diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index fe9ebd6a2e14..7246fc256315 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -110,12 +110,6 @@ static struct cgroup_subsys_state *blkcg_css(void)
 	return task_css(current, io_cgrp_id);
 }
 
-static bool blkcg_policy_enabled(struct request_queue *q,
-				 const struct blkcg_policy *pol)
-{
-	return pol && test_bit(pol->plid, q->blkcg_pols);
-}
-
 static void blkg_free_workfn(struct work_struct *work)
 {
 	struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 81868ad86330..83367086cb6a 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -459,6 +459,12 @@ static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
 		bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
 }
 
+static inline bool blkcg_policy_enabled(struct request_queue *q,
+				const struct blkcg_policy *pol)
+{
+	return pol && test_bit(pol->plid, q->blkcg_pols);
+}
+
 void blk_cgroup_bio_start(struct bio *bio);
 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
 #else	/* CONFIG_BLK_CGROUP */
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 397b6a410f9e..cfa1cd60d2c5 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1327,17 +1327,13 @@ static int blk_throtl_init(struct gendisk *disk)
 	INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
 	throtl_service_queue_init(&td->service_queue);
 
-	/*
-	 * Freeze queue before activating policy, to synchronize with IO path,
-	 * which is protected by 'q_usage_counter'.
-	 */
 	memflags = blk_mq_freeze_queue(disk->queue);
 	blk_mq_quiesce_queue(disk->queue);
 
 	q->td = td;
 	td->queue = q;
 
-	/* activate policy */
+	/* activate policy, blk_throtl_activated() will return true */
 	ret = blkcg_activate_policy(disk, &blkcg_policy_throtl);
 	if (ret) {
 		q->td = NULL;
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 3b27755bfbff..9d7a42c039a1 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -156,7 +156,13 @@ void blk_throtl_cancel_bios(struct gendisk *disk);
 
 static inline bool blk_throtl_activated(struct request_queue *q)
 {
-	return q->td != NULL;
+	/*
+	 * q->td guarantees that the blk-throttle module is already loaded,
+	 * and the plid of blk-throttle is assigned.
+	 * blkcg_policy_enabled() guarantees that the policy is activated
+	 * in the request_queue.
+	 */
+	return q->td != NULL && blkcg_policy_enabled(q, &blkcg_policy_throtl);
 }
 
 static inline bool blk_should_throtl(struct bio *bio)
@@ -164,11 +170,6 @@ static inline bool blk_should_throtl(struct bio *bio)
 	struct throtl_grp *tg;
 	int rw = bio_data_dir(bio);
 
-	/*
-	 * This is called under bio_queue_enter(), and it's synchronized with
-	 * the activation of blk-throtl, which is protected by
-	 * blk_mq_freeze_queue().
-	 */
 	if (!blk_throtl_activated(bio->bi_bdev->bd_queue))
 		return false;
 
@@ -194,7 +195,10 @@ static inline bool blk_should_throtl(struct bio *bio)
 
 static inline bool blk_throtl_bio(struct bio *bio)
 {
-
+	/*
+	 * block throttling takes effect if the policy is activated
+	 * in the bio's request_queue.
+	 */
 	if (!blk_should_throtl(bio))
 		return false;