diff -r 64bfaa6d10a9 -r d48b9b0a06bf hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp
--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Thu Jun 25 08:30:23 2015 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Thu Jun 25 10:52:37 2015 +0000
@@ -2487,7 +2487,7 @@
   // is set) so that if a waiter requests another System.gc() it doesn't
   // incorrectly see that a marking cycle is still in progress.
   if (concurrent) {
-    _cmThread->clear_in_progress();
+    _cmThread->set_idle();
   }
 
   // This notify_all() will ensure that a thread that called