--- old/src/hotspot/share/gc/z/zVirtualMemory.cpp	2019-08-09 10:45:18.388770256 +0200
+++ new/src/hotspot/share/gc/z/zVirtualMemory.cpp	2019-08-09 10:45:18.124770265 +0200
@@ -22,11 +22,51 @@
  */
 
 #include "precompiled.hpp"
+#include "gc/z/zAddress.inline.hpp"
 #include "gc/z/zGlobals.hpp"
 #include "gc/z/zVirtualMemory.inline.hpp"
 #include "logging/log.hpp"
 #include "services/memTracker.hpp"
 
+bool ZVirtualMemoryManager::reserve_range(uintptr_t start, size_t size) {
+  // Reserve address space
+  char* const marked0_addr = (char*)ZAddress::marked0(start);
+  char* const marked1_addr = (char*)ZAddress::marked1(start);
+  char* const remapped_addr = (char*)ZAddress::remapped(start);
+
+  if (!os::attempt_reserve_memory_at(size, marked0_addr)) {
+    return false;
+  }
+
+  if (!os::attempt_reserve_memory_at(size, marked1_addr)) {
+    os::release_memory(marked0_addr, size);
+    return false;
+  }
+
+  if (!os::attempt_reserve_memory_at(size, remapped_addr)) {
+    os::release_memory(marked0_addr, size);
+    os::release_memory(marked1_addr, size);
+    return false;
+  }
+
+  // Make the address view free
+  _manager.free(start, size);
+  return true;
+}
+
+size_t ZVirtualMemoryManager::reserve(uintptr_t start, size_t size) {
+  if (reserve_range(start, size)) {
+    return size;
+  }
+
+  if (size <= ZGranuleSize) {
+    return 0;
+  }
+
+  const size_t range = size / 2;
+  return reserve(start, range) + reserve(start + range, range);
+}
+
 ZVirtualMemoryManager::ZVirtualMemoryManager() :
     _manager(),
     _initialized(false) {
@@ -35,25 +75,15 @@
                      ZAddressSpaceStart, ZAddressSpaceEnd, ZAddressSpaceSize / K / G);
 
   // Reserve address space
-  if (!reserve(ZAddressSpaceStart, ZAddressSpaceSize)) {
+  if (reserve(0, ZAddressOffsetMax) < MaxHeapSize) {
+    log_error(gc)("Failed to reserve enough address space for Java heap");
     return;
   }
 
-  // Make the complete address view free
-  _manager.free(0, ZAddressOffsetMax);
-
-  // Register address space with native memory tracker
-  nmt_reserve(ZAddressSpaceStart, ZAddressSpaceSize);
-
   // Successfully initialized
   _initialized = true;
 }
 
-void ZVirtualMemoryManager::nmt_reserve(uintptr_t start, size_t size) {
-  MemTracker::record_virtual_memory_reserve((void*)start, size, CALLER_PC);
-  MemTracker::record_virtual_memory_type((void*)start, mtJavaHeap);
-}
-
 bool ZVirtualMemoryManager::is_initialized() const {
   return _initialized;
 }
--- old/src/hotspot/share/gc/z/zVirtualMemory.hpp	2019-08-09 10:45:19.336770223 +0200
+++ new/src/hotspot/share/gc/z/zVirtualMemory.hpp	2019-08-09 10:45:19.064770232 +0200
@@ -50,8 +50,8 @@
   ZMemoryManager _manager;
   bool           _initialized;
 
-  bool reserve(uintptr_t start, size_t size);
-  void nmt_reserve(uintptr_t start, size_t size);
+  bool reserve_range(uintptr_t start, size_t size);
+  size_t reserve(uintptr_t start, size_t size);
 
 public:
   ZVirtualMemoryManager();
--- old/src/hotspot/os/linux/gc/z/zVirtualMemory_linux.cpp	2019-08-09 10:45:20.180770193 +0200
+++ /dev/null	2019-02-06 06:50:20.578913862 +0100
@@ -1,41 +0,0 @@
-/*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zVirtualMemory.hpp"
-#include "logging/log.hpp"
-
-#include <sys/mman.h>
-#include <sys/types.h>
-
-bool ZVirtualMemoryManager::reserve(uintptr_t start, size_t size) {
-  // Reserve address space
-  const uintptr_t actual_start = (uintptr_t)mmap((void*)start, size, PROT_NONE,
-                                                 MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
-  if (actual_start != start) {
-    log_error(gc)("Failed to reserve address space for Java heap");
-    return false;
-  }
-
-  return true;
-}