*** old/src/share/vm/c1/c1_Runtime1.cpp	Thu Nov  6 14:06:44 2008
--- new/src/share/vm/c1/c1_Runtime1.cpp	Thu Nov  6 14:06:43 2008

*** 840,849 ****
--- 840,856 ----
      // loading it turns out it was volatile so we have to throw the
      // compiled code out and let it be regenerated.
      if (TracePatching) {
        tty->print_cr("Deoptimizing for patching volatile field reference");
      }
+     // It's possible the nmethod was invalidated in the last
+     // safepoint, but if it's still alive then make it not_entrant.
+     nmethod* nm = CodeCache::find_nmethod(caller_frame.pc());
+     if (nm != NULL) {
+       nm->make_not_entrant();
+     }
+ 
      VM_DeoptimizeFrame deopt(thread, caller_frame.id());
      VMThread::execute(&deopt);
  
      // Return to the now deoptimized frame.
    }