The quilt patch titled Subject: mm/userfaultfd: reset ptes when close() for wr-protected ones has been removed from the -mm tree. Its filename was mm-userfaultfd-reset-ptes-when-close-for-wr-protected-ones.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Peter Xu peterx@redhat.com Subject: mm/userfaultfd: reset ptes when close() for wr-protected ones Date: Mon, 22 Apr 2024 09:33:11 -0400

Userfaultfd unregister includes a step to remove wr-protect bits from all the relevant pgtable entries, but that only covered an explicit UFFDIO_UNREGISTER ioctl, not a close() on the userfaultfd itself. Cover that too. This fixes a WARN trace.

The only user visible side effect is the user can observe leftover wr-protect bits even if the user close()ed on an userfaultfd when releasing the last reference of it. However hopefully that should be harmless, and nothing bad should happen even if so.

This change is now more important after the recent page-table-check patch we merged in mm-unstable (446dd9ad37d0 ("mm/page_table_check: support userfault wr-protect entries")), as we'll do sanity check on uffd-wp bits without vma context. So it's better if we can 100% guarantee no uffd-wp bit leftovers, to make sure each report will be valid.

Link: https://lore.kernel.org/all/000000000000ca4df20616a0fe16@google.com/ Fixes: f369b07c8614 ("mm/uffd: reset write protection when unregister with wp-mode") Analyzed-by: David Hildenbrand david@redhat.com Link: https://lkml.kernel.org/r/20240422133311.2987675-1-peterx@redhat.com Reported-by: syzbot+d8426b591c36b21c750e@syzkaller.appspotmail.com Signed-off-by: Peter Xu peterx@redhat.com Reviewed-by: David Hildenbrand david@redhat.com Cc: Nadav Amit nadav.amit@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/userfaultfd.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/fs/userfaultfd.c~mm-userfaultfd-reset-ptes-when-close-for-wr-protected-ones +++ a/fs/userfaultfd.c @@ -895,6 +895,10 @@ static int userfaultfd_release(struct in prev = vma; continue; } + /* Reset ptes for the whole vma range if wr-protected */ + if (userfaultfd_wp(vma)) + uffd_wp_range(vma, vma->vm_start, + vma->vm_end - vma->vm_start, false); new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS; vma = vma_modify_flags_uffd(&vmi, prev, vma, vma->vm_start, vma->vm_end, new_flags, _

Patches currently in -mm which might be from peterx@redhat.com are

mm-hugetlb-assert-hugetlb_lock-in-__hugetlb_cgroup_commit_charge.patch mm-page_table_check-support-userfault-wr-protect-entries.patch mm-gup-fix-hugepd-handling-in-hugetlb-rework.patch