On Tue, Aug 06, 2013 at 10:43:08PM +0200, Daniel Vetter wrote: > On Wed, Jul 31, 2013 at 05:00:18PM -0700, Ben Widawsky wrote: > > This attempts to convert all the execbuf code to speak in vmas. Since > > the execbuf code is very self contained it was a nice isolated > > conversion. > > > > The meat of the code is about turning eb_objects into eb_vma, and then > > wiring up the rest of the code to use vmas instead of obj, vm pairs. > > > > Unfortunately, to do this, we must move the exec_list link from the obj > > structure. This list is reused in the eviction code, so we must also > > modify the eviction code to make this work. > > > > v2: Release table lock early, and two a 2 phase vma lookup to avoid > > having to use a GFP_ATOMIC. (Chris) > > > > Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> > > I think the leaking of preallocated vmas if execbuf fails can blow up: > 1. We call lookup_or_create and create new vmas, linked into the vma_link > chain. > 2. Later on execbuf fails somewhere (for an igt the simplest way is > probaly to use more buffers than what would fit into the gtt) and we bail > out. > -> Note that at this point we leak vmas which are on the vma_link list but > which have no gtt node allocation. > 3. Userspace dies in flames (or just quits). > 4. All buffers get their final unref and we call vma_unbind on each vma, > even the ones that do not have an allocation. > 5. hilarity ensues since vma_unbind doesn't bail out if > drm_mm_node_allocated(vma->node) == false. > > We need broken userspace to actually exercise this bug since all normal > ways for execbuf to bail out involve singals and ioclt restarting. If this > is a real bug I think we need an igt to exercise it. Forgotten to mention: Beside that error path the patch looks good. Same applies to patches 21-24 before. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
