On Wed, Nov 01, 2017 at 02:08:37PM +0000, Chris Wilson wrote: > Quoting Daniel Vetter (2017-10-31 16:38:26) > > On Tue, Oct 31, 2017 at 03:28:01PM +0200, Ville Syrjälä wrote: > > > On Tue, Oct 31, 2017 at 11:55:35AM +0000, Chris Wilson wrote: > > > > To acquire all modeset locks requires a ww_ctx to be allocated. As this > > > > is the legacy path and the allocation small, to reduce the changes > > > > required (and complex untested error handling) to the legacy drivers, we > > > > simply assume that the allocation succeeds. At present, it relies on the > > > > too-small-to-fail rule, but syzbot found that by injecting a failure > > > > here we would hit the WARN. Document that this allocation must succeed > > > > with __GFP_NOFAIL. > > > > Note that for atomic drivers at least all the core/helper paths are fixed > > up correctly. But e.g. i915 has still plenty of callsites in its own code, > > mostly debugfs. > > > > > > Reported-by: syzbot (syzkaller) > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > > > > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > Applied, thanks. > > Just curious as it hasn't shown up in drm-tip yet, so I'm worrying if it > found a crack to hide in. Indeed it found a crack :-/ Pushed now, thanks for reminding me. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
