Subject: Re: [PATCH] protect migration/%d etc from sched_setaffinity
From: Robert Love <rml@tech9.net>
To: joe.korty@ccur.com
Cc: torvalds@osdl.org, akpm@digeo.com, linux-kernel@vger.kernel.org
In-Reply-To: <20030731224604.GA24887@tsunami.ccur.com>
References: <20030731224604.GA24887@tsunami.ccur.com>
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Date: 31 Jul 2003 16:02:29 -0700
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On Thu, 2003-07-31 at 15:46, Joe Korty wrote:

> Lock out users from changing the cpu affinity of those per-cpu system
> daemons which cannot survive such a change, such as migration/%d.
> 
> Passes basic handtest of sched_setaffinity(2) on various locked and
> unlocked processes on a i386, otherwise untested except by eyeball.
> 
> Except for one line in i386, no arch needed any changes to support
> this patch.

I have been wondering what to do about processor affinity and kernel
threads. I just concluded "only root can change it, and we can let root
stab herself if she really wants to."

But if this is really an issue, why not just do:

	ret = -EINVAL;
	if (!p->mm)
		goto out_unlock;

in sys_sched_setaffinity ?

	Robert Love


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