has_intersects_mems_allowed(p, nodemask)) |
| return true; |
| |
| return false; |
| } |
| |
| /** |
| * oom_badness - heuristic function to determine which candidate task to kill |
| * @p: task struct of which task we should calculate |
| * @totalpages: total present RAM allowed for page allocation |
| * |
| * The heuristic for determining which task to kill is made to be as simple and |
| * predictable as possible. The goal is to return the highest value for the |
| * task consuming the most memory to avoid subsequent oom failures. |
| */ |
| unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg, |
| const nodemask_t *nodemask, unsigned long totalpages) |
| { |
| long points; |
| |
| if (oom_unkillable_task(p, memcg, nodemask)) |
| return 0; |
| |
| p = find_lock_task_mm(p); |
| if (!p) |
| return 0; |
| |
| if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { |
| task_unlock(p); |
| return 0; |
| } |
| |
| /* |
| * The memory controller may have a limit of 0 bytes, so avoid a divide |
| * by zero, if necessary. |
| */ |
| if (!totalpages) |
| totalpages = 1; |
| |
| /* |
| * The baseline for the badness score is the proportion of RAM that each |
| * task's rss, pagetable and swap space use. |
| */ |
| points = get_mm_rss(p->mm) + p->mm->nr_ptes; |
| points += get_mm_counter(p->mm, MM_SWAPENTS); |
| |
| points *= 1000; |
| points /= totalpages; |
| task_unlock(p); |
| |
| /* |
| * Root processes get 3% bonus, just like the __vm_enough_memory() |
| * implementation used by LSMs. |
| */ |
| if (has_capability_noaudit(p, CAP_SYS_ADMIN)) |
| points -= 30; |
| |
| /* |
| * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may |
| * either completely disable oom killing or always prefer a certain |
| * task. |
| */ |
| points += p->signal->oom_score_adj; |
| |
| /* |
| * Never return 0 for an eligible task that may be killed since it's |
| * possible that no single user task uses more than 0.1% of memory and |
| * no single admin tasks uses more than 3.0%. |
| */ |
| if (points <= 0) |
| return 1; |
| return (points < 1000) ? points : 1000; |
| } |
| |
| /* |
| * Determine the type of allocation constraint. |
| */ |
| #ifdef CONFIG_NUMA |
| static enum oom_constraint constrained_alloc(struct zonelist *zonelist, |
| gfp_t gfp_mask, nodemask_t *nodemask, |
| unsigned long *totalpages) |
| { |
| struct zone *zone; |
| struct zoneref *z; |
| enum zone_type high_zoneidx = gfp_zone(gfp_mask); |
| bool cpuset_limited = false; |
| int nid; |
| |
| /* Default to all available memory */ |
| *totalpages = totalram_pages + total_swap_pages; |
| |
| if (!zonelist) |
| return CONSTRAINT_NONE; |
| /* |
| * Reach here only when __GFP_NOFAIL is used. So, we should avoid |
| * to kill current.We have to random task kill in this case. |
| * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. |
| */ |
| if (gfp_mask & __GFP_THISNODE) |
| return CONSTRAINT_NONE; |
| |
| /* |
| * This is not a __GFP_THISNODE allocation, so a truncated nodemask in |
| * the page allocator means a mempolicy is in effect. Cpuset policy |
| * is enforced in get_page_from_freelist(). |
| */ |
| if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask)) { |
| *totalpages = total_swap_pages; |
| for_each_node_mask(nid, *nodemask) |
| *totalpages += node_spanned_pages(nid); |
| return CONSTRAINT_MEMORY_POLICY; |
| } |
| |
| /* Check this allocation failure is caused by cpuset's wall function */ |
| for_each_zone_zonelist_nodemask(zone, z, zonelist, |
| high_zoneidx, nodemask) |
| if (!cpuset_zone_allowed_softwall(zone, gfp_mask)) |
| cpuset_limited = true; |
| |
| if (cpuset_limited) { |
| *totalpages = total_swap_pages; |
| for_each_node_mask(nid, cpuset_current_mems_allowed) |
| *totalpages += node_spanned_pages(nid); |
| return CONSTRAINT_CPUSET; |
| } |
| return CONSTRAINT_NONE; |
| } |
| #else |
| static enum oom_constraint constrained_alloc(struct zonelist *zonelist, |
| gfp_t gfp_mask, nodemask_t *nodemask, |
| unsigned long *totalpages) |
| { |
| *totalpages = totalram_pages + total_swap_pages; |
| return CONSTRAINT_NONE; |
| } |
| #endif |
| |
| /* |
| * Simple selection loop. We chose the process with the highest |
| * number of 'points'. We expect the caller will lock the tasklist. |
| * |
| * (not docbooked, we don't want this one cluttering up the manual) |
| */ |
| static struct task_struct *select_bad_process(unsigned int *ppoints, |
| unsigned long totalpages, struct mem_cgroup *memcg, |
| const nodemask_t *nodemask, bool force_kill) |
| { |
| struct task_struct *g, *p; |
| struct task_struct *chosen = NULL; |
| *ppoints = 0; |
| |
| do_each_thread(g, p) { |
| unsigned int points; |
| |
| if (p->exit_state) |
| continue; |
| if (oom_unkillable_task(p, memcg, nodemask)) |
| continue; |
| |
| /* |
| * This task already has access to memory reserves and is |
| * being killed. Don't allow any other task access to the |
| * memory reserve. |
| * |
| * Note: this may have a chance of deadlock if it gets |
| * blocked waiting for another task which itself is waiting |
| * for memory. Is there a better alternative? |
| */ |
| if (test_tsk_thread_flag(p, TIF_MEMDIE)) { |
| if (unlikely(frozen(p))) |
| __thaw_task(p); |
| if (!force_kill) |
| return ERR_PTR(-1UL); |
| } |
| if (!p->mm) |
| continue; |
| |
| if (p->flags & PF_EXITING) { |
| /* |
| * If p is the current task and is in the process of |
| * releasing memory, we allow the "kill" to set |
| * TIF_MEMDIE, which will allow it to gain access to |
| * memory reserves. Otherwise, it may stall forever. |
| * |
| * The loop isn't broken here, however, in case other |
| * threads are found to have already been oom killed. |
| */ |
| if (p == current) { |
| chosen = p; |
| *ppoints = 1000; |
| } else if (!force_kill) { |
| /* |
| * If this task is not being ptraced on exit, |
| * then wait for it to finish before killing |
| * some other task unnecessarily. |
| */ |
| if (!(p->group_leader->ptrace & PT_TRACE_EXIT)) |
| return ERR_PTR(-1UL); |
| } |
| } |
| |
| points = oom_badness(p, memcg, nodemask, totalpages); |
| if (points > *ppoints) { |
| chosen = p; |
| *ppoints = points; |
| } |
| } while_each_thread(g, p); |
| |
| return chosen; |
| } |
| |
| /** |
| * dump_tasks - dump current memory state of all system tasks |
| * @mem: current's memory controller, if constrained |
| * @nodemask: nodemask passed to page allocator for mempolicy ooms |
| * |
| * Dumps the current memory state of all eligible tasks. Tasks not in the same |
| * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes |
| * are not shown. |
| * State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj |
| * value, oom_score_adj value, and name. |
| * |
| * Call with tasklist_lock read-locked. |
| */ |
| void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemask) |
| { |
| struct task_struct *p; |
| struct task_struct *task; |
| |
| pr_info("[ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name\n"); |
| for_each_process(p) { |
| if (oom_unkillable_task(p, memcg, nodemask)) |
| continue; |
| |
| task = find_lock_task_mm(p); |
| if (!task) { |
| /* |
| * This is a kthread or all of p's threads have already |
| * detached their mm's. There's no need to report |
| * them; they can't be oom killed anyway. |
| */ |
| continue; |
| } |
| |
| pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n", |
| task->pid, task_uid(task), task->tgid, |
| task->mm->total_vm, get_mm_rss(task->mm), |
| task_cpu(task), task->signal->oom_adj, |
| task->signal->oom_score_adj, task->comm); |
| task_unlock(task); |
| } |
| } |
| |
| static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, |
| struct mem_cgroup *memcg, const nodemask_t *nodemask) |
| { |
| task_lock(current); |
| pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " |
| "oom_adj=%d, oom_score_adj=%d\n", |
| current->comm, gfp_mask, order, current->signal->oom_adj, |
| current->signal->oom_score_adj); |
| cpuset_print_task_mems_allowed(current); |
| task_unlock(current); |
| dump_stack(); |
| mem_cgroup_print_oom_info(memcg, p); |
| show_mem(SHOW_MEM_FILTER_NODES); |
| if (sysctl_oom_dump_tasks) |
| dump_tasks(memcg, nodemask); |
| } |
| |
| #define K(x) ((x) << (PAGE_SHIFT-10)) |
| static void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, |
| unsigned int points, unsigned long totalpages, |
| struct mem_cgroup *memcg, nodemask_t *nodemask, |
| const char *message) |
| { |
| struct task_struct *victim = p; |
| struct task_struct *child; |
| struct task_struct *t = p; |
| struct mm_struct *mm; |
| unsigned int victim_points = 0; |
| static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, |
| DEFAULT_RATELIMIT_BURST); |
| |
| /* |
| * If the task is already exiting, don't alarm the sysadmin or kill |
| * its children or threads, just set TIF_MEMDIE so it can die quickly |
| */ |
| if (p->flags & PF_EXITING) { |
| set_tsk_thread_flag(p, TIF_MEMDIE); |
| return; |
| } |
| |
| if (__ratelimit(&oom_rs)) |
| dump_header(p, gfp_mask, order, memcg, nodemask); |
| |
| task_lock(p); |
| pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n", |
| message, task_pid_nr(p), p->comm, points); |
| task_unlock(p); |
| |
| /* |
| * If any of p's children has a different mm and is eligible for kill, |
| * the one with the highest oom_badness() score is sacrificed for its |
| * parent. This attempts to lose the minimal amount of work done while |
| * still freeing memory. |
| */ |
| do { |
| list_for_each_entry(child, &t->children, sibling) { |
| unsigned int child_points; |
| |
| if (child->mm == p->mm) |
| continue; |
| /* |
| * oom_badness() returns 0 if the thread is unkillable |
| */ |
| child_points = oom_badness(child, memcg, nodemask, |
| totalpages); |
| if (child_points > victim_points) { |
| victim = child; |
| victim_points = child_points; |
| } |
| } |
| } while_each_thread(p, t); |
| |
| victim = find_lock_task_mm(victim); |
| if (!victim) |
| return; |
| |
| /* mm cannot safely be dereferenced after task_unlock(victim) */ |
| mm = victim->mm; |
| pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n", |
| task_pid_nr(victim), victim->comm, K(victim->mm->total_vm), |
| K(get_mm_counter(victim->mm, MM_ANONPAGES)), |
| K(get_mm_counter(victim->mm, MM_FILEPAGES))); |
| task_unlock(victim); |
| |
| /* |
| * Kill all user processes sharing victim->mm in other thread groups, if |
| * any. They don't get access to memory reserves, though, to avoid |
| * depletion of all memory. This prevents mm->mmap_sem livelock when an |
| * oom killed thread cannot exit because it requires the semaphore and |
| * its contended by another thread trying to allocate memory itself. |
| * That thread will now get access to memory reserves since it has a |
| * pending fatal signal. |
| */ |
| for_each_process(p) |
| if (p->mm == mm && !same_thread_group(p, victim) && |
| !(p->flags & PF_KTHREAD)) { |
| if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) |
| continue; |
| |
| task_lock(p); /* Protect ->comm from prctl() */ |
| pr_err("Kill process %d (%s) sharing same memory\n", |
| task_pid_nr(p), p->comm); |
| task_unlock(p); |
| do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); |
| } |
| |
| set_tsk_thread_flag(victim, TIF_MEMDIE); |
| do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); |
| } |
| #undef K |
| |
| /* |
| * Determines whether the kernel must panic because of the panic_on_oom sysctl. |
| */ |
| static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, |
| int order, const nodemask_t *nodemask) |
| { |
| if (likely(!sysctl_panic_on_oom)) |
| return; |
| if (sysctl_panic_on_oom != 2) { |
| /* |
| * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel |
| * does not panic for cpuset, mempolicy, or memcg allocation |
| * failures. |
| */ |
| if (constraint != CONSTRAINT_NONE) |
| return; |
| } |
| read_lock(&tasklist_lock); |
| dump_header(NULL, gfp_mask, order, NULL, nodemask); |
| read_unlock(&tasklist_lock); |
| panic("Out of memory: %s panic_on_oom is enabled\n", |
| sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); |
| } |
| |
| #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
| void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, |
| int order) |
| { |
| unsigned long limit; |
| unsigned int points = 0; |
| struct task_struct *p; |
| |
| /* |
| * If current has a pending SIGKILL, then automatically select it. The |
| * goal is to allow it to allocate so that it may quickly exit and free |
| * its memory. |
| */ |
| if (fatal_signal_pending(current)) { |
| set_thread_flag(TIF_MEMDIE); |
| return; |
| } |
| |
| check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL); |
| limit = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT; |
| read_lock(&tasklist_lock); |
| p = select_bad_process(&points, limit, memcg, NULL, false); |
| if (p && PTR_ERR(p) != -1UL) |
| oom_kill_process(p, gfp_mask, order, points, limit, memcg, NULL, |
| "Memory cgroup out of memory"); |
| read_unlock(&tasklist_lock); |
| } |
| #endif |
| |
| static BLOCKING_NOTIFIER_HEAD(oom_notify_list); |
| |
| int register_oom_notifier(struct notifier_block *nb) |
| { |
| return blocking_notifier_chain_register(&oom_notify_list, nb); |
| } |
| EXPORT_SYMBOL_GPL(register_oom_notifier); |
| |
| int unregister_oom_notifier(struct notifier_block *nb) |
| { |
| return blocking_notifier_chain_unregister(&oom_notify_list, nb); |
| } |
| EXPORT_SYMBOL_GPL(unregister_oom_notifier); |
| |
| /* |
| * Try to acquire the OOM killer lock for the zones in zonelist. Returns zero |
| * if a parallel OOM killing is already taking place that includes a zone in |
| * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. |
| */ |
| int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) |
| { |
| struct zoneref *z; |
| struct zone *zone; |
| int ret = 1; |
| |
| spin_lock(&zone_scan_lock); |
| for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { |
| if (zone_is_oom_locked(zone)) { |
| ret = 0; |
| goto out; |
| } |
| } |
| |
| for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { |
| /* |
| * Lock each zone in the zonelist under zone_scan_lock so a |
| * parallel invocation of try_set_zonelist_oom() doesn't succeed |
| * when it shouldn't. |
| */ |
| zone_set_flag(zone, ZONE_OOM_LOCKED); |
| } |
| |
| out: |
| spin_unlock(&zone_scan_lock); |
| return ret; |
| } |
| |
| /* |
| * Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed |
| * allocation attempts with zonelists containing them may now recall the OOM |
| * killer, if necessary. |
| */ |
| void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) |
| { |
| struct zoneref *z; |
| struct zone *zone; |
| |
| spin_lock(&zone_scan_lock); |
| for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { |
| zone_clear_flag(zone, ZONE_OOM_LOCKED); |
| } |
| spin_unlock(&zone_scan_lock); |
| } |
| |
| /* |
| * Try to acquire the oom killer lock for all system zones. Returns zero if a |
| * parallel oom killing is taking place, otherwise locks all zones and returns |
| * non-zero. |
| */ |
| static int try_set_system_oom(void) |
| { |
| struct zone *zone; |
| int ret = 1; |
| |
| spin_lock(&zone_scan_lock); |
| for_each_populated_zone(zone) |
| if (zone_is_oom_locked(zone)) { |
| ret = 0; |
| goto out; |
| } |
| for_each_populated_zone(zone) |
| zone_set_flag(zone, ZONE_OOM_LOCKED); |
| out: |
| spin_unlock(&zone_scan_lock); |
| return ret; |
| } |
| |
| /* |
| * Clears ZONE_OOM_LOCKED for all system zones so that failed allocation |
| * attempts or page faults may now recall the oom killer, if necessary. |
| */ |
| static void clear_system_oom(void) |
| { |
| struct zone *zone; |
| |
| spin_lock(&zone_scan_lock); |
| for_each_populated_zone(zone) |
| zone_clear_flag(zone, ZONE_OOM_LOCKED); |
| spin_unlock(&zone_scan_lock); |
| } |
| |
| /** |
| * out_of_memory - kill the "best" process when we run out of memory |
| * @zonelist: zonelist pointer |
| * @gfp_mask: memory allocation flags |
| * @order: amount of memory being requested as a power of 2 |
| * @nodemask: nodemask passed to page allocator |
| * @force_kill: true if a task must be killed, even if others are exiting |
| * |
| * If we run out of memory, we have the choice between either |
| * killing a random task (bad), letting the system crash (worse) |
| * OR try to be smart about which process to kill. Note that we |
| * don't have to be perfect here, we just have to be good. |
| */ |
| void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, |
| int order, nodemask_t *nodemask, bool force_kill) |
| { |
| const nodemask_t *mpol_mask; |
| struct task_struct *p; |
| unsigned long totalpages; |
| unsigned long freed = 0; |
| unsigned int points; |
| enum oom_constraint constraint = CONSTRAINT_NONE; |
| int killed = 0; |
| |
| blocking_notifier_call_chain(&oom_notify_list, 0, &freed); |
| if (freed > 0) |
| /* Got some memory back in the last second. */ |
| return; |
| |
| /* |
| * If current has a pending SIGKILL, then automatically select it. The |
| * goal is to allow it to allocate so that it may quickly exit and free |
| * its memory. |
| */ |
| if (fatal_signal_pending(current)) { |
| set_thread_flag(TIF_MEMDIE); |
| return; |
| } |
| |
| /* |
| * Check if there were limitations on the allocation (only relevant for |
| * NUMA) that may require different handling. |
| */ |
| constraint = constrained_alloc(zonelist, gfp_mask, nodemask, |
| &totalpages); |
| mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL; |
| check_panic_on_oom(constraint, gfp_mask, order, mpol_mask); |
| |
| read_lock(&tasklist_lock); |
| if (sysctl_oom_kill_allocating_task && |
| !oom_unkillable_task(current, NULL, nodemask) && |
| current->mm) { |
| oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL, |
| nodemask, |
| "Out of memory (oom_kill_allocating_task)"); |
| goto out; |
| } |
| |
| p = select_bad_process(&points, totalpages, NULL, mpol_mask, |
| force_kill); |
| /* Found nothing?!?! Either we hang forever, or we panic. */ |
| if (!p) { |
| dump_header(NULL, gfp_mask, order, NULL, mpol_mask); |
| read_unlock(&tasklist_lock); |
| panic("Out of memory and no killable processes...\n"); |
| } |
| if (PTR_ERR(p) != -1UL) { |
| oom_kill_process(p, gfp_mask, order, points, totalpages, NULL, |
| nodemask, "Out of memory"); |
| killed = 1; |
| } |
| out: |
| read_unlock(&tasklist_lock); |
| |
| /* |
| * Give "p" a good chance of killing itself before we |
| * retry to allocate memory unless "p" is current |
| */ |
| if (killed && !test_thread_flag(TIF_MEMDIE)) |
| schedule_timeout_uninterruptible(1); |
| } |
| |
| /* |
| * The pagefault handler calls here because it is out of memory, so kill a |
| * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel |
| * oom killing is already in progress so do nothing. If a task is found with |
| * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit. |
| */ |
| void pagefault_out_of_memory(void) |
| { |
| if (try_set_system_oom()) { |
| out_of_memory(NULL, 0, 0, NULL, false); |
| clear_system_oom(); |
| } |
| if (!test_thread_flag(TIF_MEMDIE)) |
| schedule_timeout_uninterruptible(1); |
| } |