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Subject: Re: [PATCH v2] mm/huge_memory: prevent THP_ZERO_PAGE_ALLOC increased
 twice
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
References: <20220908035533.2186159-1-liushixin2@huawei.com>
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 <20220908132538.kjqas6q2i24mrsug@box.shutemov.name>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
From:   Liu Shixin <liushixin2@huawei.com>
Message-ID: <f03f70f7-142d-6b54-15ea-a6c5535e215d@huawei.com>
Date:   Fri, 9 Sep 2022 09:46:29 +0800
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On 2022/9/8 21:25, Kirill A. Shutemov wrote:
> On Thu, Sep 08, 2022 at 09:07:04PM +0800, Liu Shixin wrote:
>>
>> On 2022/9/8 20:31, Kirill A. Shutemov wrote:
>>> On Thu, Sep 08, 2022 at 11:55:33AM +0800, Liu Shixin wrote:
>>>> If two or more threads call get_huge_zero_page concurrently,
>>>> THP_ZERO_PAGE_ALLOC may increased two or more times. But actually,
>>>> this should only count as once since the extra zero pages has been
>>>> freed. Redefine its meaning to indicate the times a huge zero page
>>>> used for thp is successfully allocated.
>>> I don't particularly care, but it is not obvoius why the new behaviour is
>>> better.
>> The user who read the value may be more concerned about the huge zero
>> pages that are really allocated using for thp and can indicated the
>> times of calling huge_zero_page_shrinker.
>> I misunderstood when I first saw it.
> Please, explain the motivation in the commit message.
Thanks, I add the motivation.
https://lore.kernel.org/all/20220909021653.3371879-1-liushixin2@huawei.com/