From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756468AbbJVKCt (ORCPT ); Thu, 22 Oct 2015 06:02:49 -0400 Received: from mgwym03.jp.fujitsu.com ([211.128.242.42]:29142 "EHLO mgwym03.jp.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751133AbbJVKCr (ORCPT ); Thu, 22 Oct 2015 06:02:47 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.3.2 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20150223 X-SHieldMailCheckerMailID: 2dff819b10734938b95dcbc7431537a5 Subject: Re: [PATCH] mm: Introduce kernelcore=reliable option To: "Luck, Tony" , Taku Izumi , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" References: <1444915942-15281-1-git-send-email-izumi.taku@jp.fujitsu.com> <3908561D78D1C84285E8C5FCA982C28F32B5A060@ORSMSX114.amr.corp.intel.com> Cc: "qiuxishi@huawei.com" , "mel@csn.ul.ie" , "akpm@linux-foundation.org" , "Hansen, Dave" , "matt@codeblueprint.co.uk" From: Kamezawa Hiroyuki Message-ID: <5628B427.3050403@jp.fujitsu.com> Date: Thu, 22 Oct 2015 19:02:15 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F32B5A060@ORSMSX114.amr.corp.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015/10/22 3:17, Luck, Tony wrote: > + if (reliable_kernelcore) { > + for_each_memblock(memory, r) { > + if (memblock_is_mirror(r)) > + continue; > > Should we have a safety check here that there is some mirrored memory? If you give > the kernelcore=reliable option on a machine which doesn't have any mirror configured, > then we'll mark all memory as removable. You're right. > What happens then? Do kernel allocations fail? Or do they fall back to using removable memory? Maybe the kernel cannot boot because NORMAL zone is empty. > Is there a /proc or /sys file that shows the current counts for the removable zone? I just > tried this patch with a high percentage of memory marked as mirror ... but I'd like to see > how much is actually being used to tune things a bit. > I think /proc/zoneinfo can show detailed numbers per zone. Do we need some for meminfo ? Thanks, -Kame