Re: [libvirt] Destroying a suspended LXC domain

On Fri, Feb 14, 2014 at 11:14:39AM +0100, Richard Weinberger wrote: > Hi! > > If we suspend a LXC domain libvirt freezes all tasks in the cgroup using the process freezer. > Upon destroy libvirt tries to kill all tasks using SIGTERM and later SIGKILL, but as they are frozen > the tasks are unkillable. > This seems to confuse libvirt, all tasks remain but libvirt forgets the domain. > > Here a small example: > ---cut--- > lxc-host1:/etc # /opt/libvirt-dev/bin/virsh domstate my3rdcontainer > paused > > lxc-host1:/etc # /opt/libvirt-dev/bin/virsh destroy my3rdcontainer > error: Failed to destroy domain my3rdcontainer > error: internal error: Some processes refused to die > > lxc-host1:/etc # ps fax > ... > 2118 ? Dsl 0:00 /opt/libvirt-dev/lib/libvirt_lxc --name my3rdcontainer --console 19 --security=none --handshake 22 --backgr > 2128 ? Ds 0:00 \_ /sbin/init > 2152 ? Ds 0:00 \_ /usr/lib/systemd/systemd-journald > 2171 ? Ds 0:00 \_ /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation > 2174 ? Ds 0:00 \_ /usr/lib/systemd/systemd-logind > 2189 ? Dsl 0:00 \_ /usr/sbin/rsyslogd -n > 2778 ? Ds 0:00 \_ /usr/sbin/cron -n > 2782 pts/0 Ds+ 0:00 \_ /sbin/agetty --noclear -s console 115200 38400 9600 > 2786 ? Ds 0:00 \_ /usr/sbin/sshd -D > ... > ---cut--- > > I can think of three options to deal with that. > > a) Refuse to destroy a suspended LXC domain > > b) Implicitly resume it upon destroy > > c) Send a SIGKILL to each task and then thaw all tasks using the process freezer. > If the task is woken up the it sees immediately the pending SIGKILL and dies. > > I'd vote for c) because I want to destroy a LXC domain without resuming it. > I.e. I want to kill it to avoid any further IO from the already suspended domain. Yes, I think c) is the only reasonable option here. Allowing processes any window where they can continue executing is not ok.