8334085: Test crash: assert(thread->held_monitor_count() == 0) failed: Must be

Reviewed-by: dholmes, pchilanomate

src/hotspot/share/runtime/continuationFreezeThaw.cpp

@@ -2450,8 +2450,8 @@ static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::th
   intptr_t* const sp = thw.thaw(kind);
   assert(is_aligned(sp, frame::frame_alignment), "");
 
-  // All the frames have been thawed so we know they don't hold any monitors
-  assert(thread->held_monitor_count() == 0, "Must be");
+  // All or part of the frames have been thawed so we know they don't hold any monitors except JNI monitors.
+  assert(thread->held_monitor_count() == thread->jni_monitor_count(), "Must be");
 
 #ifdef ASSERT
   intptr_t* sp0 = sp;

test/hotspot/jtreg/serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,7 +24,7 @@
 
 /**
  * @test
- * @bug 8185164 8320515
+ * @bug 8185164 8320515 8334085
  * @summary Checks that a contended monitor does not show up in the list of owned monitors.
  *          8320515 piggy-backs on this test and injects an owned monitor with a dead object,
             and checks that that monitor isn't exposed to GetOwnedMonitorInfo.
@@ -86,6 +86,9 @@ public class GetOwnedMonitorInfoTest {
                 System.out.println("Thread doing JNI call: "
                                    + Thread.currentThread().getName());
 
+                // Extra unmount helps to reproduce 8334085.
+                // Two sub-sequential thaws are needed in that scenario.
+                Thread.yield();
                 jniMonitorEnterAndLetObjectDie();
             }