--- jsr166/src/jdk8/java/util/concurrent/ConcurrentHashMap.java	2017/03/08 22:13:42	1.4
+++ jsr166/src/jdk8/java/util/concurrent/ConcurrentHashMap.java	2018/10/09 01:42:02	1.5
@@ -2520,6 +2520,8 @@ public class ConcurrentHashMap<K,V> exte
                             setTabAt(tab, i, fwd);
                             advance = true;
                         }
+                        else if (f instanceof ReservationNode)
+                            throw new IllegalStateException("Recursive update");
                     }
                 }
             }