On 14.12.2016 15:56, Christian König wrote: > Am 14.12.2016 um 15:22 schrieb Nicolai Hähnle: >> On 13.12.2016 10:48, Christian König wrote: >>>>>> The attached patch has fixed these crashes for me so far, but it's >>>>>> very heavy-handed: it collects all page table shadows and the page >>>>>> directory shadow and adds them all to the reservations for the >>>>>> callers >>>>>> of amdgpu_vm_update_page_directory. >>>>> >>>>> That is most likely just a timing change, cause the shadows should end >>>>> up in the duplicates list anyway. So the patch shouldn't have any >>>>> effect. >>>> >>>> Okay, so the reason for the remaining crash is still unclear at least >>>> for me. >>> >>> Yeah, that's a really good question. Can you share the call stack of the >>> problem once more? >> >> Pretty sure I found the root cause now. amdgpu_vm_validate_pt_bos >> relies on the eviction counter to be able to skip the validation of >> the page tables. >> >> However, moving the shadow page tables out from mem_type TT to SYSTEM >> doesn't count as an eviction (it just unbinds the mapping in the GTT). >> >> Clearly, that's a problem. > > Nice catch! > >> The quick fix is to skip the num_evictions check in >> amdgpu_vm_validate_pt_bos. That has worked for me so far. >> >> The next best thing is to add an unbind counter in addition to the >> eviction counter that gets incremented whenever a BO is unbound (so it >> counts a superset of what the eviction counter counts), and then check >> that instead of the eviction counter. > > Well to complicated, we should just make the eviction counter handle > both events. > > That's also the original meaning of it, e.g. unbinding pages from the > GART is some sort of eviction as well in this case. I'll do that then. The counter does get exposed to user-space, implementing the GL_NVX_gpu_memory_info extension, so it's a change of behavior there. But that extension is pretty under-specified anyway, and it does make sense to count getting kicked out of GART as an eviction. Cheers, Nicolai > > Regards, > Christian. > >> >> Cheers, >> Nicolai >> _______________________________________________ >> amd-gfx mailing list >> amd-gfx at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx > >
