When overclocking multi core CPUs like ryzen 9 5950x one often experiences single core crash.

These things are logged in Event viewer under windows under WHEA logger showing "acpi thread id" that crashed allowing one to see which core needs a different voltage/frequency curve.

Is there anything similar on a modern Linux (kernel 6.1)?

I have my overclocking pretty much dialed in, but I still I do get an occasional crash after 12h+ of a heavy workload. I'd rather use my daily driver Linux os than having to rely on Windows for testing system stability.

Does anyone here know if there is an equivalent? Would it show the core/thread no. in journalctl?

yes, you can find the related info in logs, especially in kernel logs.
see for example here: https://ubuntu.com/server/docs/kernel-crash-dump

Thanks for the answer. Indeed it is visible in the kernel log (with journalctl - k). That particular failure happened only once, and on that occasion it didn't trigger a crash dump. It just logged a message very similar to what windows logs.

I don't have the exact wording with me now, but if was something about a "machine check exception" in cpu x bank x, where the bank number is the actual core that crashed and it's voltage needs to be adjusted higher (if one is using PBO2 to OC their ryzen 5xxx cpu).