diff --git a/block/blk-merge.c b/block/blk-merge.c
index 9b17da6..eb2a3ca 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -387,14 +387,19 @@
 	elv_merge_requests(q, req, next);
 
 	if (req->rq_disk) {
-		struct hd_struct *part =
-			disk_map_sector(req->rq_disk, req->sector);
+		struct hd_struct *part;
+
+		rcu_read_lock();
+
+		part = disk_map_sector_rcu(req->rq_disk, req->sector);
 		disk_round_stats(req->rq_disk);
 		req->rq_disk->in_flight--;
 		if (part) {
 			part_round_stats(part);
 			part->in_flight--;
 		}
+
+		rcu_read_unlock();
 	}
 
 	req->ioprio = ioprio_best(req->ioprio, next->ioprio);