Re: [PATCH net] ipv6: remove incorrect WARN_ON() in fib6_del()

On Mon, Sep 25, 2017 at 7:07 PM, Martin KaFai Lau [off-list ref] wrote:

I am probably still missing something.

Considering the del operation should be under the writer lock,
if rt->rt6i_node should be NULL (for rt that has already been
removed from fib6), why this WARN_ON() is triggered?

An example may help.

Look at the stack trace, you'll find the answers...

ip6_link_failure() -> ip6_del_rt()

Note that rt might have been deleted from the _tree_ already.