From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C9A94394470 for ; Tue, 25 Aug 2026 12:02:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787659374; cv=none; b=hwAwdGuEZ1TUXOTp1tm2nig6poOyo9cyjQM3vtdepgwnyVai5QPGiP7Qo63AgohkpPb6prAqy5clB17FRqhhM8fSxqBVup+b3DbUiCbd8SqfkLiJT03a/+9DbxmirM72fe/lp1+IK/lTw+/BwWZX4Ry6IsCx6gMCaUNwceaOxb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787659374; c=relaxed/simple; bh=B66+iK94k5Ihrk2Uexx7UdrJjFXtH9tTcEfAUdREwZY=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:Cc:To:From: References:In-Reply-To; b=tXv9b+fZtfJPEdDgkdgAHwFkxwTfkp1f2XIpk81RiLDvncowbnkBukKKkN16OXZXVUWCH+UCxCcsQzxmyu4O4+uy2Fy3BweaNNfehRMgc0vX+m3Gxr1KkWh5lI1D8OGn953DNwBNvS5XzQ1gowWbIOmMssFf8/JIZa+yrcOoBFw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bOJpczUR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bOJpczUR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A8D91F000E9; Tue, 25 Aug 2026 12:02:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787659373; bh=eXRAsEyO0FIDt5KvbTlVkgC1+/Me8/Ey163p/tCuIAQ=; h=Date:Subject:Cc:To:From:References:In-Reply-To; b=bOJpczUR6sSSpA6DdnBU8nVPInzGKm7wt3VExrO6v57+DcxuJWRu2a6eo9Gcmqn5i mniZRjBcfuAQa7vgzToLynBdLw2nCMyHZYW2FyBIrq5s+whczUdLNb/RySyxIDIYWH fu2Ix3tw2nP+mhVO9qyaxLDIMpE0dig7pp7RMq64Ysrm9NuLqWm4oxpa7wS5cba3J7 UiqQlz9vKI+P+nVNtkqt2ItbBMcmmZBPrT7Uqq6r55wOHv3cFR7qyR/WerJ8sPRAQW smBjA+jEvrI4Sh5rYTiIhvs2NievCJ9UX74sNfRUEqiLPR3ga7tJHP3aq5S9HK3GGJ UqSq7n6BBWAZA== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 25 Aug 2026 14:02:49 +0200 Message-Id: Subject: Re: [PATCH v2] drm/sched: Guard against NULL dev in drm_sched_job trace event Cc: "Matthew Brost" , "Philipp Stanner" , =?utf-8?q?Christian_K=C3=B6nig?= , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , , , "Shixiong Ou" To: From: "Danilo Krummrich" References: <20260825103615.661200-1-oushixiong1025@163.com> In-Reply-To: <20260825103615.661200-1-oushixiong1025@163.com> On Tue Aug 25, 2026 at 12:36 PM CEST, oushixiong1025 wrote: > From: Shixiong Ou > > The drm_sched_job trace event class calls dev_name() on > sched_job->sched->dev without checking for NULL. Since the > dev field in drm_sched_init_args is optional (used for > debugging), a NULL dev causes a kernel oops when the trace > event fires. > > The DRM scheduler KUnit tests do not set the dev field in > drm_sched_init_args, leaving sched->dev as NULL. This causes > a NULL pointer dereference when the drm_sched_job trace event > fires during test execution, as dev_name(NULL) is called. > > Unable to handle kernel NULL pointer dereference at virtual > address 0000000000000050 > Call trace: > trace_event_raw_event_drm_sched_job+0x90/0x258 > __traceiter_drm_sched_job_queue+0x4c/0x78 > drm_sched_entity_push_job+0x188/0x380 > drm_sched_basic_entity_cleanup+0xfc/0x240 > kunit_try_run_case+0x74/0x170 > > Signed-off-by: Shixiong Ou > --- > v1->v2: > Change each line of the message to be within 75 characters > =09 > drivers/gpu/drm/scheduler/gpu_scheduler_trace.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gp= u/drm/scheduler/gpu_scheduler_trace.h > index 261713dd7d5a..319a3ec54bec 100644 > --- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h > +++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h > @@ -61,7 +61,8 @@ DECLARE_EVENT_CLASS(drm_sched_job, > __string(name, sched_job->sched->name) > __field(u32, job_count) > __field(int, hw_job_count) > - __string(dev, dev_name(sched_job->sched->dev)) > + __string(dev, sched_job->sched->dev ? > + dev_name(sched_job->sched->dev) : "none") I don't think that we should make such changes for Kunit tests only; it imp= lies that a NULL dev now would be a valid value for the scheduler. Why can't we have the Kunit test create a fake device for this? For instanc= e, this is where struct faux_device becomes useful.