From: Danilo Krummrich <dakr@kernel.org>
To: Matthew Brost <matthew.brost@intel.com>
Cc: "Simona Vetter" <simona.vetter@ffwll.ch>,
"Christian König" <christian.koenig@amd.com>,
"Philipp Stanner" <phasta@kernel.org>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/sched: Discourage usage of separate workqueues
Date: Wed, 4 Jun 2025 18:53:44 +0200 [thread overview]
Message-ID: <aEB6GOTlC_Z_Rq8b@cassiopeiae> (raw)
In-Reply-To: <aEB4DFFE2C7gElRL@lstrano-desk.jf.intel.com>
On Wed, Jun 04, 2025 at 09:45:00AM -0700, Matthew Brost wrote:
> On Wed, Jun 04, 2025 at 05:07:15PM +0200, Simona Vetter wrote:
> > We should definitely document this trick better though, I didn't find any
> > place where that was documented.
>
> This is a good idea.
I think - and I also mentioned this a few times in the patch series that added
the workqueue support - we should also really document the pitfalls of this.
If the scheduler shares a workqueue with the driver, the driver needs to take
special care when submitting work that it's not possible to prevent run_job and
free_job work from running by doing this.
For instance, if it's a single threaded workqueue and the driver submits work
that allocates with GFP_KERNEL, this is a deadlock condition.
More generally, if the driver submits N work that, for instance allocates with
GFP_KERNEL, it's also a deadlock condition if N == max_active.
next prev parent reply other threads:[~2025-06-04 16:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-04 8:16 [PATCH] drm/sched: Discourage usage of separate workqueues Philipp Stanner
2025-06-04 9:41 ` Christian König
2025-06-04 15:07 ` Simona Vetter
2025-06-04 16:45 ` Matthew Brost
2025-06-04 16:53 ` Danilo Krummrich [this message]
2025-06-04 17:10 ` Matthew Brost
2025-06-06 14:08 ` Simona Vetter
2025-06-05 9:59 ` Philipp Stanner
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