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

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Message-ID: <4c3d1891-e784-4599-9640-4ff092ba7a31@arm.com>
Date: Tue, 27 Feb 2024 09:11:35 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org,
 linux-mm@...ck.org, David Hildenbrand <david@...hat.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 27/02/2024 03:18, Barry Song wrote:
> 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.

Don't worry about it. Don't feel you need to update it on my account.

> 
>> 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