From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id 37FE26B004D for ; Tue, 27 Nov 2012 08:04:59 -0500 (EST) Message-ID: <50B4B6BE.3000902@cn.fujitsu.com> Date: Tue, 27 Nov 2012 20:49:02 +0800 From: Tang Chen MIME-Version: 1.0 Subject: Re: [PATCH v2 0/5] Add movablecore_map boot option References: <1353667445-7593-1-git-send-email-tangchen@cn.fujitsu.com> <50B479FA.6010307@cn.fujitsu.com> In-Reply-To: Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8; format=flowed Sender: owner-linux-mm@kvack.org List-ID: To: Bob Liu Cc: hpa@zytor.com, akpm@linux-foundation.org, rob@landley.net, isimatu.yasuaki@jp.fujitsu.com, laijs@cn.fujitsu.com, wency@cn.fujitsu.com, linfeng@cn.fujitsu.com, jiang.liu@huawei.com, yinghai@kernel.org, kosaki.motohiro@jp.fujitsu.com, minchan.kim@gmail.com, mgorman@suse.de, rientjes@google.com, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, m.szyprowski@samsung.com On 11/27/2012 08:09 PM, Bob Liu wrote: > On Tue, Nov 27, 2012 at 4:29 PM, Tang Chen wrote: >> Hi Liu, >> >> This feature is used in memory hotplug. >> >> In order to implement a whole node hotplug, we need to make sure the >> node contains no kernel memory, because memory used by kernel could >> not be migrated. (Since the kernel memory is directly mapped, >> VA = PA + __PAGE_OFFSET. So the physical address could not be changed.) >> >> User could specify all the memory on a node to be movable, so that the >> node could be hot-removed. >> > > Thank you for your explanation. It's reasonable. > > But i think it's a bit duplicated with CMA, i'm not sure but maybe we > can combine it with CMA which already in mainline? > Hi Liu, Thanks for your advice. :) CMA is Contiguous Memory Allocator, right? What I'm trying to do is controlling where is the start of ZONE_MOVABLE of each node. Could CMA do this job ? And also, after a short investigation, CMA seems need to base on memblock. But we need to limit memblock not to allocate memory on ZONE_MOVABLE. As a result, we need to know the ranges before memblock could be used. I'm afraid we still need an approach to get the ranges, such as a boot option, or from static ACPI tables such as SRAT/MPST. I'm don't know much about CMA for now. So if you have any better idea, please share with us, thanks. :) -- 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