--- a/block/blk-throttle.c	2022-04-16 06:56:37.857427700 +0800
+++ b/block/blk-throttle.c	2022-04-16 07:15:44.803445700 +0800
@@ -493,9 +493,9 @@ static void throtl_pd_offline(struct blk
 		throtl_upgrade_state(tg->td);
 }
 
-static void throtl_pd_free(struct blkg_policy_data *pd)
+static void throtl_grp_free_workfn(struct work_struct *work)
 {
-	struct throtl_grp *tg = pd_to_tg(pd);
+	struct throtl_grp *tg = container_of(work, struct throtl_grp, free_work);
 
 	del_timer_sync(&tg->service_queue.pending_timer);
 	blkg_rwstat_exit(&tg->stat_bytes);
@@ -503,6 +503,14 @@ static void throtl_pd_free(struct blkg_p
 	kfree(tg);
 }
 
+static void throtl_pd_free(struct blkg_policy_data *pd)
+{
+	struct throtl_grp *tg = pd_to_tg(pd);
+
+	INIT_WORK(&tg->free_work, throtl_grp_free_workfn);
+	queue_work(system_unbound_wq, &tg->free_work);
+}
+
 static struct throtl_grp *
 throtl_rb_first(struct throtl_service_queue *parent_sq)
 {
--- a/block/blk-throttle.h	2022-04-16 06:56:24.885706800 +0800
+++ b/block/blk-throttle.h	2022-04-16 07:06:21.260907700 +0800
@@ -141,6 +141,8 @@ struct throtl_grp {
 
 	struct blkg_rwstat stat_bytes;
 	struct blkg_rwstat stat_ios;
+
+	struct work_struct free_work;
 };
 
 extern struct blkcg_policy blkcg_policy_throtl;