linux-kernel - Re: [PATCH 2/3] drm/scheduler: Don't call wait_event

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Date:   Thu, 26 Apr 2018 08:34:05 -0400
From:   Andrey Grodzovsky <Andrey.Grodzovsky@....com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, Alexander.Deucher@....com,
        Christian.Koenig@....com, David.Panariti@....com,
        akpm@...ux-foundation.org
Subject: Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for
 signaled process.



On 04/25/2018 08:01 PM, Eric W. Biederman wrote:
> Andrey Grodzovsky <Andrey.Grodzovsky@....com> writes:
>
>> On 04/25/2018 01:17 PM, Oleg Nesterov wrote:
>>> On 04/25, Andrey Grodzovsky wrote:
>>>> here (drm_sched_entity_fini) is also a bad idea, but we still want to be
>>>> able to exit immediately
>>>> and not wait for GPU jobs completion when the reason for reaching this code
>>>> is because of KILL
>>>> signal to the user process who opened the device file.
>>> Can you hook f_op->flush method?
>> But this one is called for each task releasing a reference to the the file, so
>> not sure I see how this solves the problem.
> The big question is why do you need to wait during the final closing a
> file?
>
> The wait can be terminated so the wait does not appear to be simply a
> matter of correctness.

Well, as I understand it, it just means that you don't want to abruptly 
terminate GPU work in progress without a good
reason (such as KILL signal). When we exit we are going to release 
various resources GPU is still using so we either
wait for it to complete or terminate the remaining jobs.

Andrey

>
> Eric