--- old/src/share/vm/memory/genCollectedHeap.cpp	2015-05-13 14:05:34.253144351 +0200
+++ new/src/share/vm/memory/genCollectedHeap.cpp	2015-05-13 14:05:34.141140628 +0200
@@ -700,7 +700,7 @@
   // older-gen scanning.
   if (level == 0) {
     older_gens->set_generation(_old_gen);
-    rem_set()->younger_refs_iterate(_old_gen, older_gens);
+    rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
     older_gens->reset_generation();
   }