--- old/src/hotspot/share/runtime/handshake.cpp	2018-10-28 21:03:55.864674591 +0100
+++ new/src/hotspot/share/runtime/handshake.cpp	2018-10-28 21:03:55.569664675 +0100
@@ -357,6 +357,8 @@
 
 void HandshakeState::process_by_vmthread(JavaThread* target) {
   assert(Thread::current()->is_VM_thread(), "should call from vm thread");
+  // Threads_lock must be held here, but that is assert()ed in
+  // possibly_vmthread_can_process_handshake().
 
   if (!has_operation()) {
     // JT has already cleared its handshake