Re: [PATCH] mm/huge_memory: consolidate order-related checks into folio_split_supported()

[Wei Yang <richard.weiyang@gmail.com>]

On Fri, Nov 14, 2025 at 08:36:20PM +0100, David Hildenbrand (Red Hat) wrote:
>On 14.11.25 16:03, Wei Yang wrote:
>> On Fri, Nov 14, 2025 at 09:49:34AM +0100, David Hildenbrand (Red Hat) wrote:
>> > On 14.11.25 08:57, Wei Yang wrote:
>> > > The primary goal of the folio_split_supported() function is to validate
>> > > whether a folio is suitable for splitting and to bail out early if it is
>> > > not.
>> > > 
>> > > Currently, some order-related checks are scattered throughout the
>> > > calling code rather than being centralized in folio_split_supported().
>> > > 
>> > > This commit moves all remaining order-related validation logic into
>> > > folio_split_supported(). This consolidation ensures that the function
>> > > serves its intended purpose as a single point of failure and improves
>> > > the clarity and maintainability of the surrounding code.
>> > 
>> > Combining the EINVAL handling sounds reasonable.
>> > 
>> 
>> You mean:
>> 
>> This commit combines the EINVAL handling logic into folio_split_supported().
>> This consolidation ... ?
>
>It was not a suggestion to change, it was rather only a comment from my side
>:)
>
>[...]
>
>> > 
>> > The mapping_max_folio_order() check is new now. What is the default value of that? Is it always initialized properly?
>> > 
>> 
>> Not sure "is new now" means what?
>> 
>> Original check use mapping_large_folio_support() which calls
>> mapping_max_folio_order(). It looks not new to me.
>
>Right, but we did not actually care about the exact value.
>
>IOW, we didn't check for order <= mapping_max_folio_order() before.
>
>SO I'm just curious if that is universally fine.
>

Hi, David

I just happened to come across some code that might address your question
here.

Take a look at the function __filemap_get_folio(). It uses
mapping_max_folio_order() and mapping_min_folio_order() to determine the
appropriate folio order for page cache allocation.

Just want to share what I found.

>-- 
>Cheers
>
>David

-- 
Wei Yang
Help you, Help me