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