Date: Mon, 18 Nov 2013 19:02:59 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>,
        Jeff Layton <jlayton@redhat.com>, Greg KH <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-nfs@vger.kernel.org, devel@openvz.org, bfields@fieldses.org,
        bharrosh@panasas.com
Subject: Re: call_usermodehelper in containers
Message-ID: <20131118180259.GA11722@redhat.com>
References: <20131111071825.62da01d1@tlielax.poochiereds.net> <20131112004703.GB15377@kroah.com> <20131112061201.04cf25ab@tlielax.poochiereds.net> <528226EC.4050701@parallels.com> <20131112083043.0ab78e67@tlielax.poochiereds.net> <5285FA0A.2080802@parallels.com> <871u2incyo.fsf@xmission.com> <20131118172844.GA10005@redhat.com>
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Sender: linux-nfs-owner@vger.kernel.org

On 11/18, Oleg Nesterov wrote:
>
> On 11/15, Eric W. Biederman wrote:
> >
> > I don't understand that one.  Having a preforked thread with the proper
> > environment that can act like kthreadd in terms of spawning user mode
> > helpers works and is simple.
>
> Can't we ask ->child_reaper to create the non-daemonized kernel thread
> with the "right" ->nsproxy, ->fs, etc?
>
> IOW. Please the the "patch" below. It is obviously incomplete and wrong,
> and it can be more clear/clean. And probably we need another API. Just
> to explain what I mean.

Or, perhaps UMH_IN_MY_NS should only work if ->child_reaper explicitly
does, say, prctl(PR_SPAWN_UMH_IN_NS_HELPER) which forks the non-daemonized
kernel kthread_worker thread, I dunno.

Oleg.