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Date:   Fri, 26 Feb 2021 12:13:14 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Yu Zhao <yuzhao@google.com>
Cc:     akpm@linux-foundation.org, alex.shi@linux.alibaba.com,
        vbabka@suse.cz, guro@fb.com, hannes@cmpxchg.org, hughd@google.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        mhocko@kernel.org, vdavydov.dev@gmail.com
Subject: Re: [PATCH v2 3/3] mm: use PF_ONLY_HEAD for PG_active and
 PG_unevictable
Message-ID: <20210226121314.GB2723601@casper.infradead.org>
References: <20210224084807.2179942-1-yuzhao@google.com>
 <20210226091718.2927291-1-yuzhao@google.com>
 <20210226091718.2927291-4-yuzhao@google.com>
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On Fri, Feb 26, 2021 at 02:17:18AM -0700, Yu Zhao wrote:
> All places but one test, set or clear PG_active and PG_unevictable on
> small or head pages. Use compound_head() explicitly for that singleton
> so the rest can rid of redundant compound_head().

How do you know it's only one place?  I really wish you'd work with me
on folios.  They make the compiler prove that it's not a tail page.