linux-kernel - Re: [PATCH 7/7] mm/thp: remap_page() is only needed on anonymous THP

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Date:   Fri, 4 Jun 2021 19:41:03 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     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 7/7] mm/thp: remap_page() is only needed on anonymous THP

On Tue, Jun 01, 2021 at 02:17:19PM -0700, Hugh Dickins wrote:
> THP splitting's unmap_page() only sets TTU_SPLIT_FREEZE when PageAnon,
> and migration entries are only inserted when TTU_MIGRATION (unused here)
> or TTU_SPLIT_FREEZE is set: so it's just a waste of time for remap_page()
> to search for migration entries to remove when !PageAnon.
> 
> Fixes: baa355fd3314 ("thp: file pages support for split_huge_page()")
> Signed-off-by: Hugh Dickins <hughd@...gle.com>

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

-- 
 Kirill A. Shutemov