== SRU Justification ==
This bug causes Samba mount and umounts in docker container to trigger
a kernel Oops. When running 2 docker containers, one as samba server and
another one as samba client that mounts and umounts a smb share a kernel
OOps can be triggered.
This bug happens in Xenial and Zesty, and is fixed by the following two commits:
76da0704507b ("ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER")
12d94a804946 ("ipv6: fix NULL dereference in ip6_route_dev_notify()")
Both commits are clean cherry picks. 76da0704507b is in mainline as of v4.12.
Commit 12d94a804946 is in mainline as of v4.13-rc6.
== Fixes ==
commit 76da0704507bbc51875013f6557877ab308cfd0a
Author: WANG Cong <xiyou.wangcong at gmail.com>
Date: Tue Jun 20 11:42:27 2017 -0700
ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
commit 12d94a804946af291e24b80fc53ec86264765781
Author: Eric Dumazet <edumazet at google.com>
Date: Tue Aug 15 04:09:51 2017 -0700
ipv6: fix NULL dereference in ip6_route_dev_notify()
== Regression Potential ==
Both commits are specific to ipv6 and fix a regression introduced into Xenial and Zesty.
== Test Case ==
A test kernel was built with these patches and tested by the original bug reporter.
The bug reporter states the test kernel resolved the bug.
The kernel message:
unregister_netdevice: waiting for lo to become free. Usage count = 1
shows up, some minutes later the oops and/or warnings happens.
The scripts to trigger the kernel Oops can be found at: https://github.com/fho/docker-samba-loop
I was able to reproduce kernel Oopses on a clean Ubuntu 16.0.4 installation with:
- linux-image-4.4.0-93-generic=4.4.0-93.116~14.04.1
- linux-image-4.10.0-32-generic=4.10.0-32.36~16.04.1
- linux-image-4.11.0-14-generic=4.11.0-14.20~16.04.1
In a different scenario were Ubuntu 16.04 servers were running multiple docker containers with Nginx or small network applications in parallel, I was also able to reproduce the kernel Oopses also on:
- linux-image-4.10.0-1004-gcp
- linux-image-4.12.10-041210-generic=4.12.10-041210.20170830
I haven't tried again to reproduce it with those kernels on a clean Ubuntu
installation and unfortunately didn't kept the kernel logs.
The "unregister_netdevice: waiting for lo to become free. Usage count = 1" messages are related to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407 which is handled as separate issue.
According to https://github.com/moby/moby/issues/35068 the crash is fixed by:
https://patchwork.ozlabs.org/patch/801533/
https://patchwork.ozlabs.org/patch/778449/
---
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Nov 3 09:51 seq
crw-rw---- 1 root audio 116, 33 Nov 3 09:51 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: N/A
DistroRelease: Ubuntu 16.04
IwConfig: Error: [Errno 2] No such file or directory
Lsusb: Error: command ['lsusb'] failed with exit code 1:
MachineType: Google Google Compute Engine
Package: linux (not installed)
PciMultimedia:
ProcEnviron:
TERM=rxvt-unicode-256color
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB:
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.10.0-37-generic root=UUID=bf9a017a-931d-4191-84bc-b8434dbba527 ro scsi_mod.use_blk_mq=Y console=ttyS0
ProcVersionSignature: Ubuntu 4.10.0-37.41~16.04.1-generic 4.10.17
RelatedPackageVersions:
linux-restricted-modules-4.10.0-37-generic N/A
linux-backports-modules-4.10.0-37-generic N/A
linux-firmware N/A
RfKill: Error: [Errno 2] No such file or directory
Tags: xenial uec-images xenial uec-images
Uname: Linux 4.10.0-37-generic x86_64
UnreportableReason: The report belongs to a package that is not installed.
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:
_MarkForUpload: False
dmi.bios.date: 01/01/2011
dmi.bios.vendor: Google
dmi.bios.version: Google
dmi.board.asset.tag: A3DDBB61-646B-C60C-3999-1F1D7B7A334A
dmi.board.name: Google Compute Engine
dmi.board.vendor: Google
dmi.chassis.type: 1
dmi.chassis.vendor: Google
dmi.modalias: dmi:bvnGoogle:bvrGoogle:bd01/01/2011:svnGoogle:pnGoogleComputeEngine:pvr:rvnGoogle:rnGoogleComputeEngine:rvr:cvnGoogle:ct1:cvr:
dmi.product.name: Google Compute Engine
dmi.sys.vendor: Google
This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:
apport-collect 1729637
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.