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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 A3C42C10F14 for ; Mon, 22 Apr 2019 03:29:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76BBC2075A for ; Mon, 22 Apr 2019 03:29:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726669AbfDVD3c (ORCPT ); Sun, 21 Apr 2019 23:29:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58790 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbfDVD3c (ORCPT ); Sun, 21 Apr 2019 23:29:32 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D53CA307D855; Mon, 22 Apr 2019 03:29:31 +0000 (UTC) Received: from localhost (ovpn-12-166.pek2.redhat.com [10.72.12.166]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E13361B84; Mon, 22 Apr 2019 03:29:28 +0000 (UTC) Date: Mon, 22 Apr 2019 11:29:26 +0800 From: Baoquan He To: Dave Young Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, piliu@redhat.com, Yinghai Lu , Eric Biederman Subject: Re: [PATCH 2/2 update] X86/kdump: fall back to reserve high crashkernel memory Message-ID: <20190422032926.GA3584@localhost.localdomain> References: <20190421035058.943630505@redhat.com> <20190421035303.669870129@redhat.com> <20190422031905.GA8387@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190422031905.GA8387@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 22 Apr 2019 03:29:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/22/19 at 11:19am, Dave Young wrote: > crashkernel=xM tries to reserve crashkernel memory under 4G, which > is enough for usual cases. But this could fail sometimes, for example > one tries to reserve a big chunk like 2G, it is possible to fail. > > So let the crashkernel=xM just fall back to use high memory in case it > fails to find a suitable low range. Do not set the ,high as default > because it allocates extra low memory for DMA buffers and swiotlb, this is > not always necessary for all machines. Typically like crashkernel=128M > usually work with low reservation under 4G, so still keep <4G as default. > > Signed-off-by: Dave Young > Reviewed-by: Ingo Molnar > --- Ack the whole series, thanks for the effort. Acked-by: Baoquan He > Documentation/admin-guide/kernel-parameters.txt | 7 +++++-- > arch/x86/kernel/setup.c | 22 ++++++++++++++-------- > 2 files changed, 19 insertions(+), 10 deletions(-) > > --- linux-x86.orig/arch/x86/kernel/setup.c > +++ linux-x86/arch/x86/kernel/setup.c > @@ -541,21 +541,27 @@ static void __init reserve_crashkernel(v > } > > /* 0 means: find the address automatically */ > - if (crash_base <= 0) { > + if (!crash_base) { > /* > * Set CRASH_ADDR_LOW_MAX upper bound for crash memory, > - * as old kexec-tools loads bzImage below that, unless > - * "crashkernel=size[KMG],high" is specified. > + * crashkernel=x,high reserves memory over 4G, also allocates > + * 256M extra low memory for DMA buffers and swiotlb. > + * but the extra memory is not required for all machines. > + * So prefer low memory first, and fall back to high memory > + * unless "crashkernel=size[KMG],high" is specified. > */ > - crash_base = memblock_find_in_range(CRASH_ALIGN, > - high ? CRASH_ADDR_HIGH_MAX > - : CRASH_ADDR_LOW_MAX, > - crash_size, CRASH_ALIGN); > + if (!high) > + crash_base = memblock_find_in_range(CRASH_ALIGN, > + CRASH_ADDR_LOW_MAX, > + crash_size, CRASH_ALIGN); > + if (!crash_base) > + crash_base = memblock_find_in_range(CRASH_ALIGN, > + CRASH_ADDR_HIGH_MAX, > + crash_size, CRASH_ALIGN); > if (!crash_base) { > pr_info("crashkernel reservation failed - No suitable area found.\n"); > return; > } > - > } else { > unsigned long long start; > > --- linux-x86.orig/Documentation/admin-guide/kernel-parameters.txt > +++ linux-x86/Documentation/admin-guide/kernel-parameters.txt > @@ -704,8 +704,11 @@ > upon panic. This parameter reserves the physical > memory region [offset, offset + size] for that kernel > image. If '@offset' is omitted, then a suitable offset > - is selected automatically. Check > - Documentation/kdump/kdump.txt for further details. > + is selected automatically. > + [KNL, x86_64] select a region under 4G first, and > + fall back to reserve region above 4G in case without > + '@offset'. > + See Documentation/kdump/kdump.txt for further details. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory