From: Li Zefan <lizefan@huawei.com>
Date: Thu, 27 Feb 2014 10:19:36 +0000 (+0800)
Subject: cpuset: fix a race condition in __cpuset_node_allowed_softwall()
X-Git-Tag: v3.10.39~230
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4bdd401e8b7384a685606f2254e634805580a2aa;p=platform%2Fkernel%2Flinux-3.10.git

cpuset: fix a race condition in __cpuset_node_allowed_softwall()

commit 99afb0fd5f05aac467ffa85c36778fec4396209b upstream.

It's not safe to access task's cpuset after releasing task_lock().
Holding callback_mutex won't help.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index d313870..d9dd521 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2422,9 +2422,9 @@ int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
 
 	task_lock(current);
 	cs = nearest_hardwall_ancestor(task_cs(current));
+	allowed = node_isset(node, cs->mems_allowed);
 	task_unlock(current);
 
-	allowed = node_isset(node, cs->mems_allowed);
 	mutex_unlock(&callback_mutex);
 	return allowed;
 }