On 4/13/22 01:59, Erico Nunes wrote: > On Tue, Apr 12, 2022 at 9:41 PM Andrey Grodzovsky > <andrey.grodzovsky@xxxxxxx> wrote: >> >> >> On 2022-04-12 14:20, Dmitry Osipenko wrote: >>> On 4/12/22 19:51, Andrey Grodzovsky wrote: >>>> On 2022-04-11 18:15, Dmitry Osipenko wrote: >>>>> Interrupt context can't sleep. Drivers like Panfrost and MSM are taking >>>>> mutex when job is released, and thus, that code can sleep. This results >>>>> into "BUG: scheduling while atomic" if locks are contented while job is >>>>> freed. There is no good reason for releasing scheduler's jobs in IRQ >>>>> context, hence use normal context to fix the trouble. >>>> >>>> I am not sure this is the beast Idea to leave job's sw fence signalling >>>> to be >>>> executed in system_wq context which is prone to delays of executing >>>> various work items from around the system. Seems better to me to leave the >>>> fence signaling within the IRQ context and offload only the job freeing or, >>>> maybe handle rescheduling to thread context within drivers implemention >>>> of .free_job cb. Not really sure which is the better. >>> We're talking here about killing jobs when driver destroys context, >>> which doesn't feel like it needs to be a fast path. I could move the >>> signalling into drm_sched_entity_kill_jobs_cb() and use unbound wq, but >>> do we really need this for a slow path? >> >> >> You can't move the signaling back to drm_sched_entity_kill_jobs_cb >> since this will bring back the lockdep splat that 'drm/sched: Avoid >> lockdep spalt on killing a processes' >> was fixing. >> >> I see your point and i guess we can go this way too. Another way would >> be to add to >> panfrost and msm job a work_item and reschedule to thread context from >> within their >> .free_job callbacks but that probably to cumbersome to be justified here. > > FWIW since this mentioned individual drivers, commit 'drm/sched: Avoid > lockdep spalt on killing a processes' also introduced problems for > lima. > There were some occurrences in our CI > https://gitlab.freedesktop.org/mesa/mesa/-/jobs/20980982/raw . > Later I found it also reproducible on normal usage when just closing > applications, so it may be affecting users too. > > I tested this patch and looks like it fixes things for lima. This patch indeed should fix that lima bug. Feel free to give yours tested-by :)
