[PATCH 05/19] mm/gup: Detect huge pfnmap entries in gup-fast

Peter Xu
2024-08-09T16:09:29Z

Since gup-fast doesn't have the vma reference, teach it to detect such huge
pfnmaps by checking the special bit for pmd/pud too, just like ptes.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/gup.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index d19884e097fd..a49f67a512ee 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3038,6 +3038,9 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
return 0;

+ if (pmd_special(orig))
+ return 0;
+
if (pmd_devmap(orig)) {
if (unlikely(flags & FOLL_LONGTERM))
return 0;
@@ -3082,6 +3085,9 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, flags & FOLL_WRITE))
return 0;

+ if (pud_special(orig))
+ return 0;
+
if (pud_devmap(orig)) {
if (unlikely(flags & FOLL_LONGTERM))
return 0;
--
2.45.0