Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754422Ab3GWHrD (ORCPT ); Tue, 23 Jul 2013 03:47:03 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56170 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752706Ab3GWHrA (ORCPT ); Tue, 23 Jul 2013 03:47:00 -0400 Date: Tue, 23 Jul 2013 00:46:30 -0700 From: tip-bot for Toshi Kani Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, kosaki.motohiro@jp.fujitsu.com, toshi.kani@hp.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, toshi.kani@hp.com, kosaki.motohiro@jp.fujitsu.com In-Reply-To: <1374256068-26016-1-git-send-email-toshi.kani@hp.com> References: <1374256068-26016-1-git-send-email-toshi.kani@hp.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default Git-Commit-ID: a0842b704b0f7c2d925473676f2012ea5dc39976 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Tue, 23 Jul 2013 00:46:37 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4110 Lines: 99 Commit-ID: a0842b704b0f7c2d925473676f2012ea5dc39976 Gitweb: http://git.kernel.org/tip/a0842b704b0f7c2d925473676f2012ea5dc39976 Author: Toshi Kani AuthorDate: Fri, 19 Jul 2013 11:47:48 -0600 Committer: Ingo Molnar CommitDate: Mon, 22 Jul 2013 11:13:34 +0200 mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default CONFIG_ARCH_MEMORY_PROBE enables the /sys/devices/system/memory/probe interface, which allows a given memory address to be hot-added as follows: # echo start_address_of_new_memory > /sys/devices/system/memory/probe (See Documentation/memory-hotplug.txt for more details.) This probe interface is required on powerpc. On x86, however, ACPI notifies a memory hotplug event to the kernel, which performs its hotplug operation as the result. Therefore, regular users do not need this interface on x86. This probe interface is also error-prone and misleading that the kernel blindly adds a given memory address without checking if the memory is present on the system; no probing is done despite of its name. The kernel crashes when a user requests to online a memory block that is not present on the system. This interface is currently used for testing as it can fake a hotplug event. This patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86, adds its Kconfig menu entry on x86, and clarifies its use in Documentation/ memory-hotplug.txt. Signed-off-by: Toshi Kani Acked-by: KOSAKI Motohiro Cc: linux-mm@kvack.org Cc: dave@sr71.net Cc: isimatu.yasuaki@jp.fujitsu.com Cc: tangchen@cn.fujitsu.com Cc: vasilis.liaskovitis@profitbricks.com Link: http://lkml.kernel.org/r/1374256068-26016-1-git-send-email-toshi.kani@hp.com [ Edited it slightly. ] Signed-off-by: Ingo Molnar --- Documentation/memory-hotplug.txt | 16 +++++++++------- arch/x86/Kconfig | 6 +++++- 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index 8e5eacb..8fd254c 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -210,13 +210,15 @@ If memory device is found, memory hotplug code will be called. 4.2 Notify memory hot-add event by hand ------------ -In some environments, especially virtualized environment, firmware will not -notify memory hotplug event to the kernel. For such environment, "probe" -interface is supported. This interface depends on CONFIG_ARCH_MEMORY_PROBE. - -Now, CONFIG_ARCH_MEMORY_PROBE is supported only by powerpc but it does not -contain highly architecture codes. Please add config if you need "probe" -interface. +On powerpc, the firmware does not notify a memory hotplug event to the kernel. +Therefore, "probe" interface is supported to notify the event to the kernel. +This interface depends on CONFIG_ARCH_MEMORY_PROBE. + +CONFIG_ARCH_MEMORY_PROBE is supported on powerpc only. On x86, this config +option is disabled by default since ACPI notifies a memory hotplug event to +the kernel, which performs its hotplug operation as the result. Please +enable this option if you need the "probe" interface for testing purposes +on x86. Probe interface is located at /sys/devices/system/memory/probe diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b32ebf9..2f9d957 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1344,8 +1344,12 @@ config ARCH_SELECT_MEMORY_MODEL depends on ARCH_SPARSEMEM_ENABLE config ARCH_MEMORY_PROBE - def_bool y + bool "Enable sysfs memory/probe interface" depends on X86_64 && MEMORY_HOTPLUG + help + This option enables a sysfs memory/probe interface for testing. + See Documentation/memory-hotplug.txt for more information. + If you are unsure how to answer this question, answer N. config ARCH_PROC_KCORE_TEXT def_bool y -- 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/