diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 9d00f62c05ecd..ad37043297ed5 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2163,7 +2163,7 @@ bool blk_throtl_bio(struct bio *bio)
 	struct request_queue *q = bio->bi_disk->queue;
 	struct blkcg_gq *blkg = bio->bi_blkg;
 	struct throtl_qnode *qn = NULL;
-	struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
+	struct throtl_grp *tg = blkg_to_tg(blkg);
 	struct throtl_service_queue *sq;
 	bool rw = bio_data_dir(bio);
 	bool throttled = false;