The following test failed in the JDK18 CI:

applications/runthese/RunThese24H.java

Here's a snippet from the log file:

[74693.990s][info ][class,unload] unloading class javasoft.sqe.jck.lib.javax.jce.CryptoUtil 0x0000000805775000
[74693.991s][info ][class,unload] unloading class javasoft.sqe.javatest.lib.MultiTest 0x0000000802b83000
[74693.991s][info ][class,unload] unloading class javasoft.sqe.javatest.Test 0x000000080322bc00
[74694.853s][info ][gc ] GC(2683) Pause Remark 722M->722M(2192M) 954.812ms
[74696.006s][info ][gc ] GC(2683) Pause Cleanup 866M->866M(2192M) 0.372ms
[74696.185s][info ][gc ] GC(2683) Concurrent Mark Cycle 4356.182ms
[74715.271s][info ][gc ] GC(2684) Pause Young (Prepare Mixed) (G1 Evacuation Pause) 1554M->593M(2192M) 95.247ms
[74717.433s][info ][gc ] GC(2685) Pause Young (Mixed) (G1 Evacuation Pause) 641M->557M(2192M) 118.170ms
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000001fd8001c81c, pid=35076, tid=40276
#
# JRE version: Java(TM) SE Runtime Environment (18.0+20) (fastdebug build 18-ea+20-1194)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 18-ea+20-1194, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, windows-amd64)
# Problematic frame:
# j java.util.ArrayList.add(Ljava/lang/Object;[Ljava/lang/Object;I)V+0 java.base@18-ea
#
# Core dump will be written. Default location: T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_runthese_RunThese24H_java\\scratch\\0\\hs_err_pid35076.mdmp
#
# JFR recording file will be written. Location: T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_runthese_RunThese24H_java\\scratch\\0\\hs_err_pid35076.jfr
#
Unsupported internal testing APIs have been used.

# An error report file with more information is saved as:
# T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_runthese_RunThese24H_java\\scratch\\0\\hs_err_pid35076.log
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
Checking for JDK Version : 1.1
Creating StreamObject from spec
Creating StreamObject from Object
----------System.err:(1016/79602)*----------


Here's the crashing thread's stack:

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

Current thread (0x000001fe1dfa8cd0): JavaThread "javasoft.sqe.tests.api.java.util.Base64.EncodingDecodingMimeCustom_3 " daemon [_thread_in_Java, id=40276, stack(0x00000089f6c00000,0x00000089f6d00000)]

Stack: [0x00000089f6c00000,0x00000089f6d00000], sp=0x00000089f6cfd970, free space=1014k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C 0x000001fd8001c81c


siginfo: EXCEPTION_ACCESS_VIOLATION (0xc0000005), reading address 0x000000085656572e


Here's another snippet from the hs_err_pid:

RCX=0x00000000000000b1 is an unknown value
RDX=
[error occurred during error reporting (printing register info), id 0xe0000000, Internal Error (t:\workspace\open\src\hotspot\share\gc/g1/g1BlockOffsetTable.inline.hpp:113)]

Registers:
RAX=0x0000000856565656, RBX=0x00000008000345e0, RCX=0x00000000000000b1, RDX=0x00000002545b12d0
RSP=0x00000089f6cfd970, RBP=0x00000089f6cfd9d0, RSI=0x0000000000000001, RDI=0x0000000000000028
R8 =0x0000000000000000, R9 =0x00000002545a7088, R10=0x0000000800000000, R11=0x00000002545a7070
R12=0x0000000000000000, R13=0x0000000800724eae, R14=0x00000089f6cfd9f8, R15=0x000001fe1dfa8cd0
RIP=0x000001fd8001c81c, EFLAGS=0x0000000000010206


The info on the actual crash itself is very limited. However, the
test's log file shows a GC event just before the crash:

[74717.433s][info ][gc ] GC(2685) Pause Young (Mixed) (G1 Evacuation Pause) 641M->557M(2192M) 118.170ms
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000001fd8001c81c, pid=35076, tid=40276

and the hs_err_pid shows a secondary error in G1 code:

[error occurred during error reporting (printing register info), id 0xe0000000, Internal Error (t:\workspace\open\src\hotspot\share\gc/g1/g1BlockOffsetTable.inline.hpp:113)]

So I'm starting this failure in hotspot/gc for initial triage.