diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8eb90f25bd7b..391d5e991e5f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5033,6 +5033,8 @@ css_get_next(struct cgroup_subsys *ss, int id,
 		return NULL;
 
 	BUG_ON(!ss->use_id);
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
 	/* fill start point for scan */
 	tmpid = id;
 	while (1) {
@@ -5040,10 +5042,7 @@ css_get_next(struct cgroup_subsys *ss, int id,
 		 * scan next entry from bitmap(tree), tmpid is updated after
 		 * idr_get_next().
 		 */
-		spin_lock(&ss->id_lock);
 		tmp = idr_get_next(&ss->idr, &tmpid);
-		spin_unlock(&ss->id_lock);
-
 		if (!tmp)
 			break;
 		if (tmp->depth >= depth && tmp->stack[depth] == rootid) {