Messages in this thread | | | Date | Mon, 28 Nov 2022 09:18:47 +0100 | Subject | Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage | From | David Hildenbrand <> |
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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@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> >>> --- >>> 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!
-- Thanks,
David / dhildenb
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