linux-kernel - Re: [PATCH V3] arm64/hugetlb: Consistently use pud_sect

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Message-ID: <5edf6a80-1fbd-4be2-912b-497c044ba0f8@arm.com>
Date: Tue, 25 Feb 2025 14:54:36 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Anshuman Khandual <anshuman.khandual@....com>,
 linux-arm-kernel@...ts.infradead.org
Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] arm64/hugetlb: Consistently use pud_sect_supported()

On 20/02/2025 05:05, Anshuman Khandual wrote:
> Let's be consistent in using pud_sect_supported() for PUD_SIZE sized pages.
> Hence change hugetlb_mask_last_page() and arch_make_huge_pte() as required.
> Also re-arranged the switch statement for a common warning message.

Thanks, Anshuman, this looks much cleaner now, to my eye at least.

> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Reviewed-by: Ryan Roberts <ryan.roberts@....com>

> ---
> This patch applies on v6.14-rc3
> 
> Changes in V3:
> 
> - Re-arranged the switch statement for a common warning message per Ryan
> 
> Changes in V2:
> 
> https://lore.kernel.org/linux-arm-kernel/20250218113639.475947-1-anshuman.khandual@arm.com/
> 
> - Added an warning when PUD_SIZE is requested but not supported per Ryan
> 
> Changes in V1:
> 
> https://lore.kernel.org/linux-arm-kernel/20250217065414.49489-1-anshuman.khandual@arm.com/
> 
>  arch/arm64/mm/hugetlbpage.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 98a2a0e64e25..fd7448bb8c80 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -342,7 +342,9 @@ unsigned long hugetlb_mask_last_page(struct hstate *h)
>  	switch (hp_size) {
>  #ifndef __PAGETABLE_PMD_FOLDED
>  	case PUD_SIZE:
> -		return PGDIR_SIZE - PUD_SIZE;
> +		if (pud_sect_supported())
> +			return PGDIR_SIZE - PUD_SIZE;
> +		break;
>  #endif
>  	case CONT_PMD_SIZE:
>  		return PUD_SIZE - CONT_PMD_SIZE;
> @@ -364,23 +366,21 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
>  	switch (pagesize) {
>  #ifndef __PAGETABLE_PMD_FOLDED
>  	case PUD_SIZE:
> -		entry = pud_pte(pud_mkhuge(pte_pud(entry)));
> +		if (pud_sect_supported())
> +			return pud_pte(pud_mkhuge(pte_pud(entry)));
>  		break;
>  #endif
>  	case CONT_PMD_SIZE:
> -		entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
> -		fallthrough;
> +		return pmd_pte(pmd_mkhuge(pmd_mkcont(pte_pmd(entry))));
>  	case PMD_SIZE:
> -		entry = pmd_pte(pmd_mkhuge(pte_pmd(entry)));
> -		break;
> +		return pmd_pte(pmd_mkhuge(pte_pmd(entry)));
>  	case CONT_PTE_SIZE:
> -		entry = pte_mkcont(entry);
> -		break;
> +		return pte_mkcont(entry);
>  	default:
> -		pr_warn("%s: unrecognized huge page size 0x%lx\n",
> -			__func__, pagesize);
>  		break;
>  	}
> +	pr_warn("%s: unrecognized huge page size 0x%lx\n",
> +		__func__, pagesize);
>  	return entry;
>  }
>