From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754906Ab1JaNVv (ORCPT ); Mon, 31 Oct 2011 09:21:51 -0400 Received: from mtagate1.uk.ibm.com ([194.196.100.161]:59248 "EHLO mtagate1.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754728Ab1JaNVu (ORCPT ); Mon, 31 Oct 2011 09:21:50 -0400 Message-ID: <1320067306.2796.34.camel@br98xy6r> Subject: [PATCH v2] kdump: Add udev events for memory online/offline From: Michael Holzheu Reply-To: holzheu@linux.vnet.ibm.com To: Andrew Morton Cc: Heiko Carstens , Vivek Goyal , "Eric W. Biederman" , schwidefsky@de.ibm.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Kay Sievers , Dave Hansen Date: Mon, 31 Oct 2011 14:21:46 +0100 In-Reply-To: <20111028154630.77c7b96c.akpm@linux-foundation.org> References: <1319645292.3321.24.camel@br98xy6r> <20111026192449.GE355@redhat.com> <20111027073058.GA2422@osiris.boeblingen.de.ibm.com> <1319707965.2830.1.camel@br98xy6r> <20111028154630.77c7b96c.akpm@linux-foundation.org> Organization: IBM Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.2.0- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-10-28 at 15:46 -0700, Andrew Morton wrote: > On Thu, 27 Oct 2011 11:32:45 +0200 [snip] > I think a safer place from which to send the uevent is > memory_block_change_state() or even memory_block_action(). Because if > either of those functions later gets new callers, those callers might > forget to send the uevent? Ok fine. I put the code into memory_block_change_state(). This also has the advantage that we are serialized by "mem->state_mutex". Not sure if we need that, but for CPU hotplug the udev events are also serialized with a lock. See "drivers/base/cpu.c" -> cpu_hotplug_driver_lock() Do you think the following patch is acceptable? --- From: Michael Holzheu Currently no udev events for memory hotplug "online" and "offline" are generated: # udevadm monitor # echo offline > /sys/devices/system/memory/memory4/state ==> No event When kdump is loaded, kexec detects the current memory configuration and stores it in the pre-allocated ELF core header. Therefore, for kdump it is necessary to reload the kdump kernel with kexec when the memory configuration changes (e.g. for online/offline hotplug memory). In order to do this automatically, udev rules should be used. This kernel patch adds udev events for "online" and "offline". Together with this kernel patch, the following udev rules for online/offline have to be added to "/etc/udev/rules.d/98-kexec.rules": SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/etc/init.d/kdump restart" SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/etc/init.d/kdump restart" Signed-off-by: Michael Holzheu --- drivers/base/memory.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -291,11 +291,22 @@ static int memory_block_change_state(str ret = memory_block_action(mem->start_section_nr, to_state); - if (ret) + if (ret) { mem->state = from_state_req; - else - mem->state = to_state; + goto out; + } + mem->state = to_state; + switch (mem->state) { + case MEM_OFFLINE: + kobject_uevent(&mem->sysdev.kobj, KOBJ_OFFLINE); + break; + case MEM_ONLINE: + kobject_uevent(&mem->sysdev.kobj, KOBJ_ONLINE); + break; + default: + break; + } out: mutex_unlock(&mem->state_mutex); return ret;