--- old/src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.hpp	2019-05-02 09:57:43.946865298 +0200
+++ new/src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.hpp	2019-05-02 09:57:43.702857240 +0200
@@ -32,35 +32,39 @@
 
 class ZPhysicalMemoryBacking {
 private:
-  ZMemoryManager _manager;
   ZBackingFile   _file;
+  ZMemoryManager _committed;
+  ZMemoryManager _uncommitted;
+
+  void warn_available_space(size_t max) const;
+  void warn_max_map_count(size_t max) const;
 
-  void check_max_map_count(size_t max_capacity) const;
-  void check_available_space_on_filesystem(size_t max_capacity) const;
   void map_failed(ZErrno err) const;
 
-  void advise_view(uintptr_t addr, size_t size) const;
+  void advise_view(uintptr_t addr, size_t size, int advice) const;
   void pretouch_view(uintptr_t addr, size_t size) const;
-  void map_view(ZPhysicalMemory pmem, uintptr_t addr, bool pretouch) const;
-  void unmap_view(ZPhysicalMemory pmem, uintptr_t addr) const;
+  void map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const;
+  void unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const;
 
 public:
-  ZPhysicalMemoryBacking(size_t max_capacity);
-
   bool is_initialized() const;
 
-  size_t try_expand(size_t old_capacity, size_t new_capacity);
+  void warn_commit_limits(size_t max) const;
+  bool supports_uncommit();
+
+  size_t commit(size_t size);
+  size_t uncommit(size_t size);
 
   ZPhysicalMemory alloc(size_t size);
-  void free(ZPhysicalMemory pmem);
+  void free(const ZPhysicalMemory& pmem);
 
   uintptr_t nmt_address(uintptr_t offset) const;
 
-  void map(ZPhysicalMemory pmem, uintptr_t offset) const;
-  void unmap(ZPhysicalMemory pmem, uintptr_t offset) const;
+  void map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
 
-  void debug_map(ZPhysicalMemory pmem, uintptr_t offset) const;
-  void debug_unmap(ZPhysicalMemory pmem, uintptr_t offset) const;
+  void debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
 };
 
 #endif // OS_CPU_LINUX_X86_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_X86_HPP