[ovs-discuss] tnl arp causes infinite reentrant stack death.

David Evans davidjoshuaevans at gmail.com
Wed Sep 16 16:32:00 UTC 2015

Thank you Jesse,
The patch stopped the program call stack from killing ovs.
Will do some more tests today.

On 9/15/15, 10:54 PM, "Jesse Gross" <jesse at nicira.com> wrote:

>On Tue, Sep 15, 2015 at 7:38 PM, David Evans <davidjoshuaevans at gmail.com>
>> Thanks Jesse!
>> I think you may be close, but it is the ovs code that is re-entering
>> self, this isn't an arp storm from a circle of traffic path, as far as
>>i can
>> tell. it is an attempt to transmit a single packet.. but never gets
>>even the
>> arp out to the stack at all.
>> you can see build_tunnel_send 3 times as the stack trace goes in the
>> original post. but no packets make it out. the program call stack is
>> frames deep - which is why it crashed.
>When tunneling is done in userspace (such as with DPDK), the Linux
>stack is not involved at all since the point of DPDK is to avoid the
>kernel for performance reasons. That's why you see OVS reentering
>itself repeatedly as it tries to forward and then generate more ARP
>I just sent out a patch CC'd to you that should fix this issue. Can
>you test it? Note that in this case 'fix' means that it will prevent
>OVS from crashing. However, traffic won't flow until the loop in the
>configuration is resolved. Based on the stack trace, my guess is that
>you have one or more patch ports connecting the bridges.

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