Subject: Re: [0/8] netpoll/bridge fixes

From: Yanko Kaneti <[email-masked]>
Date: Tue, 29 Jun 2010 15:53:51 +0300

On Thu, 2010-06-10 at 22:40 +1000, Herbert Xu wrote:
> Hi:
> 
> Qianfeng Zhang reported that he was seeing crashes with the
> attached backtrace.
> 
> I tracked this down to the recently added netpoll support in
> the bridge device.  It's a classic use-after-free problem.
> 
> Trying to solve it brought out a host of other issues, some of
> which existed prior to the new bridge code.  The following patches
> attempt to address some of these issues.
> 
> Warning, this is completely untested (apart from compiling with
> everything enabled) so please look but don't merge :)

FWIW 2.6.35-0.2.rc3.git0.fc14.x86_64 and later rawhide kernels are
causing quite reproducible __br_deliver crashes on routine f13
netinstalls in a kvm guest here.

To test I cherry picked this series +
netpoll-Use-correct-primitives-for-RCU-dereferencing and
net-fix-netpoll-Allow-netpoll_setup-cleanup-recursion from net-next on
top of 2.6.35-0.15.rc3.git3.fc14.x86_64 (which is todays linus tree) and
it seems to fix the crashes for me.

Perhaps the netpoll fixes should find their way to a rc before 2.6.35
goes golden.

Regards
Yanko