Bug 672836

Summary: reproducible hang when unplugging USB sound card
Product: [Fedora] Fedora Reporter: Dave Allan <dallan>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED INSUFFICIENT_DATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 14CC: gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-11-29 18:45:00 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
output of bt -a none

Description Dave Allan 2011-01-26 14:58:53 UTC 
Description of problem:
When I unplug my USB sound card in very specific circumstances, the machine will hard lock.  I was able to get a crash dump with nmi watchdog.

Version-Release number of selected component (if applicable):
kernel-2.6.35.10-74.fc14.x86_64

How reproducible:
very; around 8/10 times; I was doing some triage to try to narrow down the steps to reproduce, so that number may be slightly inaccurate.

Steps to Reproduce:
1. boot machine
2. login
3. plug in USB sound card
4. Select the USB soundcard as the Pulseaudio input and output with System->Preferences->Sound->[Input|Output]->choose USB soundcard
5. start alsamixer, select USB card, adjust volume, leave alsamixer running
6. start firefox and make a call with Google Voice; hang up the call
7. unplug the USB soundcard


Actual results:
System immediately hangs; if NMI watchdog is configured, system dumps

Expected results:
No hang

Additional info:
I was able to open the crashdump and confirm that the backtrace seems to implicate the sound code [exception RIP: snd_pcm_pre_stop+21], but I am no longer a kernel guy, so my analysis is pretty much limited to that.

I'll attach the full backtrace as an attachment, but I can provide the dump and corresponding vmlinux if needed.

I'm happy to try out test kernels to see if it fixes things.  I've tried several times to reproduce it with Totem producing audio instead of Google Voice, but so far it has not reproduced.
Comment 1 Dave Allan 2011-01-26 15:09:21 UTC 
Created attachment 475412 [details]
output of bt -a
Comment 2 Dave Allan 2011-11-29 18:45:00 UTC 
I'm no longer using Google Voice so I no longer see this problem.  I'm closing as INSUFFICIENT_DATA.
Comment 3 Dave Allan 2011-12-05 21:38:27 UTC 
That'll teach me--after not seeing this hang for months, it reappeared today without Google Voice.