[PATCH] mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic_pte

[Miaohe Lin]

In MCOPY_ATOMIC_CONTINUE case with a non-shared VMA, pages in the page
cache are installed in the ptes. But hugepage_add_new_anon_rmap is called
for them mistakenly because they're not vm_shared. This will corrupt the
page->mapping used by page cache code.

Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8d379e03f672..b232e1508e49 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6038,7 +6038,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 	if (!huge_pte_none_mostly(huge_ptep_get(dst_pte)))
 		goto out_release_unlock;
 
-	if (vm_shared) {
+	if (page_in_pagecache) {
 		page_dup_file_rmap(page, true);
 	} else {
 		ClearHPageRestoreReserve(page);
-- 
2.23.0