Re: [PATCH v3 15/17] mm: pgtable: remove tlb_remove_page_ptdesc()

[Mike Rapoport <rppt@kernel.org>]

On Mon, Dec 23, 2024 at 05:41:01PM +0800, Qi Zheng wrote:
> Here we are explicitly dealing with struct page, and the following logic
> semms strange:
> 
> tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));
> 
> tlb_remove_page_ptdesc
> --> tlb_remove_page(tlb, ptdesc_page(pt));
> 
> So remove tlb_remove_page_ptdesc() and make callers call tlb_remove_page()
> directly.

Please don't. The ptdesc wrappers are there as a part of reducing the size
of struct page project [1]. 

For now struct ptdesc overlaps struct page, but the goal is to have them
separate and always operate on struct ptdesc when working with page tables.

[1] https://kernelnewbies.org/MatthewWilcox/Memdescs
 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  arch/csky/include/asm/pgalloc.h      | 2 +-
>  arch/hexagon/include/asm/pgalloc.h   | 2 +-
>  arch/loongarch/include/asm/pgalloc.h | 2 +-
>  arch/m68k/include/asm/sun3_pgalloc.h | 2 +-
>  arch/mips/include/asm/pgalloc.h      | 2 +-
>  arch/nios2/include/asm/pgalloc.h     | 2 +-
>  arch/openrisc/include/asm/pgalloc.h  | 2 +-
>  arch/riscv/include/asm/pgalloc.h     | 2 +-
>  arch/sh/include/asm/pgalloc.h        | 2 +-
>  arch/um/include/asm/pgalloc.h        | 8 ++++----
>  include/asm-generic/tlb.h            | 6 ------
>  11 files changed, 13 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
> index f1ce5b7b28f22..936a43a49e704 100644
> --- a/arch/csky/include/asm/pgalloc.h
> +++ b/arch/csky/include/asm/pgalloc.h
> @@ -64,7 +64,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
>  #define __pte_free_tlb(tlb, pte, address)		\
>  do {							\
>  	pagetable_dtor(page_ptdesc(pte));		\
> -	tlb_remove_page_ptdesc(tlb, page_ptdesc(pte));	\
> +	tlb_remove_page(tlb, (pte));			\
>  } while (0)
>  
>  extern void pagetable_init(void);
> diff --git a/arch/hexagon/include/asm/pgalloc.h b/arch/hexagon/include/asm/pgalloc.h
> index 40e42a0e71673..8b1550498f1bf 100644
> --- a/arch/hexagon/include/asm/pgalloc.h
> +++ b/arch/hexagon/include/asm/pgalloc.h
> @@ -90,7 +90,7 @@ static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
>  #define __pte_free_tlb(tlb, pte, addr)				\
>  do {								\
>  	pagetable_dtor((page_ptdesc(pte)));			\
> -	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #endif
> diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
> index 7211dff8c969e..5a4f22aeb6189 100644
> --- a/arch/loongarch/include/asm/pgalloc.h
> +++ b/arch/loongarch/include/asm/pgalloc.h
> @@ -58,7 +58,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
>  #define __pte_free_tlb(tlb, pte, address)			\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), page_ptdesc(pte));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #ifndef __PAGETABLE_PMD_FOLDED
> diff --git a/arch/m68k/include/asm/sun3_pgalloc.h b/arch/m68k/include/asm/sun3_pgalloc.h
> index 2b626cb3ad0ae..63d9f95f5e3dd 100644
> --- a/arch/m68k/include/asm/sun3_pgalloc.h
> +++ b/arch/m68k/include/asm/sun3_pgalloc.h
> @@ -20,7 +20,7 @@ extern const char bad_pmd_string[];
>  #define __pte_free_tlb(tlb, pte, addr)				\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), page_ptdesc(pte));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
> diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
> index 36d9805033c4b..bbee21345154b 100644
> --- a/arch/mips/include/asm/pgalloc.h
> +++ b/arch/mips/include/asm/pgalloc.h
> @@ -57,7 +57,7 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
>  #define __pte_free_tlb(tlb, pte, address)			\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), page_ptdesc(pte));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #ifndef __PAGETABLE_PMD_FOLDED
> diff --git a/arch/nios2/include/asm/pgalloc.h b/arch/nios2/include/asm/pgalloc.h
> index 12a536b7bfbd4..641cec8fb2a22 100644
> --- a/arch/nios2/include/asm/pgalloc.h
> +++ b/arch/nios2/include/asm/pgalloc.h
> @@ -31,7 +31,7 @@ extern pgd_t *pgd_alloc(struct mm_struct *mm);
>  #define __pte_free_tlb(tlb, pte, addr)					\
>  	do {								\
>  		pagetable_dtor(page_ptdesc(pte));			\
> -		tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
> +		tlb_remove_page((tlb), (pte));				\
>  	} while (0)
>  
>  #endif /* _ASM_NIOS2_PGALLOC_H */
> diff --git a/arch/openrisc/include/asm/pgalloc.h b/arch/openrisc/include/asm/pgalloc.h
> index 596e2355824e3..e9b9bc53ece0b 100644
> --- a/arch/openrisc/include/asm/pgalloc.h
> +++ b/arch/openrisc/include/asm/pgalloc.h
> @@ -69,7 +69,7 @@ extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm);
>  #define __pte_free_tlb(tlb, pte, addr)				\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #endif
> diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
> index c8907b8317115..ab4f9b2cf9e11 100644
> --- a/arch/riscv/include/asm/pgalloc.h
> +++ b/arch/riscv/include/asm/pgalloc.h
> @@ -29,7 +29,7 @@ static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
>  		tlb_remove_ptdesc(tlb, pt);
>  	} else {
>  		pagetable_dtor(pt);
> -		tlb_remove_page_ptdesc(tlb, pt);
> +		tlb_remove_page(tlb, ptdesc_page((struct ptdesc *)pt));
>  	}
>  }
>  
> diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h
> index 96d938fdf2244..43812b2363efd 100644
> --- a/arch/sh/include/asm/pgalloc.h
> +++ b/arch/sh/include/asm/pgalloc.h
> @@ -35,7 +35,7 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
>  #define __pte_free_tlb(tlb, pte, addr)				\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #endif /* __ASM_SH_PGALLOC_H */
> diff --git a/arch/um/include/asm/pgalloc.h b/arch/um/include/asm/pgalloc.h
> index f0af23c3aeb2b..98190c318a8e9 100644
> --- a/arch/um/include/asm/pgalloc.h
> +++ b/arch/um/include/asm/pgalloc.h
> @@ -28,7 +28,7 @@ extern pgd_t *pgd_alloc(struct mm_struct *);
>  #define __pte_free_tlb(tlb, pte, address)			\
>  do {								\
>  	pagetable_dtor(page_ptdesc(pte));			\
> -	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
> +	tlb_remove_page((tlb), (pte));				\
>  } while (0)
>  
>  #if CONFIG_PGTABLE_LEVELS > 2
> @@ -36,15 +36,15 @@ do {								\
>  #define __pmd_free_tlb(tlb, pmd, address)			\
>  do {								\
>  	pagetable_dtor(virt_to_ptdesc(pmd));			\
> -	tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pmd));	\
> +	tlb_remove_page((tlb), virt_to_page(pmd));		\
>  } while (0)
>  
>  #if CONFIG_PGTABLE_LEVELS > 3
>  
>  #define __pud_free_tlb(tlb, pud, address)			\
>  do {								\
> -	pagetable_dtor(virt_to_ptdesc(pud));		\
> -	tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pud));	\
> +	pagetable_dtor(virt_to_ptdesc(pud));			\
> +	tlb_remove_page((tlb), virt_to_page(pud));		\
>  } while (0)
>  
>  #endif
> diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
> index 69de47c7ef3c5..8d6cfe5058543 100644
> --- a/include/asm-generic/tlb.h
> +++ b/include/asm-generic/tlb.h
> @@ -504,12 +504,6 @@ static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
>  	tlb_remove_table(tlb, pt);
>  }
>  
> -/* Like tlb_remove_ptdesc, but for page-like page directories. */
> -static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
> -{
> -	tlb_remove_page(tlb, ptdesc_page(pt));
> -}
> -
>  static inline void tlb_change_page_size(struct mmu_gather *tlb,
>  						     unsigned int page_size)
>  {
> -- 
> 2.20.1
> 

-- 
Sincerely yours,
Mike.