From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx177.postini.com [74.125.245.177]) by kanga.kvack.org (Postfix) with SMTP id 24E486B0031 for ; Wed, 17 Jul 2013 19:33:57 -0400 (EDT) Received: by mail-ob0-f171.google.com with SMTP id dn14so3052416obc.30 for ; Wed, 17 Jul 2013 16:33:56 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1374103783.24916.49.camel@misato.fc.hp.com> References: <1374097503-25515-1-git-send-email-toshi.kani@hp.com> <1374103783.24916.49.camel@misato.fc.hp.com> From: KOSAKI Motohiro Date: Wed, 17 Jul 2013 19:33:35 -0400 Message-ID: Subject: Re: [PATCH] mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: Andrew Morton , "linux-mm@kvack.org" , LKML , x86@kernel.org, Yasuaki Ishimatsu , Tang Chen , "vasilis.liaskovitis" On Wed, Jul 17, 2013 at 7:29 PM, Toshi Kani wrote: > On Wed, 2013-07-17 at 19:22 -0400, KOSAKI Motohiro wrote: >> On Wed, Jul 17, 2013 at 5:45 PM, 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, users should not be >> > required to use this interface on x86. This probe interface is also >> > error-prone 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 patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86, >> > and clarifies it in Documentation/memory-hotplug.txt. >> >> Why don't you completely remove it? Who should use this strange interface? > > According to the comment below, this probe interface is used on powerpc. > So, we cannot remove it, but to disable it on x86. I meant x86. Why can't we completely remove ARCH_MEMORY_PROBE section from x86 Kconfig? -- 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