--- old/src/hotspot/share/runtime/objectMonitor.hpp	2020-07-14 21:33:18.000000000 -0400
+++ new/src/hotspot/share/runtime/objectMonitor.hpp	2020-07-14 21:33:18.000000000 -0400
@@ -330,8 +330,10 @@
   void*     object() const;
   void*     object_addr();
   void      set_object(void* obj);
+  void      release_set_allocation_state(AllocationState s);
   void      set_allocation_state(AllocationState s);
   AllocationState allocation_state() const;
+  AllocationState allocation_state_acquire() const;
   bool      is_free() const;
   bool      is_old() const;
   bool      is_new() const;
--- old/src/hotspot/share/runtime/objectMonitor.inline.hpp	2020-07-14 21:33:19.000000000 -0400
+++ new/src/hotspot/share/runtime/objectMonitor.inline.hpp	2020-07-14 21:33:19.000000000 -0400
@@ -191,6 +191,10 @@
   return prev;
 }
 
+inline void ObjectMonitor::release_set_allocation_state(ObjectMonitor::AllocationState s) {
+  Atomic::release_store((int*)&_allocation_state, (int)s);
+}
+
 inline void ObjectMonitor::set_allocation_state(ObjectMonitor::AllocationState s) {
   _allocation_state = s;
 }
@@ -199,12 +203,16 @@
   return _allocation_state;
 }
 
+inline ObjectMonitor::AllocationState ObjectMonitor::allocation_state_acquire() const {
+  return (AllocationState)Atomic::load_acquire((int*)&_allocation_state);
+}
+
 inline bool ObjectMonitor::is_free() const {
   return _allocation_state == Free;
 }
 
 inline bool ObjectMonitor::is_old() const {
-  return _allocation_state == Old;
+  return allocation_state_acquire() == Old;
 }
 
 inline bool ObjectMonitor::is_new() const {
--- old/src/hotspot/share/runtime/synchronizer.cpp	2020-07-14 21:33:20.000000000 -0400
+++ new/src/hotspot/share/runtime/synchronizer.cpp	2020-07-14 21:33:20.000000000 -0400
@@ -1908,7 +1908,8 @@
       // Once ObjectMonitor is configured and the object is associated
       // with the ObjectMonitor, it is safe to allow async deflation:
       assert(m->is_new(), "freshly allocated monitor must be new");
-      m->set_allocation_state(ObjectMonitor::Old);
+      // Release semantics needed to keep allocation_state from floating up.
+      m->release_set_allocation_state(ObjectMonitor::Old);
 
       // Hopefully the performance counters are allocated on distinct cache lines
       // to avoid false sharing on MP systems ...
@@ -1965,6 +1966,8 @@
     // Once the ObjectMonitor is configured and object is associated
     // with the ObjectMonitor, it is safe to allow async deflation:
     assert(m->is_new(), "freshly allocated monitor must be new");
+    // Release semantics are not needed to keep allocation_state from
+    // floating up since cas_set_mark() takes care of it.
     m->set_allocation_state(ObjectMonitor::Old);
 
     // Hopefully the performance counters are allocated on distinct