[dpdk-dev] Memory leak when adding/removing vhost_user ports

[Christian Ehrhardt <christian.ehrhardt@canonical.com>]

I assume there is a leak somewhere on adding/removing vhost_user ports.
Although it could also be "only" a fragmentation issue.

Reproduction is easy:
I set up a pair of nicely working OVS-DPDK connected KVM Guests.
Then in a loop I
   - add up to more 512 ports
   - test connectivity between the two guests
   - remove up to 512 ports

Depending on memory and the amount of multiqueue/rxq I use it seems to
slightly change when exactly it breaks. But for my default setup of 4
queues and 5G Hugepages initialized by DPDK it always breaks at the sixth
iteration.
Here a link to the stack trace indicating a memory shortage (TBC):
https://launchpadlibrarian.net/253916410/apport-retrace.log

Known Todos:
- I want to track it down more, and will try to come up with a non
openvswitch based looping testcase that might show it as well to simplify
debugging.
- in use were Openvswitch-dpdk 2.5 and DPDK 2.2; Retest with DPDK 16.04 and
Openvswitch master is planned.

I will go on debugging this and let you know, but I wanted to give a heads
up to everyone.
In case this is a known issue for some of you please let me know.

Kind Regards,
Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd

P.S. I think it is a dpdk issue, but adding Daniele on CC to represent
ovs-dpdk as well.