On Mon, Nov 28, 2022 at 5:19 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 28.11.22 09:17, Hans Verkuil wrote: > > Hi David, > > > > On 27/11/2022 11:35, David Hildenbrand wrote: > >> On 16.11.22 11:26, 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@xxxxxxxxx> > >>> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > >>> Cc: Tomasz Figa <tfiga@xxxxxxxxxxxx> > >>> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > >>> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > >>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> > >>> --- > >>> 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; > >> > >> > >> Hi Andrew, > >> > >> see the discussion at [1] regarding a conflict and how to proceed with > >> upstreaming. The conflict would be easy to resolve, however, also > >> the patch description doesn't make sense anymore with [1]. > > > > Might it be easier and less confusing if you post a v2 of this series > > with my patch first? That way it is clear that 1) my patch has to come > > first, and 2) that it is part of a single series and should be merged > > by the mm subsystem. > > > > Less chances of things going wrong that way. > > > > Just mention in the v2 cover letter that the first patch was added to > > make it easy to backport that fix without being hampered by merge > > conflicts if it was added after your frame_vector.c patch. > > Yes, that's the way I would naturally do, it, however, Andrew prefers > delta updates for minor changes. > > @Andrew, whatever you prefer! > > Thanks! > However you folks proceed with taking this patch, feel free to add my Acked-by. Thanks! Best regards, Tomasz > -- > Thanks, > > David / dhildenb >