--- a/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -84,11 +84,6 @@
 
   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
 
-  if (VerifyDuringGC) {
-      G1CollectedHeap* g1h = G1CollectedHeap::heap();
-      g1h->checkConcurrentMark();
-  }
-
   mark_sweep_phase2();
 
   // Don't add any more derived pointers during phase3
@@ -179,6 +174,29 @@
 
   assert(GenMarkSweep::_marking_stack.is_empty(),
          "stack should be empty by now");
+
+  if (VerifyDuringGC) {
+    HandleMark hm;  // handle scope
+    COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
+    gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
+    Universe::heap()->prepare_for_verify();
+    // Note: we can verify only the heap here. When an object is
+    // marked, the previous value of the mark word (including
+    // identity hash values, ages, etc) is preserved, and the mark
+    // word is set to markOop::marked_value - effectively removing
+    // any hash values from the mark word. These hash values are
+    // used when verifying the dictionaries and so removing them
+    // from the mark word can make verification of the dictionaries
+    // fail. At the end of the GC, the orginal mark word values
+    // (including hash values) are restored to the appropriate
+    // objects.
+    Universe::heap()->verify(/* allow dirty */ true,
+                             /* silent      */ false,
+                             /* option      */ VerifyOption_G1UseMarkWord);
+
+    G1CollectedHeap* g1h = G1CollectedHeap::heap();
+    gclog_or_tty->print_cr("]");
+  }
 }
 
 class G1PrepareCompactClosure: public HeapRegionClosure {