Re: [Patch v3 2/2] mm/huge_memory: merge uniform_split_supported() and non_uniform_split_supported()

[Zi Yan <ziy@nvidia.com>]

On 21 Nov 2025, at 13:39, Andrew Morton wrote:

> On Fri, 21 Nov 2025 12:00:51 -0500 Zi Yan <ziy@nvidia.com> wrote:
>
>> On 21 Nov 2025, at 11:50, Andrew Morton wrote:
>>
>>> On Fri, 21 Nov 2025 09:59:42 -0500 Zi Yan <ziy@nvidia.com> wrote:
>>>
>>>>>
>>>>> 2. A further cleanup attempt:
>>>>>
>>>>> https://lkml.kernel.org/r/136E8B1C-3352-412C-8038-627F5CC8A112@nvidia.com
>>>>>
>>>>> This one is the related mail.
>>>>>
>>>>> I proposed one version in
>>>>>
>>>>> http://lkml.kernel.org/r/20251114075703.10434-1-richard.weiyang@gmail.com
>>>>>
>>>>> But it is not proper, will do follow up work later.
>>>>
>>>> Please refrain from sending more patches related to __folio_split() and its
>>>> related functions until the above hotfix is merged.
>>>
>>> You're referring to
>>> https://lkml.kernel.org/r/20251119235302.24773-1-richard.weiyang@gmail.com?
>>
>> Yes.
>>
>>>
>>>> I also have an ongoing
>>>> cleanup patchset[1] and want to get it in before any other changes.
>>>
>>> I remain unclear on the status of this patchset.  Is it considered good
>>> to upstream or is additional work required?
>>
>> I am still having a discussion with David Hildenbrand about it and hopefully
>> get it sorted out soon. The reason is that the above hotfix is good for
>> backport but future user of folio_split_supported() can still dereference
>> a NULL folio->mapping unless they check folio->mapping != NULL beforehand.
>> I would like to avoid that by refactoring folio_split_support().
>>
>> Wei’s further cleanup patch can come after my refactoring by just moving
>> a code hunk above.
>>
>
> This is coming down to the wire.  I'm considering dropping
>
> mm-huge_memory-introduce-enum-split_type-for-clarity.patch
> mm-huge_memory-introduce-enum-split_type-for-clarity-fix.patch
> mm-huge_memory-merge-uniform_split_supported-and-non_uniform_split_supported.patch
>
> and
>
> mm-huge_memoryc-introduce-folio_split_unmapped.patch
> mm-huge_memoryc-introduce-folio_split_unmapped-v2.patch
> mm-huge_memoryc-introduce-folio_split_unmapped-v2-fix.patch
> mm-huge_memoryc-introduce-folio_split_unmapped-v2-fix-fix.patch
>
> and we can revisit after the upcoming merge window.  Thoughts?

These patches are fine as is. The patch I asked Wei to hold on sending
is “[PATCH] mm/huge_memory: consolidate order-related checks into
folio_split_supported()”[1]. The current mm-new, mm-unstable trees
look good to me. Sorry if it was not clear.


[1] https://lore.kernel.org/linux-mm/20251114075703.10434-1-richard.weiyang@gmail.com/

Best Regards,
Yan, Zi