On Mon, Sep 29, 2014 at 5:24 PM, Ben Greear [off-list ref] wrote:

On 09/29/2014 01:39 PM, Cong Wang wrote:

quoted

On Mon, Sep 29, 2014 at 12:48 PM, Ben Greear [off-list ref] wrote:

quoted

We are going to be running up to 20 concurrent scripts that
will be dumping routes & ips, and configuring ip addresses
and routes during bringup.

I don't have a simple stand-alone way to reproduce this,
but at least when we reported the problem is was very easy
for us to reproduce with our tool.

Maybe 20 scripts running in parallel that randomly configured and dumped routes
and ip addresses on random interfaces would do the trick?

I think the most important question is why is this related with macvlan?
IPv6 is L3 while macvlan pure L2, if this is a IPv6 routing bug, it should
not be limited to macvlan.

We saw it using mac-vlans on top of ixgbe.  Probably it can be reproduced
elsewhere, but since we had a good test case, we didn't bother trying lots
of other combinations.

Just enabling some debug code caused the problem to be much harder
to reproduce, so it is probably some sort of race.  Maybe lots of mac-vlans
make it easier to hit.

quoted

What does your IPv6 routing table look like? And how do you configure those
macvlan interfaces?

Each interface would have it's own routing table, with at least as subnet
route.  I'm not sure we were adding a default gateway or not.

The main routing table would also have some auto-created routes
I think.

It is configured using 'ip' to add and dump routes.

Ben

Just saw this thread.  Can you check if this commit makes a difference:
commit 40b8fe45d1f094e3babe7b2dc2b71557ab71401d
Author: Vlad Yasevich [off-list ref]
Date:   Mon Sep 22 16:34:17 2014 -0400

    macvtap: Fix race between device delete and open.

Thanks
-vlad

Thanks,
Ben

--
Ben Greear [off-list ref]
Candela Technologies Inc  http://www.candelatech.com

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