On 11/05/18 15:34, Chris Wilson wrote:
Quoting Lionel Landwerlin (2018-05-11 15:28:24)
On 11/05/18 15:18, Chris Wilson wrote:
Quoting Lionel Landwerlin (2018-05-11 15:14:13)
My understanding of the virtual memory addressing from the GPU is limited...
But how can the GPU poke at the kernel's allocated data?
I thought we mapped into the GPU's address space only what is allocated
through gem.
Correct. The HW should only be accessing the pages through the GTT and
the GTT should only contain known pages (or a pointer to the scratch
page). There is maybe a hole where we are freeing the memory before
the HW has finished using it (still writing through stale TLB and
whatnot even though the system has reallocated the pages), but other
than that quite, quite scary. Hence this awooga.
Oh right...
So this patch is a backup if you previous one won't fix the issue we see
on CI?
Yes. Try to fix, it we can't, we disable until we can. It may also be
purely coincidental that we've seen this bug a few times around the same
test only on this machine... ;)
-Chris
Trying on a laptop.
