From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932611AbaFIIv5 (ORCPT ); Mon, 9 Jun 2014 04:51:57 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:58480 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754979AbaFIIvZ (ORCPT ); Mon, 9 Jun 2014 04:51:25 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , "Eric W. Biederman" , Frederic Weisbecker , Mandeep Singh Baines , "Ma, Xindong" , "Tu, Xiaobing" , Andrew Morton , Linus Torvalds , Jiri Slaby Subject: [PATCH 3.12 003/146] oom_kill: has_intersects_mems_allowed() needs rcu_read_lock() Date: Mon, 9 Jun 2014 10:48:58 +0200 Message-Id: X-Mailer: git-send-email 1.9.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleg Nesterov 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit ad96244179fbd55b40c00f10f399bc04739b8e1f upstream. At least out_of_memory() calls has_intersects_mems_allowed() without even rcu_read_lock(), this is obviously buggy. Add the necessary rcu_read_lock(). This means that we can not simply return from the loop, we need "bool ret" and "break". While at it, swap the names of task_struct's (the argument and the local). This cleans up the code a little bit and avoids the unnecessary initialization. Signed-off-by: Oleg Nesterov Reviewed-by: Sergey Dyasly Tested-by: Sergey Dyasly Reviewed-by: Sameer Nanda Cc: "Eric W. Biederman" Cc: Frederic Weisbecker Cc: Mandeep Singh Baines Cc: "Ma, Xindong" Reviewed-by: Michal Hocko Cc: "Tu, Xiaobing" Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Jiri Slaby --- mm/oom_kill.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index cae791c15c51..7cdd05e685dc 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -47,18 +47,20 @@ static DEFINE_SPINLOCK(zone_scan_lock); #ifdef CONFIG_NUMA /** * has_intersects_mems_allowed() - check task eligiblity for kill - * @tsk: task struct of which task to consider + * @start: task struct of which task to consider * @mask: nodemask passed to page allocator for mempolicy ooms * * Task eligibility is determined by whether or not a candidate task, @tsk, * shares the same mempolicy nodes as current if it is bound by such a policy * and whether or not it has the same set of allowed cpuset nodes. */ -static bool has_intersects_mems_allowed(struct task_struct *tsk, +static bool has_intersects_mems_allowed(struct task_struct *start, const nodemask_t *mask) { - struct task_struct *start = tsk; + struct task_struct *tsk; + bool ret = false; + rcu_read_lock(); for_each_thread(start, tsk) { if (mask) { /* @@ -67,19 +69,20 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, * mempolicy intersects current, otherwise it may be * needlessly killed. */ - if (mempolicy_nodemask_intersects(tsk, mask)) - return true; + ret = mempolicy_nodemask_intersects(tsk, mask); } else { /* * This is not a mempolicy constrained oom, so only * check the mems of tsk's cpuset. */ - if (cpuset_mems_allowed_intersects(current, tsk)) - return true; + ret = cpuset_mems_allowed_intersects(current, tsk); } + if (ret) + break; } + rcu_read_unlock(); - return false; + return ret; } #else static bool has_intersects_mems_allowed(struct task_struct *tsk, -- 1.9.3