Hello, On Mon, 28 Sep 2015, Eric W. Biederman wrote:
> Julian Anastasov <j...@ssi.bg> writes: > > > On Mon, 28 Sep 2015, Anand Gurram wrote: > > > >> I am currently using kernel version 3.16.7 on a linux switch. > >> While creating and destroying network namespaces I am observing below logs > >> on the console > >> "unregister_netdevice: waiting for lo to become free. Usage count = 1" > >> > >> Can you please suggest and provide instructions on how to debug this issue. > >> If any fix already available can you please point me to the link. > > > > There are two commits from Linux 4.2 that may help: > > > > commit e9e4dd3267d0 ("net: do not process device backlog during > > unregistration") > > commit 2c17d27c36dc ("net: call rcu_read_lock early in process_backlog") > > > If that message repeats indefinitely it means there is a leaked > reference to the network namespaces lo device. > > If the message just spits out a few times and then goes away it simply > means that something is taking a while to cleanup and drop it's > reference. > > This is slightly complicated by the fact that it is not uncommon when a > network device goes away to redirect all references to itself to the lo > device. Yes, there is a little chance with forwarding disabled, i.e. when presence of "ipv4: Avoid crashing in ip_error" does not matter, flying packet to leave new reference somewhere, without crashing. But it may be another problem, of course. Regards -- Julian Anastasov <j...@ssi.bg> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html