Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751419AbXAFPpQ (ORCPT ); Sat, 6 Jan 2007 10:45:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751421AbXAFPpQ (ORCPT ); Sat, 6 Jan 2007 10:45:16 -0500 Received: from e33.co.us.ibm.com ([32.97.110.151]:42929 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751419AbXAFPpP (ORCPT ); Sat, 6 Jan 2007 10:45:15 -0500 Date: Sat, 6 Jan 2007 21:15:06 +0530 From: Srivatsa Vaddagiri To: Oleg Nesterov Cc: Andrew Morton , David Howells , Christoph Hellwig , Ingo Molnar , Linus Torvalds , linux-kernel@vger.kernel.org, Gautham shenoy Subject: Re: [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update Message-ID: <20070106154506.GC24274@in.ibm.com> Reply-To: vatsa@in.ibm.com References: <20061217223416.GA6872@tv-sign.ru> <20061218162701.a3b5bfda.akpm@osdl.org> <20061219004319.GA821@tv-sign.ru> <20070104113214.GA30377@in.ibm.com> <20070104142936.GA179@tv-sign.ru> <20070104091850.c1feee76.akpm@osdl.org> <20070106151036.GA951@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070106151036.GA951@tv-sign.ru> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 811 Lines: 30 On Sat, Jan 06, 2007 at 06:10:36PM +0300, Oleg Nesterov wrote: > Increment hotplug_sequence earlier, under CPU_DOWN_PREPARE. We can't > miss the event, the task running flush_workqueue() will be re-scheduled > at least once before CPU actually disappears from cpu_online_map. Eww ..what happens if flush_workqueue() starts after CPU_DOWN_PREPARE? CPU_DOWN_PREPARE(8) hotplug_sequence++ = 10 flush_workqueue() sequence = 10 flush cpus 1 ....7 CPU_DEAD(8) take_over_work(8->1) return not flushing dead cpu8 (=BUG) ?? -- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/