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-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1729573 Title: netplan breaks Xen VIF driver Status in linux package in Ubuntu: Won't Fix Status in nplan package in Ubuntu: Fix Released Status in linux source package in Xenial: Won't Fix Status in nplan source package in Xenial: Fix Committed Status in linux source package in Zesty: Won't Fix Status in nplan source package in Zesty: Fix Committed Status in linux source package in Artful: Won't Fix Status in nplan source package in Artful: Fix Released Status in linux source package in Bionic: Won't Fix Status in nplan source package in Bionic: Fix Released Bug description: [Impact] Some network interfaces on a Xen guest are broken by new behavior introduced by netplan. On a Xen guest instance, when netplan is run to 'apply' its configuration, under certain circumstances netplan will try to "reset" the interface by unbinding and then re-binding the interface driver from the interface, by using the sysfs "bind" and "unbind" functions of the driver. Normally, this results in the interface being released and then fully re-initialized by the driver. However the Xen VIF driver breaks when this is done. The internal Xen backend state of the interface remains in 'closed' state after the driver re-connects to the interface, and attempts to open and use the interface result in a kernel Oops in the Xen VIF driver. To users, it appears that the interface is unusable because it has an all 0 mac address; but if the mac is manually set and the interface brought up the driver Oopses as mentioned above. This problem makes booting painful because of very long timeouts waiting for all network interfaces to start, and affected Xen VIF interfaces will of course never complete startup. [Fix] No fix yet. Upstream kernel does not appear fixed. [Test Case] Create a guest instance under a Xen hypervisor (e.g. an AWS instance) that has Ubuntu Artful 17.10 installed. Use only a single interface at first when creating it. Then once it is ready, attach a second network interface to the instance. From inside the instance, configure the new interface in netplan (i.e. add a /etc/netplan/ config for it). Make sure the new interface is down (netplan does not appear to unbind/bind interfaces that are up), and then run: $ sudo netplan apply or for debug, $ sudo netplan --debug apply this will unbind and re-bind the second interface, which will then have all-0 mac, and will be unusable, as described above. [Regression Potential] Changes to the Xen VIF driver can result in unusable network interfaces, or problems while using Xen VIF interfaces. [Other Info] Problem appears to exist upstream also. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1729573/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
