--- x/net/sched/sch_api.c
+++ y/net/sched/sch_api.c
@@ -803,7 +803,7 @@ void qdisc_tree_reduce_backlog(struct Qd
 			break;
 		}
 		cops = sch->ops->cl_ops;
-		if (notify && cops->qlen_notify) {
+		if (notify && cops && cops->qlen_notify) {
 			/* Note that qlen_notify must be idempotent as it may get called
 			 * multiple times.
 			 */