[systemd-devel] networkd losing dhcp lease with dracut / nfs root

[Rich Freeman]

I'm running systemd-212 and dracut-037, on a diskless box with an nfs
root and pxe boot.

After a number of updates I noticed that the box would freeze up after
24h uptime - almost exactly.  This behavior is the same whether I have
systemd-networkd running or not (it is configured to set up any
interface matching e* with dhcp).

I traced this to the dhcp lease time - if I set the lease to 10min the
box freezes in 10min, with errors spewing to the network console
shortly after about not being able to reach the nfs server.

After some research, I suspect it is the result of:
https://bugzilla.redhat.com/show_bug.cgi?id=1097523

I monitored the box more closely and discovered that with a 10 minute
lease the box is renewing the lease after 5 minutes.  However, if I
run "watch ip addr" the box counts down the valid_lft from 600 seconds
down to 1 second with no change after 5 minutes.

If I disable systemd-networkd then the box doesn't renew the lease at
all, and valid_lft counts down just the same.

I suspect that systemd-networkd is renewing the lease but not updating
the valid_lft on the interface, and thus after the original lease
expires the kernel brings it down.

The only other thing that is odd is that my interface has two IPs
assigned, and I have no idea where one is coming from:
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP qlen 1000
    link/ether 00:01:2e:31:04:dc brd ff:ff:ff:ff:ff:ff
    inet 200.0.0.0/24 brd 200.0.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet 192.168.0.10/24 brd 192.168.0.255 scope global dynamic eth0
       valid_lft 220sec preferred_lft 220sec
    inet6 fe80::201:2eff:fe31:4dc/64 scope link
       valid_lft forever preferred_lft forever

Clearly systemd-networkd is managing 192.168.0.10:
Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: link is up
Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: carrier on
Jun 27 23:12:43 mythliv2 systemd[1]: Started Network Service.
Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: DHCPv4 address
192.168.0.10/24 via 192.168.0.101
Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: link configured

I'm not sure where the other IP is coming from - it shows up even if I
don't enable systemd-networkd, so perhaps dracut is setting it up.
I'm not sure if its valid_lft of forever is causing any confusion
though.

My network config:
[Match]
Name=e*

[Network]
DHCP=yes

[DHCPv4]
CriticalConnection=yes

(I get the same behavior if I drop the CriticalConnection=yes)

Any thoughts as to what is going wrong here?  I'm happy to test patches/etc.

Rich