[PATCH] mm: rmap: skip batched unmapping for UFFD vmas

[Baolin Wang <baolin.wang@linux.alibaba.com>]

As Dev reported[1], it's not ready to support batched unmapping for uffd case.
Let's still fallback to per-page unmapping for the uffd case.

[1] https://lore.kernel.org/linux-mm/20260116082721.275178-1-dev.jain@arm.com/
Reported-by: Dev Jain <dev.jain@arm.com>
Suggested-by: Barry Song <baohua@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/rmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/rmap.c b/mm/rmap.c
index f13480cb9f2e..172643092dcf 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1953,6 +1953,9 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio,
 	if (pte_unused(pte))
 		return 1;
 
+	if (userfaultfd_wp(vma))
+		return 1;
+
 	return folio_pte_batch(folio, pvmw->pte, pte, max_nr);
 }
 
-- 
2.47.3