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Date:   Thu, 29 Oct 2020 10:00:20 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Alex Shi <alex.shi@linux.alibaba.com>
Cc:     akpm@linux-foundation.org, mgorman@techsingularity.net,
        tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
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        kirill@shutemov.name, alexander.duyck@gmail.com,
        rong.a.chen@intel.com, mhocko@suse.com, vdavydov.dev@gmail.com,
        shy828301@gmail.com,
        Mika =?iso-8859-1?Q?Penttil=E4?= <mika.penttila@nextfour.com>
Subject: Re: [PATCH v20 05/20] mm/thp: Simplify lru_add_page_tail()
Message-ID: <20201029140020.GF599825@cmpxchg.org>
References: <1603968305-8026-1-git-send-email-alex.shi@linux.alibaba.com>
 <1603968305-8026-6-git-send-email-alex.shi@linux.alibaba.com>
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On Thu, Oct 29, 2020 at 06:44:50PM +0800, Alex Shi wrote:
> Simplify lru_add_page_tail(), there are actually only two cases possible:
> split_huge_page_to_list(), with list supplied and head isolated from lru
> by its caller; or split_huge_page(), with NULL list and head on lru -
> because when head is racily isolated from lru, the isolator's reference
> will stop the split from getting any further than its page_ref_freeze().
> 
> So decide between the two cases by "list", but add VM_WARN_ON()s to
> verify that they match our lru expectations.
> 
> [Hugh Dickins: rewrite commit log]
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Acked-by: Hugh Dickins <hughd@google.com>
> Cc: Kirill A. Shutemov <kirill@shutemov.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Mika Penttil? <mika.penttila@nextfour.com>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org

Acked-by: Johannes Weiner <hannes@cmpxchg.org>