linux-kernel - Re: [PATCH] mce: fix missing stack-dumping in mce

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Date:   Thu, 29 Dec 2022 20:33:55 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "Luck, Tony" <tony.luck@...el.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH] mce: fix missing stack-dumping in mce_panic()

On 2022/12/29 19:54, Borislav Petkov wrote:
> On Sat, Dec 03, 2022 at 10:19:32AM +0800, Miaohe Lin wrote:
>> So I think it's better to have at least one stack dumps. Also what the commit
>> 6e6f0a1f0fa6 ("panic: don't print redundant backtraces on oops") and commit
>> 026ee1f66aaa ("panic: fix stack dump print on direct call to panic()") want
>> to do is avoiding nested stack-dumping to have the original oops data being
>> scrolled away on a 80x50 screen but to have *at least one backtraces*. So
>> this patch acts more like a BUGFIX to ensure having at least one backtraces
>> in mce_panic().
> 

Many thanks for your reply. :)

> So which commit broke this?
> 

I think it should be Fixes: 6e6f0a1f0fa6 ("panic: don't print redundant backtraces on oops")
as there's missing stack-dumping in mce_panic() since then. Should I resend the patch with
above Fixes tag attached?

> One of the two above or
> 
> 004429956b48 ("handle recursive calls to bust_spinlocks()")
> 
> or
> 
> d896a940ef4f ("x86, mce: remove oops_begin() use in 64bit machine check")
> 
> or...?
> 
> By looking at their dates, they're pretty much too old so that this can
> go to *all* stable kernels.

Yes, it should be a really old problem. And it seems it's unnoticed yet because mce should be a
really rare event and corresponding dump-stacking might not be that attractive at that time.

Thanks!
Miaohe Lin