diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 86cb5c6..36fc0ff 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1158,18 +1158,12 @@
 {
 	lockdep_assert_held(&cgroup_mutex);
 
-	if (root->hierarchy_id) {
-		idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
-		root->hierarchy_id = 0;
-	}
+	idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
 }
 
 static void cgroup_free_root(struct cgroup_root *root)
 {
 	if (root) {
-		/* hierarchy ID should already have been released */
-		WARN_ON_ONCE(root->hierarchy_id);
-
 		idr_destroy(&root->cgroup_idr);
 		kfree(root);
 	}