On Fri, Dec 04, 2015 at 05:52:43PM +0200, Mika Kuoppala wrote: > If the context being destroyed have been last in the ring, > the ring->last_context will be left dangling. > > Later, the unpinning will happen for last_context, and as it > was already freed, we corrupt memory by doing so. > > This regression introduced in > commit 6d65ba943a2d1e4292a07ca7ddb6c5138b9efa5d > Author: Nick Hoath <nicholas.hoath@xxxxxxxxx> > Date: Tue Dec 1 14:48:57 2015 +0000 > > drm/i915: Extend LRC pinning to cover GPU context writeback > > Fix this by clearing the ring->last_context if it is the > context being destroyed. > > Cc: Nick Hoath <nicholas.hoath@xxxxxxxxx> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > Cc: David Gordon <david.s.gordon@xxxxxxxxx> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Alex Dai <yu.dai@xxxxxxxxx> > Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_lrc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c > index c3504a0..5c26fde 100644 > --- a/drivers/gpu/drm/i915/intel_lrc.c > +++ b/drivers/gpu/drm/i915/intel_lrc.c > @@ -2432,6 +2432,9 @@ intel_lr_context_clean_ring(struct intel_context *ctx, > } > } > > + if (ring->last_context == ctx) > + ring->last_context = NULL; This should be plainly impossible. ring->last_context better have a reference on it, and if that's not the case we need to fix that. Nick, can you please take a look into this asap? It's causing a BAT regression so meanwhile I'll revert your patch. Thanks, Daniel > + > WARN_ON(ctx->engine[ring->id].pin_count); > intel_ringbuffer_free(ringbuf); > drm_gem_object_unreference(&ctx_obj->base); > -- > 2.5.0 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
