On 2/3/23 23:23, Andrew Morton wrote:
> On Fri, 3 Feb 2023 18:01:32 +0800 Yajun Deng <yajun.deng@xxxxxxxxx> wrote:
>
>> The commit 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
>> pageblocks with others") has removed MIGRATE_CMA and MIGRATE_ISOLATE from
>> fallbacks list. so there is no need to add an element at the end of every
>> type.
>>
>> Reduce fallbacks to (MIGRATE_PCPTYPES - 1).
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> Thanks. `git log' suggests who should be cc'ed when fixing things...
>
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -2603,10 +2603,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
>> *
>> * The other migratetypes do not have fallbacks.
>> */
>> -static int fallbacks[MIGRATE_TYPES][3] = {
>> - [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>> - [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
>> - [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>> +static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {
Why not also reduce the first index size from [MIGRATE_TYPES] to
[MIGRATE_PCPTYPES] ?
>> + [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
>> + [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
>> + [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
>> };
>>
>> #ifdef CONFIG_CMA
>> @@ -2865,11 +2865,8 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
>> return -1;
>>
>> *can_steal = false;
>> - for (i = 0;; i++) {
>> + for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
>> fallback_mt = fallbacks[migratetype][i];
>> - if (fallback_mt == MIGRATE_TYPES)
>> - break;
>> -
>> if (free_area_empty(area, fallback_mt))
>> continue;
>>
>> --
>> 2.25.1
