linux-kernel - Re: 答复: 答复: 答复: [外部邮件] Re: [PATCH] x86/mce: Fix timer interval adjustment after logging a MCE event

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Message-ID: <20260113203356.GSaWasNAQZ7sN9vMbt@fat_crate.local>
Date: Tue, 13 Jan 2026 21:33:56 +0100
From: Borislav Petkov <bp@...en8.de>
To: Nikolay Borisov <nik.borisov@...e.com>
Cc: "Luck, Tony" <tony.luck@...el.com>,
	"Li, Rongqing" <lirongqing@...du.com>,
	Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"H . Peter Anvin" <hpa@...or.com>,
	Yazen Ghannam <yazen.ghannam@....com>,
	"Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>,
	Avadhut Naik <avadhut.naik@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
Subject: Re: 答复: 答复: 答复: [外部邮件] Re: [PATCH] x86/mce: Fix timer interval adjustment after logging a MCE event

On Tue, Jan 13, 2026 at 09:51:48PM +0200, Nikolay Borisov wrote:
> grepping around points to your 011d82611172 ("RAS: Add a Corrected Errors
> Collector"). Because looking at the commit log of my 6447828875b7
> ("x86/mce/inject: Remove call to mce_notify_irq()") I mention that
> mce_need_notify got introduced in your commit and it was called
> "notify_user" before that. Before your commit in mce_log there was an
> explicit set_bit(mce_need_notify) call .

It was removed there so that it doesn't issue the

	"Machine check events logged\n"

thing because that's the main point of the error collector - to collect errors
in the background and not upset users.

Also, there's an explicit set_bit(mce_need_notify) call in the early notifier.
So it'll get set a bit later, when the notifier chain goes.

But that same notifier does:

        set_bit(0, &mce_need_notify);
	mce_notify_irq();

so it'll clear that bit immediately.

Which means, the timer would probably never see the need_notify thing and thus
won't halve.

Which begs the question: is the timer even supposed to halve when you have the
error collector?

I guess so - we need it to log errors faster because the assumption is that
you'll be getting more errors so you need to read them out faster.

I need to think about it tomorrow on a clear head...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette