From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753612Ab0CHDG6 (ORCPT ); Sun, 7 Mar 2010 22:06:58 -0500 Received: from one.firstfloor.org ([213.235.205.2]:36999 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751900Ab0CHDGv (ORCPT ); Sun, 7 Mar 2010 22:06:51 -0500 Date: Mon, 8 Mar 2010 04:06:50 +0100 From: Andi Kleen To: Christoph Lameter Cc: Anca Emanuel , Nick Piggin , David Rientjes , Pekka Enberg , Andi Kleen , linux-kernel , linux-mm , "haicheng.li" , KAMEZAWA Hiroyuki Subject: Re: [patch] slab: add memory hotplug support Message-ID: <20100308030650.GD20695@one.firstfloor.org> References: <20100226114136.GA16335@basil.fritz.box> <20100226155755.GE16335@basil.fritz.box> <20100305062002.GV8653@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Under certain conditions this is possible. If the bad memory was modified > then you have a condition that requires termination of all processes that > are using the memory. If its the kernel then you need to reboot. > > If the memory contains a page from disk then the memory can be moved > elsewhere. > > If you can clean up a whole range like that then its possible to replace > the memory. Typically that's not possible because of the way DIMMs are interleaved -- the to be freed areas would be very large, and with a specific size there are always kernel or unmovable user areas areas in the way. In general on Linux hot DIMM replacement only works if the underlying platform does it transparently (e.g. support memory RAID and chipkill) and you have enough redundant memory for it. -Andi -- ak@linux.intel.com -- Speaking for myself only. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id A0BAA6B0078 for ; Sun, 7 Mar 2010 22:06:54 -0500 (EST) Date: Mon, 8 Mar 2010 04:06:50 +0100 From: Andi Kleen Subject: Re: [patch] slab: add memory hotplug support Message-ID: <20100308030650.GD20695@one.firstfloor.org> References: <20100226114136.GA16335@basil.fritz.box> <20100226155755.GE16335@basil.fritz.box> <20100305062002.GV8653@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Anca Emanuel , Nick Piggin , David Rientjes , Pekka Enberg , Andi Kleen , linux-kernel , linux-mm , "haicheng.li" , KAMEZAWA Hiroyuki List-ID: > Under certain conditions this is possible. If the bad memory was modified > then you have a condition that requires termination of all processes that > are using the memory. If its the kernel then you need to reboot. > > If the memory contains a page from disk then the memory can be moved > elsewhere. > > If you can clean up a whole range like that then its possible to replace > the memory. Typically that's not possible because of the way DIMMs are interleaved -- the to be freed areas would be very large, and with a specific size there are always kernel or unmovable user areas areas in the way. In general on Linux hot DIMM replacement only works if the underlying platform does it transparently (e.g. support memory RAID and chipkill) and you have enough redundant memory for it. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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