Unverified Commit 7b0b68b2 authored Apr 23, 2026 by David Carlier Committed by Pasha Tatashin May 04, 2026

mm/memfd_luo: document preservation of file seals



Commit 8a552d68 ("mm: memfd_luo: preserve file seals") started
preserving file seals across live update and restoring them via
memfd_add_seals() on retrieve, but the DOC header was not updated and
still listed seals under "Non-Preserved Properties" as being unsealed
on restore.

Move the Seals entry to the "Preserved Properties" section and describe
the actual behavior, including the MEMFD_LUO_ALL_SEALS restriction that
both preserve and retrieve enforce.

Fixes: 8a552d68 ("mm: memfd_luo: preserve file seals")
Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260423125648.152113-2-devnexen@gmail.com


Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>

parent d581fc99

mm/memfd_luo.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -50,6 +50,11 @@
		* memfds are always opened with ``O_RDWR`` and ``O_LARGEFILE``. This property
		* is maintained.
		*
		* Seals
		* File seals set on the memfd are preserved and re-applied on restore.
		* Only seals known to this LUO version (see ``MEMFD_LUO_ALL_SEALS``) may
		* be present; preservation fails with ``-EOPNOTSUPP`` otherwise.
		*
		* Non-Preserved Properties
		* ========================
		*
		@@ -61,10 +66,6 @@
		* A memfd can be created with the ``MFD_CLOEXEC`` flag that sets the
		* ``FD_CLOEXEC`` on the file. This flag is not preserved and must be set
		* again after restore via ``fcntl()``.
		*
		* Seals
		* File seals are not preserved. The file is unsealed on restore and if
		* needed, must be sealed again via ``fcntl()``.
		*/

		#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt