Quoting Lionel Landwerlin (2018-05-11 16:58:27)
On 11/05/18 16:51, Chris Wilson wrote:
Quoting Lionel Landwerlin (2018-05-11 16:43:02)
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. -Chris
I managed to reproduce a kasan backtrace on the same test. So it's not just the CI machine.
But I can't even startup a gdm on that machine with drm-tip. So maybe there is some much more broken...
Don't leave us in suspense...
Your first patch (check that OA is actually disabled) seems to get rid of the issue on my machine. Thanks a lot a for finding that!
Care to add a t-b and we'll close the bug? -Chris