linux-kernel - Re: [PATCH -next v2] mm: hwposion: support recovery from ksm_might_need_to

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Date:   Sat, 10 Dec 2022 11:37:54 +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>, Tong Tiangen <tongtiangen@...wei.com>
Subject: Re: [PATCH -next v2] mm: hwposion: support recovery from
 ksm_might_need_to_copy()


On 2022/12/10 8:50, Andrew Morton wrote:
> On Fri, 9 Dec 2022 15:28:01 +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,
>> 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.
> Thanks.  Sorry, lots of paperwork and bureaucracy:
>
>
> Is a copy of the oops(?) output available?
>
> Did someone else report this?  If so, is a Reported-by available for
> that?  And a Link: for the Reported-by:, which is a coming thing.
>
> Can we identify a Fixes: target?
>
> Is a cc:stable appropriate?
We are trying to support ARCH_HAS_COPY_MC on arm64[1] and trying to 
recover from CoW faults[2],
also tony do the same thing(recover from CoW) on X86[3]. The kernel copy 
in ksm_might_need_to_copy()
could recover, this is an enhance of COPY_MC, so I think no need to add 
Fixes and stable.

Thanks.

[1] 
https://lore.kernel.org/linux-arm-kernel/20220812070557.1028499-1-tongtiangen@huawei.com/
[2] 
https://lore.kernel.org/linux-arm-kernel/20220812070557.1028499-5-tongtiangen@huawei.com/
[3] 
https://lore.kernel.org/lkml/20221031201029.102123-2-tony.luck@intel.com/


>