linux-kernel - Re: [PATCH v2 00/12] clean-up the migration target allocation functions

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Message-ID: <CAAmzW4Ne3V6p2a9R4KiHCRX47nVp4+2A-GATmf2DxbxpzkjHBA@mail.gmail.com>
Date:   Mon, 1 Jun 2020 15:40:00 +0900
From:   Joonsoo Kim <js1304@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel-team@....com,
        Christoph Hellwig <hch@...radead.org>,
        Roman Gushchin <guro@...com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Michal Hocko <mhocko@...e.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 00/12] clean-up the migration target allocation functions

2020년 5월 29일 (금) 오후 3:50, Joonsoo Kim <js1304@...il.com>님이 작성:
>
> 2020년 5월 29일 (금) 오전 4:25, Vlastimil Babka <vbabka@...e.cz>님이 작성:
> >
> > On 5/27/20 8:44 AM, js1304@...il.com wrote:
> > > From: Joonsoo Kim <iamjoonsoo.kim@....com>
> > >
> > > This patchset clean-up the migration target allocation functions.
> > >
> > > * Changes on v2
> > > - add acked-by tags
> > > - fix missing compound_head() call for the patch #3
> > > - remove thisnode field on alloc_control and use __GFP_THISNODE directly
> > > - fix missing __gfp_mask setup for the patch
> > > "mm/hugetlb: do not modify user provided gfp_mask"
> > >
> > > * Cover-letter
> > >
> > > Contributions of this patchset are:
> > > 1. unify two hugetlb alloc functions. As a result, one is remained.
> > > 2. make one external hugetlb alloc function to internal one.
> > > 3. unify three functions for migration target allocation.
> > >
> > > The patchset is based on next-20200526.
> > > The patchset is available on:
> >
> > I went through the series and I'd like to make some high-level suggestions
> > first, that should hopefully simplify the code a bit more and reduce churn:
>
> Thanks for review!
> I have not enough time today to check your suggestions.
> I will check on next week and then reply again.
>
> Thanks.
>
> > - in the series, alloc_huge_page_nodemask() becomes the only caller of
> > alloc_migrate_huge_page(). So you can inline the code there, and it's one less
> > function out of many with similar name :)
> >
> > - after that, alloc_huge_page_nodemask(ac) uses ac mostly just to extract
> > individual fields, and only pass it as a whole to dequeue_huge_page_nodemask().
> > The only other caller of dequeue...() is dequeue_huge_page_vma() who has to
> > construct ac from scratch. It might be probably simpler not to introduce struct
> > alloc_control into hugetlb code at all, and only keep it for
> > alloc_migrate_target(), at which point it can have a more specific name as
> > discussed and there's less churn
> >
> > - I'd suggest not change signature of migrate_pages(), free_page_t and
> > new_page_t, keeping the opaque private field is fine as not all callbacks use
> > struct alloc_context pointer, and then e.g. compaction_alloc has to use the
> > private field etc. alloc_migration_target() can simply cast the private to
> > struct alloc_control *ac as the first thing

Looks like all your suggestions are reasonable. I will try them and make v3.

Thanks.