Subject: Re: [PATCH v4 19/34] pgalloc: Convert various functions to use ptdescs

From: Mike Rapoport <[email-masked]>
Date: Wed, 14 Jun 2023 17:59:17 +0300

On Mon, Jun 12, 2023 at 02:04:08PM -0700, Vishal Moola (Oracle) wrote:
> As part of the conversions to replace pgtable constructor/destructors with
> ptdesc equivalents, convert various page table functions to use ptdescs.
> 
> Some of the functions use the *get*page*() helper functions. Convert
> these to use pagetable_alloc() and ptdesc_address() instead to help
> standardize page tables further.
> 
> Signed-off-by: Vishal Moola (Oracle) <[email-masked]>
> ---
>  include/asm-generic/pgalloc.h | 62 +++++++++++++++++++++--------------
>  1 file changed, 37 insertions(+), 25 deletions(-)
> 
> diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
> index a7cf825befae..3fd6ce79e654 100644
> --- a/include/asm-generic/pgalloc.h
> +++ b/include/asm-generic/pgalloc.h
> @@ -18,7 +18,11 @@
>   */
>  static inline pte_t *__pte_alloc_one_kernel(struct mm_struct *mm)
>  {
> -	return (pte_t *)__get_free_page(GFP_PGTABLE_KERNEL);
> +	struct ptdesc *ptdesc = pagetable_alloc(GFP_PGTABLE_KERNEL, 0);
> +
> +	if (!ptdesc)
> +		return NULL;
> +	return ptdesc_address(ptdesc);
>  }
>  
>  #ifndef __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
> @@ -41,7 +45,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
>   */
>  static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
>  {
> -	free_page((unsigned long)pte);
> +	pagetable_free(virt_to_ptdesc(pte));
>  }
>  
>  /**
> @@ -49,7 +53,7 @@ static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
>   * @mm: the mm_struct of the current context
>   * @gfp: GFP flags to use for the allocation
>   *
> - * Allocates a page and runs the pgtable_pte_page_ctor().
> + * Allocates a ptdesc and runs the pagetable_pte_ctor().

Allocates memory for page table and ptdesc

>   *
>   * This function is intended for architectures that need
>   * anything beyond simple page allocation or must have custom GFP flags.

The Return: description here should be fixed up

> @@ -58,17 +62,17 @@ static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
>   */
>  static inline pgtable_t __pte_alloc_one(struct mm_struct *mm, gfp_t gfp)
>  {
> -	struct page *pte;
> +	struct ptdesc *ptdesc;
>  
> -	pte = alloc_page(gfp);
> -	if (!pte)
> +	ptdesc = pagetable_alloc(gfp, 0);
> +	if (!ptdesc)
>  		return NULL;
> -	if (!pgtable_pte_page_ctor(pte)) {
> -		__free_page(pte);
> +	if (!pagetable_pte_ctor(ptdesc)) {
> +		pagetable_free(ptdesc);
>  		return NULL;
>  	}
>  
> -	return pte;
> +	return ptdesc_page(ptdesc);
>  }
>  
>  #ifndef __HAVE_ARCH_PTE_ALLOC_ONE
> @@ -76,7 +80,7 @@ static inline pgtable_t __pte_alloc_one(struct mm_struct *mm, gfp_t gfp)
>   * pte_alloc_one - allocate a page for PTE-level user page table
>   * @mm: the mm_struct of the current context
>   *
> - * Allocates a page and runs the pgtable_pte_page_ctor().
> + * Allocates a ptdesc and runs the pagetable_pte_ctor().

Allocates memory for page table and ptdesc

>   *
>   * Return: `struct page` initialized as page table or %NULL on error

Return: ptdesc ...

>   */
> @@ -98,8 +102,10 @@ static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
>   */
>  static inline void pte_free(struct mm_struct *mm, struct page *pte_page)
>  {
> -	pgtable_pte_page_dtor(pte_page);
> -	__free_page(pte_page);
> +	struct ptdesc *ptdesc = page_ptdesc(pte_page);
> +
> +	pagetable_pte_dtor(ptdesc);
> +	pagetable_free(ptdesc);
>  }
>  
>  
> @@ -110,7 +116,7 @@ static inline void pte_free(struct mm_struct *mm, struct page *pte_page)
>   * pmd_alloc_one - allocate a page for PMD-level page table
>   * @mm: the mm_struct of the current context
>   *
> - * Allocates a page and runs the pgtable_pmd_page_ctor().
> + * Allocates a ptdesc and runs the pagetable_pmd_ctor().

Allocate memory for page table and ptdesc

>   * Allocations use %GFP_PGTABLE_USER in user context and
>   * %GFP_PGTABLE_KERNEL in kernel context.
>   *
> @@ -118,28 +124,30 @@ static inline void pte_free(struct mm_struct *mm, struct page *pte_page)
>   */
>  static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
>  {
> -	struct page *page;
> +	struct ptdesc *ptdesc;
>  	gfp_t gfp = GFP_PGTABLE_USER;
>  
>  	if (mm == &init_mm)
>  		gfp = GFP_PGTABLE_KERNEL;
> -	page = alloc_page(gfp);
> -	if (!page)
> +	ptdesc = pagetable_alloc(gfp, 0);
> +	if (!ptdesc)
>  		return NULL;
> -	if (!pgtable_pmd_page_ctor(page)) {
> -		__free_page(page);
> +	if (!pagetable_pmd_ctor(ptdesc)) {
> +		pagetable_free(ptdesc);
>  		return NULL;
>  	}
> -	return (pmd_t *)page_address(page);
> +	return ptdesc_address(ptdesc);
>  }
>  #endif
>  
>  #ifndef __HAVE_ARCH_PMD_FREE
>  static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
>  {
> +	struct ptdesc *ptdesc = virt_to_ptdesc(pmd);
> +
>  	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
> -	pgtable_pmd_page_dtor(virt_to_page(pmd));
> -	free_page((unsigned long)pmd);
> +	pagetable_pmd_dtor(ptdesc);
> +	pagetable_free(ptdesc);
>  }
>  #endif
>  
> @@ -149,11 +157,15 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
>  
>  static inline pud_t *__pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>  {
> -	gfp_t gfp = GFP_PGTABLE_USER;
> +	gfp_t gfp = GFP_PGTABLE_USER | __GFP_ZERO;

GFP_PGTABLE_USER already contains __GFP_ZERO

> +	struct ptdesc *ptdesc;
>  
>  	if (mm == &init_mm)
>  		gfp = GFP_PGTABLE_KERNEL;
> -	return (pud_t *)get_zeroed_page(gfp);
> +	ptdesc = pagetable_alloc(gfp, 0);
> +	if (!ptdesc)
> +		return NULL;
> +	return ptdesc_address(ptdesc);
>  }
>  
>  #ifndef __HAVE_ARCH_PUD_ALLOC_ONE
> @@ -175,7 +187,7 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>  static inline void __pud_free(struct mm_struct *mm, pud_t *pud)
>  {
>  	BUG_ON((unsigned long)pud & (PAGE_SIZE-1));
> -	free_page((unsigned long)pud);
> +	pagetable_free(virt_to_ptdesc(pud));
>  }
>  
>  #ifndef __HAVE_ARCH_PUD_FREE
> @@ -190,7 +202,7 @@ static inline void pud_free(struct mm_struct *mm, pud_t *pud)
>  #ifndef __HAVE_ARCH_PGD_FREE
>  static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
>  {
> -	free_page((unsigned long)pgd);
> +	pagetable_free(virt_to_ptdesc(pgd));
>  }
>  #endif
>  
> -- 
> 2.40.1
> 
> 

-- 
Sincerely yours,
Mike.

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