[Lxc-users] pivot root failures when "/" is mounted as "shared"

[Peter Simons]

Hi Michael,

 > If you've tested that and you've seen how it breaks, could you post
 > the version of systemd you are running and the error messages along
 > with some config examples here so we can see them?

I'm running lxc-0.8.0-rc2 on a systemd-195 host. When I try to start a
container, I get the following error:

  # lxc-start -n ubuntu
  lxc-start: Invalid argument - pivot_root syscall failed
  lxc-start: failed to setup pivot root
  lxc-start: failed to set rootfs for 'ubuntu'
  lxc-start: failed to setup the container
  lxc-start: invalid sequence number 1. expected 2
  lxc-start: failed to spawn 'ubuntu'
  lxc-start: Device or resource busy - failed to remove cgroup '/sys/fs/cgroup/systemd/system/lxc/ubuntu'

The container is an Ubuntu Precise, created by lxc-create. The lxc
config file and fstab are attached below, at the end of the message.


 > A short term work-around is to simply remount the root tree to
 > private before invoking LXC.

That work-around comes with significant side-effects for me. Running

 # mount --make-rprivate /
 # lxc-start -n ubuntu

gives me a working container, alright, but it also screws up my host
system real bad. The most obvious problem is that my /dev/pts directory
has disappeared, so I can no longer allocate a PTY:

  # xterm
  xterm: Error 32, errno 2: No such file or directory
  Reason: get_pty: not enough ptys

/dev/pts is not the only mount point that's gone. I've also lost the
following other ones:

  --- /tmp/old	2012-11-05 15:17:27.205674924 +0100
  +++ /tmp/new	2012-11-05 15:17:42.297486250 +0100
  @@ -3,21 +3,7 @@
   none on /sys type sysfs (rw,relatime)
   none on /dev type devtmpfs (rw,relatime,size=206136k,nr_inodes=220097,mode=755)
   none on /run type tmpfs (rw,relatime,size=206136k,mode=755)
  -none on /sys/kernel/security type securityfs (rw,relatime)
   /dev/disk/by-label/root on / type ext4 (rw,noatime,nodiratime,data=ordered)
   none on /tmp type tmpfs (rw,relatime)
  -tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,relatime)
  -none on /proc/bus/usb type usbfs (rw,relatime)
  -devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=3,mode=620,ptmxmode=000)
   tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,mode=755)
  -cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,release_agent=/nix/store/i1qpxmqwwn247y59lf2cpra5iw1rgvrh-systemd-195/lib/systemd/systemd-cgroups-agent,name=systemd)
  -cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
  -cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)
  -cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
  -cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
  -cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
  -cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
  -hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
  -mqueue on /dev/mqueue type mqueue (rw,relatime)
  -debugfs on /sys/kernel/debug type debugfs (rw,relatime)
   /dev/sda1 on /boot type ext4 (rw,noatime,nodiratime,data=ordered)

That doesn't seem right?

Take care,
Peter


-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: config
URL: <http://lists.linuxcontainers.org/pipermail/lxc-users/attachments/20121105/9887221d/attachment.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: fstab
URL: <http://lists.linuxcontainers.org/pipermail/lxc-users/attachments/20121105/9887221d/attachment-0001.ksh>