** Changed in: ifupdown (Ubuntu)
Importance: Medium => High
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https://bugs.launchpad.net/bugs/1636708
Title:
ifup -a does not start dependants last, causes deadlocks with
vlans/bonding
Status in ifupdown package in Ubuntu:
Confirmed
Status in ifupdown source package in Xenial:
New
Bug description:
This is a problem I've been struggling with since moving to 16.04.1
from 14.04 (fresh install)
I don't believe this problem affected 14.04. I have used an almost
identical interfaces file on 14.04 without problem.
On 16.04.1, however, 9/10 boots would hang during network
configuration and leave the network incorrectly configured.
When calling "ifup -a" all candidate interfaces appear to be started
in parallel leading to collisions with locks. This causes hanging
(until timeout) during booting and the network interfaces left
incorrectly configured
Imagine this /etc/network/interfaces
auto eno1 bond0 bond0.1
iface eno1 inet manual
bond-master bond0
iface bond0 inet manual
bond-slaves eno1
bond-mode 4
bond-lacp-rate 1
bond-miimon 100
bond-updelay 200
bond-downdelay 200
iface bond0.5 inet dhcp
vlan-raw-device bond0
eno1 -> bond0 -> bond0.5 -> dhcp
When calling "ifup -a" at boot time all three interfaces are started
at the same time.
bond0 and bond0.5 both attempt to share the same lock file:
/run/network/ifstate.bond0
If bond0 wins the race, the system will start correctly (1/10):
* bond0 starts and creates the bond0 device and the ifenslave.bond0 file to
indicate the bond is ready
* eno1 polls for the ifenslave.bond0 file, when it appears it attaches eno1
to bond0
* bond0 finishes and releases the lock
* bond0.5 now acquires the lock.
* bond0.5 starts dhclient, which can talk to the network and configure the
interface
If, however, bond0.2 wins the lock race, the system will hang at boot (5
mins) and fail to set up the network.
* bond0.5 is awarded the ifstate.bond0 lockfile
* bond0.5 starts dhclient waiting to hear from the network
* bond0 is blocked, so bond0 is not created nor is the bond0.ifenslave file
* eno1 polls but never finds the ifenslave.bond0 file so never attaches to
bond0
* bond0.5's dhclient is trying to talk to a disconnected network and never
receives an answer
! bond0.5 is stuck running dhclient
! bond0 is stuck waiting for bond0.5 to finish
! eno1 is stuck waiting for bond0 to create the ifenslave.bond0 file
I believe ifup should start interfaces (that share lock files) in dependant
order. The most basic interface must be awarded the lock over its dependants.
In this case:
1 eno1
2 bond0
3 bond0.5
but never:
1 eno1
2 bond0.5
3 bond0
As a work arouund, in /etc/network/interfaces
-auto eno1 bond0 bond0.1
+auto eno1 bond0
+allow-bond bond0.1
And also in /lib/systemd/system/networking.service
ExecStart=/sbin/ifup -a --read-environment
+ExecStart=/sbin/ifup -a --allow=bond --read-environment
ExecStop=/sbin/ifdown -a --read-environment
Then run:
systemctl dameon-reload
This causes all "auto" interfaces to start then, when they've
completed, all allow-bond interfaces to start.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ifupdown 0.8.10ubuntu1.1 [modified:
lib/systemd/system/networking.service]
ProcVersionSignature: Ubuntu 4.4.0-45.66-generic 4.4.21
Uname: Linux 4.4.0-45-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Wed Oct 26 06:32:57 2016
InstallationDate: Installed on 2016-10-24 (1 days ago)
InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Release amd64
(20160719)
SourcePackage: ifupdown
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.init.networking.conf: [modified]
mtime.conffile..etc.init.networking.conf: 2016-10-26T04:52:05.750927
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