--- a/src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java	Wed Nov 28 15:25:14 2018 -0800
+++ b/src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java	Wed Nov 28 15:25:14 2018 -0800
@@ -2542,6 +2542,8 @@
                             setTabAt(tab, i, fwd);
                             advance = true;
                         }
+                        else if (f instanceof ReservationNode)
+                            throw new IllegalStateException("Recursive update");
                     }
                 }
             }