--- a/src/hotspot/share/jfr/periodic/jfrModuleEvent.cpp	Fri Aug 31 12:41:00 2018 +0200
+++ b/src/hotspot/share/jfr/periodic/jfrModuleEvent.cpp	Fri Aug 31 07:03:46 2018 -0400
@@ -121,12 +121,14 @@
 
 void JfrModuleEvent::generate_module_dependency_events() {
   invocation_time = JfrTicks::now();
-  MutexLockerEx module_lock(Module_lock);
+  MutexLocker cld_lock(ClassLoaderDataGraph_lock);
+  MutexLocker module_lock(Module_lock);
   ClassLoaderDataGraph::modules_do(&module_dependency_event_callback);
 }
 
 void JfrModuleEvent::generate_module_export_events() {
   invocation_time = JfrTicks::now();
-  MutexLockerEx module_lock(Module_lock);
+  MutexLocker cld_lock(ClassLoaderDataGraph_lock);
+  MutexLocker module_lock(Module_lock);
   ClassLoaderDataGraph::packages_do(&module_export_event_callback);
 }