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

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Message-ID: <d2378cc7-d97e-4e8d-b1e7-af5ce3265d2e@suse.com>
Date: Wed, 14 Jan 2026 08:17:50 +0200
From: Nikolay Borisov <nik.borisov@...e.com>
To: Borislav Petkov <bp@...en8.de>, "Luck, Tony" <tony.luck@...el.com>
Cc: "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: [PATCH] x86/mce: Fix timer interval adjustment after logging a
 MCE event

On 14.01.26 г. 0:41 ч., Borislav Petkov wrote:
> On Tue, Jan 13, 2026 at 10:31:58PM +0100, Borislav Petkov wrote:
>> Ufff, how silly and overengineered we've made it. I need to think about
>> a cleaner solution tomorrow...
> 
> One idea I just thought of:
> 
> those two steps:
> 
> 1. setting mce_need_notify, and
> 
> 2.  testing and clearing it
> 
> are basically logically a one query: do we have logged errors, or, IOW, is the
> gen pool not empty?
> 
> IOW, this below.
> 
> That'll get rid of that gunk of when should we test and when set and will
> JustWork(tm) for what we want it to do.
> 
> But let's see how it all really works tomorrow...
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 34440021e8cf..c378d4d450b6 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -595,7 +595,7 @@ static bool mce_notify_irq(void)
>   	/* Not more than two messages every minute */
>   	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
>   
> -	if (test_and_clear_bit(0, &mce_need_notify)) {
> +	if (!mce_gen_pool_empty()) {
>   		mce_work_trigger();
>   
>   		if (__ratelimit(&ratelimit))
> @@ -618,10 +618,6 @@ static int mce_early_notifier(struct notifier_block *nb, unsigned long val,
>   	/* Emit the trace record: */
>   	trace_mce_record(err);
>   
> -	set_bit(0, &mce_need_notify);
> -
> -	mce_notify_irq();
> -

so now mce_notify_irq() is not being called from the early notifier, i.e 
the callchain mc_poll_banks -> machine_check_poll -> mce_log no longer 
call mce_notify_irq() in the early notifier chain.

>   	return NOTIFY_DONE;
>   }
>