Re: [PATCH 1/2] mm/huge_memory: introduce __split_folio_and_update_stats() to consolidate split task

["David Hildenbrand (Red Hat)" <david@kernel.org>]

On 04.11.25 00:37, Wei Yang wrote:
> On Mon, Nov 03, 2025 at 05:20:02PM +0100, David Hildenbrand (Red Hat) wrote:
>> On 01.11.25 01:29, Wei Yang wrote:
>>> The folio splitting process involves several related tasks that are
>>> executed together:
>>>
>>>       Adjusting memcg (memory control group) accounting.
>>>       Updating page owner tracking.
>>>       Splitting the folio to the target size (new_order).
>>>       Updating necessary folio statistics.
>>>
>>> This commit introduces the new helper function,
>>> __split_folio_and_update_stats(), to gather all these tasks. This
>>> consolidation improves modularity and is a necessary preparation step
>>> for further cleanup and simplification of the surrounding folio
>>> splitting logic.
>>>
>>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>>> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>>> Cc: Zi Yan <ziy@nvidia.com>
>>> ---
>>>    mm/huge_memory.c | 28 +++++++++++++++++-----------
>>>    1 file changed, 17 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>> index c37fe6ad0c96..abde0f1aa8ff 100644
>>> --- a/mm/huge_memory.c
>>> +++ b/mm/huge_memory.c
>>> @@ -3567,6 +3567,22 @@ static void __split_folio_to_order(struct folio *folio, int old_order,
>>>    		ClearPageCompound(&folio->page);
>>>    }
>>> +static void __split_folio_and_update_stats(struct folio *folio, int old_order,
>>> +		int new_order, bool is_anon)
>>
>> Is there any good reason we want to pass things like "is_anon" instead of
>> just querying it in that helper?
>>
> 
> The reason is during split, folio's attribute will not change. In
> __split_unmapped_folio() it is queried and set as const.
> 
> Otherwise we need to query it on each split.

These checks are extremely cheap. Do we really care?

-- 
Cheers

David