From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760210AbZBLWIi (ORCPT ); Thu, 12 Feb 2009 17:08:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753149AbZBLWI3 (ORCPT ); Thu, 12 Feb 2009 17:08:29 -0500 Received: from out01.mta.xmission.com ([166.70.13.231]:34965 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbZBLWI2 (ORCPT ); Thu, 12 Feb 2009 17:08:28 -0500 To: Andrew Morton Cc: fweisbec@gmail.com, mingo@elte.hu, linux-kernel@vger.kernel.org, oleg@redhat.com, travis@sgi.com, a.p.zijlstra@chello.nl, mm-commits@vger.kernel.org, rusty@rustcorp.com.au Subject: Re: + work_on_cpu-rewrite-it-to-create-a-kernel-thread-on-demand.patch added to -mm tree References: <200902031058.n13AwOoK016719@imap1.linux-foundation.org> <20090203121147.GB19979@elte.hu> <20090203112529.26e6bf76.akpm@linux-foundation.org> <20090212124835.2fc41620.akpm@linux-foundation.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Thu, 12 Feb 2009 14:08:09 -0800 In-Reply-To: <20090212124835.2fc41620.akpm@linux-foundation.org> (Andrew Morton's message of "Thu\, 12 Feb 2009 12\:48\:35 -0800") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=67.169.126.145;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 67.169.126.145 X-SA-Exim-Rcpt-To: akpm@linux-foundation.org, rusty@rustcorp.com.au, mm-commits@vger.kernel.org, a.p.zijlstra@chello.nl, travis@sgi.com, oleg@redhat.com, linux-kernel@vger.kernel.org, mingo@elte.hu, fweisbec@gmail.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: No (on in01.mta.xmission.com); Unknown failure Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > The problem with set_cpus_allowed() is that some other > suitably-privileged userspace process can come in from the side and > modify your cpus_allowed at any time. According to the comments the only reason we care is so that we get the appropriate NUMA affinity by default. I don't think it would be fatal if userspace messed around and we had a wrong value. Does work_on_cpu prevent that? Eric