On Tue, Feb 06, 2018 at 01:56:24PM +0100, Florian Westphal wrote: > Eyal Birger <eyal.bir...@gmail.com> wrote: > > Hi, > > > > We've encountered a non released device reference upon device > > unregistration which seems to stem from xfrm policy code. > > > > The setup includes: > > - an underlay device (e.g. eth0) using IPv4 > > - an xfrm IPv6 over IPv4 tunnel routed via the underlay device > > - an ipip6 tunnel over the xfrm IPv6 tunnel > > > > When tearing down the underlay device, after traffic had passed via the > > ipip6 > > tunnel, log messages of the following form are observed: > > > > unregister_netdevice: waiting for eth0 to become free. Usage count = 2 > > This looks like it might be related to a bug reported by Hangbin Liu. > > Setup is: > > Host A -- Host B > tun0 -- br0 (ipsec) -- eth0 -- eth0 (ipsec) -- tun0 > > ... where tun0 are ipip tunnels. > > module removal then hangs forever as device refcount is held by > dst_cache. > Hangbin gave following reproducer script: > > Host B: > ip link add tun0 type ipip local 192.168.7.1 remote 192.168.7.10 > ip link set tun0 up > ip addr add 10.0.0.2/24 dev tun0 > ip xfrm state add src 192.168.7.1 dst 192.168.7.10 spi 1000 proto ah > auth sha1 beef_fish_pork_salad mode transport > ip xfrm state add src 192.168.7.1 dst 192.168.7.1 spi 1000 proto ah auth > sha1 beef_fish_pork_salad mode transport > ip xfrm policy add src 192.168.7.1 dst 192.168.7.10 dir out tmpl src > 192.168.7.1 dst 192.168.7.10 proto ah spi 1000 mode transport > ip xfrm policy add src 192.168.7.10 dst 192.168.7.1 dir in tmpl src > 192.168.7.10 dst 192.168.7.1 proto ah spi 1000 mode transport level use > > On Host A (tun0 10.0.0.1, br0 192.168.7.10): > ip addr flush dev eth0 > brctl addbr br0 > brctl addif br0 eth0 > ip link set br0 up > ip addr add 192.168.7.10/24 dev br0 > > ip link add tun0 type ipip local 192.168.7.10 remote 192.168.7.1 > ip link set tun0 up > ip addr add 10.0.0.1/24 dev tun0 > > ip xfrm state add src 192.168.7.10 dst 192.168.7.1 spi 1000 > proto ah auth sha1 beef_fish_pork_salad mode transport > ip xfrm state add src 192.168.7.1 dst 192.168.7.10 spi 1000 > proto ah auth sha1 beef_fish_pork_salad mode transport > ip xfrm policy add src 192.168.7.10 dst 192.168.7.1 dir out tmpl > src 192.168.7.10 dst 192.168.7.1 proto ah spi 1000 mode transport > ip xfrm policy add src 192.168.7.1 dst 192.168.7.10 dir in tmpl src > 192.168.7.1 dst 192.168.7.10 proto ah spi 1000 mode transport level use > > # should work, else something is broken: > ping 10.0.0.2 -c 2 > > # This hangs: > modprobe -r bridge > > This hangs even when I remove the ipsec xfrm pcpu cache. > > What does work in above setup is this:
I gave the patch a quick try, but still I get this: unregister_netdevice: waiting for dummy1 to become free. Usage count = 2
