From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754040Ab3K2DYN (ORCPT ); Thu, 28 Nov 2013 22:24:13 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:39562 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752744Ab3K2DYK (ORCPT ); Thu, 28 Nov 2013 22:24:10 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.8.9 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20120718-2 Message-ID: <5298084B.7060603@jp.fujitsu.com> Date: Fri, 29 Nov 2013 12:21:47 +0900 From: HATAYAMA Daisuke User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Atsushi Kumagai CC: "bhe@redhat.com" , "tom.vaden@hp.com" , "kexec@lists.infradead.org" , "jingbai.ma@hp.com" , "ptesarik@suse.cz" , "linux-kernel@vger.kernel.org" , "lisa.mitchell@hp.com" , "anderson@redhat.com" , "ebiederm@xmission.com" , "vgoyal@redhat.com" Subject: Re: [PATCH 0/3] makedumpfile: hugepage filtering for vmcore dump References: <0910DD04CBD6DE4193FCF86B9C00BE971C855E@BPXM01GP.gisp.nec.co.jp> In-Reply-To: <0910DD04CBD6DE4193FCF86B9C00BE971C855E@BPXM01GP.gisp.nec.co.jp> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2013/11/29 12:02), Atsushi Kumagai wrote: > On 2013/11/28 16:50:21, kexec wrote: >>>> ping, in case you overlooked this... >>> >>> Sorry for the delayed response, I prioritize the release of v1.5.5 now. >>> >>> Thanks for your advice, check_cyclic_buffer_overrun() should be fixed >>> as you said. In addition, I'm considering other way to address such case, >>> that is to bring the number of "overflowed pages" to the next cycle and >>> exclude them at the top of __exclude_unnecessary_pages() like below: >>> >>> /* >>> * The pages which should be excluded still remain. >>> */ >>> if (remainder >= 1) { >>> int i; >>> unsigned long tmp; >>> for (i = 0; i < remainder; ++i) { >>> if (clear_bit_on_2nd_bitmap_for_kernel(pfn + i)) { >>> pfn_user++; >>> tmp++; >>> } >>> } >>> pfn += tmp; >>> remainder -= tmp; >>> mem_map += (tmp - 1) * SIZE(page); >>> continue; >>> } >>> >>> If this way works well, then aligning info->buf_size_cyclic will be >>> unnecessary. >>> >> >> I selected the current implementation of changing cyclic buffer size becuase >> I thought it was simpler than carrying over remaining filtered pages to next cycle >> in that there was no need to add extra code in filtering processing. >> >> I guess the reason why you think this is better now is how to detect maximum order of >> huge page is hard in some way, right? > > The maximum order will be gotten from HUGETLB_PAGE_ORDER or HPAGE_PMD_ORDER, > so I don't say it's hard. However, the carrying over method doesn't depend on > such kernel symbols, so I think it's robuster. > Then, it's better to remove check_cyclic_buffer_overrun() and rewrite part of free page filtering in __exclude_unnecessary_pages(). Could you do that too? -- Thanks. HATAYAMA, Daisuke