linux-kernel - [PATCH 1/3 for 2.6.38] oom: oom_kill_process: don't set TIF

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Message-ID: <20110314190446.GB21845@redhat.com>
Date:	Mon, 14 Mar 2011 20:04:46 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Hugh Dickins <hughd@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrey Vagin <avagin@...nvz.org>,
	David Rientjes <rientjes@...gle.com>,
	Frantisek Hrbata <fhrbata@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3 for 2.6.38] oom: oom_kill_process: don't set TIF_MEMDIE
	if !p->mm

oom_kill_process() simply sets TIF_MEMDIE and returns if PF_EXITING.
This is very wrong by many reasons. In particular, this thread can
be the dead group leader. Check p->mm != NULL.

Note: this is _not_ enough. Just a minimal fix.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---

 mm/oom_kill.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 38/mm/oom_kill.c~1_kill_fix_pf_exiting	2011-03-14 17:53:05.000000000 +0100
+++ 38/mm/oom_kill.c	2011-03-14 18:51:49.000000000 +0100
@@ -470,7 +470,7 @@ static int oom_kill_process(struct task_
 	 * If the task is already exiting, don't alarm the sysadmin or kill
 	 * its children or threads, just set TIF_MEMDIE so it can die quickly
 	 */
-	if (p->flags & PF_EXITING) {
+	if (p->flags & PF_EXITING && p->mm) {
 		set_tsk_thread_flag(p, TIF_MEMDIE);
 		boost_dying_task_prio(p, mem);
 		return 0;

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