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 A8F21C433EF for ; Tue, 5 Jul 2022 15:34:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231710AbiGEPeV (ORCPT ); Tue, 5 Jul 2022 11:34:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230030AbiGEPeT (ORCPT ); Tue, 5 Jul 2022 11:34:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FE4D13DE9 for ; Tue, 5 Jul 2022 08:34:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 81BD161B18 for ; Tue, 5 Jul 2022 15:34:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE516C341C7; Tue, 5 Jul 2022 15:34:13 +0000 (UTC) Date: Tue, 5 Jul 2022 16:34:09 +0100 From: Catalin Marinas To: Mike Rapoport Cc: Will Deacon , "guanghui.fgh" , Ard Biesheuvel , baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, david@redhat.com, jianyong.wu@arm.com, james.morse@arm.com, quic_qiancai@quicinc.com, christophe.leroy@csgroup.eu, jonathan@marek.ca, mark.rutland@arm.com, thunder.leizhen@huawei.com, anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, geert+renesas@glider.be, linux-mm@kvack.org, yaohongbo@linux.alibaba.com, alikernel-developer@linux.alibaba.com Subject: Re: [PATCH v4] arm64: mm: fix linear mem mapping access performance degradation Message-ID: References: <20220704131516.GC31684@willie-the-truck> <2ae1cae0-ee26-aa59-7ed9-231d67194dce@linux.alibaba.com> <20220704142313.GE31684@willie-the-truck> <6977c692-78ca-5a67-773e-0389c85f2650@linux.alibaba.com> <20220704163815.GA32177@willie-the-truck> <20220705095231.GB552@willie-the-truck> <5d044fdd-a61a-d60f-d294-89e17de37712@linux.alibaba.com> <20220705121115.GB1012@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 05, 2022 at 06:02:02PM +0300, Mike Rapoport wrote: > +void __init remap_crashkernel(void) > +{ > +#ifdef CONFIG_KEXEC_CORE > + phys_addr_t start, end, size; > + phys_addr_t aligned_start, aligned_end; > + > + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) > + return; > + > + if (!crashk_res.end) > + return; > + > + start = crashk_res.start & PAGE_MASK; > + end = PAGE_ALIGN(crashk_res.end); > + > + aligned_start = ALIGN_DOWN(crashk_res.start, PUD_SIZE); > + aligned_end = ALIGN(end, PUD_SIZE); > + > + /* Clear PUDs containing crash kernel memory */ > + unmap_hotplug_range(__phys_to_virt(aligned_start), > + __phys_to_virt(aligned_end), false, NULL); What I don't understand is what happens if there's valid kernel data between aligned_start and crashk_res.start (or the other end of the range). -- Catalin