Daniel Lezcano wrote: > Hi all, > > while doing ipv6 namespace, we were faced to a problem with the loopback > and the dst_destroy function. > > When the network namespace exits, the cleanup function is called by > schedule_work and this function will browse the net ops list to call the > different exit methods for the registered subsystems. > > The different subsystems will shutdown their resources and in particular > addrconf subsystem will ifdown the loopback. This function will call > rt6_ifdown > -> fib6_clean_all > -> fib6_clean_node > -> fib6_clean_tree > -> fib6_clean_node > -> fib6_del > -> fib6_del_route > -> rt6_release > ->dst_free > -> __dst_free > > The __dst_free function will schedule_delayed_work the dst_gc_work > function. > > The dst_gc_work will call dst_destroy and finally this one will call > dst->ops->destroy ops function which is ip6_dst_destroy. > > The problem here is we have the workq blocked because we are running > inside the netns cleanup function. So the delayed work will not run > until we exits the cleanup function. But the loopback is still > referenced by the ip6 routes, the netdev_unregister will loop > indefinitly => dead lock. > > By the way, this bug appears with ipv6 but it is perhaps pending with ipv4. > > Benjamin as proposed to create a separate workq for the network > namespace, so in the worst case we have the unregister looping until the > ip6 route are shut downed. Is it an acceptable solution ? > we are doing this staff in the special thread. There are a lot of difficult things to perform like synchronize_net & netdev_run_todo inside Regards, Den _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers