Re: [PATCH 4/8] mm: Add __dump_folio()

[SeongJae Park <sj@kernel.org>]

On Thu, 29 Feb 2024 04:37:31 +0000 Matthew Wilcox <willy@infradead.org> wrote:

> On Wed, Feb 28, 2024 at 01:34:58PM -0800, SeongJae Park wrote:
> >     ...linux/mm/debug.c: In function '__dump_page':
> >     ...linux/include/asm-generic/pgtable-nop4d.h:11:33: error: 'PGDIR_SHIFT' undeclared (first use in this function); did you mean 'PUD_SHIFT'?
> >        11 | #define P4D_SHIFT               PGDIR_SHIFT
> >           |                                 ^~~~~~~~~~~
> >     ...linux/include/asm-generic/pgtable-nopud.h:18:25: note: in expansion of macro 'P4D_SHIFT'
> >        18 | #define PUD_SHIFT       P4D_SHIFT
> >           |                         ^~~~~~~~~
> >     ...linux/include/linux/pgtable.h:9:26: note: in expansion of macro 'PUD_SHIFT'
> >         9 | #define PUD_ORDER       (PUD_SHIFT - PAGE_SHIFT)
> >           |                          ^~~~~~~~~
> >     ...linux/mm/debug.c:128:35: note: in expansion of macro 'PUD_ORDER'
> >       128 |                 if (idx < (1UL << PUD_ORDER)) {
> 
> Thanks.  Can you try this?
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 49d87a4d29b9..e25e86b755be 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2078,6 +2078,13 @@ static inline long folio_nr_pages(struct folio *folio)
>  #endif
>  }
>  
> +/* Only hugetlbfs can allocate folios larger than MAX_ORDER */
> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
> +#define MAX_FOLIO_NR_PAGES	(1UL << PUD_ORDER)
> +#else
> +#define MAX_FOLIO_NR_PAGES	MAX_ORDER_NR_PAGES
> +#endif
> +
>  /*
>   * compound_nr() returns the number of pages in this potentially compound
>   * page.  compound_nr() can be called on a tail page, and is defined to
> diff --git a/mm/debug.c b/mm/debug.c
> index 6149944016a7..32ac7d79fd04 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -125,7 +125,7 @@ static void __dump_page(const struct page *page)
>  	foliop = page_folio(&precise);
>  	idx = folio_page_idx(foliop, page);
>  	if (idx != 0) {
> -		if (idx < (1UL << PUD_ORDER)) {
> +		if (idx < MAX_FOLIO_NR_PAGES) {
>  			memcpy(&folio, foliop, 2 * sizeof(struct page));
>  			nr_pages = folio_nr_pages(&folio);
>  		}

Thank you for this fast and kind reply.  I confirmed this fixes my issue :)

Tested-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ