Using async-profiler (https://github.com/async-profiler/async-profiler/) on Linux 6.17.1-arch1-1 causes a complete hang of the CPU. This has been reported by many people at https://github.com/lucko/spark/issues/530. spark is a piece of software that uses async-profiler internally.
As seen in https://github.com/lucko/spark/issues/530#issuecomment-3339974827, this was bisected to 18dbcbfabfffc4a5d3ea10290c5ad27f22b0d240 perf: Fix the POLL_HUP delivery breakage. Reverting this commit on 6.17.1 fixed the issue for me.
Steps to reproduce: 1. Get a copy of async-profiler. I tested both v3 (affects older spark versions) and v4.1 (latest at time of writing). Unarchive it, this is <async-profiler-dir>. 2. Set kernel parameters kernel.perf_event_paranoid=1 and kernel.kptr_restrict=0 as instructed by https://github.com/async-profiler/async-profiler/blob/fb673227c7fb311f872ce9... 3. Install a version of Java that comes with jshell, i.e. Java 9 or newer. Note: jshell is used for ease of reproduction. Any Java application that is actively running will work. 4. Run `printf 'int acc; while (true) { acc++; }' | jshell -`. This will start an infinitely running Java process. 5. Run `jps` and take the PID next to the text RemoteExecutionControl -- this is the process that was just started. 6. Attach async-profiler to this process by running `<async-profiler-dir>/bin/asprof -d 1 <PID>`. This will run for one second, then the system should freeze entirely shortly thereafter.
I triggered a sysrq crash while the system was frozen, and the output I found in journalctl afterwards is at https://gist.github.com/octylFractal/76611ee76060051e5efc0c898dd0949e I'm not sure if that text is actually from the triggered crash, but it seems relevant. If needed, please tell me how to get the actual crash report, I'm not sure where it is.
I'm using an AMD Ryzen 9 5900X 12-Core Processor. Given that I've seen no Intel reports, it may be AMD specific. I don't have an Intel CPU on hand to test with.
/proc/version: Linux version 6.17.1-arch1-1 (linux@archlinux) (gcc (GCC) 15.2.1 20250813, GNU ld (GNU Binutils) 2.45.0) #1 SMP PREEMPT_DYNAMIC Mon, 06 Oct 2025 18:48:29 +0000 Operating System: Arch Linux uname -mi: x86_64 unknown