I have 4 servers with Ubuntu 20.04.2 with more than 5 physical ethernets interfaces each (one of then has 18 ethernets) and I had the problem with 2 of them.
I can give you access to one of the servers with bug if needed. It's not in production yet and I can cleanup everything after debug. I tried to emulate the problem using KVM. I saw errors too (apparently non directly related with this issue) when use a lot of interfaces with bridges and vlans. Maybe this script can help to debug: wget https://releases.ubuntu.com/20.04/ubuntu-20.04.2-live-server- amd64.iso qemu-img create -f qcow2 disk1.qcow2 20G sudo -E kvm -m 4096 -netdev user,id=user.0 -device e1000,netdev=user.0 -device e1000,id=n1,mac=00:e0:4c:f6:02:3d -net tap,script=no,id=n1 -device e1000,id=n2,mac=00:e0:4c:f6:03:3d -net tap,id=n2 -device e1000,id=n3,mac=00:e0:4c:f6:04:3d -net tap,id=n3 -device e1000,id=n4,mac=00:e0:4c:f6:05:3d -net tap,id=n4 -device e1000,id=n5,mac=00:e0:4c:f6:06:3d -net tap,id=n5 -device e1000,id=n6,mac=00:e0:4c:f6:07:3d -net tap,id=n6 -device e1000,id=n7,mac=00:e0:4c:f6:08:3d -net tap,id=n7 -device e1000,id=n8,mac=00:e0:4c:f6:09:3d -net tap,id=n8 -device e1000,id=n9,mac=00:e0:4c:f6:10:3d -net tap,id=n9 -device e1000,id=n10,mac=00:e0:4c:f6:11:3d -net tap,id=n10 -device e1000,id=n11,mac=00:e0:4c:f6:12:3d -net tap,id=n11 -device e1000,id=n12,mac=00:e0:4c:f6:13:3d -net tap,id=n12 -device e1000,id=n13,mac=00:e0:4c:f6:14:3d -net tap,id=n13 -device e1000,id=n14,mac=00:e0:4c:f6:15:3d -net tap,id=n14 -device e1000,id=n15,mac=00:e0:4c:f6:16:3d -net tap,id=n15 -device e1000,id=n16,mac=00:e0:4c:f6:17:3d -net tap,id=n16 -vga virtio -display gtk -hda disk1.qcow2 -cdrom ubuntu-20.04.2-live-server-amd64.iso -boot c -smp 8 # Proceed with installation # Poweroff the machine # Power on with sudo -E kvm -m 4096 -netdev user,id=user.0 -device e1000,netdev=user.0 -device e1000,id=n1,mac=00:e0:4c:f6:02:3d -net tap,script=no,id=n1 -device e1000,id=n2,mac=00:e0:4c:f6:03:3d -net tap,id=n2 -device e1000,id=n3,mac=00:e0:4c:f6:04:3d -net tap,id=n3 -device e1000,id=n4,mac=00:e0:4c:f6:05:3d -net tap,id=n4 -device e1000,id=n5,mac=00:e0:4c:f6:06:3d -net tap,id=n5 -device e1000,id=n6,mac=00:e0:4c:f6:07:3d -net tap,id=n6 -device e1000,id=n7,mac=00:e0:4c:f6:08:3d -net tap,id=n7 -device e1000,id=n8,mac=00:e0:4c:f6:09:3d -net tap,id=n8 -device e1000,id=n9,mac=00:e0:4c:f6:10:3d -net tap,id=n9 -device e1000,id=n10,mac=00:e0:4c:f6:11:3d -net tap,id=n10 -device e1000,id=n11,mac=00:e0:4c:f6:12:3d -net tap,id=n11 -device e1000,id=n12,mac=00:e0:4c:f6:13:3d -net tap,id=n12 -device e1000,id=n13,mac=00:e0:4c:f6:14:3d -net tap,id=n13 -device e1000,id=n14,mac=00:e0:4c:f6:15:3d -net tap,id=n14 -device e1000,id=n15,mac=00:e0:4c:f6:16:3d -net tap,id=n15 -device e1000,id=n16,mac=00:e0:4c:f6:17:3d -net tap,id=n16 -vga virtio -display gtk -hda disk1.qcow2 -smp 8 # Login and… sudo apt-get update sudo apt-get install ansible magic-wormhole sshpass ansible-galaxy install mrlesmithjr.netplan #Copy the unzipped attached files debug-systemd.yml and hosts to vm #at host wormhole send debug-systemd.yml wormhole send hosts #receive files at vm wormhole receive ... wormhole receive ... # Configure the hosts file properly with ssh credentials (an example is attached) ansible-playbook -i hosts debug-systemd.yml reboot #login and... networkctl -a # you will see a lot of failing/degraded/pending interfaces ip -br a # You will see a log of interfaces without ip ** Attachment added: "debug-systemd.yml.zip" https://bugs.launchpad.net/ubuntu/focal/+source/systemd/+bug/1912331/+attachment/5483521/+files/debug-systemd.yml.zip -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1912331 Title: Many interfaces lead to "kernel receive buffer overrun" To manage notifications about this bug go to: https://bugs.launchpad.net/systemd/+bug/1912331/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
