--- old/src/hotspot/share/gc/z/zMark.cpp	2019-11-22 15:12:09.456539783 +0100
+++ new/src/hotspot/share/gc/z/zMark.cpp	2019-11-22 15:12:08.893521308 +0100
@@ -159,7 +159,7 @@
   ZMarkRootsTask(ZMark* mark) :
       ZTask("ZMarkRootsTask"),
       _mark(mark),
-      _roots(false /* visit_jvmti_weak_export */) {}
+      _roots(false /* visit_jvmti_weak_export */, true /* disarm_nmethods */) {}
 
   virtual void work() {
     _roots.oops_do(&_cl);