[to-be-updated] userfaultfd-preserve-write-protection-across-uffdio_move.patch removed from -mm tree

Andrew Morton
2026-04-15T10:17:02Z

The quilt patch titled
Subject: userfaultfd: preserve write protection across UFFDIO_MOVE
has been removed from the -mm tree. Its filename was
userfaultfd-preserve-write-protection-across-uffdio_move.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Gregory Price <gourry@gourry.net>
Subject: userfaultfd: preserve write protection across UFFDIO_MOVE
Date: Thu, 9 Apr 2026 11:28:22 -0400

move_present_ptes() unconditionally makes the destination PTE writable,
dropping uffd-wp write-protection from the source PTE.

The original intent was to follow mremap() behavior, but mremap()'s
move_ptes() preserves the source write state unconditionally.

Modify uffd to preserve the source write state and check the uffd-wp
condition of the source before setting writable on the destination.

Link: https://lkml.kernel.org/r/20260409152822.1073083-1-gourry@gourry.net
Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/userfaultfd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/userfaultfd.c~userfaultfd-preserve-write-protection-across-uffdio_move
+++ a/mm/userfaultfd.c
@@ -1123,7 +1123,10 @@ static long move_present_ptes(struct mm_
orig_dst_pte = pte_mksoft_dirty(orig_dst_pte);
if (pte_dirty(orig_src_pte))
orig_dst_pte = pte_mkdirty(orig_dst_pte);
- orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma);
+ if (pte_write(orig_src_pte))
+ orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma);
+ if (pte_uffd_wp(orig_src_pte))
+ orig_dst_pte = pte_mkuffd_wp(orig_dst_pte);
set_pte_at(mm, dst_addr, dst_pte, orig_dst_pte);

src_addr += PAGE_SIZE;
_

Patches currently in -mm which might be from gourry@gourry.net are