From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id C9DD36B01B7 for ; Wed, 16 Jun 2010 21:51:47 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o5H1pjKx006028 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 17 Jun 2010 10:51:45 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 405BA45DE4F for ; Thu, 17 Jun 2010 10:51:45 +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 1BE2F45DE4E for ; Thu, 17 Jun 2010 10:51:45 +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 07CCB1DB803A for ; Thu, 17 Jun 2010 10:51:45 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id BC1641DB8038 for ; Thu, 17 Jun 2010 10:51:44 +0900 (JST) From: KOSAKI Motohiro Subject: [PATCH 9/9] oom: multi threaded process coredump don't make deadlock In-Reply-To: <20100617104311.FB7A.A69D9226@jp.fujitsu.com> References: <20100617104311.FB7A.A69D9226@jp.fujitsu.com> Message-Id: <20100617104953.FB98.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Date: Thu, 17 Jun 2010 10:51:44 +0900 (JST) Sender: owner-linux-mm@kvack.org To: LKML , linux-mm , Andrew Morton , David Rientjes , Minchan Kim , KAMEZAWA Hiroyuki , Oleg Nesterov Cc: kosaki.motohiro@jp.fujitsu.com 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 b2ea2d8..4abc5c1 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -353,7 +353,7 @@ 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