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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F67DC6379F for ; Tue, 17 Jan 2023 03:50:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235482AbjAQDuc (ORCPT ); Mon, 16 Jan 2023 22:50:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235399AbjAQDu2 (ORCPT ); Mon, 16 Jan 2023 22:50:28 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9EF72234D2 for ; Mon, 16 Jan 2023 19:49:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673927376; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=d6j1pwwcrVA2VMufpYBThaFRk5AuLZLztdhG3ETtdEQ=; b=B6B4q2quBl0RLf3y9f/7eeoKaDbl8DpYa8w54LinuRZ1A5oJRmR7qy24ySjSVGPnFbG5bI Br6ooMv/1i2ln5vhHOKiWZbGvJzbsb1OGK84CiO4AlpJVoxAWjJrkBagIYq79xzhtwk3BS sc19MVDefyUtzf4NSeKfzx0d0uyqHlE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-592-m9NhwEysOritgPQaMb4Hkg-1; Mon, 16 Jan 2023 22:49:30 -0500 X-MC-Unique: m9NhwEysOritgPQaMb4Hkg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D72FD185A794; Tue, 17 Jan 2023 03:49:29 +0000 (UTC) Received: from fedora.redhat.com (ovpn-12-229.pek2.redhat.com [10.72.12.229]) by smtp.corp.redhat.com (Postfix) with ESMTP id 336091415108; Tue, 17 Jan 2023 03:49:24 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, thunder.leizhen@huawei.com, John.p.donnelly@oracle.com, wangkefeng.wang@huawei.com, Baoquan He Subject: [PATCH 0/2] arm64: kdump: simplify the reservation behaviour of crashkernel=,high Date: Tue, 17 Jan 2023 11:49:19 +0800 Message-Id: <20230117034921.185150-1-bhe@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After crashkernel=,high support was added, our QE engineer surprisingly found the reserved crashkernel high region could cross the high low memory boundary. E.g on system with 4G as boundary, the crashkernel high region is [4G-64M, 4G+448M]. After investigation, I noticed on arm64, the area near 4G is contiguous. Not like x86, its firmware occupies the cpu address space below 4G. When memblock searches for available memory region top down, it could find a region across 4G boundary. Finally, we actually got two memory regions in low memory. This complicates the crashkernel=,high behaviour, people will be confused by this. In this patchset, simpliyfy the behaviour of crashkernel=,high. When trying to reserve memory region for crashkernel high, we only search for the region in high memory, e.g above 4G. If failed, try searching in low memory. This makes sure the crashkernel high memory limited in high memory, confusion is removed. In patch 2, I add code comment above several crashkernel reservation case to ease code reading. I put them in a separate patch 2 because I want the code change in patch 1 to be straightforward and simpler for reviewing. Please help review and check if this is helpful and worth. Baoquan He (2): arm64: kdump: simplify the reservation behaviour of crashkernel=,high arm64/kdump: add code comments for crashkernel reservation cases arch/arm64/mm/init.c | 43 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-) -- 2.34.1