Re: [PATCH v5] x86/split_lock: fix delayed detection enabling

From: Maksim Davydov
Date: Tue Mar 18 2025 - 16:45:19 EST




On 3/18/25 23:24, Ingo Molnar wrote:

* Maksim Davydov <davydov-max@xxxxxxxxxxxxxx> wrote:

If the warn mode with disabled mitigation mode is used, then on each
CPU where the split lock occurred detection will be disabled in order to
make progress and delayed work will be scheduled, which then will enable
detection back. Now it turns out that all CPUs use one global delayed
work structure. This leads to the fact that if a split lock occurs on
several CPUs at the same time (within 2 jiffies), only one CPU will
schedule delayed work, but the rest will not. The return value of
schedule_delayed_work_on() would have shown this, but it is not checked
in the code.

So we already merged the previous version into the locking tree ~10
days ago and it's all in -next already:

c929d08df8be ("x86/split_lock: Fix the delayed detection logic")

https://web.git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=c929d08df8bee855528b9d15b853c892c54e1eee

Is there anything new in your -v5 patch, other than undoing all the
changelog cleanups I did for the previous version? ;-)


Oh, sorry, I missed it.
Yes, in v5 initcall is used instead of deferred initialization.
Either v4 or v5 are good for me. Please be free to choose the more convenient variant for you. :-)

Thanks,

Ingo

--
Best regards,
Maksim Davydov