Re: [PATCH v2 2/2] mm/memfd_luo: keep memfd frozen until finish

[Samiullah Khawaja]

On Tue, Nov 10, 2026 at 06:58:53PM +0100, Pratyush Yadav wrote:
> From: "Pratyush Yadav (Google)" <pratyush@xxxxxxxxxx>
>
> After a memfd is retrieved, it immediately goes back into "normal"
> operation. The file comes back unfrozen, and its pages can migrate, it
> can be truncated, and so on. If the memfd is depended on by something,
> like iommufd, that can open a window for folios to move around before
> the consumer can re-establish its references.
>
> Finish is the conceptual point when a retrieved file can start to behave
> as "normal". So take an extra reference on the folios and freeze the
> memfd on retrieve until finish.
>
> Suggested-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: Pratyush Yadav (Google) <pratyush@xxxxxxxxxx>
> ---
> mm/memfd_luo.c | 87 +++++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 68 insertions(+), 19 deletions(-)

Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>