The following test failed in the Valhalla CI:

applications/kitchensink/Kitchensink.java

Here's a snippet from the log file:

For random generator using seed: 4210422634
To re-run test with same seed value please add "-Djdk.test.lib.random.seed=4210422634" to command line.
stress.process.properties file has created
Stress process main method is started.

SPECjbb2015 Java Business Benchmark
 (c) Standard Performance Evaluation Corporation, 2015

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S86855/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f45ddf0d-ac3b-4bb1-9235-b03e1d3e49e8/runs/a934afe8-9d6e-4aac-b49b-3a62ad84df2d/workspace/open/src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp:3612), pid=111433, tid=111536
# fatal error: DEBUG MESSAGE: verify_oop: r25: broken oop s, "broken oop in encode_heap_oop" (/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S86855/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f45ddf0d-ac3b-4bb1-9235-b03e1d3e49e8/runs/a934afe8-9d6e-4aac-b49b-3a62ad84df2d/workspace/open/src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp:5163)
#
# JRE version: Java(TM) SE Runtime Environment (27.0+1) (fastdebug build 27-valhalla+1-110)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 27-valhalla+1-110, compiled mode, tiered, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
# Problematic frame:
# V [libjvm.so+0x1471d24] MacroAssembler::debug64(char*, long, long*)+0x54
#
# Core dump will be written. Default location: Determined by the following: "/opt/core.sh %p" (alternatively, falling back to /opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S86764/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/88479d84-5eee-456a-899d-ceea5df28380/runs/fd20ca16-192c-46b2-8ed9-4288eb61b349/testoutput/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink_java/scratch/0/core.111433)
#
Unsupported internal testing APIs have been used.

# An error report file with more information is saved as:
# /opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S86764/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/88479d84-5eee-456a-899d-ceea5df28380/runs/fd20ca16-192c-46b2-8ed9-4288eb61b349/testoutput/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink_java/scratch/0/hs_err_pid111433.log
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
----------stderr:(4/613)----------

Here's the crashing thread's stack:

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

Current thread (0x0000ffff848c94d0): JavaThread "SpecJbb2005StressModule" [_thread_in_Java, id=111536, stack(0x0000fffe8fe02000,0x0000fffe90000000) (2040K)]

Stack: [0x0000fffe8fe02000,0x0000fffe90000000], sp=0x0000fffe8fffbe90, free space=2023k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x1471d24] MacroAssembler::debug64(char*, long, long*)+0x54 (macroAssembler_aarch64.cpp:3612)
Registers:

I'm not sure why the stack is so truncated.

I'm starting this issue off in hotspot/runtime for initial triage.