Comment 16 for bug 1634892

Well that was easy, now that you identified rc6 as working. I'll be willing to bet this is the fix:

commit b194c1f1dbd5f2671e49e0ac801b1b78dc7de93b
Author: Jiri Pirko <email address hidden>
Date: Fri Feb 21 14:52:57 2014 +0100

    neigh: fix setting of default gc_* values

    This patch fixes bug introduced by:
    commit 1d4c8c29841b9991cdf3c7cc4ba7f96a94f104ca
    "neigh: restore old behaviour of default parms values"

    The thing is that in neigh_sysctl_register, extra1 and extra2 which were
    previously set for NEIGH_VAR_GC_* are overwritten. That leads to
    nonsense int limits for gc_* variables. So fix this by not touching
    extra* fields for gc_* variables.

    Signed-off-by: Jiri Pirko <email address hidden>
    Signed-off-by: David S. Miller <email address hidden>

I'll build a Trusty test kernel with a pick of this commit and post a link to it shortly.