src/hotspot/share/runtime/synchronizer.cpp

rev 59856 : 8247280: more fencing needed in async deflation for non-TSO machines
Reviewed-by: dholmes

@@ -1906,11 +1906,12 @@
       object->release_set_mark(markWord::encode(m));
 
       // 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 ...
       OM_PERFDATA_OP(Inflations, inc());
       if (log_is_enabled(Trace, monitorinflation)) {

@@ -1963,10 +1964,12 @@
     }
 
     // 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
     // cache lines to avoid false sharing on MP systems ...
     OM_PERFDATA_OP(Inflations, inc());