On 2022/4/11 22:18, Christoph Hellwig wrote:
> On Sat, Apr 09, 2022 at 05:34:53PM +0800, Miaohe Lin wrote:
>> We don't need to check can_split_folio() because folio_maybe_dma_pinned()
>> is checked before. It will avoid the long term pinned pages to be swapped
>> out. And we can live with short term pinned pages. Without can_split_folio
>> checking we can simplify the code. Also activate_locked can be changed to
>> keep_locked as it's just short term pinning.
>>
>> Suggested-by: Huang, Ying <ying.huang@xxxxxxxxx>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> mm/vmscan.c | 22 ++++++++--------------
>> 1 file changed, 8 insertions(+), 14 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 4a76be47bed1..01f5db75a507 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1711,20 +1711,14 @@ static unsigned int shrink_page_list(struct list_head *page_list,
>> goto keep_locked;
>> if (folio_maybe_dma_pinned(folio))
>> goto keep_locked;
>> - if (PageTransHuge(page)) {
>> - /* cannot split THP, skip it */
>> - if (!can_split_folio(folio, NULL))
>> - goto activate_locked;
>> - /*
>> - * Split pages without a PMD map right
>> - * away. Chances are some or all of the
>> - * tail pages can be freed without IO.
>> - */
>> - if (!folio_entire_mapcount(folio) &&
>> - split_folio_to_list(folio,
>> - page_list))
>> - goto activate_locked;
>> - }
>> + /*
>> + * Split pages without a PMD map right
>> + * away. Chances are some or all of the
>> + * tail pages can be freed without IO.
>> + */
>
> This could use more of the line length and be more readable:
>
> /*
> * Split pages without a PMD map right away.
> * Chances are some or all of the tail pages
> * can be freed without IO.
> */
>
Looks better.
>> + if (PageTransHuge(page) && !folio_entire_mapcount(folio) &&
>
> Please put the folio_entire_mapcoun ont a separate line to make this a
> bit more redable.
Will do in next version. Many thanks for your comment!
> .
>
