--- old/src/share/vm/gc/g1/heapRegion.hpp	2015-08-19 10:56:18.072973957 +0200
+++ new/src/share/vm/gc/g1/heapRegion.hpp	2015-08-19 10:56:17.992971602 +0200
@@ -109,7 +109,7 @@
 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 class G1OffsetTableContigSpace: public CompactibleSpace {
   friend class VMStructs;
-  HeapWord* _top;
+  HeapWord* volatile _top;
   HeapWord* volatile _scan_top;
  protected:
   G1BlockOffsetArrayContigSpace _offsets;
@@ -134,7 +134,7 @@
   // Reset the G1OffsetTableContigSpace.
   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 
-  HeapWord** top_addr() { return &_top; }
+  HeapWord* volatile* top_addr() { return &_top; }
   // Try to allocate at least min_word_size and up to desired_size from this Space.
   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
   // space allocated.