--- a/src/hotspot/share/runtime/os.cpp	Thu Apr 25 05:54:54 2019 -0700
+++ b/src/hotspot/share/runtime/os.cpp	Thu Apr 25 10:56:31 2019 -0400
@@ -858,7 +858,7 @@
 
 void os::start_thread(Thread* thread) {
   // guard suspend/resume
-  MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
+  MutexLocker ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
   OSThread* osthread = thread->osthread();
   osthread->set_state(RUNNABLE);
   pd_start_thread(thread);