| [PATCH 0/1] Was: pidns: Support unsharing the pid namespace. [message #41729 is a reply to message #41728] |
Tue, 15 February 2011 19:15   |
Oleg Nesterov
Messages: 143
Registered: August 2006
|
Senior Member |
|
|
On 02/15, Oleg Nesterov wrote:
>
> On 02/15, Daniel Lezcano wrote:
> >
> > - Pass both nsproxy->pid_ns and task_active_pid_ns to copy_pid_ns
> > As they can now be different.
>
> But since they can be different we have to convert some users of
> current->nsproxy first? But that patch was dropped.
>
> > Unsharing of the pid namespace unlike unsharing of other namespaces
> > does not take effect immediately. Instead it affects the children
> > created with fork and clone.
>
> IOW, unshare(CLONE_NEWPID) implicitly affects the subsequent fork(),
> using the very subtle way.
>
> I have to admit, I can't say I like this very much. OK, if we need
> this, can't we just put something into, say, signal->flags so that
> copy_process can check and create the new namespace.
>
> Also. I remember, I already saw something like this and google found
> my questions. I didn't actually read the new version, perhaps my
> concerns were already answered...
>
> But what if the task T does unshare(CLONE_NEWPID) and then, say,
> pthread_create() ? Unless I missed something, the new thread won't
> be able to see T ?
>
> and, in this case the exiting sub-namespace init also kills its
> parent?
>
> OK, suppose it does fork() after unshare(), then another fork().
> In this case the second child lives in the same namespace with
> init created by the 1st fork, but it is not descendant ? This means
> in particular that if the new init exits, zap_pid_ns_processes()->
> do_wait() can't work.
>
> Or not?
And, can't resist. If we are going to change sys_unshare(), I'd like
very much to cleanup it first.
Dear all! I promise, I will resend this patch forever until somebody
explains me why it is constantly ignored ;)
Oleg.
_______________________________________________
Containers mailing list
Containers@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containe rs
|
|
|
|
OpenVZ Forum
Members
Search
Help
Register
Login
Home
