linux-kernel - Re: [PATCH] kthread: Make kthread

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Message-Id: <201309150846.HED51521.tJOFOMVFSOHQFL@I-love.SAKURA.ne.jp>
Date:	Sun, 15 Sep 2013 08:46:10 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	oleg@...hat.com
Cc:	security@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kthread: Make kthread_create() killable.

Oleg Nesterov wrote:
> I am wondering if this can be simplified...
> 
> At least you can move create->done from kthread_create_info to the
> stack, and turn create->owner into the pointer to that completion.

Use of DECLARE_COMPLETION_ONSTACK() looks harmful to me because current thread
needs to be able to terminate as soon as possible if SIGKILLed (especially when
SIGKILLed by OOM killer). If we move something from kmalloc()ed zone to stack,
current thread cannot be terminated until that something is guaranteed to no
longer be used.

I think we need to convert from on-stack objects to kmalloc()ed objects so that
current thread acquires ability to terminate as soon as possible.
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