linux-kernel - Re: [PATCH] mm/memory-failure: Use a mutex to avoid memory

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Message-ID: <20210308234240.GA23822@hori.linux.bs1.fc.nec.co.jp>
Date:   Mon, 8 Mar 2021 23:42:41 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     "Luck, Tony" <tony.luck@...el.com>
CC:     Aili Yao <yaoaili@...gsoft.com>,
        Oscar Salvador <osalvador@...e.de>,
        "david@...hat.com" <david@...hat.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "yangfeng1@...gsoft.com" <yangfeng1@...gsoft.com>
Subject: Re: [PATCH] mm/memory-failure: Use a mutex to avoid memory_failure()
 races

On Mon, Mar 08, 2021 at 02:55:04PM -0800, Luck, Tony wrote:
> There can be races when multiple CPUs consume poison from the same
> page. The first into memory_failure() atomically sets the HWPoison
> page flag and begins hunting for tasks that map this page. Eventually
> it invalidates those mappings and may send a SIGBUS to the affected
> tasks.
> 
> But while all that work is going on, other CPUs see a "success"
> return code from memory_failure() and so they believe the error
> has been handled and continue executing.
> 
> Fix by wrapping most of the internal parts of memory_failure() in
> a mutex.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>

Thanks!

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>