From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756345AbYKUIzw (ORCPT ); Fri, 21 Nov 2008 03:55:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754224AbYKUIwu (ORCPT ); Fri, 21 Nov 2008 03:52:50 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:58851 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754200AbYKUIws (ORCPT ); Fri, 21 Nov 2008 03:52:48 -0500 Message-ID: <49267624.70305@cn.fujitsu.com> Date: Fri, 21 Nov 2008 16:49:40 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.17 (Windows/20080914) MIME-Version: 1.0 To: Andrew Morton , Paul Menage , Linux Kernel Mailing List , Linux Containers Subject: [PATCH] cpuset: rcu_read_lock() to protect task_cs() even we don't dereference to task_cs()'s return value Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org task_cs() calls cgroup_subsys_state(). we must use rcu_read_lock() to protect cgroup_subsys_state(). in current_cpuset_is_being_rebound(), we don't dereference to task_cs()'s return value, but task_cs() accesses css_set, this css_set maybe freed when task_cs() called. Signed-off-by: Lai Jiangshan --- diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 3e00526..e0e087e 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1141,7 +1136,11 @@ done: int current_cpuset_is_being_rebound(void) { - return task_cs(current) == cpuset_being_rebound; + struct cpuset *cs; + rcu_read_lock(); + cs = task_cs(current); + rcu_read_unlock(); + return cs == cpuset_being_rebound; } static int update_relax_domain_level(struct cpuset *cs, s64 val)