Re: [PATCH 2/4] mm: mprotect: use walk_page_range_vma() in mprotect_fixup()

["David Hildenbrand (Arm)" <david@kernel.org>]

On 6/17/26 10:26, Kefeng Wang wrote:
> In mprotect_fixup(), the PROT_NONE PFN permission check uses
> walk_page_range() to walk the page table. Fortunately, the caller
> always passes start/end that falls within a single VMA, the
> do_mprotect_pkey() iterates per-VMA via for_each_vma_range(),
> and setup_arg_pages() passes the whole VMA.
> 
> Note, walk_page_test() isn't called in walk_page_range_vma(),
> however, prot_none_test() in prot_none_walk_ops always return 0,
> so it's safely replace walk_page_range() with walk_page_range_vma()
> to eliminates an unnecessary find_vma() lookup.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/mprotect.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 9cbf932b028c..d26e09862daa 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -753,7 +753,7 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
>  	    !vma_flags_test_any_mask(&new_vma_flags, VMA_ACCESS_FLAGS)) {
>  		pgprot_t new_pgprot = vm_get_page_prot(newflags);
>  
> -		error = walk_page_range(current->mm, start, end,
> +		error = walk_page_range_vma(vma, start, end,
>  				&prot_none_walk_ops, &new_pgprot);
>  		if (error)
>  			return error;

As Sashiko says, prot_none_test() seems unnecessary now.

Apart from that, LGTM.

-- 
Cheers,

David