Quoting Tvrtko Ursulin (2020-02-28 13:20:24)
>
> On 28/02/2020 13:10, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2020-02-28 12:59:37)
> >>
> >> On 28/02/2020 12:31, Chris Wilson wrote:
> >>> Quoting Tvrtko Ursulin (2020-02-28 12:10:23)
> >>>>
> >>>> On 27/02/2020 08:57, Chris Wilson wrote:
> >>>>> An odd and highly unlikely path caught us out. On delayed submission
> >>>>> (due to an asynchronous reset handler), we poked the priority_hint and
> >>>>> kicked the tasklet. However, we had already marked the device as wedged
> >>>>> and swapped out the tasklet for a no-op. The result was that we never
> >>>>> cleared the priority hint and became upset when we later checked.
> >>>>>
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481822445us : __i915_subtests: Running intel_execlists_live_selftests/live_error_interrupt
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481822472us : __engine_unpark: 0000:00:02.0 rcs0:
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481822491us : __gt_unpark: 0000:00:02.0
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481823220us : execlists_context_reset: 0000:00:02.0 rcs0: context:f4ee reset
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481824830us : __intel_context_active: 0000:00:02.0 rcs0: context:f51b active
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481825258us : __intel_context_do_pin: 0000:00:02.0 rcs0: context:f51b pin ring:{start:00006000, head:0000, tail:0000}
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481825311us : __i915_request_commit: 0000:00:02.0 rcs0: fence f51b:2, current 0
> >>>>> <0> [574.303565] i915_sel-6278 2d..1 481825347us : __i915_request_submit: 0000:00:02.0 rcs0: fence f51b:2, current 0
> >>>>> <0> [574.303565] i915_sel-6278 2d..1 481825363us : trace_ports: 0000:00:02.0 rcs0: submit { f51b:2, 0:0 }
> >>>>> <0> [574.303565] i915_sel-6278 2.... 481826809us : __intel_context_active: 0000:00:02.0 rcs0: context:f51c active
> >>>>> <0> [574.303565] <idle>-0 7d.h2 481827326us : cs_irq_handler: 0000:00:02.0 rcs0: CS error: 1
> >>>>> <0> [574.303565] <idle>-0 7..s1 481827377us : process_csb: 0000:00:02.0 rcs0: cs-irq head=3, tail=4
> >>>>> <0> [574.303565] <idle>-0 7..s1 481827379us : process_csb: 0000:00:02.0 rcs0: csb[4]: status=0x10000001:0x00000000
> >>>>> <0> [574.305593] <idle>-0 7..s1 481827385us : trace_ports: 0000:00:02.0 rcs0: promote { f51b:2*, 0:0 }
> >>>>> <0> [574.305611] <idle>-0 7..s1 481828179us : execlists_reset: 0000:00:02.0 rcs0: reset for CS error
> >>>>> <0> [574.305611] i915_sel-6278 2.... 481828284us : __intel_context_do_pin: 0000:00:02.0 rcs0: context:f51c pin ring:{start:00007000, head:0000, tail:0000}
> >>>>> <0> [574.305611] i915_sel-6278 2.... 481828345us : __i915_request_commit: 0000:00:02.0 rcs0: fence f51c:2, current 0
> >>>>> <0> [574.305611] <idle>-0 7dNs2 481847823us : __i915_request_unsubmit: 0000:00:02.0 rcs0: fence f51b:2, current 1
> >>>>> <0> [574.305611] <idle>-0 7dNs2 481847857us : execlists_hold: 0000:00:02.0 rcs0: fence f51b:2, current 1 on hold
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 481847863us : intel_engine_reset: 0000:00:02.0 rcs0: flags=4
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 481847945us : execlists_reset_prepare: 0000:00:02.0 rcs0: depth<-1
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 481847946us : intel_engine_stop_cs: 0000:00:02.0 rcs0:
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 538584284us : intel_engine_stop_cs: 0000:00:02.0 rcs0: timed out on STOP_RING -> IDLE
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 538584347us : __intel_gt_reset: 0000:00:02.0 engine_mask=1
> >>>>> <0> [574.305611] <idle>-0 7.Ns1 538584406us : execlists_reset_rewind: 0000:00:02.0 rcs0:
> >>>>> <0> [574.305611] <idle>-0 7dNs2 538585050us : __i915_request_reset: 0000:00:02.0 rcs0: fence f51b:2, current 1 guilty? yes
> >>>>> <0> [574.305611] <idle>-0 7dNs2 538585063us : __execlists_reset: 0000:00:02.0 rcs0: replay {head:0000, tail:0068}
> >>>>> <0> [574.306565] <idle>-0 7.Ns1 538588457us : intel_engine_cancel_stop_cs: 0000:00:02.0 rcs0:
> >>>>> <0> [574.306565] <idle>-0 7dNs2 538588462us : __i915_request_submit: 0000:00:02.0 rcs0: fence f51c:2, current 0
> >>>>> <0> [574.306565] <idle>-0 7dNs2 538588471us : trace_ports: 0000:00:02.0 rcs0: submit { f51c:2, 0:0 }
> >>>>> <0> [574.306565] <idle>-0 7.Ns1 538588474us : execlists_reset_finish: 0000:00:02.0 rcs0: depth->1
> >>>>> <0> [574.306565] kworker/-202 2.... 538588755us : i915_request_retire: 0000:00:02.0 rcs0: fence f51c:2, current 2
> >>>>> <0> [574.306565] ksoftirq-46 7..s. 538588773us : process_csb: 0000:00:02.0 rcs0: cs-irq head=11, tail=1
> >>>>> <0> [574.306565] ksoftirq-46 7..s. 538588774us : process_csb: 0000:00:02.0 rcs0: csb[0]: status=0x10000001:0x00000000
> >>>>> <0> [574.306565] ksoftirq-46 7..s. 538588776us : trace_ports: 0000:00:02.0 rcs0: promote { f51c:2!, 0:0 }
> >>>>> <0> [574.306565] ksoftirq-46 7..s. 538588778us : process_csb: 0000:00:02.0 rcs0: csb[1]: status=0x10000018:0x00000020
> >>>>> <0> [574.306565] ksoftirq-46 7..s. 538588779us : trace_ports: 0000:00:02.0 rcs0: completed { f51c:2!, 0:0 }
> >>>>> <0> [574.306565] kworker/-202 2.... 538588826us : intel_context_unpin: 0000:00:02.0 rcs0: context:f51c unpin
> >>>>> <0> [574.306565] i915_sel-6278 6.... 538589663us : __intel_gt_set_wedged.part.32: 0000:00:02.0 start
> >>>>> <0> [574.306565] i915_sel-6278 6.... 538589667us : execlists_reset_prepare: 0000:00:02.0 rcs0: depth<-0
> >>>>> <0> [574.306565] i915_sel-6278 6.... 538589710us : intel_engine_stop_cs: 0000:00:02.0 rcs0:
> >>>>> <0> [574.306565] i915_sel-6278 6.... 538589732us : execlists_reset_prepare: 0000:00:02.0 bcs0: depth<-0
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589733us : intel_engine_stop_cs: 0000:00:02.0 bcs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589757us : execlists_reset_prepare: 0000:00:02.0 vcs0: depth<-0
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589758us : intel_engine_stop_cs: 0000:00:02.0 vcs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589771us : execlists_reset_prepare: 0000:00:02.0 vcs1: depth<-0
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589772us : intel_engine_stop_cs: 0000:00:02.0 vcs1:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589778us : execlists_reset_prepare: 0000:00:02.0 vecs0: depth<-0
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589780us : intel_engine_stop_cs: 0000:00:02.0 vecs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538589786us : __intel_gt_reset: 0000:00:02.0 engine_mask=ff
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538591175us : execlists_reset_cancel: 0000:00:02.0 rcs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538591970us : execlists_reset_cancel: 0000:00:02.0 bcs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538591982us : execlists_reset_cancel: 0000:00:02.0 vcs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538591996us : execlists_reset_cancel: 0000:00:02.0 vcs1:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538592759us : execlists_reset_cancel: 0000:00:02.0 vecs0:
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538592977us : execlists_reset_finish: 0000:00:02.0 rcs0: depth->0
> >>>>> <0> [574.307591] i915_sel-6278 6.N.. 538592996us : execlists_reset_finish: 0000:00:02.0 bcs0: depth->0
> >>>>> <0> [574.307591] i915_sel-6278 6.N.. 538593023us : execlists_reset_finish: 0000:00:02.0 vcs0: depth->0
> >>>>> <0> [574.307591] i915_sel-6278 6.N.. 538593037us : execlists_reset_finish: 0000:00:02.0 vcs1: depth->0
> >>>>> <0> [574.307591] i915_sel-6278 6.N.. 538593051us : execlists_reset_finish: 0000:00:02.0 vecs0: depth->0
> >>>>> <0> [574.307591] i915_sel-6278 6.... 538593407us : __intel_gt_set_wedged.part.32: 0000:00:02.0 end
> >>>>> <0> [574.307591] kworker/-210 7d..1 551958381us : execlists_unhold: 0000:00:02.0 rcs0: fence f51b:2, current 2 hold release
> >>>>> <0> [574.307591] i915_sel-6278 0.... 559490788us : i915_request_retire: 0000:00:02.0 rcs0: fence f51b:2, current 2
> >>>>> <0> [574.307591] i915_sel-6278 0.... 559490793us : intel_context_unpin: 0000:00:02.0 rcs0: context:f51b unpin
> >>>>> <0> [574.307591] i915_sel-6278 0.... 559490798us : __engine_park: 0000:00:02.0 rcs0: parked
> >>>>> <0> [574.307591] i915_sel-6278 0.... 559490982us : __intel_context_retire: 0000:00:02.0 rcs0: context:f51c retire runtime: { total:30004ns, avg:30004ns }
> >>>>> <0> [574.307591] i915_sel-6278 0.... 559491372us : __engine_park: __engine_park:261 GEM_BUG_ON(engine->execlists.queue_priority_hint != (-((int)(~0U >> 1)) - 1))
> >>>>>
> >>>>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >>>>> ---
> >>>>> drivers/gpu/drm/i915/gt/intel_lrc.c | 3 +++
> >>>>> 1 file changed, 3 insertions(+)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>>>> index 39b0125b7143..35c5cf786726 100644
> >>>>> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>>>> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> >>>>> @@ -3724,7 +3724,10 @@ static void execlists_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> >>>>>
> >>>>> static void nop_submission_tasklet(unsigned long data)
> >>>>> {
> >>>>> + struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
> >>>>> +
> >>>>> /* The driver is wedged; don't process any more events. */
> >>>>> + WRITE_ONCE(engine->execlists.queue_priority_hint, INT_MIN);
> >>>>
> >>>> Why from the tasklet and not the place which clears the queue?
> >>>
> >>> That would be the list_move within nop_submit_request()
> >>> [i915_request_submit]
> >>>
> >>> I chose this tasklet as we do the reset in execlists_submission_tasklet()
> >>> on clearing the queue there, and so thought this was analogous.
> >>
> >> It actually looks to me it is unhold which is causing this, so it is not
> >> true we never reset the hint, it was probably overwritten:
> >>
> >> execlists_reset_cancel, at the end of it:
> >>
> >> /* Remaining _unready_ requests will be nop'ed when submitted */
> >>
> >> execlists->queue_priority_hint = INT_MIN;
> >>
> >> Just who overwrote it.. someone called unhold after
> >> execlists_reset_cancel finished.
> >>
> >> Should unhold not restore the priority hint if the requests on the hold
> >> list are -EIO?
> >
> > It is the unhold callback, it does
> >
> > if (rq_prio(rq) > engine->execlists.queue_priority_hint) {
> > engine->execlists.queue_priority_hint = rq_prio(rq);
> > tasklet_hi_schedule(&engine->execlists.tasklet);
> > }
> >
> > and queues the [now] nop_submission_tasklet. Which would be fine if it
> > behaved similarly.
>
> That I found, but who calls it?
Currently, a reset worker. Intention is that any path that first called
execlists_hold(). (E.g. holding requests across suspend is one
possible idea I have. No concrete second use case yet, just more of a
feeling this might be useful again.)
> I was thinking that since execlists_reset_cancel bothers to mark held
> requests with -EIO then unhold could be smarter and not consider them
> when setting the priority hint.
Could do, trying to keep it simple :) My preference is to push the
complexity to the edge case of wedge handling; and I'm not keen on
having to worry about -EIO here. The intent is remove from queue, place
in holding area, put back onto queue. Trying to do that correctly is
hard enough [apparently] :)
> That way the hint is immediately true, not only after tasklet is
> flushed. But okay, no big deal either way.
On the other hand, if the assertion is more troublesome than it's worth,
we just set the hint = INT_MIN on resume.
-Chris
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