Re: [PATCH mm-unstable v2 1/5] mm: consolidate anonymous folio PTE mapping into helpers

[Lance Yang <lance.yang@linux.dev>]

On 2026/2/26 09:29, Nico Pache wrote:
> The anonymous page fault handler in do_anonymous_page() open-codes the
> sequence to map a newly allocated anonymous folio at the PTE level:
> 	- construct the PTE entry
> 	- add rmap
> 	- add to LRU
> 	- set the PTEs
> 	- update the MMU cache.
> 
> Introduce a two helpers to consolidate this duplicated logic, mirroring the
> existing map_anon_folio_pmd_nopf() pattern for PMD-level mappings:
> 
> 	map_anon_folio_pte_nopf(): constructs the PTE entry, takes folio
> 	references, adds anon rmap and LRU. This function also handles the
> 	uffd_wp that can occur in the pf variant.
> 
> 	map_anon_folio_pte_pf(): extends the nopf variant to handle MM_ANONPAGES
> 	counter updates, and mTHP fault allocation statistics for the page fault
> 	path.
> 
> The zero-page read path in do_anonymous_page() is also untangled from the
> shared setpte label, since it does not allocate a folio and should not
> share the same mapping sequence as the write path. Make nr_pages = 1
> rather than relying on the variable. This makes it more clear that we
> are operating on the zero page only.
> 
> This refactoring will also help reduce code duplication between mm/memory.c
> and mm/khugepaged.c, and provides a clean API for PTE-level anonymous folio
> mapping that can be reused by future callers.
> 
> Signed-off-by: Nico Pache <npache@redhat.com>
> ---

The refactoring looks good to me.

With the change David suggested (removing nr_pages parameter from
map_anon_folio_pte_pf() and using folio_order() instead internally),

Reviewed-by: Lance Yang <lance.yang@linux.dev>