netdev - Strange routing with VRF and 5.2.7+

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Message-ID: <91749b17-7800-44c0-d137-5242b8ceb819@candelatech.com>
Date:   Tue, 10 Sep 2019 15:17:53 -0700
From:   Ben Greear <greearb@...delatech.com>
To:     netdev <netdev@...r.kernel.org>
Subject: Strange routing with VRF and 5.2.7+

Today we were testing creating 200 virtual station vdevs on ath9k, and using
VRF for the routing.

This really slows down the machine in question.

During the minutes that it takes to bring these up and configure them,
we loose network connectivity on the management port.

If I do 'ip route show', it just shows the default route out of eth0, and
the subnet route.  But, if I try to ping the gateway, I get an ICMP error
coming back from the gateway of one of the virtual stations (which should be
safely using VRFs and so not in use when I do a plain 'ping' from the shell).

I tried running tshark on eth0 in the background and running ping, and it captures
no packets leaving eth0.

After some time (and during this time, my various scripts will be (re)configuring
vrfs and stations and related vrf routing tables and such,
but should *not* be messing with the main routing table, then suddenly
things start working again.

I am curious if anyone has seen anything similar or has suggestions for more
ways to debug this.  It seems reproducible, but it is a pain to
debug.

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com