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1e99bad0d9
It's necessary to kill all threads that share an oom killed task's mm if
the goal is to lead to future memory freeing.
This patch reintroduces the code removed in 8c5cd6f3
(oom: oom_kill
doesn't kill vfork parent (or child)) since it is obsoleted.
It's now guaranteed that any task passed to oom_kill_task() does not share
an mm with any thread that is unkillable. Thus, we're safe to issue a
SIGKILL to any thread sharing the same mm.
This is especially necessary to solve an mm->mmap_sem livelock issue
whereas an oom killed thread must acquire the lock in the exit path while
another thread is holding it in the page allocator while trying to
allocate memory itself (and will preempt the oom killer since a task was
already killed). Since tasks with pending fatal signals are now granted
access to memory reserves, the thread holding the lock may quickly
allocate and release the lock so that the oom killed task may exit.
This mainly is for threads that are cloned with CLONE_VM but not
CLONE_THREAD, so they are in a different thread group. Non-NPTL threads
exist in the wild and this change is necessary to prevent the livelock in
such cases. We care more about preventing the livelock than incurring the
additional tasklist in the oom killer when a task has been killed.
Systems that are sufficiently large to not want the tasklist scan in the
oom killer in the first place already have the option of enabling
/proc/sys/vm/oom_kill_allocating_task, which was designed specifically for
that purpose.
This code had existed in the oom killer for over eight years dating back
to the 2.4 kernel.
[akpm@linux-foundation.org: add nice comment]
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
762 lines
21 KiB
C
762 lines
21 KiB
C
/*
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* linux/mm/oom_kill.c
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*
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* Copyright (C) 1998,2000 Rik van Riel
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* Thanks go out to Claus Fischer for some serious inspiration and
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* for goading me into coding this file...
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* Copyright (C) 2010 Google, Inc.
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* Rewritten by David Rientjes
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*
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* The routines in this file are used to kill a process when
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* we're seriously out of memory. This gets called from __alloc_pages()
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* in mm/page_alloc.c when we really run out of memory.
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*
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* Since we won't call these routines often (on a well-configured
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* machine) this file will double as a 'coding guide' and a signpost
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* for newbie kernel hackers. It features several pointers to major
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* kernel subsystems and hints as to where to find out what things do.
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*/
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#include <linux/oom.h>
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/sched.h>
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#include <linux/swap.h>
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#include <linux/timex.h>
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#include <linux/jiffies.h>
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#include <linux/cpuset.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/memcontrol.h>
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#include <linux/mempolicy.h>
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#include <linux/security.h>
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int sysctl_panic_on_oom;
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int sysctl_oom_kill_allocating_task;
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int sysctl_oom_dump_tasks = 1;
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static DEFINE_SPINLOCK(zone_scan_lock);
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#ifdef CONFIG_NUMA
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/**
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* has_intersects_mems_allowed() - check task eligiblity for kill
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* @tsk: task struct of which task to consider
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* @mask: nodemask passed to page allocator for mempolicy ooms
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*
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* Task eligibility is determined by whether or not a candidate task, @tsk,
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* shares the same mempolicy nodes as current if it is bound by such a policy
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* and whether or not it has the same set of allowed cpuset nodes.
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*/
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static bool has_intersects_mems_allowed(struct task_struct *tsk,
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const nodemask_t *mask)
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{
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struct task_struct *start = tsk;
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do {
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if (mask) {
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/*
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* If this is a mempolicy constrained oom, tsk's
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* cpuset is irrelevant. Only return true if its
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* mempolicy intersects current, otherwise it may be
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* needlessly killed.
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*/
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if (mempolicy_nodemask_intersects(tsk, mask))
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return true;
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} else {
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/*
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* This is not a mempolicy constrained oom, so only
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* check the mems of tsk's cpuset.
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*/
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if (cpuset_mems_allowed_intersects(current, tsk))
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return true;
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}
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} while_each_thread(start, tsk);
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return false;
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}
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#else
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static bool has_intersects_mems_allowed(struct task_struct *tsk,
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const nodemask_t *mask)
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{
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return true;
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}
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#endif /* CONFIG_NUMA */
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/*
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* If this is a system OOM (not a memcg OOM) and the task selected to be
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* killed is not already running at high (RT) priorities, speed up the
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* recovery by boosting the dying task to the lowest FIFO priority.
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* That helps with the recovery and avoids interfering with RT tasks.
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*/
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static void boost_dying_task_prio(struct task_struct *p,
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struct mem_cgroup *mem)
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{
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struct sched_param param = { .sched_priority = 1 };
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if (mem)
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return;
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if (!rt_task(p))
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sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
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}
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/*
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* The process p may have detached its own ->mm while exiting or through
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* use_mm(), but one or more of its subthreads may still have a valid
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* pointer. Return p, or any of its subthreads with a valid ->mm, with
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* task_lock() held.
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*/
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struct task_struct *find_lock_task_mm(struct task_struct *p)
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{
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struct task_struct *t = p;
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do {
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task_lock(t);
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if (likely(t->mm))
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return t;
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task_unlock(t);
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} while_each_thread(p, t);
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return NULL;
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}
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/* return true if the task is not adequate as candidate victim task. */
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static bool oom_unkillable_task(struct task_struct *p,
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const struct mem_cgroup *mem, const nodemask_t *nodemask)
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{
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if (is_global_init(p))
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return true;
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if (p->flags & PF_KTHREAD)
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return true;
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/* When mem_cgroup_out_of_memory() and p is not member of the group */
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if (mem && !task_in_mem_cgroup(p, mem))
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return true;
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/* p may not have freeable memory in nodemask */
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if (!has_intersects_mems_allowed(p, nodemask))
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return true;
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return false;
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}
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/**
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* oom_badness - heuristic function to determine which candidate task to kill
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* @p: task struct of which task we should calculate
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* @totalpages: total present RAM allowed for page allocation
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*
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* The heuristic for determining which task to kill is made to be as simple and
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* predictable as possible. The goal is to return the highest value for the
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* task consuming the most memory to avoid subsequent oom failures.
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*/
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unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
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const nodemask_t *nodemask, unsigned long totalpages)
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{
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int points;
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if (oom_unkillable_task(p, mem, nodemask))
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return 0;
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p = find_lock_task_mm(p);
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if (!p)
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return 0;
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/*
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* Shortcut check for a thread sharing p->mm that is OOM_SCORE_ADJ_MIN
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* so the entire heuristic doesn't need to be executed for something
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* that cannot be killed.
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*/
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if (atomic_read(&p->mm->oom_disable_count)) {
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task_unlock(p);
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return 0;
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}
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/*
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* When the PF_OOM_ORIGIN bit is set, it indicates the task should have
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* priority for oom killing.
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*/
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if (p->flags & PF_OOM_ORIGIN) {
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task_unlock(p);
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return 1000;
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}
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/*
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* The memory controller may have a limit of 0 bytes, so avoid a divide
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* by zero, if necessary.
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*/
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if (!totalpages)
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totalpages = 1;
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/*
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* The baseline for the badness score is the proportion of RAM that each
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* task's rss and swap space use.
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*/
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points = (get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS)) * 1000 /
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totalpages;
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task_unlock(p);
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/*
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* Root processes get 3% bonus, just like the __vm_enough_memory()
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* implementation used by LSMs.
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*/
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if (has_capability_noaudit(p, CAP_SYS_ADMIN))
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points -= 30;
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/*
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* /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may
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* either completely disable oom killing or always prefer a certain
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* task.
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*/
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points += p->signal->oom_score_adj;
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/*
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* Never return 0 for an eligible task that may be killed since it's
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* possible that no single user task uses more than 0.1% of memory and
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* no single admin tasks uses more than 3.0%.
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*/
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if (points <= 0)
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return 1;
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return (points < 1000) ? points : 1000;
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}
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/*
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* Determine the type of allocation constraint.
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*/
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#ifdef CONFIG_NUMA
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static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
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gfp_t gfp_mask, nodemask_t *nodemask,
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unsigned long *totalpages)
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{
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struct zone *zone;
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struct zoneref *z;
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enum zone_type high_zoneidx = gfp_zone(gfp_mask);
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bool cpuset_limited = false;
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int nid;
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/* Default to all available memory */
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*totalpages = totalram_pages + total_swap_pages;
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if (!zonelist)
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return CONSTRAINT_NONE;
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/*
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* Reach here only when __GFP_NOFAIL is used. So, we should avoid
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* to kill current.We have to random task kill in this case.
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* Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
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*/
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if (gfp_mask & __GFP_THISNODE)
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return CONSTRAINT_NONE;
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/*
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* This is not a __GFP_THISNODE allocation, so a truncated nodemask in
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* the page allocator means a mempolicy is in effect. Cpuset policy
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* is enforced in get_page_from_freelist().
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*/
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if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask)) {
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*totalpages = total_swap_pages;
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for_each_node_mask(nid, *nodemask)
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*totalpages += node_spanned_pages(nid);
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return CONSTRAINT_MEMORY_POLICY;
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}
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/* Check this allocation failure is caused by cpuset's wall function */
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for_each_zone_zonelist_nodemask(zone, z, zonelist,
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high_zoneidx, nodemask)
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if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
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cpuset_limited = true;
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if (cpuset_limited) {
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*totalpages = total_swap_pages;
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for_each_node_mask(nid, cpuset_current_mems_allowed)
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*totalpages += node_spanned_pages(nid);
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return CONSTRAINT_CPUSET;
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}
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return CONSTRAINT_NONE;
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}
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#else
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static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
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gfp_t gfp_mask, nodemask_t *nodemask,
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unsigned long *totalpages)
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{
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*totalpages = totalram_pages + total_swap_pages;
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return CONSTRAINT_NONE;
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}
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#endif
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/*
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* Simple selection loop. We chose the process with the highest
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* number of 'points'. We expect the caller will lock the tasklist.
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*
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* (not docbooked, we don't want this one cluttering up the manual)
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*/
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static struct task_struct *select_bad_process(unsigned int *ppoints,
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unsigned long totalpages, struct mem_cgroup *mem,
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const nodemask_t *nodemask)
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{
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struct task_struct *p;
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struct task_struct *chosen = NULL;
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*ppoints = 0;
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for_each_process(p) {
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unsigned int points;
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if (oom_unkillable_task(p, mem, nodemask))
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continue;
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/*
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* This task already has access to memory reserves and is
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* being killed. Don't allow any other task access to the
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* memory reserve.
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*
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* Note: this may have a chance of deadlock if it gets
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* blocked waiting for another task which itself is waiting
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* for memory. Is there a better alternative?
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*/
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if (test_tsk_thread_flag(p, TIF_MEMDIE))
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return ERR_PTR(-1UL);
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/*
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* This is in the process of releasing memory so wait for it
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* to finish before killing some other task by mistake.
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*
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* However, if p is the current task, we allow the 'kill' to
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* go ahead if it is exiting: this will simply set TIF_MEMDIE,
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* which will allow it to gain access to memory reserves in
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* the process of exiting and releasing its resources.
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* Otherwise we could get an easy OOM deadlock.
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*/
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if (thread_group_empty(p) && (p->flags & PF_EXITING) && p->mm) {
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if (p != current)
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return ERR_PTR(-1UL);
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chosen = p;
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*ppoints = 1000;
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}
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points = oom_badness(p, mem, nodemask, totalpages);
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if (points > *ppoints) {
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chosen = p;
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*ppoints = points;
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}
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}
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return chosen;
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}
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/**
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* dump_tasks - dump current memory state of all system tasks
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* @mem: current's memory controller, if constrained
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* @nodemask: nodemask passed to page allocator for mempolicy ooms
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*
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* Dumps the current memory state of all eligible tasks. Tasks not in the same
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* memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
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* are not shown.
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* State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj
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* value, oom_score_adj value, and name.
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*
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* Call with tasklist_lock read-locked.
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*/
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static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
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{
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struct task_struct *p;
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struct task_struct *task;
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pr_info("[ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name\n");
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for_each_process(p) {
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if (oom_unkillable_task(p, mem, nodemask))
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continue;
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task = find_lock_task_mm(p);
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if (!task) {
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/*
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* This is a kthread or all of p's threads have already
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* detached their mm's. There's no need to report
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* them; they can't be oom killed anyway.
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*/
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continue;
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}
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pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n",
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task->pid, task_uid(task), task->tgid,
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task->mm->total_vm, get_mm_rss(task->mm),
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task_cpu(task), task->signal->oom_adj,
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task->signal->oom_score_adj, task->comm);
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task_unlock(task);
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}
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}
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static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
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struct mem_cgroup *mem, const nodemask_t *nodemask)
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{
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task_lock(current);
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pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
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"oom_adj=%d, oom_score_adj=%d\n",
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current->comm, gfp_mask, order, current->signal->oom_adj,
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current->signal->oom_score_adj);
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cpuset_print_task_mems_allowed(current);
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task_unlock(current);
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dump_stack();
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mem_cgroup_print_oom_info(mem, p);
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show_mem();
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if (sysctl_oom_dump_tasks)
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dump_tasks(mem, nodemask);
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}
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#define K(x) ((x) << (PAGE_SHIFT-10))
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static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
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{
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struct task_struct *q;
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struct mm_struct *mm;
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p = find_lock_task_mm(p);
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if (!p)
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return 1;
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/* mm cannot be safely dereferenced after task_unlock(p) */
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mm = p->mm;
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pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
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task_pid_nr(p), p->comm, K(p->mm->total_vm),
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K(get_mm_counter(p->mm, MM_ANONPAGES)),
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K(get_mm_counter(p->mm, MM_FILEPAGES)));
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task_unlock(p);
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/*
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* Kill all processes sharing p->mm in other thread groups, if any.
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* They don't get access to memory reserves or a higher scheduler
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* priority, though, to avoid depletion of all memory or task
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* starvation. This prevents mm->mmap_sem livelock when an oom killed
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* task cannot exit because it requires the semaphore and its contended
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* by another thread trying to allocate memory itself. That thread will
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* now get access to memory reserves since it has a pending fatal
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* signal.
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*/
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for_each_process(q)
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if (q->mm == mm && !same_thread_group(q, p)) {
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task_lock(q); /* Protect ->comm from prctl() */
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pr_err("Kill process %d (%s) sharing same memory\n",
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task_pid_nr(q), q->comm);
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task_unlock(q);
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force_sig(SIGKILL, q);
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}
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set_tsk_thread_flag(p, TIF_MEMDIE);
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force_sig(SIGKILL, p);
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/*
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* We give our sacrificial lamb high priority and access to
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* all the memory it needs. That way it should be able to
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* exit() and clear out its resources quickly...
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*/
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boost_dying_task_prio(p, mem);
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return 0;
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}
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#undef K
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static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
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unsigned int points, unsigned long totalpages,
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struct mem_cgroup *mem, nodemask_t *nodemask,
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const char *message)
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{
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struct task_struct *victim = p;
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struct task_struct *child;
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struct task_struct *t = p;
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unsigned int victim_points = 0;
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|
if (printk_ratelimit())
|
|
dump_header(p, gfp_mask, order, mem, nodemask);
|
|
|
|
/*
|
|
* 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);
|
|
boost_dying_task_prio(p, mem);
|
|
return 0;
|
|
}
|
|
|
|
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 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;
|
|
|
|
/*
|
|
* oom_badness() returns 0 if the thread is unkillable
|
|
*/
|
|
child_points = oom_badness(child, mem, nodemask,
|
|
totalpages);
|
|
if (child_points > victim_points) {
|
|
victim = child;
|
|
victim_points = child_points;
|
|
}
|
|
}
|
|
} while_each_thread(p, t);
|
|
|
|
return oom_kill_task(victim, mem);
|
|
}
|
|
|
|
/*
|
|
* 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 *mem, gfp_t gfp_mask)
|
|
{
|
|
unsigned long limit;
|
|
unsigned int points = 0;
|
|
struct task_struct *p;
|
|
|
|
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
|
|
limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
|
|
read_lock(&tasklist_lock);
|
|
retry:
|
|
p = select_bad_process(&points, limit, mem, NULL);
|
|
if (!p || PTR_ERR(p) == -1UL)
|
|
goto out;
|
|
|
|
if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, NULL,
|
|
"Memory cgroup out of memory"))
|
|
goto retry;
|
|
out:
|
|
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
|
|
*
|
|
* 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)
|
|
{
|
|
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);
|
|
boost_dying_task_prio(current, NULL);
|
|
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 && !atomic_read(¤t->mm->oom_disable_count)) {
|
|
/*
|
|
* oom_kill_process() needs tasklist_lock held. If it returns
|
|
* non-zero, current could not be killed so we must fallback to
|
|
* the tasklist scan.
|
|
*/
|
|
if (!oom_kill_process(current, gfp_mask, order, 0, totalpages,
|
|
NULL, nodemask,
|
|
"Out of memory (oom_kill_allocating_task)"))
|
|
goto out;
|
|
}
|
|
|
|
retry:
|
|
p = select_bad_process(&points, totalpages, NULL, mpol_mask);
|
|
if (PTR_ERR(p) == -1UL)
|
|
goto out;
|
|
|
|
/* 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 (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
|
|
nodemask, "Out of memory"))
|
|
goto retry;
|
|
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);
|
|
clear_system_oom();
|
|
}
|
|
if (!test_thread_flag(TIF_MEMDIE))
|
|
schedule_timeout_uninterruptible(1);
|
|
}
|