linux-kernel - Re: [RFD PATCH] x86/mce: Make sure to send SIGBUS even after losing the race to poison a page

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Date:   Thu, 3 Sep 2020 18:55:30 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Naoya Horiguchi <naoya.horiguchi@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Youquan Song <youquan.song@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFD PATCH] x86/mce: Make sure to send SIGBUS even after losing
 the race to poison a page

On Thu, Aug 27, 2020 at 09:32:05AM -0700, Tony Luck wrote:
> The #MC used to win that race and the page was taken offline and SIGBUS
> sent to the task.
> 
> Changes to how Linux processes machine checks now mean that:
> a) Linux will offline the page based on the UCNA siganture in the
>    CMCI handler.

Let's see if that logic makes sense: if #MC offlines the page and sends
SIGBUS but CMCI only offlines the page, isn't it only logical for the
CMCI to *also* send the SIGBUS too, after having offlined the page?

I.e., both should do the proper and full recovery action. Just sayin...

-- 
Regards/Gruss,
    Boris.

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