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Date:   Tue, 9 Mar 2021 09:28:25 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     "Singh, Balbir" <bsingharora@gmail.com>
Cc:     Zhou Guanghui <zhouguanghui1@huawei.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, hannes@cmpxchg.org, hughd@google.com,
        kirill.shutemov@linux.intel.com, npiggin@gmail.com, ziy@nvidia.com,
        wangkefeng.wang@huawei.com, guohanjun@huawei.com,
        dingtianhong@huawei.com, chenweilong@huawei.com,
        rui.xiang@huawei.com
Subject: Re: [PATCH v2 1/2] mm/memcg: rename mem_cgroup_split_huge_fixup to
 split_page_memcg
Message-ID: <YEcxqTUp88sl/cq3@dhcp22.suse.cz>
References: <20210304074053.65527-1-zhouguanghui1@huawei.com>
 <20210304074053.65527-2-zhouguanghui1@huawei.com>
 <3ad50842-881f-eb88-a14d-0b6c70ce33d2@gmail.com>
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On Tue 09-03-21 09:37:29, Balbir Singh wrote:
> On 4/3/21 6:40 pm, Zhou Guanghui wrote:
[...]
> > -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >  /*
> > - * Because page_memcg(head) is not set on compound tails, set it now.
> > + * Because page_memcg(head) is not set on tails, set it now.
> >   */
> > -void mem_cgroup_split_huge_fixup(struct page *head)
> > +void split_page_memcg(struct page *head, unsigned int nr)
> >  {
> 
> Do we need input validation on nr? Can nr be aribtrary or can we enforce
> 
> VM_BUG_ON(!is_power_of_2(nr));

In practice this will be power of 2 but why should we bother to sanitze
that? 

-- 
Michal Hocko
SUSE Labs