From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 372056B01D6 for ; Wed, 30 Jun 2010 05:34:13 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o5U9YBko025450 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Wed, 30 Jun 2010 18:34:11 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 0CEC845DE51 for ; Wed, 30 Jun 2010 18:34:11 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id E188745DE4F for ; Wed, 30 Jun 2010 18:34:10 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id CB1BA1DB803A for ; Wed, 30 Jun 2010 18:34:10 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 88DFDE08002 for ; Wed, 30 Jun 2010 18:34:07 +0900 (JST) From: KOSAKI Motohiro Subject: [PATCH 11/11] oom: multi threaded process coredump don't make deadlock In-Reply-To: <20100630172430.AA42.A69D9226@jp.fujitsu.com> References: <20100630172430.AA42.A69D9226@jp.fujitsu.com> Message-Id: <20100630183322.AA68.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Wed, 30 Jun 2010 18:34:06 +0900 (JST) Sender: owner-linux-mm@kvack.org To: LKML , linux-mm , Andrew Morton , Minchan Kim , David Rientjes , KAMEZAWA Hiroyuki Cc: kosaki.motohiro@jp.fujitsu.com, Oleg Nesterov List-ID: 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 Signed-off-by: KOSAKI Motohiro --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org