diff -r 7f63c74f0974 -r 8f1d5d706bdd src/hotspot/share/gc/cms/parNewGeneration.cpp
--- a/src/hotspot/share/gc/cms/parNewGeneration.cpp	Tue May 29 09:26:00 2018 +0200
+++ b/src/hotspot/share/gc/cms/parNewGeneration.cpp	Mon Jun 18 12:11:59 2018 +0200
@@ -793,14 +793,17 @@
              par_scan_state.evacuate_followers_closure());
 }
 
-void ParNewRefProcTaskExecutor::execute(ProcessTask& task) {
+void ParNewRefProcTaskExecutor::execute(ProcessTask& task, uint ergo_workers) {
   CMSHeap* gch = CMSHeap::heap();
   WorkGang* workers = gch->workers();
   assert(workers != NULL, "Need parallel worker threads.");
+  assert(workers->active_workers() == ergo_workers,
+         "Ergonomically chosen workers (%u) must be equal to active workers (%u)",
+         ergo_workers, workers->active_workers());
   _state_set.reset(workers->active_workers(), _young_gen.promotion_failed());
   ParNewRefProcTaskProxy rp_task(task, _young_gen, _old_gen,
                                  _young_gen.reserved().end(), _state_set);
-  workers->run_task(&rp_task);
+  workers->run_task(&rp_task, workers->active_workers());
   _state_set.reset(0 /* bad value in debug if not reset */,
                    _young_gen.promotion_failed());
 }
@@ -1450,7 +1453,8 @@
                              refs_discovery_is_mt(),     // mt discovery
                              ParallelGCThreads,          // mt discovery degree
                              refs_discovery_is_atomic(), // atomic_discovery
-                             NULL);                      // is_alive_non_header
+                             NULL,                       // is_alive_non_header
+                             false);                     // disable adjusting number of processing threads
   }
 }