--- old/src/share/vm/memory/metachunk.cpp	2016-03-10 21:50:10.000000000 +0300
+++ new/src/share/vm/memory/metachunk.cpp	2016-03-10 21:50:10.000000000 +0300
@@ -98,12 +98,20 @@
 }
 
 #ifndef PRODUCT
-void Metachunk::mangle() {
+static void overwrite_chunk_payload(Metachunk* chunk, juint wordValue) {
   // Mangle the payload of the chunk and not the links that
   // maintain list of chunks.
-  HeapWord* start = (HeapWord*)(bottom() + overhead());
-  size_t size = word_size() - overhead();
-  Copy::fill_to_words(start, size, metadata_chunk_initialize);
+  HeapWord* start = (HeapWord*)(chunk->bottom() + chunk->overhead());
+  size_t size = chunk->word_size() - chunk->overhead();
+  Copy::fill_to_words(start, size, wordValue);
+}
+
+void Metachunk::mangle() {
+  overwrite_chunk_payload(this, metadata_chunk_initialize);
+}
+
+void Metachunk::zap() {
+  overwrite_chunk_payload(this, badMetaWordVal);
 }
 #endif // PRODUCT