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

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Message-ID: <20131128091358.GH10022@twins.programming.kicks-ass.net>
Date:	Thu, 28 Nov 2013 10:13:58 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Tejun Heo <htejun@...il.com>
Cc:	zhang.yi20@....com.cn, Oleg Nesterov <oleg@...hat.com>,
	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 Wed, Nov 27, 2013 at 01:31:17PM -0500, Tejun Heo wrote:
> On Wed, Nov 27, 2013 at 10:07:03AM +0800, zhang.yi20@....com.cn wrote:
> > Userspace process doesn't want the PF_NO_SETAFFINITY, but its parent may be
> > a kernel worker thread which has PF_NO_SETAFFINITY set, and this worker thread
> > can do kernel_thread() to create the child.
> > Clearing this flag in usersapce child to enable its migrating capability.
> > 
> > 
> > Signed-off-by: Zhang Yi <zhang.yi20@....com.cn>
> 
> Acked-by: Tejun Heo <tj@...nel.org>
> 
> cc'ing Ingo and Peter.  Ingo, I think this one doesn't really suit the
> workqueue tree.  Can you please pick this one up w/ Oleg's ack added
> and stable cc'd?  The original patch is
> 
>   http://article.gmane.org/gmane.linux.kernel/1602429/raw

So I don't get the problem; aren't all usermode helper thingies spawned
by the khelper task, which doesn't have PG_NO_SETAFFINITY set?

So how come this is a problem?

The Changelog is not explaining anything much -- so no I will not take
this patch.
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