From: Daniel Vetter <daniel@ffwll.ch>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
Jani Nikula <jani.nikula@linux.intel.com>,
David Airlie <airlied@linux.ie>,
intel-gfx <intel-gfx@lists.freedesktop.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [Intel-gfx] 4.10-rc2 oops in DRM connector code
Date: Mon, 9 Jan 2017 17:59:15 +0100 [thread overview]
Message-ID: <CAKMK7uGRX4xNzS5yVH+H3r1k_A_R91cEO8TOZEA93pPKTkOuYA@mail.gmail.com> (raw)
In-Reply-To: <f56df02a-61ae-e20b-c99a-cfe8ccd45c64@intel.com>
On Mon, Jan 9, 2017 at 5:50 PM, Dave Hansen <dave.hansen@intel.com> wrote:
> On 01/09/2017 08:41 AM, Daniel Vetter wrote:
>> On Mon, Jan 9, 2017 at 2:40 PM, Dave Hansen <dave.hansen@intel.com> wrote:
>>> Well, now I found where the -2 comes from.
>>> intel_dp_register_mst_connector() calls drm_connector_register(), which
>>> fails to add the kobject (warning below). But, it does zero error
>>> checking on the drm_connector_register() call and leaves the
>>> partially-constructed connector in place.
>>>
>>> The next time some poor, hapless code goes and tries to do anything with
>>> that kdev, they oops. I'm perplexed by this, though. The
>>> drm_dp_mst_topology_cbs->register_connector just returns void. It seems
>>> a bit goofy that it can't even _return_ failure.
>>>
>>> Is there some stable code to go back to here? Or, is there something
>>> about my configuration that's unique? I really wonder why nobody else
>>> is running into this.
>>>
>>> There's probably some other race going on here. This warning doesn't
>>> happen on every boot.
>> This smells more like the root-cause: Something goes wrong on boot
>> that prevents connectors from properly registering, then we fall over
>> later on. And the register callback is intentionally void, assuming
>> that any prep work has been done earlier and that therefore the
>> register step can't fail. Can you pls check whether the oops later on
>> only happens together with this warning at boot, or whether they're
>> not correlated?
>
> Looking through my logs, I can't find any instance of the oops without
> the warning at boot. So I do think the later oops is entirely caused by
> the issue warned about in early boot.
Hm, I guess then we'd need to fix that boot-up warning. Can you try to
figure out why it's unhappy? On a hunch it could be that we call
drm_connector_register from the mst probe worker before the main
driver load thread has reached the drm_dev_register call. A few printk
to decide whether that's the case (plus a few boot-up tests to gather
the statistics, sorry about that) would be real great.
If that's inconclusive I'm again a bit low on ideas ...
> My distro kernel (4.4.0-57-generic) is also unstable, but I haven't
> managed to capture a good oops there. It's hitting this, which I assume
> is unrelated:
>
> WARNING: CPU: 0 PID: 41 at /build/linux-lts-xenial-FdAdUy/linux-
> lts-xenial-4.4.0/ubuntu/i915/intel_pm.c:3675
> skl_update_other_pipe_wm+0x191/0x1a0 [i915_bpo]()
wm programming issues, which will kill your box. Needs a newer kernel
to fix (both the wm programming issues, and that wm programming issues
lead to system death).
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
next prev parent reply other threads:[~2017-01-09 16:59 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-05 19:03 4.10-rc2 oops in DRM connector code Dave Hansen
2017-01-09 10:15 ` [Intel-gfx] " Daniel Vetter
2017-01-09 12:59 ` Dave Hansen
2017-01-09 13:40 ` Dave Hansen
2017-01-09 13:46 ` Dave Hansen
2017-01-09 16:41 ` Daniel Vetter
2017-01-09 16:50 ` Dave Hansen
2017-01-09 16:59 ` Daniel Vetter [this message]
2017-01-09 17:22 ` Dave Hansen
2017-01-09 19:34 ` Alex Deucher
2017-01-09 17:42 ` Dave Hansen
2017-01-10 10:31 ` Daniel Vetter
2017-01-10 16:52 ` Dave Hansen
2017-01-11 7:43 ` Daniel Vetter
2017-01-11 15:24 ` Dave Hansen
2017-01-11 15:39 ` Daniel Vetter
2017-01-11 16:16 ` Dave Hansen
2017-01-11 22:25 ` Daniel Vetter
2017-01-11 15:40 ` Chris Wilson
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