Paul Graydon, I wouldn't get too hung up on what appears a non-related code change affecting DHCP. Honestly, this result isn't surprising given how kernel code is more inter-related than meets the eye.
Despite this, the issue you are reporting is an upstream one. Could you please report this problem following the instructions verbatim at https://wiki.ubuntu.com/Bugs/Upstream/kernel to the appropriate mailing list (TO Linus Torvalds, and Eric W. Biederman CC linux-kernel)? Please provide a direct URL to your post to the mailing list when it becomes available so that it may be tracked. Thank you for your help. ** Changed in: linux (Ubuntu) Importance: Low => High ** Changed in: linux (Ubuntu) Status: Incomplete => Triaged ** Description changed: Between kernel versions 4.4.0-53 and 4.4.0-57 a bug has been (re?)introduced that is breaking dhcp booting in the initrd environment. This is stopping instances that use iscsi storage from being able to connect. Over serial console it outputs: IP-Config: no response after 2 secs - giving up IP-Config: ens2f0 hardware address 90:e2:ba:d1:36:38 mtu 1500 DHCP RARP IP-Config: ens2f1 hardware address 90:e2:ba:d1:36:39 mtu 1500 DHCP RARP IP-Config: no response after 3 secs - giving up with increasing delays until it fails. At which point a simple ipconfig -t dhcp -d "ens2f0" works. The console output is slightly garbled but should give you an idea: (initramfs) ipconfig -t dhcp -[ 728.379793] ixgbe 0000:13:00.0 ens2f0: changing MTU from 1500 to 9000 d "ens2f0" IP-Config: ens2f0 hardware address 90:e2:ba:d1:36:38 mtu 1500 DHCP RARP IP-Config: ens2f0 guessed broadcast address 10.0.1.255 IP-Config: ens2f0 complete (dhcp from 169.254.169.254): - addres[ 728.980448] ixgbe 0000:13:00.0 ens2f0: detected SFP+: 3 + addres[ 728.980448] ixgbe 0000:13:00.0 ens2f0: detected SFP+: 3 s: 10.0.1.56 broadcast: 10.0.1.255 netmask: 255.255.255.0 - gateway: 10.0.1.1 [ 729.148410] ixgbe 0000:13:00.0 ens2f0: NIC Link is Up 10 Gbps, Flow Control: RX/TX - dns0 : 169.254.169.254 dns1 : 0.0.0.0 - rootserver: 169.254.169.254 rootpath: - filename : /ipxe.efi + gateway: 10.0.1.1 [ 729.148410] ixgbe 0000:13:00.0 ens2f0: NIC Link is Up 10 Gbps, Flow Control: RX/TX + dns0 : 169.254.169.254 dns1 : 0.0.0.0 + rootserver: 169.254.169.254 rootpath: + filename : /ipxe.efi - - tcpdumps show that dhcp requests are being received from the host, and responses sent, but not accepted by the host. When the ipconfig command is issued manually, an identical dhcp request and response happens, only this time it is accepted. It doesn't appear to be that the messages are being sent and received incorrectly, just silently ignored by ipconfig. + tcpdumps show that dhcp requests are being received from the host, and + responses sent, but not accepted by the host. When the ipconfig command + is issued manually, an identical dhcp request and response happens, only + this time it is accepted. It doesn't appear to be that the messages are + being sent and received incorrectly, just silently ignored by ipconfig. I was seeing this behaviour earlier this year, which I was able to fix by specifying "ip=dhcp" as a kernel parameter. About a month ago that was identified as causing us other problems (long story) and we dropped it, at which point we discovered the original bug was no longer an issue. Putting "ip=dhcp" back on with this kernel no longer fixes the problem. I've compared the two initrds and effectively the only thing that has changed between the two is the kernel components. - I'm going to try and track back through kernel versions to see if I can - find which version the fix happened in to maybe provide some additional - context. I'll also attach copies of the initrds, packet captures etc. + Offending commit: + # first bad commit: [fd4b5fa6e3487d15ede746f92601af008b2abbc0] mnt: Add a per mount namespace limit on the number of mounts + + The offending commit submission: + https://lkml.org/lkml/2016/10/5/308 ** Tags added: xenial -- 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/1652348 Title: initrd dhcp fails / ignores valid response Status in linux package in Ubuntu: Triaged Bug description: Between kernel versions 4.4.0-53 and 4.4.0-57 a bug has been (re?)introduced that is breaking dhcp booting in the initrd environment. This is stopping instances that use iscsi storage from being able to connect. Over serial console it outputs: IP-Config: no response after 2 secs - giving up IP-Config: ens2f0 hardware address 90:e2:ba:d1:36:38 mtu 1500 DHCP RARP IP-Config: ens2f1 hardware address 90:e2:ba:d1:36:39 mtu 1500 DHCP RARP IP-Config: no response after 3 secs - giving up with increasing delays until it fails. At which point a simple ipconfig -t dhcp -d "ens2f0" works. The console output is slightly garbled but should give you an idea: (initramfs) ipconfig -t dhcp -[ 728.379793] ixgbe 0000:13:00.0 ens2f0: changing MTU from 1500 to 9000 d "ens2f0" IP-Config: ens2f0 hardware address 90:e2:ba:d1:36:38 mtu 1500 DHCP RARP IP-Config: ens2f0 guessed broadcast address 10.0.1.255 IP-Config: ens2f0 complete (dhcp from 169.254.169.254): addres[ 728.980448] ixgbe 0000:13:00.0 ens2f0: detected SFP+: 3 s: 10.0.1.56 broadcast: 10.0.1.255 netmask: 255.255.255.0 gateway: 10.0.1.1 [ 729.148410] ixgbe 0000:13:00.0 ens2f0: NIC Link is Up 10 Gbps, Flow Control: RX/TX dns0 : 169.254.169.254 dns1 : 0.0.0.0 rootserver: 169.254.169.254 rootpath: filename : /ipxe.efi tcpdumps show that dhcp requests are being received from the host, and responses sent, but not accepted by the host. When the ipconfig command is issued manually, an identical dhcp request and response happens, only this time it is accepted. It doesn't appear to be that the messages are being sent and received incorrectly, just silently ignored by ipconfig. I was seeing this behaviour earlier this year, which I was able to fix by specifying "ip=dhcp" as a kernel parameter. About a month ago that was identified as causing us other problems (long story) and we dropped it, at which point we discovered the original bug was no longer an issue. Putting "ip=dhcp" back on with this kernel no longer fixes the problem. I've compared the two initrds and effectively the only thing that has changed between the two is the kernel components. Offending commit: # first bad commit: [fd4b5fa6e3487d15ede746f92601af008b2abbc0] mnt: Add a per mount namespace limit on the number of mounts The offending commit submission: https://lkml.org/lkml/2016/10/5/308 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1652348/+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
