linux-kernel - Re: [PATCH] arm64/mm: Remove add_huge_page

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Date:   Wed, 6 May 2020 12:36:43 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Gavin Shan <gshan@...hat.com>, linux-arm-kernel@...ts.infradead.org
Cc:     mark.rutland@....com, catalin.marinas@....com, will@...nel.org,
        linux-kernel@...r.kernel.org, shan.gavin@...il.com
Subject: Re: [PATCH] arm64/mm: Remove add_huge_page_size()



On 05/06/2020 12:16 PM, Gavin Shan wrote:
> The function add_huge_page_size(), wrapper of hugetlb_add_hstate(),
> avoids to register duplicated huge page states for same size. However,
> the same logic has been included in hugetlb_add_hstate(). So it seems
> unnecessary to keep add_huge_page_size() and this just removes it.

Makes sense.

> 
> Signed-off-by: Gavin Shan <gshan@...hat.com>
> ---
>  arch/arm64/mm/hugetlbpage.c | 18 +++++-------------
>  1 file changed, 5 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index bbeb6a5a6ba6..ed7530413941 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -441,22 +441,14 @@ void huge_ptep_clear_flush(struct vm_area_struct *vma,
>  	clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
>  }
>  
> -static void __init add_huge_page_size(unsigned long size)
> -{
> -	if (size_to_hstate(size))
> -		return;
> -
> -	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> -}
> -
>  static int __init hugetlbpage_init(void)
>  {
>  #ifdef CONFIG_ARM64_4K_PAGES
> -	add_huge_page_size(PUD_SIZE);
> +	hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
>  #endif
> -	add_huge_page_size(CONT_PMD_SIZE);
> -	add_huge_page_size(PMD_SIZE);
> -	add_huge_page_size(CONT_PTE_SIZE);
> +	hugetlb_add_hstate(CONT_PMD_SHIFT + PMD_SHIFT - PAGE_SHIFT);
> +	hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
> +	hugetlb_add_hstate(CONT_PTE_SHIFT);

Should these page order values be converted into macros instead. Also
we should probably keep (CONT_PTE_SHIFT + PAGE_SHIFT - PAGE_SHIFT) as
is to make things more clear.