--- old/src/hotspot/share/gc/z/zPageAllocator.hpp	2020-06-01 07:12:30.029963620 +0200
+++ new/src/hotspot/share/gc/z/zPageAllocator.hpp	2020-06-01 07:12:29.760954950 +0200
@@ -56,6 +56,9 @@
   ssize_t                    _reclaimed;
   ZList<ZPageAllocation>     _stalled;
   ZList<ZPageAllocation>     _satisfied;
+  ZConditionLock             _unmap_lock;
+  ZList<ZPage>               _unmap_queue;
+  bool                       _unmap_stop;
   ZConditionLock             _uncommit_lock;
   bool                       _uncommit_enabled;
   bool                       _uncommit_stop;
@@ -78,6 +81,9 @@
 
   void destroy_page(ZPage* page);
 
+  void enqueue_unmap_page(ZPage* page);
+  ZPage* dequeue_unmap_page();
+
   bool is_alloc_allowed(size_t size, bool no_reserve) const;
   bool is_alloc_allowed_from_cache(size_t size, bool no_reserve) const;
 
@@ -119,6 +125,9 @@
   ZPage* alloc_page(uint8_t type, size_t size, ZAllocationFlags flags);
   void free_page(ZPage* page, bool reclaimed);
 
+  void unmap_run();
+  void unmap_stop();
+
   void uncommit_run();
   void uncommit_stop();