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

[Andrew Morton <akpm@linux-foundation.org>]

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?