linux-kernel - Re: [PATCH v2 3/6] drm/sched: Warn if pending list is not empty

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Message-ID: <236644fd-dbf4-48b0-a341-a26c0c8b9515@igalia.com>
Date: Fri, 16 May 2025 10:40:07 +0100
From: Tvrtko Ursulin <tvrtko.ursulin@...lia.com>
To: Philipp Stanner <phasta@...nel.org>, Lyude Paul <lyude@...hat.com>,
 Danilo Krummrich <dakr@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Matthew Brost <matthew.brost@...el.com>,
 Christian König <ckoenig.leichtzumerken@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>
Cc: dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] drm/sched: Warn if pending list is not empty


On 24/04/2025 10:55, Philipp Stanner wrote:
> drm_sched_fini() can leak jobs under certain circumstances.
> 
> Warn if that happens.
> 
> Signed-off-by: Philipp Stanner <phasta@...nel.org>
> ---
>   drivers/gpu/drm/scheduler/sched_main.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index c2ad6c70bfb6..0c56b85c574f 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -1457,6 +1457,9 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
>   	sched->ready = false;
>   	kfree(sched->sched_rq);
>   	sched->sched_rq = NULL;
> +
> +	if (!list_empty(&sched->pending_list))
> +		dev_err(sched->dev, "Tearing down scheduler while jobs are pending!\n");

Is this expected to trigger for many drivers? In that case I am not sure 
if it helps anyone, apart from generating bug tracker entries across the 
world, for the issue we know about and could work
"quietly" on addressing it? Only if you think we don't really know who 
leaks and who doesn't and this will help figure out.

Hm wait, at this point in the series it would fire incorrectly for the 
mock scheduler. It should go last in the series at minimum.

Regards,

Tvrtko

>   }
>   EXPORT_SYMBOL(drm_sched_fini);
>