linux-kernel - Re: [PATCH 6/7] mm/thp: unmap_mapping_page() to fix THP truncate_cleanup

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Message-ID: <alpine.LSU.2.11.2106041601050.14037@eggly.anvils>
Date:   Fri, 4 Jun 2021 16:07:46 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
cc:     Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Wang Yugui <wangyugui@...-tech.com>,
        Matthew Wilcox <willy@...radead.org>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Alistair Popple <apopple@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>, Zi Yan <ziy@...dia.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Minchan Kim <minchan@...nel.org>, Jue Wang <juew@...gle.com>,
        Peter Xu <peterx@...hat.com>, Jan Kara <jack@...e.cz>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] mm/thp: unmap_mapping_page() to fix THP
 truncate_cleanup_page()

On Fri, 4 Jun 2021, Kirill A. Shutemov wrote:
> 
> I think adding support for THP in try_to_unmap_one() is the most
> future-proof way. We would need it there eventually.

Yes, I'd love to delete unmap_mapping_page() and use try_to_unmap(),
but couldn't easily do it.  I did cut out one paragraph which said:

"Next iteration, I would probably refactor zap_huge_pmd() so that the
same code could be used from zap_pmd_range() or try_to_unmap_one();
but that seems riskier and more trouble than this current iteration."

And I've certainly not found time to go back and try that since.

> 
> But this works too:
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Thanks,
Hugh