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From:   Joonsoo Kim <js1304@gmail.com>
Date:   Wed, 10 Jun 2020 12:07:17 +0900
Message-ID: <CAAmzW4OawW=RC4t1h_0V42Z6UKzSs9k1+Wem_MtAFqC2Ummd3g@mail.gmail.com>
Subject: Re: [PATCH v2 03/12] mm/hugetlb: introduce alloc_control structure to
 simplify migration target allocation APIs
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, kernel-team@lge.com,
        Vlastimil Babka <vbabka@suse.cz>,
        Christoph Hellwig <hch@infradead.org>,
        Roman Gushchin <guro@fb.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
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2020=EB=85=84 6=EC=9B=94 9=EC=9D=BC (=ED=99=94) =EC=98=A4=ED=9B=84 10:24, M=
ichal Hocko <mhocko@kernel.org>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
>
> On Wed 27-05-20 15:44:54, Joonsoo Kim wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > Currently, page allocation functions for migration requires some argume=
nts.
> > More worse, in the following patch, more argument will be needed to uni=
fy
> > the similar functions. To simplify them, in this patch, unified data
> > structure that controls allocation behaviour is introduced.
> >
> > For clean-up, function declarations are re-ordered.
>
> This is really hard to review without having a clear picture of the
> resulting code so bear with me. I can see some reasons why allocation
> callbacks might benefit from a agragated argument but you seem to touch
> the internal hugetlb dequeue_huge_page_vma which shouldn't really need
> that. I wouldn't mind much but I remember the hugetlb allocation
> functions layering is quite complex for hugetlb specific reasons (see
> 0c397daea1d4 ("mm, hugetlb: further simplify hugetlb allocation API")
> for more background).
>
> Is there any reason why the agregated argument cannot be limited only to
> migration callbacks. That would be alloc_huge_page_node, alloc_huge_page_=
nodemask
> and alloc_huge_page_vma.

I did it since it's simple for me, but, yes, it's not good to touch
the internal functions.

Anyway, Vlastimil already suggested not to introduce alloc_control for
any hugetlb
functions. I will try it on the next version so the next version would not =
have
alloc_control in any hugetlb functions.

Thanks.