Multiple cores/race conditions in IPv6 RA

[Kubilay Kocak]

On 9/12/2015 7:45 PM, Andrey V. Elsukov wrote:
> On 08.12.15 08:32, Jason wrote:
>> Hi,
>>
>> It appears the IPv6 router advertisement code paths were written fairly
>> lockless, assuming you would never process multiples concurrently.  We
>> are seeing multiple page faults in various places processing the
>> messages and modifying the routing table.  We have multiple L3 devices
>> and multiple v6 blocks broadcasting these messages to hardware with dual
>> uplinks in the same VLAN, which I believe is making us susceptible to
>> this.  Though I believe the dual uplink is all that's required for this,
>> as it can be seen in configurations with a single v6 block.
>>
>> We are running stable/10 @ r285800, and it doesn't appear anything
>> relevant has changed since then.  Our other widely deployed version is
>> 8.3-RELEASE, which does not see this issue.  Upon bumping a machine from
>> 8.3 -> 10 we can see it start to exhibit this behavior.  The only change
>> I see that might be relevant is r243148, but these cores are relatively
>> rare, so testing is tough without a considerable deployment.  So
>> basically I'm hoping someone with a trained eye can send us in the right
>> direction before we go down that road.
> 
> Hi,
> 
> some time ago Mark Johnston has published there the patch related to
> this problem:
> https://lists.freebsd.org/pipermail/freebsd-net/2013-February/034682.html
> 
> Maybe Mark has something to say about it.
> 

Is it worth creating an issue report to track/resolve this, with 10.3
coming up?

./koobs