After that point we should not even access net->netns_ids, we
should check the death of the current netns as early as we can in
peernet2id_alloc().
For net-next we can consider to avoid sending rtmsg totally,
it is a good optimization for netns teardown path.
Fixes: 0c7aecd4bde4 ("netns: add rtnl cmd to add and get peer netns ids") Reported-by: Andrei Vagin <avagin@gmail.com> Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>