[buildd-tools-devel] Bug#749897: schroot: Can't end session after schroot automatically restored it during boot under systemd

[Mike Hommey]

Package: schroot
Version: 1.6.10-1+b1
Severity: important

So, I had three schroot sessions active and at some point, there was a reboot
involved. I don't remember if it was a hard reboot or a soft reboot, because
it was actually a while ago, but it doesn't matter anyways.

So, after a while, i figured that it made no sense to keep all those schroot
mount points around, so I asked schroot to end the three sessions. Which it
happily did, until it stopped on a EBUSY error while rmdir'ing the root
mount point in /var/lib/schroot/mount/.

As far as I can tell, the reason why this happens is that the user session
does the schroot -e runs in a mount namespace that is not the global mount
namespace, thanks to systemd. And the schroot restore script at boot most
likely runs in the global mount namespace. So, when schroot -e does its stuff,
all it's doing is unmounting the bind mounts in the user namespace, but those
bind mounts are still active in the global mount namespace. Then rmdir fails
because of that.

Rebooting without systemd allowed schroot -e to do its job properly.

Mike


-- System Information:
Debian Release: jessie/sid
  APT prefers testing-updates
  APT policy: (500, 'testing-updates'), (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 3.14-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages schroot depends on:
ii  libboost-filesystem1.55.0       1.55.0+dfsg-1
ii  libboost-iostreams1.55.0        1.55.0+dfsg-1
ii  libboost-program-options1.55.0  1.55.0+dfsg-1
ii  libboost-regex1.55.0            1.55.0+dfsg-1
ii  libboost-system1.55.0           1.55.0+dfsg-1
ii  libc6                           2.18-7
ii  libgcc1                         1:4.9.0-4
ii  libpam0g                        1.1.8-3
ii  libstdc++6                      4.9.0-4
ii  libuuid1                        2.20.1-5.7
ii  schroot-common                  1.6.10-1

schroot recommends no packages.

Versions of packages schroot suggests:
pn  aufs-modules | unionfs-modules  <none>
ii  btrfs-tools                     3.14.1-1
ii  debootstrap                     1.0.60
ii  lvm2                            2.02.106-1
pn  qemu-user-static                <none>

-- Configuration Files:
/etc/schroot/default/fstab changed [not included]

-- no debconf information