diff -r 0ef29304c2b4 -r 6a4a6c499e89 src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp	Tue Jul 17 17:07:44 2018 +0200
+++ b/src/share/vm/runtime/arguments.cpp	Fri Jul 20 03:07:49 2018 -0400
@@ -1377,11 +1377,6 @@
     CFLS_LAB::modify_initialization(OldPLABSize, OldPLABWeight);
   }
 
-  if (!ClassUnloading) {
-    FLAG_SET_CMDLINE(bool, CMSClassUnloadingEnabled, false);
-    FLAG_SET_CMDLINE(bool, ExplicitGCInvokesConcurrentAndUnloadsClasses, false);
-  }
-
   if (PrintGCDetails && Verbose) {
     tty->print_cr("MarkStackSize: %uk  MarkStackSizeMax: %uk",
       (unsigned int) (MarkStackSize / K), (uint) (MarkStackSizeMax / K));
@@ -1748,6 +1743,13 @@
     // Keeping the heap 100% free is hard ;-) so limit it to 99%.
     FLAG_SET_ERGO(uintx, MinHeapFreeRatio, 99);
   }
+
+  // If class unloading is disabled, also disable concurrent class unloading.
+  if (!ClassUnloading) {
+    FLAG_SET_CMDLINE(bool, CMSClassUnloadingEnabled, false);
+    FLAG_SET_CMDLINE(bool, ClassUnloadingWithConcurrentMark, false);
+    FLAG_SET_CMDLINE(bool, ExplicitGCInvokesConcurrentAndUnloadsClasses, false);
+  }
 #else // INCLUDE_ALL_GCS
   assert(verify_serial_gc_flags(), "SerialGC unset");
 #endif // INCLUDE_ALL_GCS