[Lxc-users] lxc-destroy does not destroy cgroup

[Arie Skliarouk]

Hi,

Most of the time the lxc-destroy works properly, removing the cgroup with
the same name as the container.

Today something strange happened on one of my vservers - suddenly it
stopped responding to requests and any attempt to connect just hanged (as
if connection was successful, but no data was coming through).
Checking dmesg on the host machine revealed that the vserver got into
out-of-memory situation:

*[304880.371274] Memory cgroup out of memory: Kill process 1959 (init)
score 1 or sacrifice child
[304880.403765] Killed process 10638 (apache2) total-vm:40608kB,
anon-rss:12kB, file-rss:4088kB
[304881.719832] bash invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=0,
oom_score_adj=0
...
[304881.719965] Task in /master killed as a result of limit of /master
[304881.719970] memory: usage 976564kB, limit 976564kB, failcnt 60487010
...
[304881.835887] [ 8938] 20081  8938     2625       90   6
0             0 sshd
[304881.835897] Memory cgroup out of memory: Kill process 1959 (init) score
1 or sacrifice child
[304881.836836] Killed process 19680 (apache2) total-vm:41372kB,
anon-rss:0kB, file-rss:4504kB
[304884.298748] bash invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=0,
oom_score_adj=0
...
[304884.414478] Memory cgroup out of memory: Kill process 1959 (init) score
1 or sacrifice child
[304884.415428] Killed process 1959 (init) total-vm:3188kB, anon-rss:0kB,
file-rss:476kB*

Note that the last process that got killed was init. IMHO it should be the
last process to be killed, immediately after sshd, but that's a minor
problem.

When I tried to restart the vserver, it did not came up. Long story short,
I found that lxc-destroy did not destroy the cgroup of the same name as the
server. The cgroup remains visible in the /sys/fs/cgroup/cpu/master
directory. The tasks file is empty though.

I had to rename the container to be able to start it.

All this on ubuntu 11.04, 3.0.0-12-server amd64. Thoughts, comments?

--
Arie
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