cpuset: fix a race condition in __cpuset_node_allowed_softwall()

It's not safe to access task's cpuset after releasing task_lock(). Holding callback_mutex won't help. Cc: <[email protected]> Signed-off-by: Li Zefan <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
ddstreet · Feb 27, 2014 · 99afb0f · 99afb0f
1 parent 4729583
commit 99afb0f
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
@@ -2482,9 +2482,9 @@ 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;
 }