--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Mon Nov 03 12:02:40 2014 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Thu Oct 02 10:55:36 2014 +0200
@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "classfile/metadataOnStackMark.hpp"
 #include "classfile/symbolTable.hpp"
 #include "code/codeCache.hpp"
 #include "gc_implementation/g1/concurrentMark.inline.hpp"
@@ -2602,17 +2603,27 @@
     G1RemarkGCTraceTime trace("Unloading", G1Log::finer());
 
     if (ClassUnloadingWithConcurrentMark) {
+      // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack
+      // part is too slow to be done serially, so it is handled during the weakRefsWorkParallelPart phase.
+      // Defer the cleaning until we have complete on_stack data.
+      MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */);
+
       bool purged_classes;
 
       {
         G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest());
-        purged_classes = SystemDictionary::do_unloading(&g1_is_alive);
+        purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
       }
 
       {
         G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest());
         weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
       }
+
+      {
+        G1RemarkGCTraceTime trace("Deallocate Metadata", G1Log::finest());
+        ClassLoaderDataGraph::free_deallocate_lists();
+      }
     }
 
     if (G1StringDedup::is_enabled()) {