diff --git a/[refs] b/[refs]
index 1d318f709374..74f9325d6251 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1f64d69c7ad2e48e697493e45590679f7a69b7b2
+refs/heads/master: 55cfaa3cbdd29c4919ecb5fb8965c310f357e48c
diff --git a/trunk/mm/mempolicy.c b/trunk/mm/mempolicy.c
index 4a57f135b76e..11ff260fb282 100644
--- a/trunk/mm/mempolicy.c
+++ b/trunk/mm/mempolicy.c
@@ -1307,15 +1307,18 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
 		goto out;
 
 	/* Find the mm_struct */
+	rcu_read_lock();
 	read_lock(&tasklist_lock);
 	task = pid ? find_task_by_vpid(pid) : current;
 	if (!task) {
 		read_unlock(&tasklist_lock);
+		rcu_read_unlock();
 		err = -ESRCH;
 		goto out;
 	}
 	mm = get_task_mm(task);
 	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 
 	err = -EINVAL;
 	if (!mm)