linux-kernel - Re: [PATCH -next resend v3] mm: hwposion: support recovery from ksm_might_need_to

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Message-ID: <e3dc7816-ad60-6ee6-e023-5f4932dec375@huawei.com>
Date:   Wed, 1 Feb 2023 09:33:34 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <naoya.horiguchi@....com>, <linux-mm@...ck.org>,
        <tony.luck@...el.com>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>, David Hildenbrand <david@...hat.com>
Subject: Re: [PATCH -next resend v3] mm: hwposion: support recovery from
 ksm_might_need_to_copy()



On 2023/2/1 8:32, Andrew Morton wrote:
> On Tue, 13 Dec 2022 20:05:23 +0800 Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
> 
>> When the kernel copy a page from ksm_might_need_to_copy(), but runs
>> into an uncorrectable error, it will crash since poisoned page is
>> consumed by kernel, this is similar to Copy-on-write poison recovery,
>> When an error is detected during the page copy, return VM_FAULT_HWPOISON
>> in do_swap_page(), and install a hwpoison entry in unuse_pte() when
>> swapoff, which help us to avoid system crash. Note, memory failure on
>> a KSM page will be skipped, but still call memory_failure_queue() to
>> be consistent with general memory failure process.
> 
> I believe we're awaiting a v4 of this?

Sorry, forget this one.
> 
> Did we consider a -stable backport?  "kernel crash" sounds undesirable...

This one depends on Copy-on-write poison recovery patchset, and I check 
the commit a873dfe1032a ("mm, hwpoison: try to recover from copy-on 
write faults") is not included into stable, and both of them are 
enhancement of COPY_MC feature, so it seems that we don't need to
backport to stable.

> 
> Can we identify a Fixes: target for this?

As it is a part of COPY_MC, I don't think it is need a Fixes tag.

I will resend a new one to address the comments of  HORIGUCHI NAOYA(堀口 
直也).

Thanks.