Subject: Re: [vserver] Problem starting vservers with linux-3.0-rc5-vs2.3.1-pre3
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Wed, 20 Jul 2011 15:29:49 +0200

On Tue, Jul 12, 2011 at 10:34:30AM +0200, Sebastian Steinhuber wrote:
> Hi all!

> Vservers don't start on my box with a custom linux-3.0-rc5-vs2.3.1-pre3
> and util-vserver-0.30.216-pre2981 on debian unstable, though they do
> with linux-2.6.38.8-vs2.3.0.37-rc17 (didn't test 2.6.39 because of the
> patch's donotuse flag). Linux 3.0-rc5 was built after a 'make oldconfig'.

> I can't find relevant information in the logs and web search engine.
> I'm hoping that the masters have an idea. Where to start, what can I do
> to investigate the issue?

sorry for the delayed response ...

> #vserver dds start
> vcontext: vc_ctx_create(): Function not implemented

this is a mainline/upstream bug, which basically happens
when unsharing the USER namespace. what happens is that
all capabilities are dropped, and as result, the userspace
tool cannot issue Linux-VServer syscall commands anymore
(because of missing CAP_CONTEXT)

this can be verified on vanilla linux-3.0 kernels with
http://vserver.13thfloor.at/Stuff/clone_newuser.c
in the following way:

gcc -o clone_newuser clone_newuser.c
./clone_newuser ls /root/

assuming that /root does not have any right for 'other'
this will result in a permission denied (when the USER
namespace is compiled into the kernel)

as it is rather hard to disable the USER namespace in
linux-3.0-rc5-vs2.3.1-pre3, I prepared a new patch which
allows you to disable that namespace for now until the
issue is fixed upstream ...

best,
Herbert

> An error occured while executing the vserver startup sequence; when
> there are no other messages, it is very likely that the init-script
> (/etc/init.d/rc 3) failed.

> Common causes are:
> /etc/rc.d/rc on Fedora Core 1 and RH9 fails always; the 'apt-rpm' build
>   method knows how to deal with this, but on existing installations,
>   appending 'true' to this file will help.

> Failed to start vserver 'dds'


> Thanks in advance for consideration,
> Sebastian

> Btw, isn't occured a typo (occurred)?