From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755529AbZAZWSd (ORCPT ); Mon, 26 Jan 2009 17:18:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752989AbZAZWSW (ORCPT ); Mon, 26 Jan 2009 17:18:22 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:41629 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753020AbZAZWSV (ORCPT ); Mon, 26 Jan 2009 17:18:21 -0500 Date: Mon, 26 Jan 2009 23:17:29 +0100 From: Ingo Molnar To: Oleg Nesterov Cc: Andrew Morton , a.p.zijlstra@chello.nl, rusty@rustcorp.com.au, travis@sgi.com, mingo@redhat.com, davej@redhat.com, cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] work_on_cpu: Use our own workqueue. Message-ID: <20090126221729.GA10215@elte.hu> References: <20090124001537.7cfde78e.akpm@linux-foundation.org> <200901261711.43943.rusty@rustcorp.com.au> <20090125230130.bcdab2e5.akpm@linux-foundation.org> <20090126171618.GA32091@elte.hu> <20090126103529.cb124a58.akpm@linux-foundation.org> <20090126202022.GA8867@elte.hu> <20090126130046.37b8f34e.akpm@linux-foundation.org> <20090126212727.GA13670@elte.hu> <20090126133551.fab5e27a.akpm@linux-foundation.org> <20090126215049.GA3493@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090126215049.GA3493@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Oleg Nesterov wrote: > But "[PATCH 1/3] work_on_cpu: dont try to get_online_cpus() in > work_on_cpu." removes get_online_cpus/put_online_cpus, this means the > work can run on the wrong CPU anyway. Or work_on_cpu() can hang forever > if CPU has already gone away before queue_work_on(). > > Confused. The idea was to require work_on_cpu() users to be CPU hotplug-safe. But ... Rusty pointed it out in the past that this might be fragile, and we could put back the get_online_cpus()/put_online_cpus() calls. Rusty, what do you think? Ingo