From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756698AbYKUIzb (ORCPT ); Fri, 21 Nov 2008 03:55:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754068AbYKUIwr (ORCPT ); Fri, 21 Nov 2008 03:52:47 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:59355 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753931AbYKUIwq (ORCPT ); Fri, 21 Nov 2008 03:52:46 -0500 Message-ID: <49267621.2070706@cn.fujitsu.com> Date: Fri, 21 Nov 2008 16:49:37 +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() 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(). it's correct that top_cpuset is never freed, but cgroup_subsys_state() accesses css_set, this css_set maybe freed when task_cs() called. we use use rcu_read_lock() to protect it. 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 @@ -363,14 +363,9 @@ void cpuset_update_task_memory_state(void) struct task_struct *tsk = current; struct cpuset *cs; - if (task_cs(tsk) == &top_cpuset) { - /* Don't need rcu for top_cpuset. It's never freed. */ - my_cpusets_mem_gen = top_cpuset.mems_generation; - } else { - rcu_read_lock(); - my_cpusets_mem_gen = task_cs(tsk)->mems_generation; - rcu_read_unlock(); - } + rcu_read_lock(); + my_cpusets_mem_gen = task_cs(tsk)->mems_generation; + rcu_read_unlock(); if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) { mutex_lock(&callback_mutex);