Linux Ethernet Bridging - Apr 2007 - [Bridge] unregister_netdevice: waiting for br0 to become free. Usage count = 1 (2.6.12.3)

Hi Robert,

2. Any ideas of something to try in order to make this
repeatable?
> 
What i would do to reproduce it, is make a script establishing the bridge, 
then flooding the bridge with some external ping -f, then shuting down the 
bridge. If there is a refcount release problem, it should appear on eavy 
load (some buffer overflow, or something like that).
Also, are you playing with ebtables? How do you use this bridge?
#Louis.


Date: Wed, 31 Aug 2005 19:04:01 -0700
> From: Robert Scott <rbscott@axentra.net>
> Subject: [Bridge] unregister_netdevice: waiting for br0 to become
> free. Usage count =3D 1 (2.6.12.3 <http://2.6.12.3/>)
> To: bridge@lists.osdl.org
> Message-ID: <8189B9F5-DF6E-4032-8D2D-D5301A02A081@axentra.net>
> Content-Type: text/plain; charset=3DUS-ASCII; delsp=3Dyes; format=3Dflowed
> 
> Hello,
> 
> I know that this bug has been discussed before at length on this
> mailing list, but previous post seemed to indicate that it was fixed
> before kernel 2.6.12. I am still seeing this occasionally in kernel
> 2.6.12.3 <http://2.6.12.3/>. The system is running knoppix, and IPV6
is
> not compiled
> into the kernel(other posts mentioned numerous problems with the IPV6
> code). But every so often, when bringing down the bridge (it doesn't
> happen every time), the process hangs, and the following message
> appears in dmesg repeatedly:
> 
> 'unregister_netdevice: waiting for br0 to become free. Usage count =3D
1'
> 
> None of the processes involved can be killed, and an attempt to run
> an ifconfig results in a process that is also waiting forever. At
> this point the box must be rebooted forcefully.
> 
> Two questions.
> 1. In a previous post, someone mentioned one solution was to
> commenting out the check that is hanging in the kernel. Does this
> check preventing something terrible from happening(i assumed that it
> does), or is it safe to remove it.
> 2. Any ideas of something to try in order to make this repeatable?
> 
> thanks,
> --robert scott
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Hello,

I know that this bug has been discussed before at length on this  
mailing list, but previous post seemed to indicate that it was fixed  
before kernel 2.6.12.  I am still seeing this occasionally in kernel  
2.6.12.3.  The system is running knoppix, and IPV6 is not compiled  
into the kernel(other posts mentioned numerous problems with the IPV6  
code).  But every so often, when bringing down the bridge (it doesn't  
happen every time), the process hangs, and the following message  
appears in dmesg repeatedly:

'unregister_netdevice: waiting for br0 to become free. Usage count = 1'

None of the processes involved can be killed, and an attempt to run  
an ifconfig results in a process that is also waiting forever.  At  
this point the box must be rebooted forcefully.

Two questions.
1. In a previous post, someone mentioned one solution was to  
commenting out the check that is hanging in the kernel.   Does this  
check preventing something terrible from happening(i assumed that it  
does), or is it safe to remove it.
2. Any ideas of something to try in order to make this repeatable?

thanks,
--robert scott