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    SubjectRe: [PATCH mm-unstable v1 15/20] media: pci/ivtv: remove FOLL_FORCE usage
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    On 16/11/2022 11:26, David Hildenbrand wrote:
    > FOLL_FORCE is really only for ptrace access. R/O pinning a page is
    > supposed to fail if the VMA misses proper access permissions (no VM_READ).
    >
    > Let's just remove FOLL_FORCE usage here; there would have to be a pretty
    > good reason to allow arbitrary drivers to R/O pin pages in a PROT_NONE
    > VMA. Most probably, FOLL_FORCE usage is just some legacy leftover.

    I'm pretty sure about that as well, so:

    Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

    Regards,

    Hans

    >
    > Cc: Andy Walls <awalls@md.metrocast.net>
    > Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
    > Signed-off-by: David Hildenbrand <david@redhat.com>
    > ---
    > drivers/media/pci/ivtv/ivtv-udma.c | 2 +-
    > drivers/media/pci/ivtv/ivtv-yuv.c | 5 ++---
    > 2 files changed, 3 insertions(+), 4 deletions(-)
    >
    > diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
    > index 210be8290f24..99b9f55ca829 100644
    > --- a/drivers/media/pci/ivtv/ivtv-udma.c
    > +++ b/drivers/media/pci/ivtv/ivtv-udma.c
    > @@ -115,7 +115,7 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
    >
    > /* Pin user pages for DMA Xfer */
    > err = pin_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
    > - dma->map, FOLL_FORCE);
    > + dma->map, 0);
    >
    > if (user_dma.page_count != err) {
    > IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
    > diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c b/drivers/media/pci/ivtv/ivtv-yuv.c
    > index 4ba10c34a16a..582146f8d70d 100644
    > --- a/drivers/media/pci/ivtv/ivtv-yuv.c
    > +++ b/drivers/media/pci/ivtv/ivtv-yuv.c
    > @@ -63,12 +63,11 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
    >
    > /* Pin user pages for DMA Xfer */
    > y_pages = pin_user_pages_unlocked(y_dma.uaddr,
    > - y_dma.page_count, &dma->map[0], FOLL_FORCE);
    > + y_dma.page_count, &dma->map[0], 0);
    > uv_pages = 0; /* silence gcc. value is set and consumed only if: */
    > if (y_pages == y_dma.page_count) {
    > uv_pages = pin_user_pages_unlocked(uv_dma.uaddr,
    > - uv_dma.page_count, &dma->map[y_pages],
    > - FOLL_FORCE);
    > + uv_dma.page_count, &dma->map[y_pages], 0);
    > }
    >
    > if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {

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