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From:   Zi Yan <ziy@nvidia.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Roman Gushchin <roman.gushchin@linux.dev>, linux-mm@kvack.org,
        Shuah Khan <shuah@kernel.org>, Yang Shi <shy828301@gmail.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Hugh Dickins <hughd@google.com>,
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        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH 1/5] mm: memcg: make memcg huge page split support any order split.
Date:   Mon, 21 Mar 2022 16:26:55 -0400
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Content-Type: text/plain

On 21 Mar 2022, at 15:54, Matthew Wilcox wrote:

> On Mon, Mar 21, 2022 at 03:07:46PM -0400, Zi Yan wrote:
>> Yes. Will change it to new_nr to be consistent.
>
> uh, you're going to call ilog2?

fortunately, no. Inside split_page_memcg(), I probably
need to add VM_BUG_ON(nr % new_nr != 0) to make sure
new_nr is a divisor of nr, since there are a couple
of nr / new_nr operations. Otherwise, new_nr works.

>
> I think this would look less inconsistent if 'nr' were an unsigned long
> (how long until we need 16GB pages?  Think PPC already supports those)


--
Best Regards,
Yan, Zi

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