linux-kernel - Re: [External] [PATCH 1/2] hugetlb: remove prep_compound_huge

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Message-ID: <CAMZfGtVqJjVVgG+sd33er8Eg-MieF7V=nVExvQZTFhbxteaCGQ@mail.gmail.com>
Date:   Tue, 22 Jun 2021 17:09:14 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jann Horn <jannh@...gle.com>,
        Youquan Song <youquan.song@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Jan Kara <jack@...e.cz>, John Hubbard <jhubbard@...dia.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [External] [PATCH 1/2] hugetlb: remove prep_compound_huge_page cleanup

On Tue, Jun 22, 2021 at 10:15 AM Mike Kravetz <mike.kravetz@...cle.com> wrote:
>
> The routine prep_compound_huge_page is a simple wrapper to call either
> prep_compound_gigantic_page or prep_compound_page.  However, it is only
> called from gather_bootmem_prealloc which only processes gigantic pages.
> Eliminate the routine and call prep_compound_gigantic_page directly.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>

Nice clean-up. Thanks.

Reviewed-by: Muchun Song <songmuchun@...edance.com>

> ---
>  mm/hugetlb.c | 29 ++++++++++-------------------
>  1 file changed, 10 insertions(+), 19 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 760b5fb836b8..50596b7d6da9 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1320,8 +1320,6 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
>         return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
>  }
>
> -static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
> -static void prep_compound_gigantic_page(struct page *page, unsigned int order);
>  #else /* !CONFIG_CONTIG_ALLOC */
>  static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
>                                         int nid, nodemask_t *nodemask)
> @@ -2759,16 +2757,10 @@ int __alloc_bootmem_huge_page(struct hstate *h)
>         return 1;
>  }
>
> -static void __init prep_compound_huge_page(struct page *page,
> -               unsigned int order)
> -{
> -       if (unlikely(order > (MAX_ORDER - 1)))
> -               prep_compound_gigantic_page(page, order);
> -       else
> -               prep_compound_page(page, order);
> -}
> -
> -/* Put bootmem huge pages into the standard lists after mem_map is up */
> +/*
> + * Put bootmem huge pages into the standard lists after mem_map is up.
> + * Note: This only applies to gigantic (order > MAX_ORDER) pages.
> + */
>  static void __init gather_bootmem_prealloc(void)
>  {
>         struct huge_bootmem_page *m;
> @@ -2777,20 +2769,19 @@ static void __init gather_bootmem_prealloc(void)
>                 struct page *page = virt_to_page(m);
>                 struct hstate *h = m->hstate;
>
> +               VM_BUG_ON(!hstate_is_gigantic(h));
>                 WARN_ON(page_count(page) != 1);
> -               prep_compound_huge_page(page, huge_page_order(h));
> +               prep_compound_gigantic_page(page, huge_page_order(h));
>                 WARN_ON(PageReserved(page));
>                 prep_new_huge_page(h, page, page_to_nid(page));
>                 put_page(page); /* free it into the hugepage allocator */
>
>                 /*
> -                * If we had gigantic hugepages allocated at boot time, we need
> -                * to restore the 'stolen' pages to totalram_pages in order to
> -                * fix confusing memory reports from free(1) and another
> -                * side-effects, like CommitLimit going negative.
> +                * We need to restore the 'stolen' pages to totalram_pages
> +                * in order to fix confusing memory reports from free(1) and
> +                * other side-effects, like CommitLimit going negative.
>                  */
> -               if (hstate_is_gigantic(h))
> -                       adjust_managed_page_count(page, pages_per_huge_page(h));
> +               adjust_managed_page_count(page, pages_per_huge_page(h));
>                 cond_resched();
>         }
>  }
> --
> 2.31.1
>