Re: [PATCH 3/6] mm/page_alloc: Export free_frozen_pages() instead of free_unref_page()

[David Hildenbrand <david@redhat.com>]

On 31.05.22 17:06, Matthew Wilcox (Oracle) wrote:
> This API makes more sense for slab to use and it works perfectly
> well for swap.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  mm/internal.h   |  4 ++--
>  mm/page_alloc.c | 18 +++++++++---------
>  mm/swap.c       |  2 +-
>  3 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/internal.h b/mm/internal.h
> index c0f8fbe0445b..f1c0dab2b98e 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -362,8 +362,8 @@ extern void post_alloc_hook(struct page *page, unsigned int order,
>  					gfp_t gfp_flags);
>  extern int user_min_free_kbytes;
>  
> -extern void free_unref_page(struct page *page, unsigned int order);
> -extern void free_unref_page_list(struct list_head *list);
> +void free_frozen_pages(struct page *, unsigned int order);
> +void free_unref_page_list(struct list_head *list);
>  
>  extern void zone_pcp_update(struct zone *zone, int cpu_online);
>  extern void zone_pcp_reset(struct zone *zone);
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6a8676cb69db..825922000781 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -687,14 +687,6 @@ static inline bool pcp_allowed_order(unsigned int order)
>  	return false;
>  }
>  
> -static inline void free_frozen_pages(struct page *page, unsigned int order)
> -{
> -	if (pcp_allowed_order(order))		/* Via pcp? */
> -		free_unref_page(page, order);
> -	else
> -		__free_pages_ok(page, order, FPI_NONE);
> -}
> -
>  /*
>   * Higher-order pages are called "compound pages".  They are structured thusly:
>   *
> @@ -3428,7 +3420,7 @@ static void free_unref_page_commit(struct page *page, int migratetype,
>  /*
>   * Free a pcp page
>   */
> -void free_unref_page(struct page *page, unsigned int order)
> +static void free_unref_page(struct page *page, unsigned int order)
>  {
>  	unsigned long flags;
>  	unsigned long pfn = page_to_pfn(page);
> @@ -3458,6 +3450,14 @@ void free_unref_page(struct page *page, unsigned int order)
>  	local_unlock_irqrestore(&pagesets.lock, flags);
>  }
>  
> +void free_frozen_pages(struct page *page, unsigned int order)
> +{
> +	if (pcp_allowed_order(order))		/* Via pcp? */
> +		free_unref_page(page, order);
> +	else
> +		__free_pages_ok(page, order, FPI_NONE);
> +}
> +
>  /*
>   * Free a list of 0-order pages
>   */
> diff --git a/mm/swap.c b/mm/swap.c
> index f3922a96b2e9..c474bdf838e3 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -103,7 +103,7 @@ static void __put_single_page(struct page *page)
>  {
>  	__page_cache_release(page);
>  	mem_cgroup_uncharge(page_folio(page));
> -	free_unref_page(page, 0);
> +	free_frozen_pages(page, 0);
>  }
>  
>  static void __put_compound_page(struct page *page)


IIUC, the net change is 0, because we'll always take the
pcp_allowed_order() path due to order==0, correct?

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb