Comment 87 for bug 245779

First it is not really clear why -18 works and -19 does not. Looking over the patches in between, none of them immediately would looks as like it could be the cause for that. And actually I wonder whether all comments really are about the same problem or just the same symptom.
Anyway, as the kernel in question is relatively old its hard to get any upstream help on this, especially as it seem to be no issue any more. I found one patch that looks like it could be related but this is a bit of a wild guess.

commit 2bf86b7aa8e74bf81a9872f7b610f49b610a4649 (2.6.25.y)
Author: Jay Vosburgh <email address hidden>
Date: Fri Mar 21 22:29:33 2008 -0700

    bonding: Fix locking in 802.3ad mode

But still might be worth trying, I put test kernel packages to http://people.canonical.com/~smb/lp245779/
If that does still fail, then we need the help of someone affected to do bisects between the working and non-working kernels.