--- old/src/share/vm/gc_implementation/g1/concurrentMark.cpp	2015-02-03 11:18:15.200334867 +0100
+++ new/src/share/vm/gc_implementation/g1/concurrentMark.cpp	2015-02-03 11:18:15.126332730 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2015, 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
@@ -115,7 +115,7 @@
 }
 
 size_t CMBitMap::compute_size(size_t heap_size) {
-  return heap_size / mark_distance();
+  return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
 }
 
 size_t CMBitMap::mark_distance() {