diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index a6bcc779c9124e64f959bb53e4e5271c9b24387d..ee9f24ca7eeab916d3d414aa00db697cbd559975 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -643,6 +643,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 		   struct bfq_group *bfqg)
 {
 	struct bfq_entity *entity = &bfqq->entity;
+	struct bfq_group *old_parent = bfqq_group(bfqq);
 
 	/*
 	 * Get extra reference to prevent bfqq from being freed in
@@ -664,18 +665,22 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
 	else if (entity->on_st_or_in_serv)
 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
-	bfqg_and_blkg_put(bfqq_group(bfqq));
 
 	entity->parent = bfqg->my_entity;
 	entity->sched_data = &bfqg->sched_data;
 	/* pin down bfqg and its associated blkg  */
 	bfqg_and_blkg_get(bfqg);
 
-	if (bfq_bfqq_busy(bfqq)) {
-		if (unlikely(!bfqd->nonrot_with_queueing))
-			bfq_pos_tree_add_move(bfqd, bfqq);
+	/*
+	 * Don't leave the bfqq->pos_root to old bfqg, since the ref to old
+	 * bfqg will be released and the bfqg might be freed.
+	 */
+	if (unlikely(!bfqd->nonrot_with_queueing))
+		bfq_pos_tree_add_move(bfqd, bfqq);
+	bfqg_and_blkg_put(old_parent);
+
+	if (bfq_bfqq_busy(bfqq))
 		bfq_activate_bfqq(bfqd, bfqq);
-	}
 
 	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
 		bfq_schedule_dispatch(bfqd);
@@ -927,6 +932,7 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
 
 put_async_queues:
 	bfq_put_async_queues(bfqd, bfqg);
+	pd->plid = BLKCG_MAX_POLS;
 
 	spin_unlock_irqrestore(&bfqd->lock, flags);
 	/*
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 26776bdbdf360c97635c6fb197b0b3c497689f2e..5a6cb0513c4f92116d9d8dc687f37480050b98da 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -1695,6 +1695,15 @@ void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
  */
 void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
 {
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+	/* If parent group is offlined, move the bfqq to root group */
+	if (bfqq->entity.parent) {
+		struct bfq_group *bfqg = bfq_bfqq_to_bfqg(bfqq);
+
+		if (bfqg->pd.plid >= BLKCG_MAX_POLS)
+			bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
+	}
+#endif
 	bfq_log_bfqq(bfqd, bfqq, "add to busy");
 
 	bfq_activate_bfqq(bfqd, bfqq);