Re: RFC [patch 00/34] PID Virtualization Overview

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Maw, 2006-01-17 at 10:12 -0800, Dave Hansen wrote:
> You do assign new pids, at least as far as the kernel is concerned.
> However, any processes that continue to run would get confused if their
> pid changed.  You have to make sure that the tasks have a _consistent_
> view of which process is which pid.

Don't reassign the pid at all. Keep task->container and do the job
explicitly. Most task searches for a pid are abstracted already and most
users of ->pid who try and use it for comparing two tasks for equality
or for keeping a task reference are already terminally racey and want
fixing anyway.

It raises a few other minor questions - one is /proc - but if container
0 was the usual one then putting the other containers into a subdir
would break nothing. Alternatively proc could allow multiple mounts and
a container = option to get the fs view right in chroot trees. The
subdirectories would be nice for management views.

You'd also need some process management items for other contexts - kill
etc but most of that can be done just by having a fork_into_container()
ability.

Alan

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