Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932473AbaJCWea (ORCPT ); Fri, 3 Oct 2014 18:34:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47779 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755504AbaJCWeG (ORCPT ); Fri, 3 Oct 2014 18:34:06 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleg Nesterov , Sergey Dyasly , Sameer Nanda , "Eric W. Biederman" , Frederic Weisbecker , Mandeep Singh Baines , "Ma, Xindong" , Michal Hocko , "Tu, Xiaobing" , David Rientjes , Andrew Morton , Linus Torvalds , Li Zefan Subject: [PATCH 3.10 141/143] oom_kill: has_intersects_mems_allowed() needs rcu_read_lock() Date: Fri, 3 Oct 2014 14:35:36 -0700 Message-Id: <20141003213318.700415452@linuxfoundation.org> X-Mailer: git-send-email 2.1.2 In-Reply-To: <20141003213314.470709810@linuxfoundation.org> References: <20141003213314.470709810@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov 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 Cc: Li Zefan Signed-off-by: Greg Kroah-Hartman --- mm/oom_kill.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- 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( * 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, -- 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/