Re: [v7 PATCH 04/12] mm: vmscan: remove memcg_shrinker_map_size

[Vlastimil Babka]

On 2/9/21 9:43 PM, Roman Gushchin wrote:
> On Tue, Feb 09, 2021 at 09:46:38AM -0800, Yang Shi wrote:
>> Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the
>> map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both.
>> Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the
>> bit map.
>> 
>> Acked-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
>> Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

>> ---
>>  mm/vmscan.c | 18 +++++++++---------
>>  1 file changed, 9 insertions(+), 9 deletions(-)
>> 
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index e4ddaaaeffe2..641077b09e5d 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -185,8 +185,10 @@ static LIST_HEAD(shrinker_list);
>>  static DECLARE_RWSEM(shrinker_rwsem);
>>  
>>  #ifdef CONFIG_MEMCG
>> +static int shrinker_nr_max;
>>  
>> -static int memcg_shrinker_map_size;
>> +#define NR_MAX_TO_SHR_MAP_SIZE(nr_max) \
>> +	(DIV_ROUND_UP(nr_max, BITS_PER_LONG) * sizeof(unsigned long))
> 
> How about something like this?
> 
> static inline int shrinker_map_size(int nr_items)
> {
> 	return DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long);
> }
> 
> I think it look less cryptic.

Yeah that looks nicer so I'm fine with that potential change.

> The rest of the patch looks good to me.
> 
> Thanks!
>