linux-kernel - Re: [PATCH] mm: export folio_pte_batch as a couple of modules might need it

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Date: Tue, 27 Feb 2024 16:18:16 +1300
From: Barry Song <21cnbao@...il.com>
To: akpm@...ux-foundation.org, linux-mm@...ck.org, 
	David Hildenbrand <david@...hat.com>, Ryan Roberts <ryan.roberts@....com>
Cc: linux-kernel@...r.kernel.org, Barry Song <v-songbaohua@...o.com>, 
	Lance Yang <ioworker0@...il.com>, Yin Fengwei <fengwei.yin@...el.com>
Subject: Re: [PATCH] mm: export folio_pte_batch as a couple of modules might
 need it

On Tue, Feb 27, 2024 at 3:41 PM Barry Song <21cnbao@...il.com> wrote:
>
> From: Barry Song <v-songbaohua@...o.com>
>
> madvise and some others might need folio_pte_batch to check if a range
> of PTEs are completely mapped to a large folio with contiguous physcial
> addresses. Let's export it for others to use.
>
> Cc: Lance Yang <ioworker0@...il.com>
> Cc: Ryan Roberts <ryan.roberts@....com>
> Cc: David Hildenbrand <david@...hat.com>

Hi David, Ryan,

Sorry, I realize I just made a mistake and your tags should be both
Suggested-by. Please feel
free to review the patch and give comments. I will fix the tags
together with addressing your
review comments in v2.

> Cc: Yin Fengwei <fengwei.yin@...el.com>
> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> ---
>  -v1:
>  at least two jobs madv_free and madv_pageout depend on it. To avoid
>  conflicts and dependencies, after discussing with Lance, we prefer
>  this one can land earlier.
>
>  mm/internal.h | 13 +++++++++++++
>  mm/memory.c   | 11 +----------
>  2 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index 13b59d384845..8e2bc304f671 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -83,6 +83,19 @@ static inline void *folio_raw_mapping(struct folio *folio)
>         return (void *)(mapping & ~PAGE_MAPPING_FLAGS);
>  }
>
> +/* Flags for folio_pte_batch(). */
> +typedef int __bitwise fpb_t;
> +
> +/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */
> +#define FPB_IGNORE_DIRTY               ((__force fpb_t)BIT(0))
> +
> +/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
> +#define FPB_IGNORE_SOFT_DIRTY          ((__force fpb_t)BIT(1))
> +
> +extern int folio_pte_batch(struct folio *folio, unsigned long addr,
> +               pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
> +               bool *any_writable);
> +
>  void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
>                                                 int nr_throttled);
>  static inline void acct_reclaim_writeback(struct folio *folio)
> diff --git a/mm/memory.c b/mm/memory.c
> index 1c45b6a42a1b..319b3be05e75 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -953,15 +953,6 @@ static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma,
>         set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr);
>  }
>
> -/* Flags for folio_pte_batch(). */
> -typedef int __bitwise fpb_t;
> -
> -/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */
> -#define FPB_IGNORE_DIRTY               ((__force fpb_t)BIT(0))
> -
> -/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
> -#define FPB_IGNORE_SOFT_DIRTY          ((__force fpb_t)BIT(1))
> -
>  static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags)
>  {
>         if (flags & FPB_IGNORE_DIRTY)
> @@ -982,7 +973,7 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags)
>   * If "any_writable" is set, it will indicate if any other PTE besides the
>   * first (given) PTE is writable.
>   */
> -static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
> +int folio_pte_batch(struct folio *folio, unsigned long addr,
>                 pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
>                 bool *any_writable)
>  {
> --
> 2.34.1
>

Thanks
Barry