Re: [PATCH]: exec: avoid propagating PF_NO_SETAFFINITY into userspace child

[Oleg Nesterov <oleg@redhat.com>]

On 11/28, Peter Zijlstra wrote:
>
> On Thu, Nov 28, 2013 at 09:13:29AM -0500, Tejun Heo wrote:
> > > A single parent process for all usermode helpers makes so much sense;
> > > not doing it is just weird.
> >
> > If we're gonna allow userland to play with the parent attributes,
> > yeah, that'd make sense.  I'm not sure whether that's an interface
> > that we'd want to commit to tho?  Do we really want to tell userland
> > "there will always be a kernel task khelper and if you change that
> > one's attributes all processes forked from it will inherit those
> > attributes no matter what they are."  I think we'd want something more
> > specific cause that's a lot of commitment to things that we haven't
> > carefully thought about.
>
> It seems like a perfectly fine interface to me. And much preferable to
> creating yet another weird interface to manage tasks.

OK. I am not sure, but perhaps this makes sense.

(Although this means that we will always have the problem with the
 recursive UMH_WAIT_* requests).

In this case khelper should be turned into kthread_worker, this looks
simple.

But note that in the longer term we might want even more. We probably
want a non-daemonized thread controlled by the user-space. And even
more, this thread should be per-namespace (this needs a lot more
discussion).

But whataver we do later, I believe that the patch from Zhang should
be applied now.

Oleg.