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

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Message-ID: <20260113224152.GVaWbKMMzManQ5WwlT@fat_crate.local>
Date: Tue, 13 Jan 2026 23:41:52 +0100
From: Borislav Petkov <bp@...en8.de>
To: "Luck, Tony" <tony.luck@...el.com>
Cc: "Li, Rongqing" <lirongqing@...du.com>,
	Nikolay Borisov <nik.borisov@...e.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 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();
-
 	return NOTIFY_DONE;
 }
 
-- 
Regards/Gruss,
    Boris.

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