From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx139.postini.com [74.125.245.139]) by kanga.kvack.org (Postfix) with SMTP id 70AC96B0037 for ; Mon, 12 Aug 2013 13:24:18 -0400 (EDT) Message-ID: <52091A10.4030501@zytor.com> Date: Mon, 12 Aug 2013 10:23:28 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE. References: <1375956979-31877-1-git-send-email-tangchen@cn.fujitsu.com> <20130812145016.GI15892@htj.dyndns.org> <52090225.6070208@gmail.com> <20130812154623.GL15892@htj.dyndns.org> <52090AF6.6020206@gmail.com> <20130812162247.GM15892@htj.dyndns.org> <520914D5.7080501@gmail.com> In-Reply-To: <520914D5.7080501@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tang Chen Cc: Tejun Heo , Tang Chen , robert.moore@intel.com, lv.zheng@intel.com, rjw@sisk.pl, lenb@kernel.org, tglx@linutronix.de, mingo@elte.hu, akpm@linux-foundation.org, trenn@suse.de, yinghai@kernel.org, jiang.liu@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, mgorman@suse.de, minchan@kernel.org, mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, riel@redhat.com, jweiner@redhat.com, prarit@redhat.com, zhangyanfei@cn.fujitsu.com, yanghy@cn.fujitsu.com, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org On 08/12/2013 10:01 AM, Tang Chen wrote: >> >>> I'm just thinking of a more extreme case. For example, if a machine >>> has only one node hotpluggable, and the kernel resides in that node. >>> Then the system has no hotpluggable node. >> >> Yeah, sure, then there's no way that node can be hotpluggable and the >> right thing to do is booting up the machine and informing the userland >> that memory is not hotpluggable. >> >>> If we can prevent the kernel from using hotpluggable memory, in such >>> a machine, users can still do memory hotplug. >>> >>> I wanted to do it as generic as possible. But yes, finding out the >>> nodes the kernel resides in and make it unhotpluggable can work. >> >> Short of being able to remap memory under the kernel, I don't think >> this can be very generic and as a compromise trying to keep as many >> hotpluggable nodes as possible doesn't sound too bad. > > I think making one of the node hotpluggable is better. But OK, it is > no big deal. There won't be such machine in reality, I think. :) > The user may very well have configured a system with mirrored memory for the kernel node as that will be non-hotpluggable, but not for the others. One can wonder how much that actually buys in real life, but still... -hpa -- 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