Re: [PATCH] mm: migrate: drop redundant anonymous statistics for file folios migration

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2024/12/5 13:00, Barry Song wrote:
> On Thu, Dec 5, 2024 at 4:54 PM Baolin Wang
> <baolin.wang@linux.alibaba.com> wrote:
>>
>> Commit 5d65c8d758f2 ("mm: count the number of anonymous THPs per size") adds
>> a new anonymous counter per THP size, however, when folio_mapping() is not NULL
>> during folio migration, it means this is not an anonymous folio, so remove the
>> redundant anonymous statistics in this case.
> 
> why? Are you sure anon folios won't call __folio_migrate_mapping()?
> folio->mapping is PAGE_MAPPING_ANON for anon folios.
> 
> static __always_inline bool folio_test_anon(const struct folio *folio)
> {
>          return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
> }

Ah, sorry for noise. This just caught my eyes when reading the code, and 
I did not think about it deeply before sending a quick patch. Thanks to 
Barry and Ying for the reminder.

Andrew, please drop this quick patch. Sorry for the trouble.