Re: [BUG, NET] deadlock tearing down a bridged interface

[Ben Greear]

Dave Chinner wrote:
> On Fri, Jul 18, 2008 at 08:44:58AM -0700, Ben Greear wrote:
>   
> > Dave Chinner wrote:
> >     
> > > Folks,
> > >
> > > I just deadlocked networking on a 2.6.24 kernel. Basically I
> > > was trying to restart the bridge interface I use for UML sessions
> > > because it wasn't passing packets. This happens occasionally
> > > when I leave a UML session too long in gdb, so I bounced the
> > > bridge to get it working again.
> > >   
> > >       
> > We have been chasing a refcount bug in 2.6.25 that only happens when
> > IPv6 module is loaded.
> >     
>
> Which causes what problem? The deadlock I reported or the bridge occasionally
> hanging? Is that a problem in 2.6.24?
>
> The deadlock is the one I'm concerned about - it appears that
> netdev_run_todo() can only wait on a single interface at a time,
> so if we are tearing down two interfaces concurrently where one
> has a reference on the other a deadlock is just waiting to happen...
>   
Our problem is the refcount hang while trying to remove a netdevice.  It 
appears
to be an ipv6 related leakage of some sort, and not directly related to 
bridges.

Thanks,
Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx> 
Candela Technologies Inc  http://www.candelatech.com


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