--- a/hotspot/src/share/vm/gc/serial/genMarkSweep.cpp	Wed Jun 10 07:37:11 2015 +0200
+++ b/hotspot/src/share/vm/gc/serial/genMarkSweep.cpp	Tue Jun 16 14:30:27 2015 -0700
@@ -208,7 +208,7 @@
                            level,
                            false, // Younger gens are not roots.
                            GenCollectedHeap::SO_None,
-                           GenCollectedHeap::StrongRootsOnly,
+                           ClassUnloading,
                            &follow_root_closure,
                            &follow_root_closure,
                            &follow_cld_closure);

--- a/hotspot/src/share/vm/runtime/arguments.cpp	Wed Jun 10 07:37:11 2015 +0200
+++ b/hotspot/src/share/vm/runtime/arguments.cpp	Tue Jun 16 14:30:27 2015 -0700
@@ -1384,6 +1384,12 @@
   if (!FLAG_IS_DEFAULT(OldPLABSize) || !FLAG_IS_DEFAULT(OldPLABWeight)) {
     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));