On Sat, Jul 8, 2017 at 3:02 AM, David Miller <[email protected]> wrote: > From: Nicolas Dichtel <[email protected]> > Date: Wed, 5 Jul 2017 17:57:25 +0200 > >> From: Hongjun Li <[email protected]> >> >> When the netdev event NETDEV_CHANGEMTU is triggered, the inet[6]dev may be >> created even if the corresponding device is down. This may lead to a leak >> in the procfs when the device is unregistered, and finally trigger a >> backtrace: > ... >> When a device changes from one netns to another, it's first unregistered, >> then the netns reference is updated and the dev is registered in the new >> netns. Thus, when a slave moves to another netns, it is first >> unregistered. This triggers a NETDEV_UNREGISTER event which is caught by >> the bonding driver. The driver calls bond_release(), which calls >> dev_set_mtu() and thus triggers NETDEV_CHANGEMTU (the device is still in >> the old netns). >> >> Signed-off-by: Hongjun Li <[email protected]> >> Signed-off-by: Nicolas Dichtel <[email protected]> > > I'm still not convinced about this. > > We have lots of code which iterates ipv6 idevs, and then has a > check for IFF_UP. > > So having an idev attached to a down interface is not a bug nor > illegal. > > In fact, addrconf_cleanup() walks all of the init_net idevs and > calls addrconf_ifdown() with how=1 regardless of IFF_UP or not. > > This entire area is quite a mess.
+1. I fixed a nasty bug with how=1 for loopback before... > > Can you show exactly why the procfs state isn't cleaned up for > these devices moving between namespaces? Maybe that is the real > bug and a better place to fix this. > It is because the ipv6_add_dev() adds these proc files back after NETDEV_UNREGISTER event.
