[PATCH 5.15-stable] mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic_pte

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From: Miaohe Lin <linmiaohe@xxxxxxxxxx>

commit ab74ef708dc51df7cf2b8a890b9c6990fac5c0c6 upstream.

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.

Link: https://lkml.kernel.org/r/20220712130542.18836-1-linmiaohe@xxxxxxxxxx
Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 405793b8cf0d..d61b665c45d6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5371,7 +5371,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 	if (!huge_pte_none(huge_ptep_get(dst_pte)))
 		goto out_release_unlock;
 
-	if (vm_shared) {
+	if (page_in_pagecache) {
 		page_dup_rmap(page, true);
 	} else {
 		ClearHPageRestoreReserve(page);
-- 
2.37.2.672.g94769d06f0-goog




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