--- old/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp	2015-01-09 12:22:06.762584526 +0100
+++ new/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp	2015-01-09 12:22:06.634584524 +0100
@@ -49,9 +49,11 @@
   // Bitmap used for verification of commit/uncommit operations.
   BitMap _committed;
 
-  // For _special spaces we need to keep track if the memory needs to be zeroed
-  // after commit or not.
-  BitMap _needs_zeroing;
+  // Bitmap used to keep track of which pages are dirty or not for _special
+  // spaces. This is needed because for those spaces the underlying memory
+  // will only be zero filled the first time it is committed. Calls to commit
+  // will use this bitmap and return whether or not the memory is zero filled.
+  BitMap _dirty;
 
   // Indicates that the entire space has been committed and pinned in memory,
   // os::commit_memory() or os::uncommit_memory() have no function.