Messages in this thread | | | Subject | Re: [PATCH v8 17/26] media/v4l2-core: set pages dirty upon releasing DMA buffers | From | John Hubbard <> | Date | Mon, 9 Dec 2019 21:48:24 -0800 |
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On 12/9/19 4:56 PM, Andrew Morton wrote: > On Mon, 9 Dec 2019 14:53:35 -0800 John Hubbard <jhubbard@nvidia.com> wrote: > >> After DMA is complete, and the device and CPU caches are synchronized, >> it's still required to mark the CPU pages as dirty, if the data was >> coming from the device. However, this driver was just issuing a >> bare put_page() call, without any set_page_dirty*() call. >> >> Fix the problem, by calling set_page_dirty_lock() if the CPU pages >> were potentially receiving data from the device. >> >> Reviewed-by: Christoph Hellwig <hch@lst.de> >> Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> >> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> >> Cc: <stable@vger.kernel.org> > > What are the user-visible effects of this change?
I'll have to defer to Hans or other experts, because I merely spotted this by reading the code.
> > As it's cc:stable I'd normally send this to Linus within 1-2 weeks, or > sooner. Please confirm that this is a standalone fix, independent of > the rest of this series. > >
Yes, this is a stand-alone fix. Of course, as part of this series, the put_page() gets converted to put_user_pages_dirty() in the next patch, and that in turn gets renamed to unpin_user_pages_dirty() in a later patch. Just so we keep that in mind when moving patches around.
thanks, -- John Hubbard NVIDIA
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