The following test failed in the Valhalla CI:

java/nio/file/WatchService/UpdateInterference.java

Here's a snippet from the log file:

#section:main
----------messages:(8/257)----------
command: main UpdateInterference
reason: User specified action: run main UpdateInterference
started: Tue Feb 10 17:32:19.921 UTC 2026
Mode: agentvm
Agent id: 21
Process id: 1167285
finished: Tue Feb 10 17:34:27.465 UTC 2026
elapsed time (seconds): 127.544
----------configuration:(12/1459)----------

<snip>

----------stdout:(19/1420)----------
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (type.cpp:1446), pid=1167285, tid=1167302
# Error: ShouldNotReachHere()
#
# JRE version: Java(TM) SE Runtime Environment (27.0+1) (build 27-valhalla+1-116)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (27-valhalla+1-116, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x112916a] Type::typerr(Type const*) const [clone .constprop.0]+0x1a
#
# 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-S114221/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/7ce8c8a4-f085-4325-93ed-9c1a2e081622/runs/cca22a3e-2130-4110-ac92-b81db8cbf7b9/testoutput/test-support/jtreg_open_test_jdk_tier2_part2/scratch/3/core.1167285)
#
# An error report file with more information is saved as:
# /opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S114221/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/7ce8c8a4-f085-4325-93ed-9c1a2e081622/runs/cca22a3e-2130-4110-ac92-b81db8cbf7b9/testoutput/test-support/jtreg_open_test_jdk_tier2_part2/scratch/3/hs_err_pid1167285.log
[thread 1174361 also had an error]

------ Timeout during error reporting after 120 s. ------
# [ timer expired, abort... ]
result: Error. Agent communication error: java.io.EOFException; check console log for any additional details

Here's the crashing thread's stack trace:

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

Current thread (0x00007f7564150920): JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=1167302, stack(0x00007f753cc12000,0x00007f753cd12000) (1024K)]


Current CompileTask:
C2:61143 4659 ! 4 sun.nio.fs.LinuxWatchService$Poller::run (323 bytes)

Stack: [0x00007f753cc12000,0x00007f753cd12000], sp=0x00007f753cd0d6c0, free space=1005k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x112916a] Type::typerr(Type const*) const [clone .constprop.0]+0x1a (type.cpp:1446)
V [libjvm.so+0x113f45a] TypeInstPtr::xmeet_helper(Type const*) const+0x4ea (type.cpp:4494)
V [libjvm.so+0x1129656] TypePtr::xmeet(Type const*) const+0x16 (type.cpp:2809)
V [libjvm.so+0x112db19] Type::filter_helper(Type const*, bool) const+0x19 (type.hpp:220)
V [libjvm.so+0xa07d26] InlineTypeNode::Value(PhaseGVN*) const+0x46 (type.hpp:303)
V [libjvm.so+0xf2453f] PhaseIterGVN::transform_old(Node*)+0x14f (phaseX.cpp:2177)
V [libjvm.so+0xf1ca84] PhaseIterGVN::optimize()+0x74 (phaseX.cpp:1064)
V [libjvm.so+0x73b1bf] Compile::Optimize()+0x19f (compile.cpp:2894)
V [libjvm.so+0x73effd] Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x10ed (compile.cpp:886)
V [libjvm.so+0x63f31e] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x1ee (c2compiler.cpp:149)
V [libjvm.so+0x7464b1] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x951 (compileBroker.cpp:2345)
V [libjvm.so+0x7476d0] CompileBroker::compiler_thread_loop()+0x4d0 (compileBroker.cpp:1989)
V [libjvm.so+0xa6c3f8] JavaThread::thread_main_inner() [clone .part.0]+0xb8 (javaThread.cpp:777)
V [libjvm.so+0x110ee8f] Thread::call_run()+0x9f (thread.cpp:243)
V [libjvm.so+0xec6ab6] thread_native_entry(Thread*)+0xc6 (os_linux.cpp:929)