linux-kernel - Re: [PATCH 3/5] drm/sched: Warn if pending list is not empty

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Message-ID: <9607e5a54b8c5041dc7fc134425cc36c0c70b5f3.camel@mailbox.org>
Date: Thu, 17 Apr 2025 09:45:35 +0200
From: Philipp Stanner <phasta@...lbox.org>
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>, Tvrtko
 Ursulin <tvrtko.ursulin@...lia.com>
Cc: dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] drm/sched: Warn if pending list is not empty

On Mon, 2025-04-07 at 17:22 +0200, 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 | 4 ++++

I hear a lot of amazed silence for this series ^_^

If there's no major pushback, my intention is to pull this in once the
blocking Nouveau-bug has been fixed (by pulling my patch).


In the mean time, let me review my own stuff:

>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c
> b/drivers/gpu/drm/scheduler/sched_main.c
> index 6b72278c4b72..ae3152beca14 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -1465,6 +1465,10 @@ 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, "%s: Tearing down scheduler
> while jobs are pending!\n",
> +			__func__);

The "%s" here will be removed since dev_err() alreday prints the
function name.

I find this dev_err() print more useful than the stack a WARN_ON prints
(telling you about invalid_asm_exec_op or stuff like that).

Plus, I guess the places where drivers call drm_sched_fini() are very
well defined and known, so a callstack wouldn't really be useful in the
first place.


P.

>  }
>  EXPORT_SYMBOL(drm_sched_fini);
>