Re: [RESEND v7 10/29] mm: make PMD migration-entry splitting explicit

[Kiryl Shutsemau]

On Mon, Sep 14, 2026 at 05:28:00AM -0700, Usama Arif wrote:
> __split_huge_pmd() and friends take a "freeze" boolean that every caller
> has to pass and almost every caller passes as false. The name says nothing
> about what it selects, and the one thing it does select - PTE migration
> entries instead of PTE mappings - is only ever wanted by the rmap migration
> path.
> 
> Rename it to use_migration_entries, keep it private to mm/huge_memory.c,
> and add split_pmd_to_migration_entries() for try_to_migrate_one(), the only
> caller that wants it.
> 
> migrate_vma_split_unmapped_folio() also passed freeze=true, but only ever
> runs on a PMD that is already a migration entry, which the generic helper
> expands into PTE migration entries either way. Its folio_get() only existed
> to balance the put_page() that freeze=true performs, so both go.
> 
> No functional change intended.
> 
> Suggested-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Signed-off-by: Usama Arif <usama.arif@xxxxxxxxx>

Nice cleanup!

Reviewed-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov