Messages in this thread Patch in this message | | | From | KOSAKI Motohiro <> | Subject | [PATCH 11/11] oom: multi threaded process coredump don't make deadlock | Date | Wed, 30 Jun 2010 18:34:06 +0900 (JST) |
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Oleg pointed out current PF_EXITING check is wrong. Because PF_EXITING is per-thread flag, not per-process flag. He said,
Two threads, group-leader L and its sub-thread T. T dumps the code. In this case both threads have ->mm != NULL, L has PF_EXITING.
The first problem is, select_bad_process() always return -1 in this case (even if the caller is T, this doesn't matter).
The second problem is that we should add TIF_MEMDIE to T, not L.
I think we can remove this dubious PF_EXITING check. but as first step, This patch add the protection of multi threaded issue.
Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> --- mm/oom_kill.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 0858b18..b04e557 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -360,7 +360,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints, * the process of exiting and releasing its resources. * Otherwise we could get an easy OOM deadlock. */ - if ((p->flags & PF_EXITING) && p->mm) { + if (thread_group_empty(p) && (p->flags & PF_EXITING) && p->mm) { if (p != current) return ERR_PTR(-1UL); -- 1.6.5.2
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