From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750998Ab0CAK1j (ORCPT ); Mon, 1 Mar 2010 05:27:39 -0500 Received: from smtp-out.google.com ([216.239.33.17]:6018 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750831Ab0CAK1i (ORCPT ); Mon, 1 Mar 2010 05:27:38 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=oTv/5nlYfBI0+zEEJ42y6qDNdGIM6YVLv+smrekQe2Ljnmgj2zoYC77E5mL+jJ+AA E4X9U09EqYi3+8RYafCHA== Date: Mon, 1 Mar 2010 02:27:31 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: KAMEZAWA Hiroyuki cc: Andi Kleen , Christoph Lameter , Pekka Enberg , Nick Piggin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haicheng.li@intel.com Subject: Re: [PATCH] [4/4] SLAB: Fix node add timer race in cache_reap In-Reply-To: <20100301105932.5db60c93.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20100220090154.GB11287@basil.fritz.box> <4B862623.5090608@cs.helsinki.fi> <20100226114136.GA16335@basil.fritz.box> <20100226155755.GE16335@basil.fritz.box> <20100226173115.GG16335@basil.fritz.box> <20100301105932.5db60c93.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 1 Mar 2010, KAMEZAWA Hiroyuki wrote: > > > Well Kamesan indicated that this worked if a cpu became online. > > > > I mean in the general case. There were tons of problems all over. > > > Then, it's cpu hotplug matter, not memory hotplug. > cpu hotplug callback should prepaare > > > l3 = searchp->nodelists[node]; > BUG_ON(!l3); > > before onlined. Rather than taking care of races. > I can only speak for x86 and not the abundance of memory hotplug support that exists for powerpc, but cpu hotplug doesn't do _anything_ when a memory region that has a corresponding ACPI_SRAT_MEM_HOT_PLUGGABLE entry in the SRAT is hotadded and requires a new nodeid. That can be triggered via the acpi layer with plug and play or explicitly from the command line via CONFIG_ARCH_MEMORY_PROBE. Relying on cpu hotplug to set up nodelists in such a circumstance simply won't work. You need memory hotplug support such as in my patch. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 2C4C16B0078 for ; Mon, 1 Mar 2010 05:27:41 -0500 (EST) Received: from spaceape14.eur.corp.google.com (spaceape14.eur.corp.google.com [172.28.16.148]) by smtp-out.google.com with ESMTP id o21ARakA001129 for ; Mon, 1 Mar 2010 10:27:36 GMT Received: from pwi10 (pwi10.prod.google.com [10.241.219.10]) by spaceape14.eur.corp.google.com with ESMTP id o21ARYPL007920 for ; Mon, 1 Mar 2010 02:27:34 -0800 Received: by pwi10 with SMTP id 10so1367635pwi.25 for ; Mon, 01 Mar 2010 02:27:34 -0800 (PST) Date: Mon, 1 Mar 2010 02:27:31 -0800 (PST) From: David Rientjes Subject: Re: [PATCH] [4/4] SLAB: Fix node add timer race in cache_reap In-Reply-To: <20100301105932.5db60c93.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20100220090154.GB11287@basil.fritz.box> <4B862623.5090608@cs.helsinki.fi> <20100226114136.GA16335@basil.fritz.box> <20100226155755.GE16335@basil.fritz.box> <20100226173115.GG16335@basil.fritz.box> <20100301105932.5db60c93.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Andi Kleen , Christoph Lameter , Pekka Enberg , Nick Piggin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haicheng.li@intel.com List-ID: On Mon, 1 Mar 2010, KAMEZAWA Hiroyuki wrote: > > > Well Kamesan indicated that this worked if a cpu became online. > > > > I mean in the general case. There were tons of problems all over. > > > Then, it's cpu hotplug matter, not memory hotplug. > cpu hotplug callback should prepaare > > > l3 = searchp->nodelists[node]; > BUG_ON(!l3); > > before onlined. Rather than taking care of races. > I can only speak for x86 and not the abundance of memory hotplug support that exists for powerpc, but cpu hotplug doesn't do _anything_ when a memory region that has a corresponding ACPI_SRAT_MEM_HOT_PLUGGABLE entry in the SRAT is hotadded and requires a new nodeid. That can be triggered via the acpi layer with plug and play or explicitly from the command line via CONFIG_ARCH_MEMORY_PROBE. Relying on cpu hotplug to set up nodelists in such a circumstance simply won't work. You need memory hotplug support such as in my patch. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org