--- a/src/hotspot/share/gc/z/zDriver.cpp	Tue Oct 16 13:43:04 2018 +0200
+++ b/src/hotspot/share/gc/z/zDriver.cpp	Tue Oct 16 13:14:18 2018 +0200
@@ -336,7 +336,7 @@
   // Phase 2: Concurrent Mark
   {
     ZStatTimer timer(ZPhaseConcurrentMark);
-    ZHeap::heap()->mark();
+    ZHeap::heap()->mark(true /* initial */);
   }
 
   // Phase 3: Pause Mark End
@@ -345,7 +345,7 @@
     while (!vm_operation(&cl)) {
       // Phase 3.5: Concurrent Mark Continue
       ZStatTimer timer(ZPhaseConcurrentMarkContinue);
-      ZHeap::heap()->mark();
+      ZHeap::heap()->mark(false /* initial */);
     }
   }