From: Andrew Collins <acoll...@cradlepoint.com> Date: Tue, 29 Mar 2016 11:25:03 -0600
> This is an RFC patch to fix a relatively easily reproducible kernel > panic related to the all_adj_list handling for netdevs in recent kernels. > > This is more to generate discussion than anything else. I don't > particularly like this approach, I'm hoping someone has a better idea. > > The following sequence of commands will reproduce the issue: > > ip link add link eth0 name eth0.100 type vlan id 100 > ip link add link eth0 name eth0.200 type vlan id 200 > ip link add name testbr type bridge > ip link set eth0.100 master testbr > ip link set eth0.200 master testbr > ip link add link testbr mac0 type macvlan > ip link delete dev testbr > > This creates an upper/lower tree of (excuse the poor ASCII art): > > /---eth0.100-eth0 > mac0-testbr- > \---eth0.200-eth0 > > When testbr is deleted, the all_adj_lists are walked, and eth0 is deleted > twice from > the mac0 list. Unfortunately, during setup in __netdev_upper_dev_link, only > one > reference to eth0 is added, so this results in a panic. > > This change adds reference count propagation so things are handled properly. > > Matthias Schiffer reported a similar crash in batman-adv: > > https://github.com/freifunk-gluon/gluon/issues/680 > https://www.open-mesh.org/issues/247 > > which this patch also seems to resolve. Veaceslav, please look into this. Thanks.
