Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752734Ab0HSKyM (ORCPT <rfc822;w@1wt.eu>);
	Thu, 19 Aug 2010 06:54:12 -0400
Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:43067 "EHLO
	fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752377Ab0HSKyK (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 19 Aug 2010 06:54:10 -0400
X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: [PATCH 2/2] oom: fix tasklist_lock leak
Cc: kosaki.motohiro@jp.fujitsu.com, LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <20100819194707.5FC4.A69D9226@jp.fujitsu.com>
References: <20100819194707.5FC4.A69D9226@jp.fujitsu.com>
Message-Id: <20100819195346.5FCA.A69D9226@jp.fujitsu.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
X-Mailer: Becky! ver. 2.50.07 [ja]
Date: Thu, 19 Aug 2010 19:54:06 +0900 (JST)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2352
Lines: 77

commit 0aad4b3124 (oom: fold __out_of_memory into out_of_memory)
introduced tasklist_lock leak. Then it caused following obvious
danger warings and panic.

    ================================================
    [ BUG: lock held when returning to user space! ]
    ------------------------------------------------
    rsyslogd/1422 is leaving the kernel with locks still held!
    1 lock held by rsyslogd/1422:
     #0:  (tasklist_lock){.+.+.+}, at: [<ffffffff810faf64>] out_of_memory+0x164/0x3f0
    BUG: scheduling while atomic: rsyslogd/1422/0x00000002
    INFO: lockdep is turned off.

This patch fixes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 mm/oom_kill.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 17d48a6..c48c5ef 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -646,6 +646,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 	unsigned long freed = 0;
 	unsigned int points;
 	enum oom_constraint constraint = CONSTRAINT_NONE;
+	int killed = 0;
 
 	blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
 	if (freed > 0)
@@ -683,7 +684,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 		if (!oom_kill_process(current, gfp_mask, order, 0, totalpages,
 				NULL, nodemask,
 				"Out of memory (oom_kill_allocating_task)"))
-			return;
+			goto out;
 	}
 
 retry:
@@ -691,7 +692,7 @@ retry:
 			constraint == CONSTRAINT_MEMORY_POLICY ? nodemask :
 								 NULL);
 	if (PTR_ERR(p) == -1UL)
-		return;
+		goto out;
 
 	/* Found nothing?!?! Either we hang forever, or we panic. */
 	if (!p) {
@@ -703,13 +704,15 @@ retry:
 	if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
 				nodemask, "Out of memory"))
 		goto retry;
+	killed = 1;
+out:
 	read_unlock(&tasklist_lock);
 
 	/*
 	 * Give "p" a good chance of killing itself before we
 	 * retry to allocate memory unless "p" is current
 	 */
-	if (!test_thread_flag(TIF_MEMDIE))
+	if (killed && !test_thread_flag(TIF_MEMDIE))
 		schedule_timeout_uninterruptible(1);
 }
 
-- 
1.6.5.2



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/