From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965240AbXCAPRf (ORCPT ); Thu, 1 Mar 2007 10:17:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965238AbXCAPRf (ORCPT ); Thu, 1 Mar 2007 10:17:35 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:48042 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965202AbXCAPRc (ORCPT ); Thu, 1 Mar 2007 10:17:32 -0500 From: "Rafael J. Wysocki" To: Andrew Morton Subject: [PATCH -mm 1/7] Freezer: Read PF_BORROWED_MM in a nonracy way Date: Thu, 1 Mar 2007 16:06:46 +0100 User-Agent: KMail/1.9.5 Cc: Pavel Machek , LKML , Oleg Nesterov , Aneesh Kumar , "Paul E. McKenney" , Srivatsa Vaddagiri , Gautham R Shenoy References: <200702260800.49603.rjw@sisk.pl> <200703011605.46692.rjw@sisk.pl> In-Reply-To: <200703011605.46692.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200703011606.47776.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki The reading of PF_BORROWED_MM in is_user_space() without task_lock() is racy. Fix it. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek --- kernel/power/process.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) Index: linux-2.6.20-mm2/kernel/power/process.c =================================================================== --- linux-2.6.20-mm2.orig/kernel/power/process.c 2007-02-25 14:02:55.000000000 +0100 +++ linux-2.6.20-mm2/kernel/power/process.c 2007-02-25 14:03:51.000000000 +0100 @@ -8,6 +8,7 @@ #undef DEBUG +#include #include #include #include @@ -87,7 +88,12 @@ static void cancel_freezing(struct task_ static inline int is_user_space(struct task_struct *p) { - return p->mm && !(p->flags & PF_BORROWED_MM); + int ret; + + task_lock(p); + ret = p->mm && !(p->flags & PF_BORROWED_MM); + task_unlock(p); + return ret; } static unsigned int try_to_freeze_tasks(int freeze_user_space)