[systemd-devel] [PATCH] [RFC] Ignore OOMScoreAdjust in Linux containers

[Richard Weinberger]

Am 09.04.2014 19:19, schrieb Tom Gundersen:
> On Mon, Apr 7, 2014 at 9:47 PM, Richard Weinberger <richard at nod.at> wrote:
>> At least LXC does not allow the container root to change
>> the OOM Score adjust value.
>>
>> Signed-off-by: Richard Weinberger <richard at nod.at>
>> ---
>> Hi!
>>
>> Within Linux containers we cannot use OOMScoreAdjust nor CapabilityBoundingSet (and maybe
>> more related settings).
>> This patch tells systemd to ignore OOMScoreAdjust if it detects
>> a container.
>>
>> Are you fine with such a change?
>> Otherweise regular distros need a lot of changes in their .service file
>> to make them work within LXC.
>>
>> As detect_virtualization() detects more than LXC we have to find out
>> whether OOMScoreAdjust cannot be used on OpenVZ and other container as well.
>>
>> I'd volunteer to identify all settings and sending patches...
> 
> Hm, is there a fundamental reason why this is not possible in
> containers in general, or is it simply an LXC restriction? Regardless,
> would it not be best to simply degrade gracefully and ignore the
> setting with a warning if it fails? See the comment Lennart just
> posted on the recent PrivateNetwork= patch. This sounds like a very
> similar situation.

Writing to oom_score_adj is disallowed by design within user namespaces.
Please see: https://lkml.org/lkml/2013/4/25/596

I'm also fine with ignoring OOMScoreAdjust if it fails.
All I want is a painless Linux userspace on top of systemd within
my Containers. :-)

Thanks,
//richard