linux-kernel - Re: [PATCH 0/6] Unshare support for the pid namespace.

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Message-ID: <20100620215646.GB17517@redhat.com>
Date:	Sun, 20 Jun 2010 23:56:46 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Louis Rilling <louis.rilling@...labs.com>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Linux Containers <containers@...ts.osdl.org>,
	linux-kernel@...r.kernel.org, Daniel Lezcano <dlezcano@...ibm.com>
Subject: Re: [PATCH 0/6] Unshare support for the pid namespace.

On 06/20, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@...hat.com> writes:
>
> > And. I do not think these series can fix the discussed problems. ns->dead
> > definitely can't, no?
>
> I'm am fairly confident that we have the signal sending races fixed so
> we can reasonably expect having sent SIGKILL to all processes in a pid
> namespace

Sorry, didn't notice this part...

Which races? I am talking about the current problems with pid_ns_release_proc(),
we have at least 3 bugs, from the 2/2 changelog:

	- Nobody does mntput() if copy_process() fails after
	  pid_ns_prepare_proc().

	- proc_flush_task() checks upid->nr == 1 to verify we are init,
	  this is wrong if a multi-threaded init does exec.

	- As Louis pointed out, this namespace can have the detached
	  EXIT_DEAD tasks which can use ns->proc_mnt after this mntput().

Oleg.

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