[pvrusb2] Kernel oops?

[Mike Isely]

On Wed, 14 Sep 2005, Andreas Korinek wrote:

> On Tuesday 13 September 2005 22:22, Mike Isely wrote:
> > Can you please post entries from your system log leading up to this?
> > Thanks.
> >
> > Obviously the oops involved the driver, but it would be far more helpful
> > to see the circumstances as well.
> >
> > If you can reproduce the crash at will and isolate the key actions that
> > lead to it, that would also be quite helpful.
>
> This is the full log, my kernel is 2.6.13.1 with Gentoo patchset. I could not
> reproduce this so far, it just happened after running xawtv for a while.
>

OK, this helps a lot.  See further:

>
> Sep 13 21:54:13 [kernel] pvrusb2 subsys mask changing
> 0x7fff:0xffffffffffffffff from 0x7ff to 0x7fff
> Sep 13 21:54:13 [kernel] pvrusb2 /*---TRACE_CTL----*/ pvr2_encoder_configure
> Sep 13 21:54:13 [kernel] pvrusb2 /*---TRACE_CTL----*/
> pvr2_decoder_enable_output(1)
> Sep 13 21:54:13 [kernel] pvrusb2 /*---TRACE_CTL----*/
> pvr2_hdw_cmd_usbstream(1)
> Sep 13 21:54:13 [kernel] pvrusb2 /*---TRACE_CTL----*/ pvr2_encoder_start
> Sep 13 21:54:13 [kernel] pvrusb2 /*---TRACE_READ---*/ pvr2_ioread_start
> id=ffff810031763600
> Sep 13 22:00:01 [cron] (root) CMD (test -x /usr/sbin/run-crons
> && /usr/sbin/run-crons )
> Sep 13 22:00:01 [cron] (root) CMD (rm -f /var/spool/cron/lastrun/cron.hourly)
> Sep 13 22:10:01 [cron] (root) CMD (test -x /usr/sbin/run-crons
> && /usr/sbin/run-crons )
> Sep 13 22:10:20 [kernel] pvrusb2 /*---TRACE_READ---*/ pvr2_ioread_stop
> id=ffff810031763600
> Sep 13 22:10:20 [kernel] Unable to handle kernel NULL pointer dereference at
> 0000000000000038 RIP:
> Sep 13 22:10:20 [kernel] <ffffffff884e9669>{:pvrusb2:pvr2_buffer_set_idle+121}
> Sep 13 22:10:20 [kernel] PGD 269c5067 PUD 269f4067 PMD 0
> Sep 13 22:10:20 [kernel] CPU 0
> Sep 13 22:10:20 [kernel] Modules linked in: saa7115 msp3400 tuner pvrusb2
> v4l2_common v4l1_compat videodev tveeprom nvnet i2c_nforce2 snd_seq
> snd_ice1724 snd_ice17xx_ak4xxx snd_ac97_codec snd_ak4114 snd_pcm snd_timer
> snd_page_alloc snd_ak4xxx_adda snd_mpu401_uart snd_rawmidi snd_seq_device snd
> soundcore lirc_i2c lirc_dev nvidia
> Sep 13 22:10:20 [kernel] Pid: 12930, comm: xawtv Tainted: P
> 2.6.13-gentoo-r1
> Sep 13 22:10:20 [kernel] RIP: 0010:[<ffffffff884e9669>]


> <ffffffff884e9669>{:pvrusb2:pvr2_buffer_set_idle+121}

This is the key.  This is the point where the problem started.
Interestingly enough, this appears to be the place where one other person
reported an oops - that I had posted here about a week ago.

Here's what I want you to do (and anyone else who suspects they are
getting had by this problem):  Edit pvrusb2-io.c and uncomment line 31
which defines SANITY_CHECK_BUFFERS.  This will enable a bunch of sanity
checking that hopefully should be able to trap this problem and report
additional useful information.  Please turn that on and run again until
you get another failure.  Turning this on will generate additional log
output during stream start / stop but nothing else new will be logged
until a problem is found, i.e. don't worry about this filling up your log.

   [...]



> Sep 13 22:10:20 [kernel] scheduling while atomic: xawtv/0x00000001/12930

OK, now this is also interesting, but not nearly as much as above.  This
is a second trap, but it's probably collateral damage from the first trap.
This probably happened because xawtv runs by repeatedly opening
/dev/video0 (or whatever), doing something to it and closing it again.
It's very possible that in spite of the earlier kernel oops that xawtv
kept on going and forced an action that caused something else illegal to
take place.

In the other instance of the above oops that I know about, mplayer was
being used instead of xawtv.  In that case mplayer just died right away
and so there wasn't any more "shrapnel" being tossed around through the
kernel.

So let's not worry about this subsequent traps and focus on the first one,
the one that start things failing...



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