--- a/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	Mon Nov 25 12:32:40 2019 +0100
+++ b/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	Mon Nov 25 12:33:15 2019 +0100
@@ -210,7 +210,7 @@
       return false;
     }
     new_val = cur - tax;
-  } while (Atomic::cmpxchg(new_val, &_budget, cur) != cur);
+  } while (Atomic::cmpxchg(&_budget, cur, new_val) != cur);
   return true;
 }