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 939ABC10F14 for ; Mon, 22 Apr 2019 03:19:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6980420870 for ; Mon, 22 Apr 2019 03:19:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726724AbfDVDTO (ORCPT ); Sun, 21 Apr 2019 23:19:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58594 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbfDVDTO (ORCPT ); Sun, 21 Apr 2019 23:19:14 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 784ED309264F; Mon, 22 Apr 2019 03:19:13 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-124.pek2.redhat.com [10.72.12.124]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 29D5C60139; Mon, 22 Apr 2019 03:19:08 +0000 (UTC) Date: Mon, 22 Apr 2019 11:19:05 +0800 From: Dave Young To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, bhe@redhat.com, piliu@redhat.com, Yinghai Lu , Eric Biederman Subject: [PATCH 2/2 update] X86/kdump: fall back to reserve high crashkernel memory Message-ID: <20190422031905.GA8387@dhcp-128-65.nay.redhat.com> References: <20190421035058.943630505@redhat.com> <20190421035303.669870129@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190421035303.669870129@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 22 Apr 2019 03:19:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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