When using CentOS 6 as a container under a Debian Sid host, you may face the following problem.

amoe@inktvis $ sudo lxc-create -n mycontainer -t centos
Host CPE ID from /etc/os-release: 
This is not a CentOS or Redhat host and release is missing, defaulting to 6 use -R|--release to specify release
Checking cache download in /var/cache/lxc/centos/x86_64/6/rootfs ... 
Downloading CentOS minimal ...

You have enabled checking of packages via GPG keys. This is a good thing. 
However, you do not have any GPG public keys installed. You need to download
the keys for packages you wish to install and install them.
You can do that by running the command:
    rpm --import public.gpg.key

Alternatively you can specify the url to the key you would like to use
for a repository in the 'gpgkey' option in a repository section and yum 
will install it for you.

For more information contact your distribution or package provider.

Problem repository: base
/usr/share/lxc/templates/lxc-centos: line 405: 24156 Segmentation fault      (core dumped) chroot $INSTALL_ROOT rpm --quiet -q yum 2> /dev/null
Reinstalling packages ...
mkdir: cannot create directory ‘/var/cache/lxc/centos/x86_64/6/partial/etc/yum.repos.disabled’: File exists
mv: cannot stat '/var/cache/lxc/centos/x86_64/6/partial/etc/yum.repos.d/*.repo': No such file or directory
mknod: /var/cache/lxc/centos/x86_64/6/partial//var/cache/lxc/centos/x86_64/6/partial/dev/null: File exists
mknod: /var/cache/lxc/centos/x86_64/6/partial//var/cache/lxc/centos/x86_64/6/partial/dev/urandom: File exists
/usr/share/lxc/templates/lxc-centos: line 405: 24168 Segmentation fault      (core dumped) chroot $INSTALL_ROOT $YUM0 install $PKG_LIST
Failed to download the rootfs, aborting.
Failed to download 'CentOS base'
failed to install CentOS
lxc-create: lxccontainer.c: create_run_template: 1427 container creation template for mycontainer failed
lxc-create: tools/lxc_create.c: main: 326 Error creating container mycontainer

This is due to vsyscall changes in recent kernels. To get this working, you need to add vsyscall=emulate parameter to your kernel command line (to be perfectly specific, the command line of the host because containers share a kernel.) To do this you can modify /etc/default/grub and run update-grub.