Re: [PATCH v2] mm/huge_memory: prevent THP_ZERO_PAGE_ALLOC increased twice

[Liu Shixin]

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.
>
> All huge zero pages are freed apart from possibly the last one allocated.
>