Re: [PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Ye Liu]

在 2026/4/14 22:59, Joshua Hahn 写道:
> On Tue, 14 Apr 2026 17:15:20 +0800 Ye Liu <ye.liu@xxxxxxxxx> wrote:
> 
>> From: Ye Liu <liuye@xxxxxxxxxx>
>>
>> Replace the single call to __node_stat_mod_folio()
>> with node_stat_mod_folio(), and remove the dead inline __node_stat_*
>> wrapper definitions from include/linux/vmstat.h.
>>
>> Signed-off-by: Ye Liu <liuye@xxxxxxxxxx>
>> ---
>>  include/linux/vmstat.h | 18 ------------------
>>  mm/page-writeback.c    |  2 +-
>>  2 files changed, 1 insertion(+), 19 deletions(-)
>>
>> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
>> index 3c9c266cf782..54da7d820f78 100644
>> --- a/include/linux/vmstat.h
>> +++ b/include/linux/vmstat.h
>> @@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
>>  	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
>>  }
>>  
>> -static inline void __node_stat_mod_folio(struct folio *folio,
>> -		enum node_stat_item item, long nr)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, nr);
>> -}
>> -
>> -static inline void __node_stat_add_folio(struct folio *folio,
>> -		enum node_stat_item item)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
>> -}
>> -
>> -static inline void __node_stat_sub_folio(struct folio *folio,
>> -		enum node_stat_item item)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
>> -}
>> -
>>  static inline void node_stat_mod_folio(struct folio *folio,
>>  		enum node_stat_item item, long nr)
>>  {
>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>> index 6f9b7b081ab7..ed3301753e89 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
>>  
>>  		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
>>  		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
>> -		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
>> +		node_stat_mod_folio(folio, NR_DIRTIED, nr);
> 
> Hi Ye, thank you for the patch,
> 
> In addition to what Matthew has pointed out, I also wanted to note that this
> substitution isn't trivial; there are differences between the __ prefixed
> version of node_stat_mod_folio and the one without. Even though the correctness
> of the two versions might be the same, I think that a change like this should
> be supplemented by a description of what side effects this change has
> (i.e. introducing additional overhead from the cmpxchg loop).
> 
> Thank you, I hope you have a great day!
> Joshua

Thank you for your review, Joshua. Regarding the difference between
__node_stat_mod_folio and node_stat_mod_folio: in the current implementation,
both functions ultimately use __mod_node_page_state, as mod_node_page_state
is defined as __mod_node_page_state. There is no functional difference
between them in terms of atomicity or overhead. The __ prefixed versions
were wrappers that are now unused, which is why we're removing them.

-- 
Thanks,
Ye Liu