[PATCH v6 18/26] mm/gup: Don't allow FOLL_LONGTERM pinning of FS DAX pages

[Alistair Popple]

Longterm pinning of FS DAX pages should already be disallowed by
various pXX_devmap checks. However a future change will cause these
checks to be invalid for FS DAX pages so make
folio_is_longterm_pinnable() return false for FS DAX pages.

Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f267b06..01edca9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2078,6 +2078,10 @@ static inline bool folio_is_longterm_pinnable(struct folio *folio)
 	if (folio_is_device_coherent(folio))
 		return false;
 
+	/* DAX must also always allow eviction. */
+	if (folio_is_fsdax(folio))
+		return false;
+
 	/* Otherwise, non-movable zone folios can be pinned. */
 	return !folio_is_zone_movable(folio);
 
-- 
git-series 0.9.1