** Changed in: unattended-upgrades (Debian)
Status: New => Fix Released
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https://bugs.launchpad.net/bugs/1654600
Title:
unattended-upgrade-shutdown hangs when /var is a separate filesystem
Status in unattended-upgrades package in Ubuntu:
Fix Released
Status in unattended-upgrades source package in Xenial:
Fix Committed
Status in unattended-upgrades source package in Yakkety:
Fix Committed
Status in unattended-upgrades source package in Zesty:
Fix Committed
Status in unattended-upgrades package in Debian:
Fix Released
Bug description:
[SRU justification]
This fix is needed to make sure that the system does not hang on shutdown
when /var is a speparate file system
[Impact]
System can hang up to 10 minutes if not fixed.
[Fix]
Change the systemd unit's ExecStart to an ExecStop so the unit is correctly
sequenced.
Change WantedBy to multi-user.target. This requires working around Debian Bug
#797108 which causes the new unit not to be enabled.
Remove the unneeded override_dh_isntallinit
Add Default-Start levels to the SysV initscript
Improve DEP8 testing
[Test Case]
In a VM with /var separated from the / file system, shutdown the VM. It will
hang for 10 minutes
[Regression]
Upgrade has been tested on Xenial, Yakkety, Zesty. do-release-upgrade has
been tested from Trusty to Xenial. All behave as expected.
A change of behavior may occur now that the systemd unit is correctly
enabled, which would make functionalities like InstallOnShutdown to
work as expected whereas it could have been broken previously. This
cannot be considered as a regression as it is expected behavior.
Shutdown may be slowed down as it now correctly depends on /var and
/boot to be available so the unit will run earlier than previously.
[Original description of the problem]
The systemd unit file unattended-upgrades.service is used to stop a running
unattended-upgrade
process during shutdown. This unit file is running together with all
filesystem
unmount services.
The unattended-upgrades service checks if the lockfile for unattended-upgrade
(in /var/run) exists, and if it does, there is an unattended-upgrade in
progress
and the service will wait until it finishes (and therefore automatically wait
at
shutdown).
However, if /var is a separate filesystem, it will get unmounted even though
/var/run
is a tmpfs that's still mounted on top of the /var/run directory in the /var
filesystem.
The unattended-upgrade script will fail to find lockfile, sleeps for 5
seconds, and
tries to check the lockfile again. After 10 minutes (the default timeout), it
will finally
exit and the system will continue shutdown.
The problem is the error handling in
/usr/share/unattended-upgrades/unattended-upgrade-shutdown
where it tries to lock itself:
while True:
res = apt_pkg.get_lock(options.lock_file)
logging.debug("get_lock returned %i" % res)
# exit here if there is no lock
if res > 0:
logging.debug("lock not taken")
break
lock_was_taken = True
The function apt_pkg.get_lock() either returns a file descriptor, or -1 on an
error.
File descriptors are just C file descriptors, so they are always positive
integers.
The code should check the result to be negative, not positive. I have
attached a patch
to reverse the logic.
Additional information:
1)
Description: Ubuntu 16.04.1 LTS
Release: 16.04
2)
unattended-upgrades:
Installed: 0.90ubuntu0.3
Candidate: 0.90ubuntu0.3
Version table:
*** 0.90ubuntu0.3 500
500 http://nl.archive.ubuntu.com/ubuntu xenial-updates/main amd64
Packages
500 http://nl.archive.ubuntu.com/ubuntu xenial-updates/main i386
Packages
100 /var/lib/dpkg/status
0.90 500
500 http://nl.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
500 http://nl.archive.ubuntu.com/ubuntu xenial/main i386 Packages
3)
Fast reboot
4)
Very slow reboot (after a 10 minutes timeout)
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