| Message ID | 20220107003143.326046-1-John.C.Harrison@Intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/guc: Don't error on reset of banned context | expand |
On 1/6/2022 16:31, John.C.Harrison@Intel.com wrote: > From: John Harrison <John.C.Harrison@Intel.com> > > There is a race (already documented in the code) whereby a context can > be (re-)queued for submission at the same time as it is being banned > due to a hang and reset. That leads to a hang/reset report from GuC > for a context which i915 thinks is already banned. > > While the race is indented to be fixed in a future GuC update, there > is no actual harm beyond the wasted execution time of that new hang > detection period. The context has already been banned for bad > behaviour so a fresh hang is hardly surprising and certainly isn't > going to be losing any work that wouldn't already have been lost if > there was no race. > > So don't treat this situation as an error. The error message is seen > by the CI system as something fatal and causes test failures. Instead, > just print an informational so the user at least knows a context reset > occurred (given that the error capture is being skipped). > > Signed-off-by: John Harrison <John.C.Harrison@Intel.com> PS: Meant to add: Fixes: 249af7242af72 ("drm/i915/guc: Report error on invalid reset notification")
On Thu, Jan 06, 2022 at 04:31:43PM -0800, John.C.Harrison@Intel.com wrote: > From: John Harrison <John.C.Harrison@Intel.com> > > There is a race (already documented in the code) whereby a context can > be (re-)queued for submission at the same time as it is being banned > due to a hang and reset. That leads to a hang/reset report from GuC > for a context which i915 thinks is already banned. > I think there are 2 issues here. 1. Banning of context (e.g. user closes a non-persistent context) results in an context reset. In this case we will receive a G2H indicating a context reset and we want to convert the context reset to a nop. 2. A GT reset races with a context reset result in the context getting banned before the G2H is processed. Again we want to convert the context reset to a nop. This race should be sealed when we can flush the G2H handler in the reset path. Flushing G2H handler depends on the error capture not allocating memory in non-sleeping contexts. Thomas H had a patch for this. In both cases we shouldn't print an error. > While the race is indented to be fixed in a future GuC update, there > is no actual harm beyond the wasted execution time of that new hang > detection period. The context has already been banned for bad > behaviour so a fresh hang is hardly surprising and certainly isn't > going to be losing any work that wouldn't already have been lost if > there was no race. > See above, I think you are confusing the issues here. This won't be fixed by an updated GuC firmware. > So don't treat this situation as an error. The error message is seen > by the CI system as something fatal and causes test failures. Instead, > just print an informational so the user at least knows a context reset > occurred (given that the error capture is being skipped). > > Signed-off-by: John Harrison <John.C.Harrison@Intel.com> > --- > drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > index 9989d121127d..e8a32a7e7daf 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > @@ -3978,6 +3978,10 @@ static void guc_handle_context_reset(struct intel_guc *guc, > !context_blocked(ce))) { > capture_error_state(guc, ce); > guc_context_replay(ce); > + } else if (intel_context_is_banned(ce)) { > + drm_info(&guc_to_gt(guc)->i915->drm, > + "Reset notificaion for banned context 0x%04X on %s", > + ce->guc_id.id, ce->engine->name); The context being blocking isn't an error either. I think real fix is changing the below drm_err to drm_info and call it a day. Matt > } else { > drm_err(&guc_to_gt(guc)->i915->drm, > "Invalid GuC engine reset notificaion for 0x%04X on %s: banned = %d, blocked = %d", > -- > 2.25.1 >
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 9989d121127d..e8a32a7e7daf 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -3978,6 +3978,10 @@ static void guc_handle_context_reset(struct intel_guc *guc, !context_blocked(ce))) { capture_error_state(guc, ce); guc_context_replay(ce); + } else if (intel_context_is_banned(ce)) { + drm_info(&guc_to_gt(guc)->i915->drm, + "Reset notificaion for banned context 0x%04X on %s", + ce->guc_id.id, ce->engine->name); } else { drm_err(&guc_to_gt(guc)->i915->drm, "Invalid GuC engine reset notificaion for 0x%04X on %s: banned = %d, blocked = %d",