Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756660Ab3HGAgb (ORCPT ); Tue, 6 Aug 2013 20:36:31 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:57879 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756331Ab3HGAg2 (ORCPT ); Tue, 6 Aug 2013 20:36:28 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.0.1 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20120718-3 Message-ID: <52019667.3010405@jp.fujitsu.com> Date: Wed, 7 Aug 2013 09:35:51 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: , , , , Subject: Re: acpi_bus_trim does not detach devices in post order References: <52006888.5030203@jp.fujitsu.com> <5200CAAD.5080102@jp.fujitsu.com> <8453998.khIH1RyxM0@vostro.rjw.lan> In-Reply-To: <8453998.khIH1RyxM0@vostro.rjw.lan> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-SecurityPolicyCheck-GC: OK by FENCE-Mail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2786 Lines: 71 (2013/08/06 23:26), Rafael J. Wysocki wrote: > On Tuesday, August 06, 2013 07:06:37 PM Yasuaki Ishimatsu wrote: >> (2013/08/06 12:07), Yasuaki Ishimatsu wrote: >>> >>> I acked the following commit but I hit a problem by the commit. >>> So I report it. >>> >>> commit cecdb193c8d91a42d9489d00618cc3dfff92e55a >>> Author: Rafael J. Wysocki >>> Date: Tue Jan 15 13:24:02 2013 +0100 >>> >>> ACPI / scan: Change the implementation of acpi_bus_trim() >>> >>> Before applying the commit, acpi_bus_trim() detachs devices in post order. >>> >>> When I hot add memory devices and processor devices by container device >>> in my x86 box, memory devices are added first and processor devices are added >>> second. So I expect that processor devices are removed first and memory >>> devices are removed second when I remove them. And before applying the >>> commit, acpi_bus_trim() did so. >>> >>> But after appling the commit, acpi_bus_trim() does not detach devices in >>> post order. So when I remove them, memory devices are removed first and >>> processor devices are removed second. >>> >>> By this, I hit a problem. >>> >>> In Linux on x86 arch, NUMA node is depend on memory devices. So new NUMA >>> node is created at memory hot adding. Thus when I hot add memory devices and >>> processor devices, we must hot add memory device first. Otherwise, processor >>> devices are not set to correct NUMA node number. >>> >>> And Linux expects that when removing them, processor devices are removed >>> first before removing memory devices. But acpi_bus_trim() does not do so. >>> By this, NUMA node is not cleared in my x86 box when hot removing memory device >>> and processor devices. When removing memory devices, NUMA node is cleared. >>> But if there are processor devices related with the NUMA node, NUMA node is >>> not be cleared at memory hot removing. >>> >>> So when I remove them, NUMA node's sysfs file remained as follows: >> >> I had little mistake. CPU also tries to clear NUMA node. >> But current implementation has bug. So I'll fix it. > > Do I understand correctly that with your fix at > > https://patchwork.kernel.org/patch/2839298/ > > the current acpi_bus_trim() implementation will be sufficient? No. The patch just fixed implementation of CPU hotplug. A problem I think is that acpi_bus_trim() does not detach devices in post-order. And my patch does not fix it. So if some device has dependency of other device, similar problem will occur. Thanks, Yasuaki Ishimatsu > > Rafael > > -- 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/