From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759025AbXH1KSk (ORCPT ); Tue, 28 Aug 2007 06:18:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752027AbXH1KSP (ORCPT ); Tue, 28 Aug 2007 06:18:15 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:53242 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751694AbXH1KSO (ORCPT ); Tue, 28 Aug 2007 06:18:14 -0400 Date: Tue, 28 Aug 2007 12:18:01 +0200 From: Ingo Molnar To: Hugh Dickins Cc: linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: fix bogus hotplug cpu warning Message-ID: <20070828101801.GA27153@elte.hu> References: <20070828090709.GA24578@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -0.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-0.5 required=5.9 tests=BAYES_20 autolearn=no SpamAssassin version=3.1.7-deb -0.5 BAYES_20 BODY: Bayesian spam probability is 5 to 20% [score: 0.0999] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Hugh Dickins wrote: > > so if this check triggered for the cpu-offline code it's because > > keventd was _not_ per-cpu (perhaps because the cpu offline code > > broke its affinity?). So your patch hides a real bug. > > No, keventd is properly per-cpu, but the task which is calling > current_is_keventd() is a normal user task, so smp_processor_id() did > warn about it. It wouldn't make much sense to have a function > current_is_keventd() if you could only call it from a keventd, would > it ;-? Take a look at it (kernel/workqueue.c), I believe what it does > is unusual (hence that comment about being "preempt-safe") but valid. ok, you are right indeed. Ingo