--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1787,6 +1787,9 @@ static inline void blk_free_request(requ
 	if (rq->flags & REQ_ELVPRIV)
 		elv_put_request(q, rq);
 	mempool_free(rq, q->rq.rq_pool);
+
+	if (rq == q->last_merge)
+		q->last_merge = NULL;
 }
 
 static inline struct request *