--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Jan 21 11:14:19 2009 -0500
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Fri Jan 23 10:41:28 2009 -0500
@@ -3018,6 +3018,16 @@
 }
 
 void
+ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) {
+  if (freelistLock()->owned_by_self()) {
+    Generation::safe_object_iterate(cl);
+  } else {
+    MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag);
+    Generation::safe_object_iterate(cl);
+  }
+}
+
+void
 ConcurrentMarkSweepGeneration::pre_adjust_pointers() {
 }
 
@@ -6623,7 +6633,11 @@
   if (_bitMap->isMarked(addr)) {
     // it's marked; is it potentially uninitialized?
     if (p->klass_or_null() != NULL) {
-      if (CMSPermGenPrecleaningEnabled && !p->is_parsable()) {
+      // If is_conc_safe is false, the object may be undergoing
+      // change by the VM outside a safepoint.  Don't try to
+      // scan it, but rather leave it for the remark phase.
+      if (CMSPermGenPrecleaningEnabled &&
+          (!p->is_conc_safe() || !p->is_parsable())) {
         // Signal precleaning to redirty the card since
         // the klass pointer is already installed.
         assert(size == 0, "Initial value");
@@ -7001,7 +7015,6 @@
       _mut->clear_range(mr);
     }
   DEBUG_ONLY(})
-
   // Note: the finger doesn't advance while we drain
   // the stack below.
   PushOrMarkClosure pushOrMarkClosure(_collector,
@@ -8062,9 +8075,13 @@
     #ifdef DEBUG
       if (oop(addr)->klass_or_null() != NULL &&
           (   !_collector->should_unload_classes()
-           || oop(addr)->is_parsable())) {
+           || (oop(addr)->is_parsable()) &&
+               oop(addr)->is_conc_safe())) {
         // Ignore mark word because we are running concurrent with mutators
         assert(oop(addr)->is_oop(true), "live block should be an oop");
+        // is_conc_safe is checked before performing this assertion
+        // because an object that is not is_conc_safe may yet have
+        // the return from size() correct.
         assert(size ==
                CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()),
                "P-mark and computed size do not agree");
@@ -8077,6 +8094,13 @@
            (!_collector->should_unload_classes()
             || oop(addr)->is_parsable()),
            "Should be an initialized object");
+    // Note that there are objects used during class redefinition
+    // (e.g., merge_cp in VM_RedefineClasses::merge_cp_and_rewrite()
+    // which are discarded with their is_conc_safe state still
+    // false.  These object may be floating garbage so may be
+    // seen here.  If they are floating garbage their size
+    // should be attainable from their klass.  Do not that
+    // is_conc_safe() is true for oop(addr).
     // Ignore mark word because we are running concurrent with mutators
     assert(oop(addr)->is_oop(true), "live block should be an oop");
     // Verify that the bit map has no bits marked between