--- old/src/share/vm/gc/g1/heapRegion.cpp	2015-11-03 17:15:25.552159726 +0100
+++ new/src/share/vm/gc/g1/heapRegion.cpp	2015-11-03 17:15:25.468159309 +0100
@@ -695,8 +695,7 @@
         HeapRegion* to   = _g1h->heap_region_containing(obj);
         if (from != NULL && to != NULL &&
             from != to &&
-            !to->is_pinned() &&
-            !from->is_continues_humongous()) {
+            !to->is_pinned()) {
           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
           jbyte cv_field = *_bs->byte_for_const(p);
           const jbyte dirty = CardTableModRefBS::dirty_card_val();
@@ -808,6 +807,13 @@
     _offsets.verify();
   }
 
+  if (is_region_humongous) {
+    oop obj = oop(this->humongous_start_region()->bottom());
+    if ((HeapWord*)obj > bottom() || (HeapWord*)obj + obj->size() < bottom()) {
+      gclog_or_tty->print_cr("this humongous region is not part of its' humongous object " PTR_FORMAT, p2i(obj));
+    }
+  }
+
   if (!is_region_humongous && p != top()) {
     gclog_or_tty->print_cr("end of last object " PTR_FORMAT " "
                            "does not match top " PTR_FORMAT, p2i(p), p2i(top()));
@@ -906,6 +912,7 @@
 }
 
 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
+  assert(new_end == _bottom + HeapRegion::GrainWords, "set_end should only ever be set to _bottom + HeapRegion::GrainWords");
   Space::set_end(new_end);
   _offsets.resize(new_end - bottom());
 }