From c027a474a68065391c8773f6e83ed5412657e369 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 30 Jul 2011 16:35:02 +0200 Subject: oom: task->mm == NULL doesn't mean the memory was freed exit_mm() sets ->mm == NULL then it does mmput()->exit_mmap() which frees the memory. However select_bad_process() checks ->mm != NULL before TIF_MEMDIE, so it continues to kill other tasks even if we have the oom-killed task freeing its memory. Change select_bad_process() to check ->mm after TIF_MEMDIE, but skip the tasks which have already passed exit_notify() to ensure a zombie with TIF_MEMDIE set can't block oom-killer. Alternatively we could probably clear TIF_MEMDIE after exit_mmap(). Signed-off-by: Oleg Nesterov Reviewed-by: KOSAKI Motohiro Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index eafff89b3dd6..626303b52f3c 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -303,7 +303,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, do_each_thread(g, p) { unsigned int points; - if (!p->mm) + if (p->exit_state) continue; if (oom_unkillable_task(p, mem, nodemask)) continue; @@ -319,6 +319,8 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, */ if (test_tsk_thread_flag(p, TIF_MEMDIE)) return ERR_PTR(-1UL); + if (!p->mm) + continue; if (p->flags & PF_EXITING) { /* -- cgit v1.2.3-70-g09d2