From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx111.postini.com [74.125.245.111]) by kanga.kvack.org (Postfix) with SMTP id D72536B0034 for ; Tue, 13 Aug 2013 10:46:04 -0400 (EDT) Message-ID: <1376405088.10300.384.camel@misato.fc.hp.com> Subject: Re: [PATCH] mm/hotplug: Remove stop_machine() from try_offline_node() From: Toshi Kani Date: Tue, 13 Aug 2013 08:44:48 -0600 In-Reply-To: <3940091.8hz2Z6IIgz@vostro.rjw.lan> References: <1376336071-9128-1-git-send-email-toshi.kani@hp.com> <3940091.8hz2Z6IIgz@vostro.rjw.lan> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Rafael J. Wysocki" Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, kosaki.motohiro@jp.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com, tangchen@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, liwanp@linux.vnet.ibm.com On Tue, 2013-08-13 at 13:41 +0200, Rafael J. Wysocki wrote: > On Monday, August 12, 2013 01:34:31 PM Toshi Kani wrote: > > lock_device_hotplug() serializes hotplug & online/offline operations. > > The lock is held in common sysfs online/offline interfaces and ACPI > > hotplug code paths. > > > > try_offline_node() off-lines a node if all memory sections and cpus > > are removed on the node. It is called from acpi_processor_remove() > > and acpi_memory_remove_memory()->remove_memory() paths, both of which > > are in the ACPI hotplug code. > > > > try_offline_node() calls stop_machine() to stop all cpus while checking > > all cpu status with the assumption that the caller is not protected from > > CPU hotplug or CPU online/offline operations. However, the caller is > > always serialized with lock_device_hotplug(). Also, the code needs to > > be properly serialized with a lock, not by stopping all cpus at a random > > place with stop_machine(). > > > > 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. > > > > Signed-off-by: Toshi Kani > > Acked-by: Rafael J. Wysocki Thanks! -Toshi -- 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