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From:   Zi Yan <ziy@nvidia.com>
To:     Roman Gushchin <roman.gushchin@linux.dev>
Cc:     Matthew Wilcox <willy@infradead.org>, linux-mm@kvack.org,
        Shuah Khan <shuah@kernel.org>, Yang Shi <shy828301@gmail.com>,
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        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH 2/5] mm: page_owner: add support for splitting to any order in split page_owner.
Date:   Mon, 21 Mar 2022 15:08:15 -0400
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On 21 Mar 2022, at 15:02, Roman Gushchin wrote:

> On Mon, Mar 21, 2022 at 10:21:25AM -0400, Zi Yan wrote:
>> From: Zi Yan <ziy@nvidia.com>
>>
>> It adds a new_order parameter to set new page order in page owner and
>> uses old_order instead of nr to make the parameters look consistent.
>> It prepares for upcoming changes to support split huge page to any
>> lower order.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>>  include/linux/page_owner.h | 12 +++++++-----
>>  mm/huge_memory.c           |  3 ++-
>>  mm/page_alloc.c            |  2 +-
>>  mm/page_owner.c            | 13 +++++++------
>>  4 files changed, 17 insertions(+), 13 deletions(-)
>>
>> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
>> index 119a0c9d2a8b..16050cc89274 100644
>> --- a/include/linux/page_owner.h
>> +++ b/include/linux/page_owner.h
>> @@ -11,7 +11,8 @@ extern struct page_ext_operations page_owner_ops;
>>  extern void __reset_page_owner(struct page *page, unsigned short orde=
r);
>>  extern void __set_page_owner(struct page *page,
>>  			unsigned short order, gfp_t gfp_mask);
>> -extern void __split_page_owner(struct page *page, unsigned int nr);
>> +extern void __split_page_owner(struct page *page, unsigned short old_=
order,
>> +			unsigned short new_order);
>
> Unsigned short here,
>
>>  extern void __folio_copy_owner(struct folio *newfolio, struct folio *=
old);
>>  extern void __set_page_owner_migrate_reason(struct page *page, int re=
ason);
>>  extern void __dump_page_owner(const struct page *page);
>> @@ -31,10 +32,11 @@ static inline void set_page_owner(struct page *pag=
e,
>>  		__set_page_owner(page, order, gfp_mask);
>>  }
>>
>> -static inline void split_page_owner(struct page *page, unsigned int n=
r)
>> +static inline void split_page_owner(struct page *page, unsigned int o=
ld_order,
>> +			unsigned int new_order)
>
> but unsigned int here.
>
>>  {
>>  	if (static_branch_unlikely(&page_owner_inited))
>> -		__split_page_owner(page, nr);
>> +		__split_page_owner(page, old_order, new_order);
>>  }
>>  static inline void folio_copy_owner(struct folio *newfolio, struct fo=
lio *old)
>>  {
>> @@ -56,11 +58,11 @@ static inline void reset_page_owner(struct page *p=
age, unsigned short order)
>>  {
>>  }
>>  static inline void set_page_owner(struct page *page,
>> -			unsigned int order, gfp_t gfp_mask)
>> +			unsigned short order, gfp_t gfp_mask)
>>  {
>>  }
>>  static inline void split_page_owner(struct page *page,
>> -			unsigned short order)
>> +			unsigned short old_order, unsigned short new_order)
>>  {
>>  }
>>  static inline void folio_copy_owner(struct folio *newfolio, struct fo=
lio *folio)
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 640040c386f0..fcfa46af6c4c 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -2367,6 +2367,7 @@ static void __split_huge_page(struct page *page,=
 struct list_head *list,
>>  	struct lruvec *lruvec;
>>  	struct address_space *swap_cache =3D NULL;
>>  	unsigned long offset =3D 0;
>> +	unsigned int order =3D thp_order(head);
>>  	unsigned int nr =3D thp_nr_pages(head);
>>  	int i;
>>
>> @@ -2408,7 +2409,7 @@ static void __split_huge_page(struct page *page,=
 struct list_head *list,
>>  	unlock_page_lruvec(lruvec);
>>  	/* Caller disabled irqs, so they are still disabled here */
>>
>> -	split_page_owner(head, nr);
>> +	split_page_owner(head, order, 0);
>>
>>  	/* See comment in __split_huge_page_tail() */
>>  	if (PageAnon(head)) {
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index d982919b9e51..9cac40c26c58 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -3514,7 +3514,7 @@ void split_page(struct page *page, unsigned int =
order)
>>
>>  	for (i =3D 1; i < (1 << order); i++)
>>  		set_page_refcounted(page + i);
>> -	split_page_owner(page, 1 << order);
>> +	split_page_owner(page, order, 0);
>>  	split_page_memcg(page, 1 << order, 0);
>>  }
>>  EXPORT_SYMBOL_GPL(split_page);
>> diff --git a/mm/page_owner.c b/mm/page_owner.c
>> index 0a9588506571..52013c846d19 100644
>> --- a/mm/page_owner.c
>> +++ b/mm/page_owner.c
>> @@ -202,19 +202,20 @@ void __set_page_owner_migrate_reason(struct page=
 *page, int reason)
>>  	page_owner->last_migrate_reason =3D reason;
>>  }
>>
>> -void __split_page_owner(struct page *page, unsigned int nr)
>> +void __split_page_owner(struct page *page, unsigned short old_order,
>> +			unsigned short new_order)
>
> And short again here. Please, make it consistent.
>
> Other than that, looks good to me. Please, feel free to add
> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
> after fixing the type inconsistency.

Sure. Will fix all the inconsistent types. Thanks.


--
Best Regards,
Yan, Zi

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