diff --git a/block/blk-core.c b/block/blk-core.c
index b3c48aaa6dc0..80a33af0050d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1796,8 +1796,11 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
 		/*
 		 * If this is the first request added after a plug, fire
 		 * of a plug trace.
+		 *
+		 * @request_count may become stale because of schedule
+		 * out, so check plug list again.
 		 */
-		if (!request_count)
+		if (!request_count || list_empty(&plug->list))
 			trace_block_plug(q);
 		else {
 			struct request *last = list_entry_rq(plug->list.prev);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index aaea6ea66fac..434cb5f7d9ae 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1380,6 +1380,13 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
 		struct request *last = NULL;
 
 		blk_mq_bio_to_request(rq, bio);
+
+		/*
+		 * @request_count may become stale because of schedule
+		 * out, so check the list again.
+		 */
+		if (list_empty(&plug->mq_list))
+			request_count = 0;
 		if (!request_count)
 			trace_block_plug(q);
 		else