Messages in this thread | | | Date | Wed, 16 Nov 2022 11:50:31 +0100 | From | Daniel Vetter <> | Subject | Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage |
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On Wed, Nov 16, 2022 at 11:26:55AM +0100, David Hildenbrand wrote: > FOLL_FORCE is really only for ptrace access. According to commit > 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are always > writable"), get_vaddr_frames() currently pins all pages writable as a > workaround for issues with read-only buffers. > > FOLL_FORCE, however, seems to be a legacy leftover as it predates > commit 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are > always writable"). Let's just remove it. > > Once the read-only buffer issue has been resolved, FOLL_WRITE could > again be set depending on the DMA direction. > > Cc: Hans Verkuil <hverkuil@xs4all.nl> > Cc: Marek Szyprowski <m.szyprowski@samsung.com> > Cc: Tomasz Figa <tfiga@chromium.org> > Cc: Marek Szyprowski <m.szyprowski@samsung.com> > Cc: Mauro Carvalho Chehab <mchehab@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com>
Also code I looked at while looking at follow_pfn stuff
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> --- > drivers/media/common/videobuf2/frame_vector.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c > index 542dde9d2609..062e98148c53 100644 > --- a/drivers/media/common/videobuf2/frame_vector.c > +++ b/drivers/media/common/videobuf2/frame_vector.c > @@ -50,7 +50,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > start = untagged_addr(start); > > ret = pin_user_pages_fast(start, nr_frames, > - FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, > + FOLL_WRITE | FOLL_LONGTERM, > (struct page **)(vec->ptrs)); > if (ret > 0) { > vec->got_ref = true; > -- > 2.38.1 >
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
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