From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Tue, 10 Aug 2010 00:19:42 +0000 (-0700)
Subject: oom: multi threaded process coredump don't make deadlock
X-Git-Tag: v2.6.36-rc1~407
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cef1d3523d33ebc35fc29e454b1f4bab953fabbf;p=pandora-kernel.git

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>
---

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