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

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Message-ID: <36b42ced-f1e8-4eb0-b6f8-2a9434d5d26c@suse.com>
Date: Mon, 12 Jan 2026 10:56:47 +0200
From: Nikolay Borisov <nik.borisov@...e.com>
To: lirongqing <lirongqing@...du.com>, Thomas Gleixner <tglx@...nel.org>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 "H . Peter Anvin" <hpa@...or.com>, Tony Luck <tony.luck@...el.com>,
 Yazen Ghannam <yazen.ghannam@....com>, Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
 Avadhut Naik <avadhut.naik@....com>, linux-kernel@...r.kernel.org,
 linux-edac@...r.kernel.org
Subject: Re: [PATCH] x86/mce: Fix timer interval adjustment after logging a
 MCE event

On 12.01.26 г. 10:27 ч., lirongqing wrote:
> From: Li RongQing <lirongqing@...du.com>
> 
> Since commit 011d82611172 ("RAS: Add a Corrected Errors Collector"),
> mce_notify_irq() in should_enable_timer() always returns false even

should_enable_timer doesn't call mce_notify_irq

> when an MCE event is logged, because bit 0 of mce_need_notify is not
> set in mce_log. This prevents the timer interval from being properly
> adjusted.
> 
> Fix this by modifying machine_check_poll() to return a boolean indicating
> whether an MCE was logged, and update mc_poll_banks() to propagate this
> return value. The timer interval logic in mce_timer_fn() now uses this
> return value directly instead of relying on mce_notify_irq().

This warrants a bit more explanation why it's correct. Because 
mce_notify_irq is really a misnomer, it will ideally be named 
mce_notify_user(). That function is called from 2 places:

1. Early notifier block, but there it's guaranteed to do the right thing 
as mce_need_notify is explicitly set.

2. From the timer function, where as you have pointed out 
mce_need_notify is never set by the polling code, hence the function is 
a noop. But actually calling mce_log() processes all logged errors in 
the gen pool and that is processed by calling the x86_mce_decoder_chain 
which will DTRT w.r.t to mce_notify_irq since the early notifier will be 
called from there.

<snip>