Re: [PATCH v5 02/16] iov_iter: add iterator type for dmabuf maps

[Anuj gupta]

On Sat, Aug 1, 2026 at 9:19 PM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote:
> @@ -841,7 +857,7 @@ static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
>
>  unsigned long iov_iter_alignment(const struct iov_iter *i)
>  {
> -       if (likely(iter_is_ubuf(i))) {
> +       if (likely(iter_is_ubuf(i)) || iov_iter_is_dmabuf_map(i)) {
>                 size_t size = i->count;
>                 if (size)
>                         return ((unsigned long)i->ubuf + i->iov_offset) | size;

dmabuf_map shares the same union slot as ubuf, so this reads the map
pointer as a user address. gap_alignment() below already returns 0
correctly for dmabuf - this should too. Checked the rest of this patch
(advance/revert/restore) - none of them dereference the union pointer
for dmabuf, so it's isolated to this one spot. Doesn't affect the
current series, nothing reaches this with a dmabuf iter yet.

> @@ -872,7 +888,7 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
>         size_t size = i->count;
>         unsigned k;
>
> -       if (iter_is_ubuf(i))
> +       if (iter_is_ubuf(i) || iov_iter_is_dmabuf_map(i))
>                 return 0;