Re: [PATCHv2 2/5] mm/rmap: Fix a mlock race condition in folio_referenced_one()

[Shakeel Butt]

On Fri, Sep 19, 2025 at 01:40:33PM +0100, Kiryl Shutsemau wrote:
> From: Kiryl Shutsemau <kas@xxxxxxxxxx>
> 
> The mlock_vma_folio() function requires the page table lock to be held
> in order to safely mlock the folio. However, folio_referenced_one()
> mlocks a large folios outside of the page_vma_mapped_walk() loop where
> the page table lock has already been dropped.
> 
> Rework the mlock logic to use the same code path inside the loop for
> both large and small folios.
> 
> Use PVMW_PGTABLE_CROSSED to detect when the folio is mapped across a
> page table boundary.
> 
> Signed-off-by: Kiryl Shutsemau <kas@xxxxxxxxxx>

Nice, this simplifies the code.

Reviewed-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>