Re: [PATCH v2 5/5] mm/mmu_gather: Store and process pages in contig ranges

[Matthew Wilcox <willy@infradead.org>]

On Wed, Aug 30, 2023 at 10:50:11AM +0100, Ryan Roberts wrote:
> +++ b/include/asm-generic/tlb.h
> @@ -246,11 +246,11 @@ struct mmu_gather_batch {
>  	struct mmu_gather_batch	*next;
>  	unsigned int		nr;
>  	unsigned int		max;
> -	struct page		*pages[];
> +	struct pfn_range	folios[];

I think it's dangerous to call this 'folios' as it lets you think that
each entry is a single folio.  But as I understand this patch, you can
coagulate contiguous ranges across multiple folios.

> -void free_pages_and_swap_cache(struct page **pages, int nr)
> +void free_folios_and_swap_cache(struct pfn_range *folios, int nr)
>  {
>  	lru_add_drain();
>  	for (int i = 0; i < nr; i++)
> -		free_swap_cache(pages[i]);
> -	release_pages(pages, nr);
> +		free_swap_cache(pfn_to_page(folios[i].start));

... but here, you only put the swapcache for the first folio covered by
the range, not for each folio.

> +	folios_put_refs(folios, nr);

It's kind of confusing to have folios_put() which takes a struct folio *
and then folios_put_refs() which takes a struct pfn_range *.
pfn_range_put()?