The following tests fail in the JDK15 CI:

jdk/jfr/api/consumer/security/TestRecordingStream.java
jdk/jfr/api/consumer/security/TestStreamingLocal.java
jdk/jfr/jmx/security/TestEnoughPermission.java
jdk/jfr/jmx/security/TestNotificationListenerPermission.java

Here's a snippet from the TestRecordingStream.java log file:

#section:main
----------messages:(5/375)----------
command: main jdk.jfr.api.consumer.security.TestStreamingLocal
reason: User specified action: run main/othervm/secure=java.lang.SecurityManager/java.security.policy=local-streaming.policy jdk.jfr.api.consumer.security.TestStreamingLocal
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jfr,java.management
elapsed time (seconds): 4.367
----------configuration:(3/51)----------
Boot Layer
  add modules: jdk.jfr java.management

----------System.out:(1/140)----------
[1.670s][warning][jfr,system] Could not initialize JDK events. access denied ("java.lang.reflect.ReflectPermission" "suppressAccessChecks")
----------System.err:(4/204)----------

Exception: java.lang.StackOverflowError thrown from the UncaughtExceptionHandler in thread "MainThread"

Exception: java.lang.StackOverflowError thrown from the UncaughtExceptionHandler in thread "main"
----------rerun:(41/6121)*----------

It appears that these test failures are related to the push
for the following bug:

    JDK-8235521 Replacement API for Unsafe::ensureClassInitialized