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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH 02/11] oom: oom_kill_process() doesn't select kthread child
Cc: kosaki.motohiro@jp.fujitsu.com, LKML <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>,
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> On Wed, Jun 30, 2010 at 06:27:52PM +0900, KOSAKI Motohiro wrote:
> > Now, select_bad_process() have PF_KTHREAD check, but oom_kill_process
> > doesn't. It mean oom_kill_process() may choose wrong task, especially,
> > when the child are using use_mm().
> 
> Is it possible child is kthread even though parent isn't kthread?

Usually unhappen. but crappy driver can do any strange thing freely.
As I said, oom code should have conservative assumption as far as possible.