[Intel-gfx] [PATCH 4/4] i915: fix remap_io_sg to verify the pgprot

[Christoph Hellwig]

On Mon, May 17, 2021 at 04:09:42PM +0300, Serge Belyshev wrote:
> Christoph Hellwig <hch at lst.de> writes:
> 
> > As an ad-hoc experiment:  can you replace the call to remap_pfn_range
> > with remap_pfn_range_notrack (and export it if you build i915 modular)
> > in remap_io_sg and see if that makes any difference?
> 
> That worked, thanks -- no artifacts seen.

Looks like it is caused by the validation failure then.  Which means the
existing code is doing something wrong in its choice of the page
protection bit.  I really need help from the i915 maintainers here..