Re: Multitude of dst obsolescense race conditions

On Wed, May 14, 2014, at 2:57, dormando wrote:

Given a machine with frequently changing routes (ie; a router with an
active internet BGP table and multiple interfaces), there're at least
several places where obsolete dst's are handled improperly. If I pause
the
route changes, the crashes appear to stop. This first one has a crash
utility we've made, so I was able to more quickly find a patch and test
it. The others take time to reproduce.

I'm testing against 3.10.39, but I think if these were fixed they'd be
backported to stable? I've also had recent 3.12's running that have
crashed in the same spots. Anyway correct me if I'm wrong...

Just a hunch:
You use macvlan? Could you somehow try without?
Maybe... some ref overflow? (You could add some testing code in dst_hold
with atomic_inc_return and WARN_ON).

dst_release already contains such a check, so I am not sure at all if
that could happen.

Bye,

  Hannes