diff --git a/block/elevator.c b/block/elevator.c
index 2bcbd8c..249cc5e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -186,6 +186,12 @@
 	struct elevator_type *e = NULL;
 	int err;
 
+	/*
+	 * q->sysfs_lock must be held to provide mutual exclusion between
+	 * elevator_switch() and here.
+	 */
+	lockdep_assert_held(&q->sysfs_lock);
+
 	if (unlikely(q->elevator))
 		return 0;