linux-kernel - Re: [PATCH RESEND] x86/split_lock: Warn for bus locks once for each task

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Message-ID: <hs7b3ghxpr2oq6rmqitw33xkunkqpvjkpnwzhqfq4em5vxvymw@rn4c6mr636es>
Date: Wed, 17 Sep 2025 16:37:21 +0100
From: Pedro Falcato <pfalcato@...e.de>
To: Maksim Davydov <davydov-max@...dex-team.ru>
Cc: "H. Peter Anvin" <hpa@...or.com>, 
	"Peter Zijlstra (Intel)" <peterz@...radead.org>, linux-kernel@...r.kernel.org, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Subject: Re: [PATCH RESEND] x86/split_lock: Warn for bus locks once for each
 task

On Wed, Sep 17, 2025 at 05:41:11PM +0300, Maksim Davydov wrote:
> Hi!

Hi!

> I've tested this patch (VM w/ bus lock detection and w/o split lock
> detection). The warn mode works fine and as expected with only one
> notification per task. However, the ratelimit mode has been changed too:
> only one notification per task will be in dmesg, because this mode reuses
> notification code of warn mode. But in the documentation for ratelimit mode
> there is nothing about the limit of notifications: "Limit bus lock rate to N
> bus locks per second system wide and warn on bus locks.". Thus, I think that
> ratelimit mode should remain old behaviour.
>

So, you're suggesting different "warn" behaviors depending on =warn vs
=ratelimit? I don't have a particularly strong opinion here, but I was assuming
that "warn on bus locks" means "do whatever =warn is supposed to do". I'm not
sure warning every time gains you much, though.

-- 
Pedro