Commit a67fe41e214f ("mm: rmap: support batched unmapping for file large folios") extended batched unmapping for file folios. That also required making install_uffd_wp_ptes_if_needed() support batching, but that was left out for the time being, and correctness was maintained by stopping batching in case the VMA the folio belongs to is marked uffd-wp. Now that we have a batched version called install_uffd_wp_ptes_if_needed, simply call that. folio_unmap_pte_batch() ensures that the original state of the ptes is either all uffd or all non-uffd, so we maintain correctness. If uffd-wp bit is there, we have the following transitions of ptes after unmapping: 1) anon folio: present -> uffd-wp swap 2) file folio: present -> uffd-wp marker We must ensure that these ptes are not reprocessed by the while loop - if the batch length is less than the number of pages in the folio, then we must skip over this batch. The page_vma_mapped_walk API ensures this - check_pte() will return true only if any of [pvmw->pfn, pvmw->pfn + nr_pages) is mapped by the pte. There is no pfn underlying either a uffd-wp swap pte or a uffd-wp marker pte, so check_pte returns false and we keep skipping until we hit a present entry, which is where we want to batch from next. Signed-off-by: Dev Jain --- mm/rmap.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 20e1fb81c33fc..7a150edd96819 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1965,9 +1965,6 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, if (pte_unused(pte)) return 1; - if (userfaultfd_wp(vma)) - return 1; - /* * If unmap fails, we need to restore the ptes. To avoid accidentally * upgrading write permissions for ptes that were not originally @@ -2263,7 +2260,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * we may want to replace a none pte with a marker pte if * it's file-backed, so we don't lose the tracking info. */ - install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, pteval, 1); + install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, pteval, nr_pages); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.34.1