diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4a57f13..11ff260 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1307,15 +1307,18 @@
 		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)