Teach folio_walk_start() to recognize special pmd/pud mappings, and fail
them properly as it means there's no folio backing them.
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
mm/pagewalk.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index cd79fb3b89e5..12be5222d70e 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -753,7 +753,7 @@ struct folio *folio_walk_start(struct folio_walk *fw,
fw->pudp = pudp;
fw->pud = pud;
- if (!pud_present(pud) || pud_devmap(pud)) {
+ if (!pud_present(pud) || pud_devmap(pud) || pud_special(pud)) {
spin_unlock(ptl);
goto not_found;
} else if (!pud_leaf(pud)) {
@@ -783,7 +783,7 @@ struct folio *folio_walk_start(struct folio_walk *fw,
fw->pmdp = pmdp;
fw->pmd = pmd;
- if (pmd_none(pmd)) {
+ if (pmd_none(pmd) || pmd_special(pmd)) {
spin_unlock(ptl);
goto not_found;
} else if (!pmd_leaf(pmd)) {
--
2.45.0
