From e18641e19a9204f241f04a5ac700168dcd18de4f Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Tue, 26 Oct 2010 14:21:23 -0700 Subject: [PATCH] oom: avoid killing a task if a thread sharing its mm cannot be killed The oom killer's goal is to kill a memory-hogging task so that it may exit, free its memory, and allow the current context to allocate the memory that triggered it in the first place. Thus, killing a task is pointless if other threads sharing its mm cannot be killed because of its /proc/pid/oom_adj or /proc/pid/oom_score_adj value. This patch checks whether any other thread sharing p->mm has an oom_score_adj of OOM_SCORE_ADJ_MIN. If so, the thread cannot be killed and oom_badness(p) returns 0, meaning it's unkillable. Signed-off-by: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Rik van Riel Cc: Ying Han Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 4029583a1024..4395f371bc7c 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -162,10 +162,11 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, return 0; /* - * Shortcut check for OOM_SCORE_ADJ_MIN so the entire heuristic doesn't - * need to be executed for something that cannot be killed. + * Shortcut check for a thread sharing p->mm that is OOM_SCORE_ADJ_MIN + * so the entire heuristic doesn't need to be executed for something + * that cannot be killed. */ - if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { + if (atomic_read(&p->mm->oom_disable_count)) { task_unlock(p); return 0; } @@ -680,7 +681,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, read_lock(&tasklist_lock); if (sysctl_oom_kill_allocating_task && !oom_unkillable_task(current, NULL, nodemask) && - (current->signal->oom_adj != OOM_DISABLE)) { + 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 -- 2.20.1