--- old/src/share/vm/gc/g1/ptrQueue.cpp	2017-04-25 16:44:46.271174800 +0200
+++ new/src/share/vm/gc/g1/ptrQueue.cpp	2017-04-25 16:44:46.159174804 +0200
@@ -72,16 +72,7 @@
 
 void PtrQueue::locking_enqueue_completed_buffer(BufferNode* node) {
   assert(_lock->owned_by_self(), "Required.");
-
-  // We have to unlock _lock (which may be Shared_DirtyCardQ_lock) before
-  // we acquire DirtyCardQ_CBL_mon inside enqueue_complete_buffer as they
-  // have the same rank and we may get the "possible deadlock" message
-  _lock->unlock();
-
   qset()->enqueue_complete_buffer(node);
-  // We must relock only because the caller will unlock, for the normal
-  // case.
-  _lock->lock_without_safepoint_check();
 }