This is how it should have been to begin with. It would be very bad if
we actually set PageUptodate with a UFFDIO_CONTINUE, as UFFDIO_CONTINUE
doesn't actually set/update the contents of the page, so we would be
exposing a non-zeroed page to the user.
The reason this change is being made now is because UFFDIO_CONTINUEs on
subpages definitely shouldn't set this page flag on the head page.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
mm/hugetlb.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1a7dc7b2e16c..650761cdd2f6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6097,7 +6097,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
* preceding stores to the page contents become visible before
* the set_pte_at() write.
*/
- __SetPageUptodate(page);
+ if (!is_continue)
+ __SetPageUptodate(page);
+ else
+ VM_WARN_ON_ONCE_PAGE(!PageUptodate(page), page);
/* Add shared, newly allocated pages to the page cache. */
if (vm_shared && !is_continue) {
--
2.38.0.135.g90850a2211-goog
