On 17.02.2017 11:08, Christian König wrote:
Am 17.02.2017 um 00:21 schrieb Nicolai Hähnle:
On 17.02.2017 00:02, Alex Deucher wrote:
On Thu, Feb 16, 2017 at 5:55 PM, Nicolai Hähnle <nhaeh...@gmail.com>
wrote:
From: Nicolai Hähnle <nicolai.haeh...@amd.com>
When the fast blit path fails while attempting to move a buffer from
RAM
to VRAM, we fall back to a CPU-based memcpy that cannot handle split
VRAM
buffers. Instead of crashing, simply fail the buffer move.
Ideally, we would teach TTM about split buffers so that the fallback
still
works in this case, but that is quite involved. So for now, apply the
simplest possible fix.
Fixes: 40361bb1704b ("drm/amdgpu: add VRAM manager v2")
Signed-off-by: Nicolai Hähnle <nicolai.haeh...@amd.com>
Possibly fixes this bug report?
https://bugzilla.kernel.org/show_bug.cgi?id=194579
It's related, but I think that report is a false positive. It does
point at code that is not too pretty, though. I've commented on that
bug report as well.
In any case, that overflow should indeed happen whenever the bug
addressed by this patch happens, but (a) this patch doesn't change
that, and (b) I'm pretty sure that the overflow reported by PaX is
benign.
Yes, agree. The bug report is indeed a false positive.
Nicolai what do you think about removing the offset from the BO
structure and only calculate it on demand?
I think it's a good idea. There are lots of uses in other drivers,
though, so a first step would be adding a helper analogous to
amdgpu_bo_gpu_offset in ttm_bo_api.h.
We may still have other bugs with split BOs, though.
Yeah, agree as well. I was also considering disabling that feature by
default for the moment if it helps with your corruption bug.
Good point, I'll give that a try as well.
Cheers,
Nicolai
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