Re: [PATCH v3 09/18] mm/huge_memory: move anon_vma and filemap management into split helpers

[Kairui Song]

On Thu, Aug 27, 2026 at 06:36:18PM +0800, David Hildenbrand (Arm) wrote:
> On 8/20/26 20:55, Kairui Song via B4 Relay wrote:
> > From: Kairui Song <kasong@xxxxxxxxxxx>
> > 
> > Only anon split needs vma info, and only file split needs the filemap
> > handling. Move the related code into separate helpers so they are
> > genuinely more self-contained.
> 
> This patch seems to do more than that, like relocating the
> folio_expected_ref_count check (and duplicating it, which is not so nice).

We can keep it where it is right now, but this patch is moving the
anon_vma_lock_write and i_mmap_lock_read into the two anon / file
helpers seperately, so keeping the folio_expected_ref_count check
outside and before the helper call will cause a potential higher
false positive / negative rate of this check? Leads to unnecessary
call to unmap_folio.

How about moving the folio_expected_ref_count check into
unmap_folio since the purpose of the ref check is to avoid
unnecessary unmap? No more duplication that way.