diff a/src/hotspot/share/gc/g1/g1ConcurrentMarkThread.hpp b/src/hotspot/share/gc/g1/g1ConcurrentMarkThread.hpp
--- a/src/hotspot/share/gc/g1/g1ConcurrentMarkThread.hpp
+++ b/src/hotspot/share/gc/g1/g1ConcurrentMarkThread.hpp
@@ -48,11 +48,12 @@
     UndoCycleResetForNextCycle
   };
 
   Atomic<ServiceState> _state;
 
-  ServiceState state() const { return _state.load_relaxed(); }
+  ServiceState state() const { return _state.load_acquire(); }
+  void set_state(ServiceState new_state) { _state.release_store(new_state); }
 
   // Returns whether we are in a "Full" cycle.
   bool is_in_full_concurrent_cycle() const;
 
   // Wait for next cycle. Returns the command passed over.