diff --git a/nova/objects/resource_provider.py b/nova/objects/resource_provider.py
index ed9efe304e4a..7e6b6e067794 100644
--- a/nova/objects/resource_provider.py
+++ b/nova/objects/resource_provider.py
@@ -1258,6 +1258,7 @@ class UsageList(base.ObjectListBase, base.NovaObject):
 
     @classmethod
     def get_all_by_resource_provider_uuid(cls, context, rp_uuid):
+        _ensure_rc_cache(context)
         usage_list = cls._get_all_by_resource_provider_uuid(context, rp_uuid)
         return base.obj_make_list(context, cls(context), Usage, usage_list)