Re: kern/49875 (kernel crash with i915drmkms on Intel 82855GM)

tsu...@netbsd.org

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Jul 25, 2015, 2:44:27 PM7/25/15

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Synopsis: kernel crash with i915drmkms on Intel 82855GM

Responsible-Changed-From-To: kern-bug-people->riastradh
Responsible-Changed-By: tsu...@NetBSD.org
Responsible-Changed-When: Sat, 25 Jul 2015 15:04:49 +0000
Responsible-Changed-Why:
Could you please take a look at this PR?
Is it okay to apply upstream change as mentioned in PR?
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=19656430a874132a1d79c56387a6eec1ef9a5689
Thanks,

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Taylor R Campbell

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Jul 25, 2015, 10:12:30 PM7/25/15

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Date: Sat, 25 Jul 2015 15:04:49 +0000 (UTC)
From: tsu...@NetBSD.org

Could you please take a look at this PR?
Is it okay to apply upstream change as mentioned in PR?
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=19656430a874132a1d79c56387a6eec1ef9a5689

We can apply the change, although it's not clear to me that that fixes
whatever the real problem here is. Does X successfully start -- with
an apparently harmless warning in dmesg -- or does it fail in some
other way with the change?

Taylor R Campbell

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Jul 25, 2015, 10:15:09 PM7/25/15

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The following reply was made to PR kern/49875; it has been noted by GNATS.

From: Taylor R Campbell <rias...@NetBSD.org>
To: gnats...@NetBSD.org
Cc: kern-bu...@netbsd.org, netbs...@netbsd.org,
gnats...@netbsd.org, tsu...@NetBSD.org, dieter...@pandora.be
Subject: Re: kern/49875 (kernel crash with i915drmkms on Intel 82855GM)
Date: Sun, 26 Jul 2015 02:12:14 +0000

Date: Sat, 25 Jul 2015 15:04:49 +0000 (UTC)
From: tsu...@NetBSD.org

Could you please take a look at this PR?
Is it okay to apply upstream change as mentioned in PR?

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?i=
d=3D19656430a874132a1d79c56387a6eec1ef9a5689

Izumi Tsutsui

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Jul 26, 2015, 3:10:17 AM7/26/15

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The following reply was made to PR kern/49875; it has been noted by GNATS.

From: Izumi Tsutsui <tsu...@ceres.dti.ne.jp>
To: rias...@NetBSD.org
Cc: gnats...@NetBSD.org, tsu...@ceres.dti.ne.jp
Subject: Re: kern/49875 (kernel crash with i915drmkms on Intel 82855GM)
Date: Sun, 26 Jul 2015 16:08:38 +0900

> We can apply the change, although it's not clear to me that that fixes
> whatever the real problem here is.

- The real problem is kernel panic (NULL pointer dereference?)
in i915_gem_object_pin_to_display_plane() on starting Xserver

> Does X successfully start -- with
> an apparently harmless warning in dmesg -- or does it fail in some
> other way with the change?

- With the upstream change X successfully starts with warnings
(at least no kernel panic)
- The warnings are not stable:
- On the first startup
"DRM error in intel_pipe_set_base: pin & fence failed"
- On the second (and further) startups
"DRM error in i8xx_irq_handler: pipe B underrun"
- Xserver sometimes renders garbages and hangs when
multiple heavy GTK applications (firefox + mikutter etc.)
are running
(I'm not sure if this is 855GM specific or not, though)

In short word, "the upstream fix is not perfect but much better".

---
Izumi Tsutsui

matthew green

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Jul 26, 2015, 4:06:54 AM7/26/15

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tsu...@NetBSD.org writes:
> Synopsis: kernel crash with i915drmkms on Intel 82855GM
>
> Responsible-Changed-From-To: kern-bug-people->riastradh
> Responsible-Changed-By: tsu...@NetBSD.org
> Responsible-Changed-When: Sat, 25 Jul 2015 15:04:49 +0000
> Responsible-Changed-Why:
> Could you please take a look at this PR?
> Is it okay to apply upstream change as mentioned in PR?
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=19656430a874132a1d79c56387a6eec1ef9a5689
> Thanks,

my limited understanding says this is OK to commit. and to send
for a pullup...

.mrg.

matthew green

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Jul 26, 2015, 4:07:03 AM7/26/15

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The following reply was made to PR kern/49875; it has been noted by GNATS.

From: matthew green <m...@eterna.com.au>
To: gnats...@NetBSD.org
Cc: rias...@NetBSD.org, kern-bu...@netbsd.org,
netbs...@netbsd.org, gnats...@netbsd.org, tsu...@NetBSD.org,
dieter...@pandora.be

Taylor R Campbell

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Jul 26, 2015, 10:55:12 AM7/26/15

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The following reply was made to PR kern/49875; it has been noted by GNATS.

From: Taylor R Campbell <rias...@NetBSD.org>

To: Izumi Tsutsui <tsu...@ceres.dti.ne.jp>
Cc: gnats...@NetBSD.org, tsu...@ceres.dti.ne.jp

Subject: Re: kern/49875 (kernel crash with i915drmkms on Intel 82855GM)
Date: Sun, 26 Jul 2015 14:50:57 +0000

Date: Sun, 26 Jul 2015 16:08:38 +0900
From: Izumi Tsutsui <tsu...@ceres.dti.ne.jp>

- Xserver sometimes renders garbages and hangs when
multiple heavy GTK applications (firefox + mikutter etc.)
are running
(I'm not sure if this is 855GM specific or not, though)

So it sounds like there is still a problem here, and it is probably
855GM specific. I'll apply the change, but leave this open, unless
you or the original submitter would like to submit a separate PR for
the symptoms that the change reveals.