linux-kernel - Re: [PATCH v2] mm/huge_memory: prevent THP_ZERO_PAGE

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Date:   Thu, 8 Sep 2022 15:31:02 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Liu Shixin <liushixin2@...wei.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrea Arcangeli <aarcange@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: Re: [PATCH v2] mm/huge_memory: prevent THP_ZERO_PAGE_ALLOC increased
 twice

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.

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

-- 
  Kiryl Shutsemau / Kirill A. Shutemov