src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/z/ZPageTableEntry.java

@@ -33,12 +33,20 @@
     ZPageTableEntry(Address address) {
         entry = address;
     }
 
     ZPage page() {
-        return (ZPage)VMObjectFactory.newObject(ZPage.class, entry.andWithMask(~1L));
+        return (ZPage)VMObjectFactory.newObject(ZPage.class, zPageBits());
+    }
+
+    private Address zPageBits() {
+        return entry.andWithMask(~1L);
     }
 
     boolean relocating() {
         return (entry.asLongValue() & 1) == 1;
     }
+
+    boolean isEmpty() {
+        return entry == null || zPageBits() == null;
+    }
 }