linux-kernel - Re: [PATCH] x86/mce: Lower throttling MCE messages to warnings

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Message-ID: <20191009175608.GK10395@zn.tnic>
Date:   Wed, 9 Oct 2019 19:56:08 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Benjamin Berg <bberg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Christian Kellner <ckellner@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-edac@...r.kernel.org
Subject: Re: [PATCH] x86/mce: Lower throttling MCE messages to warnings

On Wed, Oct 09, 2019 at 05:54:24PM +0200, Benjamin Berg wrote:
> On modern CPUs it is quite normal that the temperature limits are
> reached and the CPU is throttled. In fact, often the thermal design is
> not sufficient to cool the CPU at full load and limits can quickly be
> reached when a burst in load happens. This will even happen with
> technologies like RAPL limitting the long term power consumption of
> the package.
> 
> So these messages do not usually indicate a hardware issue (e.g.
> insufficient cooling). Log them as warnings to avoid confusion about
> their severity.
> 
> Signed-off-by: Benjamin Berg <bberg@...hat.com>
> Tested-by: Christian Kellner <ckellner@...hat.com>
> ---
>  arch/x86/kernel/cpu/mce/therm_throt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
> index 6e2becf547c5..bc441d68d060 100644
> --- a/arch/x86/kernel/cpu/mce/therm_throt.c
> +++ b/arch/x86/kernel/cpu/mce/therm_throt.c
> @@ -188,7 +188,7 @@ static void therm_throt_process(bool new_event, int event, int level)
>  	/* if we just entered the thermal event */
>  	if (new_event) {
>  		if (event == THERMAL_THROTTLING_EVENT)
> -			pr_crit("CPU%d: %s temperature above threshold, cpu clock throttled (total events = %lu)\n",
> +			pr_warn("CPU%d: %s temperature above threshold, cpu clock throttled (total events = %lu)\n",
>  				this_cpu,
>  				level == CORE_LEVEL ? "Core" : "Package",
>  				state->count);
> -- 

This has carried over since its very first addition in

commit 3867eb75b9279c7b0f6840d2ad9f27694ba6c4e4
Author: Dave Jones <davej@...e.de>
Date:   Tue Apr 2 20:02:27 2002 -0800

    [PATCH] x86 bluesmoke update.
    
    o  Make MCE compile time optional       (Paul Gortmaker)
    o  P4 thermal trip monitoring.          (Zwane Mwaikambo)
    o  Non-fatal MCE logging.               (Me)


It used to be KERN_EMERG back then, though.

And yes, this issue has come up in the past already so I think I'll take
it. I'll just give Intel folks a couple of days to object should there
be anything to object to.

Thx.

-- 
Regards/Gruss,
    Boris.

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