Assertion sometimes fails in jdk25+24, only observed in GenShen so far, on x86_64 and aarch64.

java -Xms18g -Xmx18g -XX:+UseShenandoahGC -XX:+UnlockExperimentalVMOptions -XX:ShenandoahGCMode=generational VirtualThreadJfr 600 100000000


#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/ws/jdk25/src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.cpp:630), pid=30377, tid=30535
# assert(*start_bp == CardTable::clean_card_val()) failed: Should be clean: 0x00007d4ba78755d0
#
# JRE version: OpenJDK Runtime Environment (25.0) (fastdebug build 25-internal-adhoc.katkerem.jdk25)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug 25-internal-adhoc.katkerem.jdk25, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, shenandoah gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x1a92dcd] ShenandoahDirectCardMarkRememberedSet::swap_card_tables()+0xdd
#
# Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport -p%p -s%s -c%c -d%d -P%P -u%u -g%g -- %E" (or dumping to /home/ubuntu/app/output/core.30377)
#
# JFR recording file will be written. Location: /home/ubuntu/app/output/hs_err_pid30377.jfr
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: -Djava.library.path=/home/ubuntu/app/cache/lib -Xms18g -Xmx18g -XX:+UseShenandoahGC -XX:+UnlockExperimentalVMOptions -XX:ShenandoahGCMode=generational -XX:ErrorFile=/home/ubuntu/app/output/crash_reports/stress-apps/hs_err_VirtualThreadJfr_%p_27-05-2025.log VirtualThreadJfr 600 100000000

Host: ip-172-31-28-106, Intel(R) Xeon(R) Platinum 8488C, 64 cores, 123G, Ubuntu 24.04.2 LTS
Time: Tue May 27 21:05:26 2025 UTC elapsed time: 140.283364 seconds (0d 0h 2m 20s)

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

Current thread (0x00007d4bc4254160): VMThread "VM Thread" [id=30535, stack(0x00007d4b955d7000,0x00007d4b956d7000) (1024K)]

Stack: [0x00007d4b955d7000,0x00007d4b956d7000], sp=0x00007d4b956d53a0, free space=1016k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x1a92dcd] ShenandoahDirectCardMarkRememberedSet::swap_card_tables()+0xdd (shenandoahScanRemembered.cpp:630)
V [libjvm.so+0x196ee3e] ShenandoahDegenGC::op_degenerated()+0x57e (shenandoahDegeneratedGC.cpp:141)
V [libjvm.so+0x196f86f] ShenandoahDegenGC::entry_degenerated()+0x1bf (shenandoahDegeneratedGC.cpp:85)
V [libjvm.so+0x1ac85ab] VM_ShenandoahDegeneratedGC::doit()+0x5b (shenandoahVMOperations.cpp:101)
V [libjvm.so+0x1d7a7f3] VM_Operation::evaluate()+0x193 (vmOperations.cpp:74)
V [libjvm.so+0x1d96aba] VMThread::evaluate_operation(VM_Operation*)+0x15a (vmThread.cpp:282)
V [libjvm.so+0x1d97a43] VMThread::inner_execute(VM_Operation*)+0x433 (vmThread.cpp:426)
V [libjvm.so+0x1d97bec] VMThread::loop()+0x8c (vmThread.cpp:492)
V [libjvm.so+0x1d97d08] VMThread::run()+0x98 (vmThread.cpp:176)
V [libjvm.so+0x1c8a65a] Thread::call_run()+0xba (thread.cpp:224)
V [libjvm.so+0x1754288] thread_native_entry(Thread*)+0x128 (os_linux.cpp:869)
C [libc.so.6+0x9caa4]