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Date:   Sun, 16 Apr 2023 12:51:46 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Zi Yan <ziy@nvidia.com>
cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Yang Shi <shy828301@gmail.com>, Yu Zhao <yuzhao@google.com>,
        linux-mm@kvack.org,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Ryan Roberts <ryan.roberts@arm.com>,
        =?ISO-8859-15?Q?Michal_Koutn=FD?= <mkoutny@suse.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Zach O'Keefe <zokeefe@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 6/7] mm: truncate: split huge page cache page to a
 non-zero order if possible.
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> As this code stands, truncate a 2M huge page at 1M and you get two 1M
> pieces (one then discarded) - nice; but truncate it at 1M+1 and you get
> lots of order 2 (forced up from 1) pieces.  Seems weird, and not worth
> the effort.

I've probably said that wrong: truncate at 1M+1 and you'd get lots of
order 0 pieces.

Hugh