--- a/src/hotspot/share/gc/shared/oopStorage.hpp	Fri Oct 05 16:47:27 2018 +0200
+++ b/src/hotspot/share/gc/shared/oopStorage.hpp	Mon Oct 08 14:48:12 2018 +0200
@@ -220,7 +220,7 @@
   mutable SingleWriterSynchronizer _protect_active;
 
   // mutable because this gets set even for const iteration.
-  mutable bool _concurrent_iteration_active;
+  mutable int _concurrent_iteration_count;
 
   Block* find_block_or_null(const oop* ptr) const;
   void delete_empty_block(const Block& block);