--- old/src/hotspot/share/gc/z/vmStructs_z.hpp	2018-07-19 22:49:36.582520649 +0900
+++ new/src/hotspot/share/gc/z/vmStructs_z.hpp	2018-07-19 22:49:36.377519265 +0900
@@ -68,6 +68,8 @@
                                                                                                      \
   nonstatic_field(ZPage,                        _type,                const uint8_t)                 \
   nonstatic_field(ZPage,                        _virtual,             const ZVirtualMemory)          \
+  volatile_nonstatic_field(ZPage,               _top,                 uintptr_t)                     \
+  volatile_nonstatic_field(ZPage,               _refcount,            uint32_t)                      \
   nonstatic_field(ZPage,                        _forwarding,          ZForwardingTable)              \
                                                                                                      \
   nonstatic_field(ZPageAllocator,               _physical,            ZPhysicalMemoryManager)        \
@@ -101,6 +103,7 @@
   declare_constant(ZAddressOffsetShift)                                                              \
   declare_constant(ZAddressOffsetBits)                                                               \
   declare_constant(ZAddressOffsetMask)                                                               \
+  declare_constant(ZAddressOffsetMax)                                                                \
   declare_constant(ZAddressSpaceStart)
 
 #define VM_TYPES_ZGC(declare_type, declare_toplevel_type, declare_integer_type)                      \