On Tue, Jul 16, 2019 at 07:04:52PM +0200, Michel Dänzer wrote: > On 2019-07-16 6:35 p.m., Jason Gunthorpe wrote: > > On Tue, Jul 16, 2019 at 06:31:09PM +0200, Michel Dänzer wrote: > >> On 2019-07-15 7:25 p.m., Jason Gunthorpe wrote: > >>> On Mon, Jul 15, 2019 at 06:51:06PM +0200, Michel Dänzer wrote: > >>>> > >>>> With a KASAN enabled kernel built from amd-staging-drm-next, the > >>>> attached use-after-free is pretty reliably detected during a piglit gpu run. > >>> > >>> Does this branch you are testing have the hmm.git merged? I think from > >>> the name it does not? > >> > >> Indeed, no. > >> > >> > >>> Use after free's of this nature were something that was fixed in > >>> hmm.git.. > >>> > >>> I don't see an obvious way you can hit something like this with the > >>> new code arrangement.. > >> > >> I tried merging the hmm-devmem-cleanup.4 changes[0] into my 5.2.y + > >> drm-next for 5.3 kernel. While the result didn't hit the problem, all > >> GL_AMD_pinned_memory piglit tests failed, so I suspect the problem was > >> simply avoided by not actually hitting the HMM related functionality. > >> > >> It's possible that I made a mistake in merging the changes, or that I > >> missed some other required changes. But it's also possible that the HMM > >> changes broke the corresponding user-pointer functionality in amdgpu. > > > > Not sure, this was all Tested by the AMD team so it should work, I > > hope. > > It can't, due to the issue pointed out by Linus in the "drm pull for > 5.3-rc1" thread: DRM_AMDGPU_USERPTR still depends on ARCH_HAS_HMM, which > no longer exists, so it can't be enabled. Somehow that merge resolution got missed, but I think the AMD folks must have included it when they did their merge & test. Jason
