[alsa-devel] Kernel crash with 2.6.20.x : snd-usb-audio implicated...

[Chris Rankin]

Hi,

The 2.6.20.x kernels all crash on my SMP-HT machine, and the oops report always shows that udev
was trying to access an endpoint belonging to the snd-usb-audio driver. The frustrating part is
that this particular endpoint shouldn't even exist! (It doesn't exist whenever I check the
/sys/class/usb_endpoint directory.) Is there any way that userspace ("winecfg" in my case) can
cause the snd-usb-audio driver to switch from (If# = 2, Alt = 0) to (If# = 2, Alt > 0) please?
Because that is currently the only way that I can see this endpoint ever being created.

Thanks,
Chris

--- bugme-daemon at bugzilla.kernel.org wrote:

> Date: Sat, 14 Apr 2007 05:22:23 -0700
> From: bugme-daemon at bugzilla.kernel.org
> To: rankincj at yahoo.com
> Subject: [Bug 8198] udevd triggers oops when walking through /sys
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=8198
>
> ------- Additional Comments From rankincj at yahoo.com  2007-04-14 05:22 -------
> Created an attachment (id=11144)
>  --> (http://bugzilla.kernel.org/attachment.cgi?id=11144&action=view)
> dmesg output from 2.6.20.7 oops
> 
> I don't know if this output is any more useful than any of the others. And I
> can't see where the "single bit error" comes from when the output is full of
> "use after free" poison. However, this much at least is different:
> 
> EIP: [<6b6b6b6b>] 0x6b6b6b6b SS:ESP 0068:ec9eaf48
>  <3>Slab corruption: start=eceea92c, len=512
> Redzone: 0x5a2cf071/0x5a2cf071.
> Last user: [<c0226642>](kfree_skbmem+0xb/0x9c)
> 080: 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> Single bit error detected. Probably bad RAM.
> Run memtest86+ or a similar memory test tool.
> Prev obj: start=eceea720, len=512
> Redzone: 0x170fc2a5/0x170fc2a5.
> Last user: [<f886eda5>](usb_create_ep_files+0xf1/0x2c2 [usbcore])
> 000: f8 fd 1b c2 e0 ee 4e f7 01 00 00 00 00 00 00 00
> 010: 30 a7 ee ec 30 a7 ee ec f4 91 1e c0 96 90 1e c0
> Next obj: start=eceeab38, len=512
> Redzone: 0x5a2cf071/0x5a2cf071.
> Last user: [<c0226642>](kfree_skbmem+0xb/0x9c)
> 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> 
> Again, it's claiming that the last sysfs file accessed was the non-existent
> /class/usb_endpoint/usbdev1.3_ep84/dev, which I simply cannot explain because
> this endpoint belongs to If# = 2, Alt > 0:
> 
> I:  If#= 2 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio
> I:  If#= 2 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio
> E:  Ad=84(I) Atr=01(Isoc) MxPS=  90 Ivl=1ms
> I:  If#= 2 Alt= 2 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio
> E:  Ad=84(I) Atr=01(Isoc) MxPS=  46 Ivl=1ms
> I:  If#= 2 Alt= 3 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio
> E:  Ad=84(I) Atr=01(Isoc) MxPS=  25 Ivl=1ms
> I:  If#= 2 Alt= 4 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio
> E:  Ad=84(I) Atr=01(Isoc) MxPS=  16 Ivl=1ms
> 
> Could the ALSA USB audio driver be changing the "Alt" on the fly somehow,
> causing usbcore to need to create the extra endpoint in /sys?


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