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

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Message-ID: <Z9nWjlIYHXWYJ0eV@gmail.com>
Date: Tue, 18 Mar 2025 21:24:46 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Maksim Davydov <davydov-max@...dex-team.ru>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	den-plotnikov@...dex-team.ru, gpiccoli@...lia.com, mingo@...hat.com,
	bp@...en8.de, dave.hansen@...ux.intel.com, tglx@...utronix.de,
	hpa@...or.com
Subject: Re: [PATCH v5] x86/split_lock: fix delayed detection enabling


* Maksim Davydov <davydov-max@...dex-team.ru> 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? ;-)

Thanks,

	Ingo