--- old/src/hotspot/share/prims/jvmtiEventController.cpp	2020-08-31 18:03:16.598644163 +0900
+++ new/src/hotspot/share/prims/jvmtiEventController.cpp	2020-08-31 18:03:16.517641966 +0900
@@ -331,10 +331,14 @@
   EC_TRACE(("[%s] # Entering interpreter only mode",
             JvmtiTrace::safe_get_thread_name(state->get_thread())));
   EnterInterpOnlyModeClosure hs;
-  if (SafepointSynchronize::is_at_safepoint()) {
-    hs.do_thread(state->get_thread());
+  assert(state->get_thread()->is_Java_thread(), "just checking");
+  JavaThread *target = (JavaThread *)state->get_thread();
+  Thread *current = Thread::current();
+  if ((target == current) || (target->active_handshaker() == current)) {
+    hs.do_thread(target);
   } else {
-    Handshake::execute_direct(&hs, state->get_thread());
+    bool executed = Handshake::execute_direct(&hs, target);
+    assert(executed, "Direct handshake failed. Target thread is still alive?");
   }
 }
 
@@ -980,21 +984,21 @@
 
 void
 JvmtiEventController::set_frame_pop(JvmtiEnvThreadState *ets, JvmtiFramePop fpop) {
-  MutexLocker mu(SafepointSynchronize::is_at_safepoint() ? NULL : JvmtiThreadState_lock);
+  assert_lock_strong(JvmtiThreadState_lock);
   JvmtiEventControllerPrivate::set_frame_pop(ets, fpop);
 }
 
 
 void
 JvmtiEventController::clear_frame_pop(JvmtiEnvThreadState *ets, JvmtiFramePop fpop) {
-  MutexLocker mu(SafepointSynchronize::is_at_safepoint() ? NULL : JvmtiThreadState_lock);
+  assert_lock_strong(JvmtiThreadState_lock);
   JvmtiEventControllerPrivate::clear_frame_pop(ets, fpop);
 }
 
 
 void
 JvmtiEventController::clear_to_frame_pop(JvmtiEnvThreadState *ets, JvmtiFramePop fpop) {
-  MutexLocker mu(SafepointSynchronize::is_at_safepoint() ? NULL : JvmtiThreadState_lock);
+  assert_lock_strong(JvmtiThreadState_lock);
   JvmtiEventControllerPrivate::clear_to_frame_pop(ets, fpop);
 }