--- a/src/hotspot/share/gc/parallel/psMarkSweep.cpp	Thu Apr 26 12:54:53 2018 +0200
+++ b/src/hotspot/share/gc/parallel/psMarkSweep.cpp	Thu May 03 14:09:00 2018 +0200
@@ -65,9 +65,11 @@
 jlong               PSMarkSweep::_time_of_last_gc   = 0;
 CollectorCounters*  PSMarkSweep::_counters = NULL;
 
+SpanSubjectToDiscoveryClosure PSMarkSweep::_span_based_discoverer;
+
 void PSMarkSweep::initialize() {
-  MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
-  set_ref_processor(new ReferenceProcessor(mr));     // a vanilla ref proc
+  _span_based_discoverer.set_span(ParallelScavengeHeap::heap()->reserved_region());
+  set_ref_processor(new ReferenceProcessor(&_span_based_discoverer));     // a vanilla ref proc
   _counters = new CollectorCounters("PSMarkSweep", 1);
 }