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

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@huawei.com
Fixes: 816d55e417af ("userfaultfd: add UFFDIO_CONTINUE ioctl")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2480ba627aa5e3e1f4a465897f28a509a2aed32a..e070b8593b3765c998bc4d742afc862a1d42adaf 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6041,7 +6041,7 @@ 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);