--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp	Mon May 03 17:23:58 2010 -0400
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp	Mon May 03 20:19:05 2010 -0700
@@ -163,6 +163,7 @@
 // GenCollectedHeap heap.
 void VM_GenCollectFullConcurrent::doit() {
   assert(Thread::current()->is_VM_thread(), "Should be VM thread");
+  assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected");
 
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   if (_gc_count_before == gch->total_collections()) {
@@ -190,7 +191,7 @@
     CMSCollector::disable_icms();
     // In case CMS thread was in icms_wait(), wake it up.
     CMSCollector::start_icms();
-    // Nudge the CMS thread to start a concurrent collection
+    // Nudge the CMS thread to start a concurrent collection.
     CMSCollector::request_full_gc(_full_gc_count_before);
   } else {
     FullGCCount_lock->notify_all();  // Inform the Java thread its work is done
@@ -231,7 +232,9 @@
   // e.g. at the rate of 1 full gc per ms, this could
   // overflow in about 1000 years.
   GenCollectedHeap* gch = GenCollectedHeap::heap();
-  if (gch->total_full_collections_completed() <= _full_gc_count_before) {
+  if (_gc_cause != GCCause::_gc_locker &&
+      gch->total_full_collections_completed() <= _full_gc_count_before) {
+    assert(ExplicitGCInvokesConcurrent, "Error");
     // Now, wait for witnessing concurrent gc cycle to complete,
     // but do so in native mode, because we want to lock the
     // FullGCEvent_lock, which may be needed by the VM thread