--- old/src/hotspot/share/gc/z/zPhysicalMemory.hpp	2018-01-13 12:11:24.965099795 +0900
+++ new/src/hotspot/share/gc/z/zPhysicalMemory.hpp	2018-01-13 12:11:24.697099070 +0900
@@ -65,6 +65,8 @@
 };
 
 class ZPhysicalMemoryManager VALUE_OBJ_CLASS_SPEC {
+  friend class VMStructs;
+
 private:
   ZPhysicalMemoryBacking _backing;
   const size_t           _max_capacity;