The following test crashed in the JDK18 CI:

applications/kitchensink/Kitchensink24HStress.java

Here's a snippet from the log file:

Output and diagnostic info for process 21680 was saved into 'pid-21680-output.log'
[stress.process.out] #
[stress.process.out] # A fatal error has been detected by the Java Runtime Environment:
[stress.process.out] #
[stress.process.out] # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffaf0e01040, pid=13276, tid=12136
[stress.process.out] #
[stress.process.out] # JRE version: Java(TM) SE Runtime Environment (18.0+14) (build 18-ea+14-715)
[stress.process.out] # Java VM: Java HotSpot(TM) 64-Bit Server VM (18-ea+14-715, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, windows-amd64)
[stress.process.out] # Problematic frame:
[stress.process.out] # V [jvm.dll+0x11040] AccessInternal::PostRuntimeDispatch<CardTableBarrierSet::AccessBarrier<548932,CardTableBarrierSet>,2,548932>::oop_access_barrier+0x0
[stress.process.out] #
[stress.process.out] # No core dump will be written. Minidumps are not enabled by default on client versions of Windows
[stress.process.out] #
[stress.process.out] Unsupported internal testing APIs have been used.
[stress.process.out]
[stress.process.out] # An error report file with more information is saved as:
[stress.process.out] # T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink24HStress_java\\scratch\\0\\hs_err_pid13276.log
[stress.process.out] #
[stress.process.out] # If you would like to submit a bug report, please visit:
[stress.process.out] # https://bugreport.java.com/bugreport/crash.jsp
[stress.process.out] #
[2021-09-08T11:09:12.359110600Z] Gathering output for process 12284


Here's the crashing thread's stack:

--------------- T H R E A D ---------------

Current thread (0x0000027fe13a8aa0): JavaThread "Finalizer" daemon [_thread_in_Java, id=12136, stack(0x000000c9bc500000,0x000000c9bc600000)]

Stack: [0x000000c9bc500000,0x000000c9bc600000], sp=0x000000c9bc5ff338, free space=1020k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [jvm.dll+0x11040] AccessInternal::PostRuntimeDispatch<CardTableBarrierSet::AccessBarrier<548932,CardTableBarrierSet>,2,548932>::oop_access_barrier+0x0 (access.inline.hpp:81)

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
v ~RuntimeStub::_complete_monitor_locking_Java
J 32057 c2 jdk.nio.zipfs.ZipFileSystem.close()V jdk.zipfs@18-ea (390 bytes) @ 0x0000027fdabdcffc [0x0000027fdabda160+0x0000000000002e9c]
J 113282 c2 jdk.nio.zipfs.ZipFileSystem.finalize()V jdk.zipfs@18-ea (5 bytes) @ 0x0000027fda0b7bd4 [0x0000027fda0b7ba0+0x0000000000000034]
J 106443 c2 java.lang.ref.Finalizer.runFinalizer(Ljdk/internal/access/JavaLangAccess;)V java.base@18-ea (131 bytes) @ 0x0000027fda4a4838 [0x0000027fda4a44c0+0x0000000000000378]
J 24485% c2 java.lang.ref.Finalizer$FinalizerThread.run()V java.base@18-ea (56 bytes) @ 0x0000027fd9c8088c [0x0000027fd9c80700+0x000000000000018c]
v ~StubRoutines::call_stub

siginfo: EXCEPTION_ACCESS_VIOLATION (0xc0000005), reading address 0xffffffffffffffff

The only clue I have here is that we're in a compiled frame:

J 32057 c2 jdk.nio.zipfs.ZipFileSystem.close()V jdk.zipfs@18-ea (390 bytes) @ 0x0000027fdabdcffc [0x0000027fdabda160+0x0000000000002e9c]

and are trying to complete an optimized Java monitor lock:

v ~RuntimeStub::_complete_monitor_locking_Java

I'm starting this bug off in hotspot/compiler for initial eval.