diff -r 439a147b2c0c -r f080b08daace src/hotspot/share/runtime/mutexLocker.hpp
--- a/src/hotspot/share/runtime/mutexLocker.hpp	Wed Nov 13 14:08:04 2019 -0800
+++ b/src/hotspot/share/runtime/mutexLocker.hpp	Wed Nov 13 18:00:30 2019 -0500
@@ -68,6 +68,7 @@
                                                  // fore- & background GC threads.
 extern Monitor* STS_lock;                        // used for joining/leaving SuspendibleThreadSet.
 extern Monitor* FullGCCount_lock;                // in support of "concurrent" full gc
+extern Monitor* G1OldGCCount_lock;               // in support of "concurrent" full gc
 extern Monitor* DirtyCardQ_CBL_mon;              // Protects dirty card Q
                                                  // completed buffer queue.
 extern Mutex*   Shared_DirtyCardQ_lock;          // Lock protecting dirty card