The following test failed in the JDK18 CI:

applications/kitchensink/Kitchensink24HStress.java

Here's a snippet from the log file:

[stress.process.err] Iteration done: LockDeflation at Sun Sep 26 09:26:25 UTC 2021
[stress.process.err] Unexpected Exception in thread Finalizer.
[stress.process.err] java.lang.NullPointerException: Cannot assign field "next" because "this.prev" is null
[stress.process.err] at java.base/java.lang.ref.Finalizer.runFinalizer(Finalizer.java:77)
[stress.process.err] at java.base/java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:173)
[Sun Sep 26 09:26:55 UTC 2021] (1632648415626) Picker module is about to shutdown
Picker module expected time before shutdown for: Jcmd: 30s
Picker module expected time before shutdown for: Jfr: 3m 20s
Picker module expected time before shutdown for: Jstat: 5m
Picker module expected time before shutdown for: Monitor: 1m
Picker module expected time before shutdown for: NMT: 1m
Picker module expected time before shutdown for: Perfmon: 5m
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: Jstat
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: NMT
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: Perfmon
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: Jfr
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: Jcmd
Picker module finished at [Sun Sep 26 09:26:55 UTC 2021]: Monitor
[Sun Sep 26 09:26:55 UTC 2021] (1632648415628) Picker module has been shutdown
[Sun Sep 26 09:26:55 UTC 2021] (1632648415628) Stress process is about to shutdown
Going to request to stop or kill stress process: 39340
WARNING: The process 39340 has already finished.
[Sun Sep 26 09:26:55 UTC 2021] (1632648415628) Stress process has been shutdown
[Sun Sep 26 09:26:55 UTC 2021] Execution finished.
[Sun Sep 26 09:26:55 UTC 2021] Analyzer failed with: java.lang.NullPointerException: Cannot assign field "next" because "this.prev" is null
at java.base/java.lang.ref.Finalizer.runFinalizer(Finalizer.java:77)
at java.base/java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:173)

java.lang.RuntimeException: java.lang.NullPointerException: Cannot assign field "next" because "this.prev" is null
at java.base/java.lang.ref.Finalizer.runFinalizer(Finalizer.java:77)
at java.base/java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:173)

at applications.kitchensink.process.glue.Main.analyzeResults(Main.java:387)
at applications.kitchensink.process.glue.Main.main(Main.java:224)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:833)

JavaTest Message: Test threw exception: java.lang.RuntimeException: java.lang.NullPointerException: Cannot assign field "next" because "this.prev" is null
at java.base/java.lang.ref.Finalizer.runFinalizer(Finalizer.java:77)
at java.base/java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:173)

JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: java.lang.NullPointerException: Cannot assign field "next" because "this.prev" is null at java.base/java.lang.ref.Finalizer.runFinalizer(Finalizer.java:77) at java.base/java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:173)
----------rerun:(42/6764)*----------

This looks like it might be a test harness issue so I'm
starting this bug in hotspot/test.