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Date:   Wed, 15 Jun 2022 13:49:33 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     HORIGUCHI =?UTF-8?B?TkFPWUE=?= (=?UTF-8?B?5aCA5Y+j44CA55u05Lmf?=) 
        <naoya.horiguchi@nec.com>
Cc:     zhenwei pi <pizhenwei@bytedance.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "david@redhat.com" <david@redhat.com>,
        "linmiaohe@huawei.com" <linmiaohe@huawei.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH v6 1/1] mm/memory-failure: disable unpoison once hw
 error happens
Message-Id: <20220615134933.66f3ba7f3b169b936b2128de@linux-foundation.org>
In-Reply-To: <20220615103406.GA1669251@hori.linux.bs1.fc.nec.co.jp>
References: <20220615093209.259374-1-pizhenwei@bytedance.com>
        <20220615093209.259374-2-pizhenwei@bytedance.com>
        <20220615103406.GA1669251@hori.linux.bs1.fc.nec.co.jp>
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On Wed, 15 Jun 2022 10:34:06 +0000 HORIGUCHI NAOYA(堀口　直也) <naoya.horiguchi@nec.com> wrote:

> On Wed, Jun 15, 2022 at 05:32:09PM +0800, zhenwei pi wrote:
> > Currently unpoison_memory(unsigned long pfn) is designed for soft
> > poison(hwpoison-inject) only. Since 17fae1294ad9d, the KPTE gets
> > cleared on a x86 platform once hardware memory corrupts.
> > 
> > Unpoisoning a hardware corrupted page puts page back buddy only,
> > the kernel has a chance to access the page with *NOT PRESENT* KPTE.
> > This leads BUG during accessing on the corrupted KPTE.
> > 
> > Suggested by David&Naoya, disable unpoison mechanism when a real HW error
> > happens to avoid BUG like this:
> > 
>
> ...
>
> > 
> > Fixes: 847ce401df392 ("HWPOISON: Add unpoisoning support")
> > Fixes: 17fae1294ad9d ("x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned")
> > Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
> > Cc: David Hildenbrand <david@redhat.com>
> > Cc: Oscar Salvador <osalvador@suse.de>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Acked-by: David Hildenbrand <david@redhat.com>
> > Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> 
> Thank you very much.
> 
> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

I added cc:stable to this.  But the dual Fixes: are going to confuse
people regarding which kernel versions need the fix.  Can we be more
specific?