--- old/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	2013-09-23 17:51:17.230146305 -0700
+++ new/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	2013-09-23 17:51:17.120144435 -0700
@@ -788,12 +788,12 @@
              && _survivor_chunk_index == 0),
          "Error");
 
-  // Choose what strong roots should be scanned depending on verification options
+  // Choose what strong roots should be scanned depending on verification options.
+  // If CMSClassUnloadingEnabled is on, root scanning option is set during
+  // setup_cms_unloading_and_verification_state() on each CMS cycle.
   if (!CMSClassUnloadingEnabled) {
     // If class unloading is disabled we want to include all classes into the root set.
     add_root_scanning_option(SharedHeap::SO_AllClasses);
-  } else {
-    add_root_scanning_option(SharedHeap::SO_SystemClasses);
   }
 
   NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;)
@@ -3310,6 +3310,17 @@
                              || VerifyBeforeExit;
   const  int  rso           =   SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
 
+  // We set the proper root for this CMS cycle here.
+  // When class unloading is disabled, we set the default root scanning option
+  // once in the CMSCollector constructor.
+  if (CMSClassUnloadingEnabled) {
+    if (should_unload_classes()) {
+      set_root_scanning_option(SharedHeap::SO_SystemClasses);
+    } else {
+      set_root_scanning_option(SharedHeap::SO_AllClasses | rso);
+    }
+  }
+
   if (should_unload_classes()) {   // Should unload classes this cycle
     remove_root_scanning_option(rso);  // Shrink the root set appropriately
     set_verifying(should_verify);    // Set verification state for this cycle
--- old/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	2013-09-23 17:51:17.720154631 -0700
+++ new/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	2013-09-23 17:51:17.620152931 -0700
@@ -591,6 +591,7 @@
   // Root scanning options for perm gen
   int _roots_scanning_options;
   int roots_scanning_options() const      { return _roots_scanning_options; }
+  void set_root_scanning_option(int o)    { _roots_scanning_options = o;    }
   void add_root_scanning_option(int o)    { _roots_scanning_options |= o;   }
   void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o;  }