--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Thu Mar 12 10:11:20 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Thu Mar 12 14:09:36 2015 +0100
@@ -396,6 +396,10 @@
   // Resizing support
   void set_end(HeapWord* value);  // override
 
+  // Never mangle CompactibleFreeListSpace
+  void mangle_unused_area() {}
+  void mangle_unused_area_complete() {}
+
   // Mutual exclusion support
   Mutex* freelistLock() const { return &_freelistLock; }
 

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Thu Mar 12 10:11:20 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Thu Mar 12 14:09:36 2015 +0100
@@ -934,6 +934,16 @@
   _offsets.resize(new_end - bottom());
 }
 
+#ifndef PRODUCT
+void G1OffsetTableContigSpace::mangle_unused_area() {
+  mangle_unused_area_complete();
+}
+
+void G1OffsetTableContigSpace::mangle_unused_area_complete() {
+  SpaceMangler::mangle_region(MemRegion(top(), end()));
+}
+#endif
+
 void G1OffsetTableContigSpace::print() const {
   print_short();
   gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Thu Mar 12 10:11:20 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Thu Mar 12 14:09:36 2015 +0100
@@ -155,6 +155,9 @@
   void set_bottom(HeapWord* value);
   void set_end(HeapWord* value);
 
+  void mangle_unused_area() PRODUCT_RETURN;
+  void mangle_unused_area_complete() PRODUCT_RETURN;
+
   HeapWord* scan_top() const;
   void record_timestamp();
   void reset_gc_time_stamp() { _gc_time_stamp = 0; }

--- a/hotspot/src/share/vm/memory/space.cpp	Thu Mar 12 10:11:20 2015 +0100
+++ b/hotspot/src/share/vm/memory/space.cpp	Thu Mar 12 14:09:36 2015 +0100
@@ -353,15 +353,6 @@
 void ContiguousSpace::mangle_unused_area_complete() {
   mangler()->mangle_unused_area_complete();
 }
-void ContiguousSpace::mangle_region(MemRegion mr) {
-  // Although this method uses SpaceMangler::mangle_region() which
-  // is not specific to a space, the when the ContiguousSpace version
-  // is called, it is always with regard to a space and this
-  // bounds checking is appropriate.
-  MemRegion space_mr(bottom(), end());
-  assert(space_mr.contains(mr), "Mangling outside space");
-  SpaceMangler::mangle_region(mr);
-}
 #endif  // NOT_PRODUCT
 
 void CompactibleSpace::initialize(MemRegion mr,

--- a/hotspot/src/share/vm/memory/space.hpp	Thu Mar 12 10:11:20 2015 +0100
+++ b/hotspot/src/share/vm/memory/space.hpp	Thu Mar 12 14:09:36 2015 +0100
@@ -128,11 +128,10 @@
 
   // For detecting GC bugs.  Should only be called at GC boundaries, since
   // some unused space may be used as scratch space during GC's.
-  // Default implementation does nothing. We also call this when expanding
-  // a space to satisfy an allocation request. See bug #4668531
-  virtual void mangle_unused_area() {}
-  virtual void mangle_unused_area_complete() {}
-  virtual void mangle_region(MemRegion mr) {}
+  // We also call this when expanding a space to satisfy an allocation
+  // request. See bug #4668531
+  virtual void mangle_unused_area() = 0;
+  virtual void mangle_unused_area_complete() = 0;
 
   // Testers
   bool is_empty() const              { return used() == 0; }
@@ -559,8 +558,6 @@
   void mangle_unused_area() PRODUCT_RETURN;
   // Mangle [top, end)
   void mangle_unused_area_complete() PRODUCT_RETURN;
-  // Mangle the given MemRegion.
-  void mangle_region(MemRegion mr) PRODUCT_RETURN;
 
   // Do some sparse checking on the area that should have been mangled.
   void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;