Re: [PATCH] MAINTAINERS: add mm GUP section

David Hildenbrand
2025-05-12T13:01:39Z

On 12.05.25 14:54, Zi Yan wrote:
> On 12 May 2025, at 3:38, Vlastimil Babka wrote:
>
>> On 5/8/25 14:23, Lorenzo Stoakes wrote:
>>>>
>>>> M for "PAGE ALLOCATOR", hmmm ..., I was hoping that Vlastimil might have
>>>> capacity for that? :)
>>>
>>> Vlastimil? ;)
>>>
>>> I'd certainly support this.
>>
>> OK, can do, thanks.
>>
>>>>
>>>>
>>>>
>>>> Not 100% sure what to do with
>>>>
>>>> * include/linux/page_isolation.h
>>>> * mm/page_isolation.c
>>>>
>>>> (I hate the word "page isolation")
>>>>
>>>> They are mostly about page migration (either for alloc_contig... or memory
>>>> hotunplug). Likely they should either go to the MIGRATION section or to the
>>>> PAGE ALLOCATOR? Maybe MIGRATION makes more sense. Thoughts?
>>>
>>> I mean it explicitly relates to migrate type and migration so seems to me
>>> it ought to be in migration.
>>>
>>> Though migrate type + the machinary around it is a product of the physical
>>> page allocator (I even cover it in the 'physical memory' section of the
>>> book).
>>>
>>> I wonder if our soon-to-be page allocator maintainer Vlastimil has
>>> thoughts? ;)
>>>
>>> I'd vote for migration though to be honest.
>>
>> I checked the code briefly and although migratetypes are related to
>> migration, it seems rather page allocator code to me.
>>
>> In fact if I didn't miss these files, I would have included them when
>> proposing the PAGE ALLOCATOR section.
>> Zi Yan has a series on that topic now and is one of the R: in PAGE
>> ALLOCATOR. What do you think?
>
> I agree with Vlastimil that these two files belong to PAGE ALLOCATOR
> section. Page isolation (actually should be pageblock isolation) is
> doing work on pageblock migratetype, which IMHO is an important part
> of anti-fragmentation mechanism for page allocation.

IIRC, it's a bit confusing, because pageblock isolation as in
mm/page_isolation.c does not have a lot to do with anti-fragmentation in
reality.

All of these functions should primarily be used for memory offlining +
alloc_contig. (where we try page migration afterwards)

Anyhow, I am fine as long as these files live somewhere related :)

--
Cheers,

David / dhildenb