Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B144C433F5 for ; Wed, 15 Dec 2021 02:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239142AbhLOCKu (ORCPT ); Tue, 14 Dec 2021 21:10:50 -0500 Received: from szxga03-in.huawei.com ([45.249.212.189]:29192 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231312AbhLOCKt (ORCPT ); Tue, 14 Dec 2021 21:10:49 -0500 Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4JDJZB3BGzz8vkc; Wed, 15 Dec 2021 10:08:34 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Wed, 15 Dec 2021 10:10:47 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Wed, 15 Dec 2021 10:10:46 +0800 Subject: Re: [PATCH v17 02/10] x86: kdump: make the lower bound of crash kernel reservation consistent To: Catalin Marinas , Borislav Petkov CC: Thomas Gleixner , Ingo Molnar , , "H . Peter Anvin" , , Dave Young , Baoquan He , Vivek Goyal , Eric Biederman , , Will Deacon , , Rob Herring , Frank Rowand , , Jonathan Corbet , , Randy Dunlap , Feng Zhou , Kefeng Wang , "Chen Zhou" References: <20211210065533.2023-1-thunder.leizhen@huawei.com> <20211210065533.2023-3-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <07e41d65-bc3a-49c4-c041-752f1765f37a@huawei.com> Date: Wed, 15 Dec 2021 10:10:34 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/12/15 3:24, Catalin Marinas wrote: > On Tue, Dec 14, 2021 at 08:07:58PM +0100, Borislav Petkov wrote: >> On Fri, Dec 10, 2021 at 02:55:25PM +0800, Zhen Lei wrote: >>> From: Chen Zhou >>> >>> The lower bounds of crash kernel reservation and crash kernel low >>> reservation are different, use the consistent value CRASH_ALIGN. >> >> A big WHY is missing here to explain why the lower bound of the >> allocation range needs to be 16M and why was 0 wrong? > > I asked the same here: > > https://lore.kernel.org/r/20210224143547.GB28965@arm.com > > IIRC Baoquan said that there is a 1MB reserved for x86 anyway in the > lower part, so that's equivalent in practice to starting from > CRASH_ALIGN. > > Anyway, I agree the commit log should describe this. OK, I will add the description. >