diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 74c002ddc0ce..08831f5d83db 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1341,11 +1341,14 @@ static int ubd_queue_one_vec(struct blk_mq_hw_ctx *hctx, struct request *req,
 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
 				 const struct blk_mq_queue_data *bd)
 {
+	struct ubd *ubd_dev = hctx->queue->queuedata;
 	struct request *req = bd->rq;
 	int ret = 0;
 
 	blk_mq_start_request(req);
 
+	spin_lock_irq(&ubd_dev->lock);
+
 	if (req_op(req) == REQ_OP_FLUSH) {
 		ret = ubd_queue_one_vec(hctx, req, 0, NULL);
 	} else {
@@ -1361,9 +1364,11 @@ static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
 		}
 	}
 out:
-	if (ret < 0) {
+	spin_unlock_irq(&ubd_dev->lock);
+
+	if (ret < 0)
 		blk_mq_requeue_request(req, true);
-	}
+
 	return BLK_STS_OK;
 }