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Date:   Tue, 4 Apr 2023 18:42:44 +0800
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Subject: Re: [PATCH 2/2] mm: ksm: Support hwpoison for ksm page
To:     =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= 
        <naoya.horiguchi@nec.com>
CC:     "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
        "linmiaohe@huawei.com" <linmiaohe@huawei.com>,
        "wangkefeng.wang@huawei.com" <wangkefeng.wang@huawei.com>,
        "sunnanyong@huawei.com" <sunnanyong@huawei.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
References: <20230330074501.205092-1-xialonglong1@huawei.com>
 <20230330074501.205092-3-xialonglong1@huawei.com>
 <20230331054243.GB1435482@hori.linux.bs1.fc.nec.co.jp>
From:   xialonglong <xialonglong1@huawei.com>
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Thank you very much for your reply. Your suggestion is indeed very 
helpful and I will take some time to consider how to implement it. Once 
I have a clear plan, I will send a separate patch to make it happen.

Best regards,
Longlong Xia
在 2023/3/31 13:42, HORIGUCHI NAOYA(堀口 直也) 写道:
> On Thu, Mar 30, 2023 at 03:45:01PM +0800, Longlong Xia wrote:
>> hwpoison_user_mappings() is updated to support ksm pages, and add
>> collect_procs_ksm() to collect processes when the error hit an ksm
>> page. The difference from collect_procs_anon() is that it also needs
>> to traverse the rmap-item list on the stable node of the ksm page.
>> At the same time, add_to_kill_ksm() is added to handle ksm pages. And
>> task_in_to_kill_list() is added to avoid duplicate addition of tsk to
>> the to_kill list. This is because when scanning the list, if the pages
>> that make up the ksm page all come from the same process, they may be
>> added repeatedly.
>>
>> Signed-off-by: Longlong Xia <xialonglong1@huawei.com>
> 
> I don't find any specific issue by code review for now, so I'll try to
> test your patches.
> 
> I have one comment about duplicated KSM pages.  It seems that KSM controls
> page duplication by limiting deduplication factor with max_page_sharing,
> primarily for performance reason.  But I think it's imporant from memory
> RAS's viewpoint too because that means we could allow recovery from memory
> errors on a KSM page by making affected processes to switch to the duplicated
> pages (without killing the processes!).  Maybe this might be beyond the scope
> of this patchset and I'm not sure how hard it is, but if you are interested
> in this issue, that's really nice.
> 
> Thanks,
> Naoya Horiguchi