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
