linux-kernel - Re: [PATCH v2 1/2] mm/memcg: rename mem_cgroup_split_huge_fixup to split_page

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Message-ID: <YEcxqTUp88sl/cq3@dhcp22.suse.cz>
Date:   Tue, 9 Mar 2021 09:28:25 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     "Singh, Balbir" <bsingharora@...il.com>
Cc:     Zhou Guanghui <zhouguanghui1@...wei.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, hannes@...xchg.org, hughd@...gle.com,
        kirill.shutemov@...ux.intel.com, npiggin@...il.com, ziy@...dia.com,
        wangkefeng.wang@...wei.com, guohanjun@...wei.com,
        dingtianhong@...wei.com, chenweilong@...wei.com,
        rui.xiang@...wei.com
Subject: Re: [PATCH v2 1/2] mm/memcg: rename mem_cgroup_split_huge_fixup to
 split_page_memcg

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