On 28/11/2022 09:18, David Hildenbrand 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! Andrew, I've resent my patch, this time with you CCed as well. Regards, Hans > > Thanks! >