Re: [PATCH 5/8] mm/vmscan: use helper folio_is_file_lru()

From: Miaohe Lin
Date: Fri Apr 01 2022 - 02:15:03 EST


On 2022/4/1 11:20, Huang, Ying wrote:
> Miaohe Lin <linmiaohe@xxxxxxxxxx> writes:
>
>> Use helper folio_is_file_lru() to check whether folio is file lru. Minor
>> readability improvement.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> mm/vmscan.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index ebd8ffb63673..31e95d627448 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1411,14 +1411,14 @@ static enum page_references folio_check_references(struct folio *folio,
>> /*
>> * Activate file-backed executable folios after first usage.
>> */
>> - if ((vm_flags & VM_EXEC) && !folio_test_swapbacked(folio))
>> + if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio))
>
> I think that this should be converted to
>
> if ((vm_flags & VM_EXEC)))
>
> We should activate swap-backed executable folios (e.g. tmpfs) after
> first usage too.
>

Dig into the git history, we can found that commit c909e99364c8 ("vmscan: activate executable pages after first usage")
activate swap-backed executable folios after first usage too. But later swap-backed executable folios is not activated
via commit b518154e59aa ("mm/vmscan: protect the workingset on anonymous LRU") to pretect the workingset from anonymous
LRU. So above change might not be wanted. Or am I miss something?

Many thanks.

> Best Regards,
> Huang, Ying
>
>> return PAGEREF_ACTIVATE;
>>
>> return PAGEREF_KEEP;
>> }
>>
>> /* Reclaim if clean, defer dirty folios to writeback */
>> - if (referenced_folio && !folio_test_swapbacked(folio))
>> + if (referenced_folio && folio_is_file_lru(folio))
>> return PAGEREF_RECLAIM_CLEAN;
>>
>> return PAGEREF_RECLAIM;
> .
>