Hi John, On Wednesday, 10 January 2024 22:02:16 CET John.C.Harrison@xxxxxxxxx wrote: > From: John Harrison <John.C.Harrison@xxxxxxxxx> > > The context persistence code does things like send super high priority > heartbeat pulses to ensure any leaked context can still be pre-empted > and thus isn't a total denial of service but only a minor denial of > service. Unfortunately, it wasn't bothering to restart the heatbeat > worker with a fresh timeout. Thus, if a persistent context happened to > be closed just before the heartbeat was going to go ping anyway then > the forced pulse would get a negligble execution time. And as the > forced pulse is super high priority, the worker thread's next step is > a reset. Which means a potentially innocent system randomly goes boom > when attempting to close a context. So, force a re-schedule of the > worker thread with the appropriate timeout. I haven't looked too much in heartbeat pulses code before, but I think I can understand your change. I've also got a positive opinion from Chris on it. I can provide my Ack, assuming the pre-merge failure reported by CI is not related, but could you please comment that failure first and/or ask BUG Filing to handle it so we have it cleaned up? Thanks, Janusz > > Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c > index 1a8e2b7db0138..4ae2fa0b61dd4 100644 > --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c > +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c > @@ -290,6 +290,9 @@ static int __intel_engine_pulse(struct intel_engine_cs *engine) > heartbeat_commit(rq, &attr); > GEM_BUG_ON(rq->sched.attr.priority < I915_PRIORITY_BARRIER); > > + /* Ensure the forced pulse gets a full period to execute */ > + next_heartbeat(engine); > + > return 0; > } > >
