linux-kernel - Re: [PATCH] [mm-unstable] mm/folio: Replace set_compound_order with folio_set

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Date:   Mon, 12 Jun 2023 09:10:40 -0700
From:   Sidhartha Kumar <sidhartha.kumar@...cle.com>
To:     Tarun Sahu <tsahu@...ux.ibm.com>, linux-mm@...ck.org
Cc:     akpm@...ux-foundation.org, muchun.song@...ux.dev,
        mike.kravetz@...cle.com, aneesh.kumar@...ux.ibm.com,
        willy@...radead.org, gerald.schaefer@...ux.ibm.com,
        linux-kernel@...r.kernel.org, jaypatel@...ux.ibm.com
Subject: Re: [PATCH] [mm-unstable] mm/folio: Replace set_compound_order with
 folio_set_order

On 6/12/23 2:35 AM, Tarun Sahu wrote:
> The patch [1] removed the need for special handling of order = 0
> in folio_set_order. Now, folio_set_order and set_compound_order becomes
> similar function. This patch removes the set_compound_order and uses
> folio_set_order instead.
> 
> [1] https://lore.kernel.org/all/20230609183032.13E08C433D2@smtp.kernel.org/
> 
> Signed-off-by: Tarun Sahu <tsahu@...ux.ibm.com>
> ---
> Moved folio_set_order to the top instead of moving prep_compound_head below
> to it so that git blame can show the proper change in prep_compound_head
> which is replacement of set_compound_order with folio_set_order.
> 
>   include/linux/mm.h | 10 ----------
>   mm/internal.h      | 32 ++++++++++++++++----------------
>   2 files changed, 16 insertions(+), 26 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 27ce77080c79..61d75e0e5b40 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1229,16 +1229,6 @@ static inline void folio_set_compound_dtor(struct folio *folio,
>   
>   void destroy_large_folio(struct folio *folio);
>   
> -static inline void set_compound_order(struct page *page, unsigned int order)
> -{
> -	struct folio *folio = (struct folio *)page;
> -
> -	folio->_folio_order = order;
> -#ifdef CONFIG_64BIT
> -	folio->_folio_nr_pages = 1U << order;
> -#endif
> -}
> -
>   /* Returns the number of bytes in this potentially compound page. */
>   static inline unsigned long page_size(struct page *page)
>   {
> diff --git a/mm/internal.h b/mm/internal.h
> index c59fe08c5b39..c460b2fde977 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -378,12 +378,27 @@ extern void memblock_free_pages(struct page *page, unsigned long pfn,
>   					unsigned int order);
>   extern void __free_pages_core(struct page *page, unsigned int order);
>   
> +/*
> + * This will have no effect, other than possibly generating a warning, if the
> + * caller passes in a non-large folio.
> + */
> +static inline void folio_set_order(struct folio *folio, unsigned int order)
> +{
> +	if (WARN_ON_ONCE(!order || !folio_test_large(folio)))
> +		return;
> +
> +	folio->_folio_order = order;
> +#ifdef CONFIG_64BIT
> +	folio->_folio_nr_pages = 1U << order;
> +#endif
> +}
> +
>   static inline void prep_compound_head(struct page *page, unsigned int order)
>   {
>   	struct folio *folio = (struct folio *)page;
>   
>   	set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
> -	set_compound_order(page, order);
> +	folio_set_order(folio, order);
>   	atomic_set(&folio->_entire_mapcount, -1);
>   	atomic_set(&folio->_nr_pages_mapped, 0);
>   	atomic_set(&folio->_pincount, 0);
> @@ -419,21 +434,6 @@ extern void *memmap_alloc(phys_addr_t size, phys_addr_t align,
>   int split_free_page(struct page *free_page,
>   			unsigned int order, unsigned long split_pfn_offset);
>   
> -/*
> - * This will have no effect, other than possibly generating a warning, if the
> - * caller passes in a non-large folio.
> - */
> -static inline void folio_set_order(struct folio *folio, unsigned int order)
> -{
> -	if (WARN_ON_ONCE(!order || !folio_test_large(folio)))
> -		return;
> -
> -	folio->_folio_order = order;
> -#ifdef CONFIG_64BIT
> -	folio->_folio_nr_pages = 1U << order;
> -#endif
> -}
> -
>   #if defined CONFIG_COMPACTION || defined CONFIG_CMA
>   
>   /*
Reviewed-by Sidhartha Kumar <sidhartha.kumar@...cle.com>