Quoting Louis Rilling (Louis.Rilling@xxxxxxxxxxx):
Hi Louis, thanks again for reviewing.
> To me the real reason is to anticipate pid namespace unsharing. And this
> together with setns() will need to re-consider much of the namespace C/R
> logic imho. For instance, checkpoint could be done from a foreign task
> having entered the container, leak detection should take such foreign
> tasks into account (see example below), etc.
...
> >
> > @@ -293,10 +295,15 @@ static int may_checkpoint_task(struct ckpt_ctx *ctx, struct task_struct *t)
> > _ckpt_err(ctx, -EPERM, "%(T)Nested net_ns unsupported\n");
> > ret = -EPERM;
> > }
> > - /* no support for >1 private pidns */
> > - if (nsproxy->pid_ns != ctx->root_nsproxy->pid_ns) {
> > - _ckpt_err(ctx, -EPERM, "%(T)Nested pid_ns unsupported\n");
> > - ret = -EPERM;
> > + /* pidns must be descendent of root_nsproxy */
> > + pidns = nsproxy->pid_ns;
>
> In case of unshared pid namespace, task_active_pid_ns(t) should be checked
> instead of t->nsproxy->pid_ns: we can't checkpoint a foreign task.
Unsharing can only be done to a child ns, so it wouldn't be foreign.
Though of course that depends on which one ends up being the original
pid_ns (see below).
Now, regarding supporting unshared pid_ns, I think that (1) it will
be a simple matter of separately doing
pid_pidns = checkpoint_obj(task_active_pid_ns(task));
nsp_pidns = checkpoint_obj(task->nsproxy->pid_ns);
since we will need to record both. In addition, (2) the most
recent emails I see on the topics are still unsure about whether
we want to have the unshared pid_ns be reflected in
ns_of_pid(task_pid(task)) or task->nsproxy->pid_ns, so I think
we'll just have to handle them when they are implemented.
-serge
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