From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id E77F86B0032 for ; Fri, 16 Aug 2013 16:31:14 -0400 (EDT) Received: by mail-ye0-f173.google.com with SMTP id g12so399708yee.4 for ; Fri, 16 Aug 2013 13:31:13 -0700 (PDT) Message-ID: <520E8C13.5020406@gmail.com> Date: Fri, 16 Aug 2013 16:31:15 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH] mm/hotplug: Remove stop_machine() from try_offline_node() References: <1376336071-9128-1-git-send-email-toshi.kani@hp.com> <520C2D04.8060408@gmail.com> <1376584540.10300.416.camel@misato.fc.hp.com> In-Reply-To: <1376584540.10300.416.camel@misato.fc.hp.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: KOSAKI Motohiro , akpm@linux-foundation.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, rjw@sisk.pl, kosaki.motohiro@jp.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com, tangchen@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, liwanp@linux.vnet.ibm.com >>> This patch removes the use of stop_machine() in try_offline_node() and >>> adds comments to try_offline_node() and remove_memory() that >>> lock_device_hotplug() is required. >> >> This patch need more verbose explanation. check_cpu_on_node() traverse cpus >> and cpu hotplug seems to use cpu_hotplug_driver_lock() instead of lock_device_hotplug(). > > As described: > > | lock_device_hotplug() serializes hotplug & online/offline operations. > | The lock is held in common sysfs online/offline interfaces and ACPI > | hotplug code paths. > > And here are their code paths. > > - CPU & Mem online/offline via sysfs online > store_online()->lock_device_hotplug() > > - Mem online via sysfs state: > store_mem_state()->lock_device_hotplug() > > - ACPI CPU & Mem hot-add: > acpi_scan_bus_device_check()->lock_device_hotplug() > > - ACPI CPU & Mem hot-delete: > acpi_scan_hot_remove()->lock_device_hotplug() O.K. -- 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