Re: [PATCH v4 3/6] mm/vmalloc: Extract vmap_set_ptes() to consolidate PTE mapping logic

[Dev Jain <dev.jain@arm.com>]

On 18/06/26 2:17 pm, Wen Jiang wrote:
> Extract the common PTE mapping logic from vmap_pte_range() into a
> shared helper vmap_set_ptes(). This handles both CONT_PTE and regular
> PTE mappings in a single function, preparing for the next patch which
> will extend vmap_pages_pte_range() to also use this helper.
> 
> The #ifdef CONFIG_HUGETLB_PAGE guard is moved inside vmap_set_ptes(),
> so callers no longer need to handle the conditional compilation.
> 
> No functional change.
> 
> Signed-off-by: Wen Jiang <jiangwen6@xiaomi.com>
> Tested-by: Xueyuan Chen <xueyuan.chen21@gmail.com>
> ---
>  mm/vmalloc.c | 44 +++++++++++++++++++++++++++++++-------------
>  1 file changed, 31 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 2c2f74a07f396..6660f240d27c9 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -91,6 +91,35 @@ struct vfree_deferred {
>  static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);
>  
>  /*** Page table manipulation functions ***/
> +
> +/*
> + * Set PTE mappings for the given PFN. Try CONT_PTE mappings first when

CONT_PTE is arm64-specific, doesn't feel right to mention this in generic code.

If you really want to put a comment, just say:

"Try contiguous mappings at the PTE level for arches which support them, and if
requested by the caller. Fall back to PAGE_SIZE mappings otherwise.

Return: mapping size."
> + * supported, otherwise fall back to PAGE_SIZE mappings.
> + *
> + * Return: mapping size.
> + */
> +static __always_inline unsigned long vmap_set_ptes(pte_t *pte,
> +		unsigned long addr, unsigned long end, u64 pfn,
> +		pgprot_t prot, unsigned int max_page_shift)
> +{
> +#ifdef CONFIG_HUGETLB_PAGE
> +	if (max_page_shift > PAGE_SHIFT) {

This if block is not needed, max_page_shift > PAGE_SHIFT is handled by
arch_vmap_pte_range_map_size.

With that:

Reviewed-by: Dev Jain <dev.jain@arm.com>


> +		unsigned long size;
> +
> +		size = arch_vmap_pte_range_map_size(addr, end, pfn, max_page_shift);
> +		if (size != PAGE_SIZE) {
> +			pte_t entry = pfn_pte(pfn, prot);
> +
> +			entry = arch_make_huge_pte(entry, ilog2(size), 0);
> +			set_huge_pte_at(&init_mm, addr, pte, entry, size);
> +			return size;
> +		}
> +	}
> +#endif
> +	set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
> +	return PAGE_SIZE;
> +}
> +
>  static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>  			phys_addr_t phys_addr, pgprot_t prot,
>  			unsigned int max_page_shift, pgtbl_mod_mask *mask)
> @@ -119,19 +148,8 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>  			BUG();
>  		}
>  
> -#ifdef CONFIG_HUGETLB_PAGE
> -		size = arch_vmap_pte_range_map_size(addr, end, pfn, max_page_shift);
> -		if (size != PAGE_SIZE) {
> -			pte_t entry = pfn_pte(pfn, prot);
> -
> -			entry = arch_make_huge_pte(entry, ilog2(size), 0);
> -			set_huge_pte_at(&init_mm, addr, pte, entry, size);
> -			pfn += PFN_DOWN(size);
> -			continue;
> -		}
> -#endif
> -		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
> -		pfn++;
> +		size = vmap_set_ptes(pte, addr, end, pfn, prot, max_page_shift);
> +		pfn += PFN_DOWN(size);
>  	} while (pte += PFN_DOWN(size), addr += size, addr != end);
>  
>  	lazy_mmu_mode_disable();