--- x/block/blk-cgroup.c
+++ y/block/blk-cgroup.c
@@ -89,9 +89,9 @@ static void blkg_free(struct blkcg_gq *b
 	kfree(blkg);
 }
 
-static void __blkg_release(struct rcu_head *rcu)
+static void blkg_free_workfn(struct work_struct *work)
 {
-	struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
+	struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, async_bio_work);
 
 	WARN_ON(!bio_list_empty(&blkg->async_bios));
 
@@ -102,6 +102,15 @@ static void __blkg_release(struct rcu_he
 	blkg_free(blkg);
 }
 
+static void __blkg_release(struct rcu_head *rcu)
+{
+	struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
+
+	/* reuse work to avoid putting blkg->q in rcu context */
+	INIT_WORK(&blkg->async_bio_work, blkg_free_workfn);
+	schedule_work(&blkg->async_bio_work);
+}
+
 /*
  * A group is RCU protected, but having an rcu lock does not mean that one
  * can access all the fields of blkg and assume these are valid.  For