[Bridge] unregister_netdevice: waiting for br0 to become free.
Usage count = 1 (18.104.22.168)
shemminger at osdl.org
Wed Aug 31 21:37:49 PDT 2005
On Wed, 31 Aug 2005 19:04:01 -0700
Robert Scott <rbscott at axentra.net> wrote:
> 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
> 22.214.171.124. 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
Really bad idea, because if the thing that is holding the reference
like packets stuck in some dead queue, ever get processed the kernel
> 2. Any ideas of something to try in order to make this repeatable?
Two other recent reports are:
1. Buggy applications that hold packets in their input queue forever,
and/or netfilters. The socket buffer's contain a reference for
packets in flight.
2. The VLAN code had a number of reference bugs, if you look through
recent netdev mailing list you will see the discussion.
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