diff --git a/block/blk-core.c b/block/blk-core.c
index 80f3e72..0c086fa 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -726,7 +726,7 @@
 	 */
 	if (q->elevator) {
 		ioc_clear_queue(q);
-		elevator_exit(q, q->elevator);
+		__elevator_exit(q, q->elevator);
 		q->elevator = NULL;
 	}
 
@@ -821,6 +821,19 @@
 	if (q->mq_ops)
 		blk_mq_exit_queue(q);
 
+	/*
+	 * In theory, request pool of sched_tags belongs to request queue.
+	 * However, the current implementation requires tag_set for freeing
+	 * requests, so free the pool now.
+	 *
+	 * Queue has become frozen, there can't be any in-queue requests, so
+	 * it is safe to free requests now.
+	 */
+	mutex_lock(&q->sysfs_lock);
+	if (q->elevator)
+		blk_mq_sched_free_requests(q);
+	mutex_unlock(&q->sysfs_lock);
+
 	percpu_ref_exit(&q->q_usage_counter);
 
 	spin_lock_irq(lock);
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index d89a757..eca0389 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -462,14 +462,18 @@
 	return ret;
 }
 
+/* called in queue's release handler, tagset has gone away */
 static void blk_mq_sched_tags_teardown(struct request_queue *q)
 {
-	struct blk_mq_tag_set *set = q->tag_set;
 	struct blk_mq_hw_ctx *hctx;
 	int i;
 
-	queue_for_each_hw_ctx(q, hctx, i)
-		blk_mq_sched_free_tags(set, hctx, i);
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (hctx->sched_tags) {
+			blk_mq_free_rq_map(hctx->sched_tags);
+			hctx->sched_tags = NULL;
+		}
+	}
 }
 
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
@@ -510,6 +514,7 @@
 			ret = e->ops.mq.init_hctx(hctx, i);
 			if (ret) {
 				eq = q->elevator;
+				blk_mq_sched_free_requests(q);
 				blk_mq_exit_sched(q, eq);
 				kobject_put(&eq->kobj);
 				return ret;
@@ -521,11 +526,30 @@
 	return 0;
 
 err:
+	blk_mq_sched_free_requests(q);
 	blk_mq_sched_tags_teardown(q);
 	q->elevator = NULL;
 	return ret;
 }
 
+/*
+ * called in either blk_queue_cleanup or elevator_switch, tagset
+ * is required for freeing requests
+ */
+void blk_mq_sched_free_requests(struct request_queue *q)
+{
+	struct blk_mq_hw_ctx *hctx;
+	int i;
+
+	lockdep_assert_held(&q->sysfs_lock);
+	WARN_ON(!q->elevator);
+
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (hctx->sched_tags)
+			blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i);
+	}
+}
+
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 {
 	struct blk_mq_hw_ctx *hctx;
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index fe66076..d97e13f 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -28,6 +28,7 @@
 
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e);
+void blk_mq_sched_free_requests(struct request_queue *q);
 
 static inline bool
 blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
diff --git a/block/blk.h b/block/blk.h
index ae87e2a..6203fbe 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -5,6 +5,7 @@
 #include <linux/idr.h>
 #include <linux/blk-mq.h>
 #include "blk-mq.h"
+#include "blk-mq-sched.h"
 
 /* Amount of time in which a process may batch requests */
 #define BLK_BATCH_TIME	(HZ/50UL)
@@ -243,10 +244,18 @@
 int elevator_init_mq(struct request_queue *q);
 int elevator_switch_mq(struct request_queue *q,
 			      struct elevator_type *new_e);
-void elevator_exit(struct request_queue *, struct elevator_queue *);
+			      
+void __elevator_exit(struct request_queue *, struct elevator_queue *);
 int elv_register_queue(struct request_queue *q, bool uevent);
 void elv_unregister_queue(struct request_queue *q);
 
+static inline void elevator_exit(struct request_queue *q,
+		struct elevator_queue *e)
+{
+	blk_mq_sched_free_requests(q);
+	__elevator_exit(q, e);
+}
+
 struct hd_struct *__disk_get_part(struct gendisk *disk, int partno);
 
 #ifdef CONFIG_FAIL_IO_TIMEOUT
diff --git a/block/elevator.c b/block/elevator.c
index 5b51bc5..e7f595d 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -240,7 +240,7 @@
 	return err;
 }
 
-void elevator_exit(struct request_queue *q, struct elevator_queue *e)
+void __elevator_exit(struct request_queue *q, struct elevator_queue *e)
 {
 	mutex_lock(&e->sysfs_lock);
 	if (e->uses_mq && e->type->ops.mq.exit_sched)