From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3197DC61CE3 for ; Sat, 19 Jan 2019 01:25:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0971D2084C for ; Sat, 19 Jan 2019 01:25:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730184AbfASBZe (ORCPT ); Fri, 18 Jan 2019 20:25:34 -0500 Received: from mx0a-002e3701.pphosted.com ([148.163.147.86]:36614 "EHLO mx0a-002e3701.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729109AbfASBZd (ORCPT ); Fri, 18 Jan 2019 20:25:33 -0500 Received: from pps.filterd (m0134422.ppops.net [127.0.0.1]) by mx0b-002e3701.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x0J1G24a001735; Sat, 19 Jan 2019 01:25:08 GMT Received: from g9t5008.houston.hpe.com (g9t5008.houston.hpe.com [15.241.48.72]) by mx0b-002e3701.pphosted.com with ESMTP id 2q3ptb9245-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 19 Jan 2019 01:25:08 +0000 Received: from g4t3433.houston.hpecorp.net (g4t3433.houston.hpecorp.net [16.208.49.245]) by g9t5008.houston.hpe.com (Postfix) with ESMTP id EAA6960; Sat, 19 Jan 2019 01:25:06 +0000 (UTC) Received: from anatevka (anatevka.americas.hpqcorp.net [10.34.81.61]) by g4t3433.houston.hpecorp.net (Postfix) with ESMTP id 2050B45; Sat, 19 Jan 2019 01:25:06 +0000 (UTC) Date: Fri, 18 Jan 2019 18:25:05 -0700 From: Jerry Hoemann To: Pingfan Liu Cc: kexec@lists.infradead.org, Baoquan He , yinghai@kernel.org, Randy Dunlap , linux-kernel@vger.kernel.org, Mike Rapoport , Andrew Morton , Dave Young , vgoyal@redhat.com Subject: Re: [PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Message-ID: <20190119012505.GA21653@anatevka> Reply-To: Jerry.Hoemann@hpe.com References: <1547539623-18201-1-git-send-email-kernelfans@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1547539623-18201-1-git-send-email-kernelfans@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-HPE-SCL: -1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-18_14:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901190009 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 15, 2019 at 04:07:03PM +0800, Pingfan Liu wrote: > People reported a bug on a high end server with many pcie devices, where > kernel bootup with crashkernel=384M, and kaslr is enabled. Even > though we still see much memory under 896 MB, the finding still failed > intermittently. Because currently we can only find region under 896 MB, > if without ',high' specified. Then KASLR breaks 896 MB into several parts > randomly, and crashkernel reservation need be aligned to 128 MB, that's > why failure is found. It raises confusion to the end user that sometimes > crashkernel=X works while sometimes fails. > If want to make it succeed, customer can change kernel option to > "crashkernel=384M,high". Just this give "crashkernel=xx@yy" a very > limited space to behave even though its grammar looks more generic. > And we can't answer questions raised from customer that confidently: > 1) why it doesn't succeed to reserve 896 MB; > 2) what's wrong with memory region under 4G; > 3) why I have to add ',high', I only require 384 MB, not 3840 MB. > This patch tries to get memory region from 896 MB firstly, then [896MB,4G], > finally above 4G. While allocating crashkernel from below 4G seems fine, won't we have problems if the crash kernel gets allocated above 4G because of the SWIOTLB? thanks > Dave Young sent the original post, and I just re-post it with commit log > improvement as his requirement. > http://lists.infradead.org/pipermail/kexec/2017-October/019571.html > There was an old discussion below (previously posted by Chao Wang): > https://lkml.org/lkml/2013/10/15/601 > > Signed-off-by: Pingfan Liu > Cc: Dave Young > Cc: Baoquan He > Cc: Andrew Morton > Cc: Mike Rapoport > Cc: yinghai@kernel.org, > Cc: vgoyal@redhat.com > Cc: Randy Dunlap > --- > v6 -> v7: fix spelling mistake pointed out by Randy > arch/x86/kernel/setup.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 3d872a5..fa62c81 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -551,6 +551,22 @@ static void __init reserve_crashkernel(void) > high ? CRASH_ADDR_HIGH_MAX > : CRASH_ADDR_LOW_MAX, > crash_size, CRASH_ALIGN); > +#ifdef CONFIG_X86_64 > + /* > + * crashkernel=X reserve below 896M fails? Try below 4G > + */ > + if (!high && !crash_base) > + crash_base = memblock_find_in_range(CRASH_ALIGN, > + (1ULL << 32), > + crash_size, CRASH_ALIGN); > + /* > + * crashkernel=X reserve below 4G fails? Try MAXMEM > + */ > + if (!high && !crash_base) > + crash_base = memblock_find_in_range(CRASH_ALIGN, > + CRASH_ADDR_HIGH_MAX, > + crash_size, CRASH_ALIGN); > +#endif > if (!crash_base) { > pr_info("crashkernel reservation failed - No suitable area found.\n"); > return; > -- > 2.7.4 > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec -- ----------------------------------------------------------------------------- Jerry Hoemann Software Engineer Hewlett Packard Enterprise -----------------------------------------------------------------------------