On 17.08.2018 21:09, Samudrala, Sridhar wrote: > On 8/17/2018 2:56 AM, Harald Hoyer wrote: >> On 17.08.2018 11:51, Harald Hoyer wrote: >>> On 16.08.2018 00:17, Siwei Liu wrote: >>>> On Wed, Aug 15, 2018 at 12:05 PM, Samudrala, Sridhar >>>> <sridhar.samudrala@xxxxxxxxx> wrote: >>>>> On 8/14/2018 5:03 PM, Siwei Liu wrote: >>>>>> Are we sure all userspace apps skip and ignore slave interfaces by >>>>>> just looking at "IFLA_MASTER" attribute? >>>>>> >>>>>> When STANDBY is enabled on virtio-net, a failover master interface >>>>>> will appear, which automatically enslaves the virtio device. But it is >>>>>> found out that iSCSI (or any network boot) cannot boot strap over the >>>>>> new failover interface together with a standby virtio (without any VF >>>>>> or PT device in place). >>>>>> >>>>>> Dracut (initramfs) ends up with timeout and dropping into emergency shell: >>>>>> >>>>>> [ 228.170425] dracut-initqueue[377]: Warning: dracut-initqueue >>>>>> timeout - starting timeout scripts >>>>>> [ 228.171788] dracut-initqueue[377]: Warning: Could not boot. >>>>>> Starting Dracut Emergency Shell... >>>>>> Generating "/run/initramfs/rdsosreport.txt" >>>>>> Entering emergency mode. Exit the shell to continue. >>>>>> Type "journalctl" to view system logs. >>>>>> You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or >>>>>> /boot >>>>>> after mounting them and attach it to a bug report. >>>>>> dracut:/# ip l sh >>>>>> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN >>>>>> mode DEFAULT group default qlen 1000 >>>>>> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 >>>>>> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue >>>>>> state UP mode DEFAULT group default qlen 1000 >>>>>> link/ether 9a:46:22:ae:33:54 brd ff:ff:ff:ff:ff:ff\ >>>>>> 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast >>>>>> master eth0 state UP mode DEFAULT group default qlen 1000 >>>>>> link/ether 9a:46:22:ae:33:54 brd ff:ff:ff:ff:ff:ff >>>>>> dracut:/# >>>>>> >>>>>> If changing dracut code to ignore eth1 (with IFLA_MASTER attr), >>>>>> network boot starts to work. >>>>> >>>>> Does dracut by default tries to use all the interfaces that are UP? >>>>> >>>> Yes. The specific dracut cmdline of our case is "ip=dhcp >>>> netroot=iscsi:... ", but it's not specific to iscsi boot. And because >>>> of same MAC address for failover and standby, while dracut tries to >>>> run DHCP on all interfaces that are up it eventually gets same route >>>> for each interface. Those conflict route entries kill off the network >>>> connection. >>>> >>>>>> The reason is that dracut has its own means to differentiate virtual >>>>>> interfaces for network boot: it does not look at IFLA_MASTER and >>>>>> ignores slave interfaces. Instead, users have to provide explicit >>>>>> option e.g. bond=eth0,eth1 in the boot line, then dracut would know >>>>>> the config and ignore the slave interfaces. >>>>> >>>>> Isn't it possible to specify the interface that should be used for network >>>>> boot? >>>> As I understand it, one can only specify interface name for running >>>> DHCP but not select interface for network boot. We want DHCP to run >>>> on every NIC that is up (excluding the enslaved interfaces), and only >>>> one of them can get a route entry to the network boot server (ie.g. >>>> iSCSI target). >>>> >>>>> >>>>>> However, with automatic creation of failover interface that assumption >>>>>> is no longer true. Can we change dracut to ignore all slave interface >>>>>> by checking IFLA_MASTER? I don't think so. It has a large impact to >>>>>> existing configs. >>>>> >>>>> What is the issue with checking for IFLA_MASTER? I guess this is used with >>>>> team/bonding setups. >>>> That should be discussed within and determined by the dracut >>>> community. But the current dracut code doesn't check IFLA_MASTER for >>>> team or bonding specifically. I guess this change might have broader >>>> impact to existing userspace that might be already relying on the >>>> current behaviour. >>>> >>>> Thanks, >>>> -Siwei >>> Is there a sysfs flag for IFF_SLAVE? Or any "ip" output I can use to detect, that it is a IFF_SLAVE? >>> >> Oh, it's the other way around.. dracut should ignore "master" (eth1). > In the above example eth0 is the net_failover device and eth1 is the lower virtio_net device. > "ip" output of eth1 shows "master eth0". It indicates that eth0 is its upper/master device. > This information can also be obtained via sysfs too. /sys/class/net/eth1/upper_eth0 >> >> Can the master enslave the "eth0", if it is already "UP" and busy later on? > eth0 is the master/failover device and eth1 gets registered as its slave via NETDEV_REGISTER event. > dracut should ignore eth1 in this setup. Care to test, if that fixes your case? https://github.com/dracutdevs/dracut/pull/450/files
