Subject: Re: [PATCH v4 13/34] mm: Create ptdesc equivalents for pgtable_{pte,pmd}_page_{ctor,dtor}

From: Mike Rapoport <[email-masked]>
Date: Wed, 14 Jun 2023 17:10:49 +0300

On Mon, Jun 12, 2023 at 02:04:02PM -0700, Vishal Moola (Oracle) wrote:
> Creates pagetable_pte_ctor(), pagetable_pmd_ctor(), pagetable_pte_dtor(),
> and pagetable_pmd_dtor() and make the original pgtable
> constructor/destructors wrappers.

Nit: either "creates ... makes" or "create ... make"
I like the second form more.
 
> Signed-off-by: Vishal Moola (Oracle) <[email-masked]>

Acked-by: Mike Rapoport (IBM) <[email-masked]>

> ---
>  include/linux/mm.h | 56 ++++++++++++++++++++++++++++++++++------------
>  1 file changed, 42 insertions(+), 14 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a1af7983e1bd..dc211c43610b 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2886,20 +2886,34 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; }
>  static inline void ptlock_free(struct ptdesc *ptdesc) {}
>  #endif /* USE_SPLIT_PTE_PTLOCKS */
>  
> -static inline bool pgtable_pte_page_ctor(struct page *page)
> +static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc)
>  {
> -	if (!ptlock_init(page_ptdesc(page)))
> +	struct folio *folio = ptdesc_folio(ptdesc);
> +
> +	if (!ptlock_init(ptdesc))
>  		return false;
> -	__SetPageTable(page);
> -	inc_lruvec_page_state(page, NR_PAGETABLE);
> +	__folio_set_table(folio);

This comment is more to patch 1 ("mm: Add PAGE_TYPE_OP folio functions")

It would be better to have _pgtable here, as "table" does not necessary
mean page table.
With PageType SetPageTable was fine, but with folio I think it should be
more explicit.

I'd add a third parameter to PAGE_TYPE_OPS for that.

> +	lruvec_stat_add_folio(folio, NR_PAGETABLE);
>  	return true;
>  }
>  
> +static inline bool pgtable_pte_page_ctor(struct page *page)
> +{
> +	return pagetable_pte_ctor(page_ptdesc(page));
> +}
> +
> +static inline void pagetable_pte_dtor(struct ptdesc *ptdesc)
> +{
> +	struct folio *folio = ptdesc_folio(ptdesc);
> +
> +	ptlock_free(ptdesc);
> +	__folio_clear_table(folio);
> +	lruvec_stat_sub_folio(folio, NR_PAGETABLE);
> +}
> +
>  static inline void pgtable_pte_page_dtor(struct page *page)
>  {
> -	ptlock_free(page_ptdesc(page));
> -	__ClearPageTable(page);
> -	dec_lruvec_page_state(page, NR_PAGETABLE);
> +	pagetable_pte_dtor(page_ptdesc(page));
>  }
>  
>  #define pte_offset_map_lock(mm, pmd, address, ptlp)	\
> @@ -2981,20 +2995,34 @@ static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
>  	return ptl;
>  }
>  
> -static inline bool pgtable_pmd_page_ctor(struct page *page)
> +static inline bool pagetable_pmd_ctor(struct ptdesc *ptdesc)
>  {
> -	if (!pmd_ptlock_init(page_ptdesc(page)))
> +	struct folio *folio = ptdesc_folio(ptdesc);
> +
> +	if (!pmd_ptlock_init(ptdesc))
>  		return false;
> -	__SetPageTable(page);
> -	inc_lruvec_page_state(page, NR_PAGETABLE);
> +	__folio_set_table(folio);
> +	lruvec_stat_add_folio(folio, NR_PAGETABLE);
>  	return true;
>  }
>  
> +static inline bool pgtable_pmd_page_ctor(struct page *page)
> +{
> +	return pagetable_pmd_ctor(page_ptdesc(page));
> +}
> +
> +static inline void pagetable_pmd_dtor(struct ptdesc *ptdesc)
> +{
> +	struct folio *folio = ptdesc_folio(ptdesc);
> +
> +	pmd_ptlock_free(ptdesc);
> +	__folio_clear_table(folio);
> +	lruvec_stat_sub_folio(folio, NR_PAGETABLE);
> +}
> +
>  static inline void pgtable_pmd_page_dtor(struct page *page)
>  {
> -	pmd_ptlock_free(page_ptdesc(page));
> -	__ClearPageTable(page);
> -	dec_lruvec_page_state(page, NR_PAGETABLE);
> +	pagetable_pmd_dtor(page_ptdesc(page));
>  }
>  
>  /*
> -- 
> 2.40.1
> 
> 

-- 
Sincerely yours,
Mike.

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