Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 6 May 2021 17:37:57 +0800
From:   Aili Yao <yaoaili@kingsoft.com>
To:     Naoya Horiguchi <nao.horiguchi@gmail.com>
CC:     <linux-mm@kvack.org>, Tony Luck <tony.luck@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oscar Salvador <osalvador@suse.de>,
        "David Hildenbrand" <david@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        "Andy Lutomirski" <luto@kernel.org>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Jue Wang <juew@google.com>, <linux-kernel@vger.kernel.org>,
        <yaoaili126@gmail.com>
Subject: Re: [PATCH v4 1/2] mm/memory-failure: Use a mutex to avoid
 memory_failure() races
Message-ID: <20210506173757.586580bd@alex-virtual-machine>
In-Reply-To: <20210427062953.2080293-2-nao.horiguchi@gmail.com>
References: <20210427062953.2080293-1-nao.horiguchi@gmail.com>
        <20210427062953.2080293-2-nao.horiguchi@gmail.com>
Organization: kingsoft
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Tue, 27 Apr 2021 15:29:52 +0900
Naoya Horiguchi <nao.horiguchi@gmail.com> wrote:

> From: Tony Luck <tony.luck@intel.com>
> 
> 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@intel.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> Reviewed-by: Borislav Petkov <bp@suse.de>

Sorry to interrupt, I just thought one thing:

This mutex seems not been bind to the error page, will there be some core case
like test code or multi-poison case whick will break this mutex?

Thanks!
Aili Yao