The following test failed in the JDK18 CI:

java/io/DataOutputStream/WriteUTF.java

Here's a snippet from the log file:

#section:testng
----------messages:(4/165)----------
command: testng -Xmx4g WriteUTF
reason: User specified action: run testng/othervm -Xmx4g WriteUTF
Mode: othervm [/othervm specified]
elapsed time (seconds): 15.726
----------configuration:(0/0)----------
----------System.out:(18/1386)----------
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x0000fffc0159bcec, pid=633584, tid=633590
#
# JRE version: Java(TM) SE Runtime Environment (18.0+10) (build 18-ea+10-457)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (18-ea+10-457, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
# Problematic frame:
# V [libjvm.so+0x63bcec] G1ClearBitMapTask::G1ClearBitmapHRClosure::do_heap_region(HeapRegion*)+0x1c
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to /opt/mach5/mesos/work_dir/slaves/35546316-ed70-4084-8244-d672e7734fd1-S13270/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/1e95697c-7e22-4bf5-bb85-b68dc28dac24/runs/aee4562b-7720-41c1-8410-93c8962614e0/testoutput/test-support/jtreg_open_test_jdk_tier2_part2/scratch/1/core.633584)
#
# An error report file with more information is saved as:
# /opt/mach5/mesos/work_dir/slaves/35546316-ed70-4084-8244-d672e7734fd1-S13270/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/1e95697c-7e22-4bf5-bb85-b68dc28dac24/runs/aee4562b-7720-41c1-8410-93c8962614e0/testoutput/test-support/jtreg_open_test_jdk_tier2_part2/scratch/1/hs_err_pid633584.log
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
----------System.err:(0/0)----------
----------rerun:(36/5834)*----------

Here's the crashing thread's stack:

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

Current thread (0x0000fffbfc06a0d0): GCTaskThread "G1 Conc#0" [stack: 0x0000fffbdb080000,0x0000fffbdb280000] [id=633590]

Stack: [0x0000fffbdb080000,0x0000fffbdb280000], sp=0x0000fffbdb27e800, free space=2042k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x63bcec] G1ClearBitMapTask::G1ClearBitmapHRClosure::do_heap_region(HeapRegion*)+0x1c
V [libjvm.so+0x70e2e0] HeapRegionManager::par_iterate(HeapRegionClosure*, HeapRegionClaimer*, unsigned int) const+0xb0
V [libjvm.so+0x63bc6c] G1ClearBitMapTask::work(unsigned int)+0x6c
V [libjvm.so+0xcb8224] GangWorker::loop()+0x70
V [libjvm.so+0xcb8280] WorkGangBarrierSync::WorkGangBarrierSync()+0x0
V [libjvm.so+0xc28dac] Thread::call_run()+0x8c
V [libjvm.so+0xabab8c] thread_native_entry(Thread*)+0xdc
C [libpthread.so.0+0x7738] start_thread+0x198


siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x0000000000000000