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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-08-10 04:19:42 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-10 07:45:02 +0400
commitcef1d3523d33ebc35fc29e454b1f4bab953fabbf (patch)
tree3688cf9e7c3b1bd4e1d473d79fd1a959bd4306fb /mm/oom_kill.c
parent93b43fa55088fe977503a156d1097cc2055449a2 (diff)
downloadlinux-cef1d3523d33ebc35fc29e454b1f4bab953fabbf.tar.xz
oom: multi threaded process coredump don't make deadlock
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. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 31bd0c344fa7..0a4ca8a0234b 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);