netdev - Re: Freeing alive fib_info caused by ebc0ffae5

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Date:	Thu, 04 Nov 2010 22:23:51 +1100
From:	Michael Ellerman <michael@...erman.id.au>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: Freeing alive fib_info caused by ebc0ffae5

On Thu, 2010-11-04 at 12:21 +0100, Eric Dumazet wrote:
> Le jeudi 04 novembre 2010 à 11:30 +0100, Eric Dumazet a écrit :
> > Le jeudi 04 novembre 2010 à 21:23 +1100, Michael Ellerman a écrit :
> > > Hi all,
> > > 
> > > I'm running Linus' latest or thereabouts (ff8b16d), and I'm seeing
> > > "Freeing alive fib_info" messages, from free_fib_info().
> > > 
> > > Actually I only get one per boot, when network interfaces come up.
> > > Seemingly related I am getting refcount problems when I shutdown, ie.
> > > unregister_netdevice() sees a usage count of 1, which never decrements.
> > > 
> > > Bisect says it's ebc0ffae5 which causes the problem, or makes it appear.
> > > 
> > >     fib: RCU conversion of fib_lookup()
> > >     
> > >     fib_lookup() converted to be called in RCU protected context, no
> > >     reference taken and released on a contended cache line (fib_clntref)
> > >     
> > > 
> > > Is this a bug in that commit, or a driver bug exposed?
> > 
> > Hi Michael, thanks for the report (and painful bisection I guess)
> > 
> > Thats hard to say... Is it reproductable on my machine ?
> > 
> 
> Hmm, a review of the code spotted a bug in fib_result_assign()

Aha, I was just adding some debug in there. Let me test the patch.

cheers


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