The more I'm thinking about this, why don't we simply have these (the various possible vdsos as well as vvar) as actual files in sysfs instead of introducing a new filesystem? I don't believe sysfs actually has to be mounted in order for sysfs files to have an inode.
It could also be in procfs, I guess, but sysfs probably makes more sense. I'm thinking something like: /sys/kernel/vdso/{i386,x86_64,x32,vvar} Not only would this let the container people and so on do weird things much easier, but it ought to eliminate a whole slew of special cases. -hpa