linux-kernel - Re: [PATCH v2 10/13] EDAC/altera: Skip the panic notifier if kdump is loaded

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Message-ID: <Yv1XVRmTXHLhOkER@zn.tnic>
Date:   Wed, 17 Aug 2022 23:02:13 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     akpm@...ux-foundation.org, bhe@...hat.com, pmladek@...e.com,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
        x86@...nel.org, kernel-dev@...lia.com, kernel@...ccoli.net,
        halves@...onical.com, fabiomirmar@...il.com,
        alejandro.j.jimenez@...cle.com, andriy.shevchenko@...ux.intel.com,
        arnd@...db.de, corbet@....net, d.hatayama@...fujitsu.com,
        dave.hansen@...ux.intel.com, dyoung@...hat.com,
        feng.tang@...el.com, gregkh@...uxfoundation.org,
        mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com,
        jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org,
        luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com,
        paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org,
        senozhatsky@...omium.org, stern@...land.harvard.edu,
        tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com,
        will@...nel.org, linux-edac@...r.kernel.org,
        Dinh Nguyen <dinguyen@...nel.org>,
        Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH v2 10/13] EDAC/altera: Skip the panic notifier if kdump
 is loaded

On Wed, Aug 17, 2022 at 05:28:34PM -0300, Guilherme G. Piccoli wrote:
> My understanding is the same as yours, i.e., this is not possible to
> collect from vmcore, it requires register reading. But again: if you
> kdump your machine today, you won't collect this information, patch
> changed nothing in that regard.

Why won't you be able to collect it? You can certainly access dmesg in
the vmcore and see those errors logged there.

> The one thing it changes is that you'd skip the altera register dump if
> kdump is set AND you managed to also set "crash_kexec_post_notifiers".

What your patch changes is, it prevents s10_edac_dberr_handler() from
logging potentially important fatal hw errors when kdump is loaded.

If Dinh is fine with that, I'll take the patch. But it looks like a bad
idea to me.

-- 
Regards/Gruss,
    Boris.

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