diff -r bd441136a5ce -r c89f86385056 src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Thu Mar 19 09:13:24 2009 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Fri Mar 20 23:19:36 2009 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2008 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 2001-2009 Sun Microsystems, Inc.  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
@@ -825,6 +825,7 @@
   if (young_gen()->is_in_reserved(addr)) {
     assert(young_gen()->is_in(addr),
            "addr should be in allocated part of young gen");
+    if (Debugging)  return NULL;  // called from find() in debug.cpp
     Unimplemented();
   } else if (old_gen()->is_in_reserved(addr)) {
     assert(old_gen()->is_in(addr),