diff -r b03260081e9b -r 74ee0db180fa src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Fri Dec 17 11:26:53 2010 -0800
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Fri Dec 17 23:41:31 2010 -0800
@@ -694,6 +694,8 @@
 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
   _promotion_failed = true;
   if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
+    // Should use per-worker private stakcs hetre rather than
+    // locking a common pair of stacks.
     ThreadCritical tc;
     _preserved_oop_stack.push(obj);
     _preserved_mark_stack.push(obj_mark);