--- a/src/hotspot/share/gc/cms/cmsHeap.cpp	Thu Aug 30 12:39:26 2018 -0700
+++ b/src/hotspot/share/gc/cms/cmsHeap.cpp	Thu Aug 30 16:16:19 2018 -0400
@@ -231,7 +231,7 @@
   }
 
   if (young_gen_as_roots &&
-      !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
+      _process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
     root_closure->set_generation(young_gen());
     young_gen()->oop_iterate(root_closure);
     root_closure->reset_generation();