Quoting Mika Kuoppala (2018-03-09 13:17:09) > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > > > With a series of unusual events (a sequence of interrupted request > > allocations), we could gradually leak the ring->space estimate by > > unwinding the ring back to the start of the request, but not return the > > used space back to the ring. Eventually and with great misfortune, it > > would be possible to trigger ring->space exhaustion with no requests on > > the ring. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_request.c | 1 + > > drivers/gpu/drm/i915/intel_ringbuffer.c | 1 + > > 2 files changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c > > index d437beac3969..efa9ee557f31 100644 > > --- a/drivers/gpu/drm/i915/i915_request.c > > +++ b/drivers/gpu/drm/i915/i915_request.c > > @@ -798,6 +798,7 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx) > > > > err_unwind: > > rq->ring->emit = rq->head; > > + intel_ring_update_space(rq->ring); > > > > /* Make sure we didn't add ourselves to external state before freeing */ > > GEM_BUG_ON(!list_empty(&rq->active_list)); > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c > > index 1d599524a759..88eeb64041ae 100644 > > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c > > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > > @@ -1593,6 +1593,7 @@ static noinline int wait_for_space(struct intel_ring *ring, unsigned int bytes) > > if (intel_ring_update_space(ring) >= bytes) > > return 0; > > > > + GEM_BUG_ON(list_empty(&ring->request_list)); > > At some point, after long series of misfortunate events, we > will add a first request and need actually wait a space for this > and then we kaboom in here? That's the experience. However, I don't think this patch helps because we do the intel_ring_update_space() here inside wait_for_space anyway, so it should come out in the wash so long as we aren't corrupting the ring space calculation. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
