Re: [PATCH v2 01/12] drm/panfrost: Make sure MMU context lifetime is not bound to panfrost_priv

[Steven Price <steven.price@arm.com>]

On 21/06/2021 14:57, Alyssa Rosenzweig wrote:
>> Jobs can be in-flight when the file descriptor is closed (either because
>> the process did not terminate properly, or because it didn't wait for
>> all GPU jobs to be finished), and apparently panfrost_job_close() does
>> not cancel already running jobs. Let's refcount the MMU context object
>> so it's lifetime is no longer bound to the FD lifetime and running jobs
>> can finish properly without generating spurious page faults.
> 
> Remind me - why can't we hard stop in-flight jobs when the fd is closed?
> I've seen cases where kill -9'ing a badly behaved process doesn't end
> the fault storm, or unfreeze the desktop.
> 

Hard-stopping the in-flight jobs would also make sense. But unless we
want to actually hang the close() then there will be a period between
issuing the hard-stop and actually having completed all jobs in the context.

But equally to be fair I've been cherry-picking this patch myself for
quite some time, so we should just merge it and improve from there. So
you can have my:

Reviewed-by: Steven Price <steven.price@arm.com>