Re: [PATCH 2/2] mm: gup: cleanup the gup_fast_*() call chain

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

On 2/19/26 06:02, Aristeu Rozanski wrote:
> Refactor gup_fast functions so each step of the way returns the number of
> pages pinned. Because the previous step of the chain knows what the number
> it should be, less indicates an error. This way there's no need to pass *nr
> along.
> 
> Suggested-by: David Hildenbrand <david@kernel.org>
> Link: https://lore.kernel.org/all/85e760cf-b994-40db-8d13-221feee55c60@redhat.com/T/#u
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@kernel.org>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Peter Xu <peterx@redhat.com>
> Signed-off-by: Aristeu Rozanski <aris@ruivo.org>

[...]

> -static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
> -		unsigned long end, unsigned int flags, struct page **pages,
> -		int *nr)
> +static unsigned long gup_fast_pud_leaf(pud_t orig, pud_t *pudp,
> +		unsigned long addr, unsigned long end,
> +		unsigned int flags, struct page **pages)
>   {
>   	struct page *page;
>   	struct folio *folio;
> -	int refs;
> +	unsigned long nr_pages = 0, i;

I don't think there is a need to initialize nr_pages to 0 here.

[...]

>   
> @@ -3129,8 +3139,7 @@ static bool gup_fast_permitted(unsigned
>   static unsigned long gup_fast(unsigned long start, unsigned long end,
>   		unsigned int gup_flags, struct page **pages)
>   {
> -	unsigned long flags;
> -	int nr_pinned = 0;
> +	unsigned long flags, nr_pinned = 0;

I don't think we have to initialize nr_pinned to 0 anymore.

>   	unsigned seq;
>   
>   	if (!IS_ENABLED(CONFIG_HAVE_GUP_FAST) ||
> @@ -3154,7 +3163,7 @@ static unsigned long gup_fast(unsigned l
>   	 * that come from callers of tlb_remove_table_sync_one().
>   	 */
>   	local_irq_save(flags);
> -	gup_fast_pgd_range(start, end, gup_flags, pages, &nr_pinned);
> +	nr_pinned = gup_fast_pgd_range(start, end, gup_flags, pages);
>   	local_irq_restore(flags);
>   
>   	/*
> 

In general, LGTM, and our gup tests seem to pass.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>



Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David