On 06/02/2020 20:49, Chris Wilson wrote:
Virtual engines are fleeting. They carry a reference count and may be freed when their last request is retired. This makes them unsuitable for the task of housing engine->retire.work so assert that it is not used. Tvrtko tracked down an instance where we did indeed violate this rule. In virtual_submit_request, we flush a completed request directly with __i915_request_submit and this causes us to queue that request on the veng's breadcrumb list and signal it. Leading us down a path where we should not attach the retire. Reported-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com> Fixes: dc93c9b69315 ("drm/i915/gt: Schedule request retirement when signaler idles") Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com> --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 3 +++ drivers/gpu/drm/i915/gt/intel_gt_requests.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 0ba524a414c6..cbad7fe722ce 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -136,6 +136,9 @@ static void add_retire(struct intel_breadcrumbs *b, struct intel_timeline *tl) struct intel_engine_cs *engine = container_of(b, struct intel_engine_cs, breadcrumbs);+ if (unlikely(intel_engine_is_virtual(engine)))+ engine = intel_virtual_engine_get_sibling(engine, 0); + intel_engine_add_retire(engine, tl); }diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.cindex 7ef1d37970f6..8a5054f21bf8 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c @@ -99,6 +99,9 @@ static bool add_retire(struct intel_engine_cs *engine, void intel_engine_add_retire(struct intel_engine_cs *engine, struct intel_timeline *tl) { + /* We don't deal well with the engine disappearing beneath us */ + GEM_BUG_ON(intel_engine_is_virtual(engine)); + if (add_retire(engine, tl)) schedule_work(&engine->retire_work); }
Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com> Regards, Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
