diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index ce6a2b7d3dfb..4c94a6560f62 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1455,6 +1455,10 @@ int blkcg_activate_policy(struct request_queue *q,
 		list_for_each_entry_reverse(blkg, &q->blkg_list, q_node)
 			pol->pd_init_fn(blkg->pd[pol->plid]);
 
+	if (pol->pd_online_fn)
+		list_for_each_entry_reverse(blkg, &q->blkg_list, q_node)
+			pol->pd_online_fn(blkg->pd[pol->plid]);
+
 	__set_bit(pol->plid, q->blkcg_pols);
 	ret = 0;