Date: Tue, 3 Jun 2008 14:14:16 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: ebiederm@xmission.com, mingo@elte.hu, torvalds@linux-foundation.org,
       roland@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] introduce PF_KTHREAD flag
Message-Id: <20080603141416.43afaeba.akpm@linux-foundation.org>
In-Reply-To: <20080601153042.GA8238@tv-sign.ru>
References: <20080601153042.GA8238@tv-sign.ru>
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On Sun, 1 Jun 2008 19:30:42 +0400
Oleg Nesterov <oleg@tv-sign.ru> wrote:

> Introduce the new PF_KTHREAD flag to mark the kernel threads. It is set by
> INIT_TASK() and copied to the forked childs (we could set it in kthreadd()
> along with PF_NOFREEZE instead).
> 
> daemonize() was changed as well. In that case testing of PF_KTHREAD is racy,
> but daemonize() is hopeless anyway.
> 
> This flag is cleared in do_execve(), before search_binary_handler(). Probably
> not the best place, we can do this in exec_mmap() or in start_thread(), or
> clear it along with PF_FORKNOEXEC. But I think this doesn't matter in practice,
> and if do_execve() fails kthread should die soon.

The changelog doesn't explain why this change is being made, and I
wasn't able to work that out.

Similarly, I can kinda see what benefit "[PATCH 2/3] kill
PF_BORROWED_MM in favour of PF_KTHREAD" is bringing us, but it would be
nice to see that spelled out please.


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