Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757046Ab3GVIha (ORCPT ); Mon, 22 Jul 2013 04:37:30 -0400 Received: from mail-ea0-f182.google.com ([209.85.215.182]:42968 "EHLO mail-ea0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756933Ab3GVIh0 (ORCPT ); Mon, 22 Jul 2013 04:37:26 -0400 Date: Mon, 22 Jul 2013 10:37:22 +0200 From: Ingo Molnar To: Toshi Kani Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, dave@sr71.net, kosaki.motohiro@gmail.com, isimatu.yasuaki@jp.fujitsu.com, tangchen@cn.fujitsu.com, vasilis.liaskovitis@profitbricks.com Subject: Re: [PATCH v2] mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default Message-ID: <20130722083721.GC25976@gmail.com> References: <1374256068-26016-1-git-send-email-toshi.kani@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1374256068-26016-1-git-send-email-toshi.kani@hp.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1472 Lines: 34 * Toshi Kani wrote: > CONFIG_ARCH_MEMORY_PROBE enables /sys/devices/system/memory/probe > interface, which allows a given memory address to be hot-added as > follows. (See Documentation/memory-hotplug.txt for more detail.) > > # echo start_address_of_new_memory > /sys/devices/system/memory/probe > > 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. Could we please also fix it to never crash the kernel, even if stupid ranges are provided? Thanks, Ingo -- 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/