5.12.1-2 kworker events_unbound eats 100% single thread CPU

As reported here, there’s currently a bug that makes kworker events_unbound eating 100% CPU as a single thread, which according to perf is caused by function btrfs_preempt_reclaim_metadata_space called repeatedly.

In the same report, there’s a list of patches that seem to have solved this problem. What I want to know is whether 5.12.1-2 already contains them (thus invalidating the claim) or not (chance of having them in the next version)?

You can review the kernel package config here:

Yep, none. As all of those patches I point has btrfs in their name. Guess it can be considered for addition if upstream doesn’t include them in the next release. Right now, I think the most obvious way to avoid this problem is to go back to 5.10.X.

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I’m seeing the same when Timeshift is creating snapshot. It might be your case too?

On what kernel number? In the bug report they say it is fixed in 5.14.9. Check new kernel 5.15.2-2. I’m using LTS 5.10.79-1 and it is ok.

do you use kernel of manjaro or of arch or elsewhere

I use Manjario Stable and Manjaro kernels.

I can confirm that upgrade to kernel 5.15.2-2 resolved the CPU utilization issue.

Just be aware that my system was bricked shortly after. It may have been a coincidence, but I suspect it was somehow related.

More info at Just recovered from BTRFS bricked system. How should I keep using BTRFS if at all?