--- old/src/share/vm/gc/g1/g1RemSet.cpp	2016-09-25 19:17:49.686991157 -0400
+++ new/src/share/vm/gc/g1/g1RemSet.cpp	2016-09-25 19:17:49.582990641 -0400
@@ -668,20 +668,18 @@
   // fail arbitrarily). We tell the iteration code to perform this
   // filtering when it has been determined that there has been an actual
   // allocation in this region and making it safe to check the young type.
-  bool filter_young = true;
 
-  HeapWord* stop_point =
+  bool card_processed =
     r->oops_on_card_seq_iterate_careful(dirtyRegion,
                                         &filter_then_update_rs_oop_cl,
-                                        filter_young,
                                         card_ptr);
 
-  // If stop_point is non-null, then we encountered an unallocated region
-  // (perhaps the unfilled portion of a TLAB.)  For now, we'll dirty the
-  // card and re-enqueue: if we put off the card until a GC pause, then the
-  // unallocated portion will be filled in.  Alternatively, we might try
-  // the full complexity of the technique used in "regular" precleaning.
-  if (stop_point != NULL) {
+  // If unable to process the card then we encountered an unparsable
+  // part of the heap (e.g. a partially allocated object).  Redirty
+  // and re-enqueue: if we put off the card until a GC pause, then the
+  // allocation will have completed.
+  if (!card_processed) {
+    assert(!_g1->is_gc_active(), "Unparsable heap during GC");
     // The card might have gotten re-dirtied and re-enqueued while we
     // worked.  (In fact, it's pretty likely.)
     if (*card_ptr != CardTableModRefBS::dirty_card_val()) {