--- old/src/hotspot/share/gc/z/zMarkTerminate.inline.hpp	2019-11-21 11:55:18.525093695 +0100
+++ new/src/hotspot/share/gc/z/zMarkTerminate.inline.hpp	2019-11-21 11:55:18.265089300 +0100
@@ -49,7 +49,7 @@
     }
 
     const uint new_nworking = nworking + 1;
-    const uint prev_nworking = Atomic::cmpxchg(new_nworking, nworking_stage, nworking);
+    const uint prev_nworking = Atomic::cmpxchg(nworking_stage, nworking, new_nworking);
     if (prev_nworking == nworking) {
       // Success
       return true;