--- a/src/hotspot/share/runtime/mutexLocker.cpp	Wed Nov 13 14:08:04 2019 -0800
+++ b/src/hotspot/share/runtime/mutexLocker.cpp	Wed Nov 13 18:00:30 2019 -0500
@@ -72,6 +72,7 @@
 Monitor* CGC_lock                     = NULL;
 Monitor* STS_lock                     = NULL;
 Monitor* FullGCCount_lock             = NULL;
+Monitor* G1OldGCCount_lock            = NULL;
 Monitor* DirtyCardQ_CBL_mon           = NULL;
 Mutex*   Shared_DirtyCardQ_lock       = NULL;
 Mutex*   MarkStackFreeList_lock       = NULL;
@@ -203,6 +204,8 @@
 
   def(FullGCCount_lock             , PaddedMonitor, leaf,        true,  _safepoint_check_never);      // in support of ExplicitGCInvokesConcurrent
   if (UseG1GC) {
+    def(G1OldGCCount_lock          , PaddedMonitor, leaf,        true,  _safepoint_check_always);
+
     def(DirtyCardQ_CBL_mon         , PaddedMonitor, access,      true,  _safepoint_check_never);
     def(Shared_DirtyCardQ_lock     , PaddedMutex  , access + 1,  true,  _safepoint_check_never);