linux-kernel - Re: [PATCH]: exec: avoid propagating PF_NO

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Message-ID: <20131128160731.GA15000@redhat.com>
Date:	Thu, 28 Nov 2013 17:07:31 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Tejun Heo <htejun@...il.com>, zhang.yi20@....com.cn,
	lkml <linux-kernel@...r.kernel.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH]: exec: avoid propagating PF_NO_SETAFFINITY into
	userspace child

On 11/28, Oleg Nesterov wrote:
>
> On 11/28, Peter Zijlstra wrote:
> >
> > So there's three useful parts to having a single parent task:
> >
> >  - its a task so you can change the entire task attribute set; current
> >    and future.
>
> You can't change, say, its fs->root.
>
> OK, OK, this is almost off-topic, I am just trying to say that
> (perhaps) in the longer term we might want even more than just
> a dedicated kernel thread.
>
> >  - new children will automatically get the desired attributes.
>
> yes,
>
> >  - all children are easily identified by virtual of being children of
> >    said parent process.
>
> Well, UMH_WAIT_PROC won't work in this case, or it will be "single-threaded"
> too. OK, this is probably solvable, but nontrivial. In this case "khelper"
> should act as a /sbin/init for user-mode helpers.

But I'm afraid I got lost...

I interpreted "having a single parent task" as "parent of all usermode
helpers".

If you actually meant that every wq thread should have a parent which
represents the workqueue, well, I disagree but I leave this to you and
Tejun again ;)

Oleg.

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