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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 0328BC4338F for ; Mon, 23 Aug 2021 14:45:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4EB961378 for ; Mon, 23 Aug 2021 14:45:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230210AbhHWOpv (ORCPT ); Mon, 23 Aug 2021 10:45:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:40750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230186AbhHWOpv (ORCPT ); Mon, 23 Aug 2021 10:45:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9140F613CF; Mon, 23 Aug 2021 14:45:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629729908; bh=HS2M+wkDtx/G0MZSg6+SDwYSA3teAsEDvrv+10PPD1A=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=qPKYxgfB9GVNO/ci0L6xILxIQPPJGBHIQJy4YMnj0Zw7zF7wGjfzynHM07q/hdtFJ fzjZSr+FNFIn8DCHJscN7WHtmTm/qhJneZMJJj08w7k3nJ838qAJNWc+vVoaXF87+1 iNcj8INOwKrfvditV+DxlUtQ8DX4lAbEXz/sDy2ACAgKAp+HvHvaZhS0+UZJN4VgMH GPAZlRaNM4E4saszqP0w189j7NDctQFAvm5aZhrYjAQHhd9mTXKAONYbcAz4L1fskn IpHuinmaVCOcnYZwI5rcTj2KMKe0BjZ4hk50UN58HZdjfm9uvmn9CsDQYSUqstrZ9J Jky99juD8VeBQ== Received: by mail-ej1-f48.google.com with SMTP id n27so5597739eja.5; Mon, 23 Aug 2021 07:45:08 -0700 (PDT) X-Gm-Message-State: AOAM531MEUyxgeIaj9j3I1BTJ5VtAo4c/J7JBjNhCaINJBEdNIN8GKY6 xQU8a+/9cjlRVYzvnRkmHTosyJU97M90Mk4fTw== X-Google-Smtp-Source: ABdhPJxGMCnkZ6Wg5JPxtvBTf03t6XhofzKZ3GpTAEgQlSG7jl4bDW3CMJL9Gl4hxiY+ePwWhCIra0pqlfZDMAM51Ag= X-Received: by 2002:a17:907:b06:: with SMTP id h6mr3650075ejl.130.1629729907110; Mon, 23 Aug 2021 07:45:07 -0700 (PDT) MIME-Version: 1.0 References: <92b6718f5618d5469f67b48fbea189cca0c12f4b.1628670468.git.geert+renesas@glider.be> In-Reply-To: From: Rob Herring Date: Mon, 23 Aug 2021 09:44:55 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 1/9] MIPS: Avoid future duplicate elf core header reservation To: Mike Rapoport Cc: Geert Uytterhoeven , Russell King , Nicolas Pitre , Ard Biesheuvel , Linus Walleij , Catalin Marinas , Will Deacon , Thomas Bogendoerfer , Nick Kossifidis , Paul Walmsley , Palmer Dabbelt , Albert Ou , Frank Rowand , Dave Young , Baoquan He , Vivek Goyal , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Linux ARM , "open list:BROADCOM NVRAM DRIVER" , linux-riscv , kexec@lists.infradead.org, Linux-Renesas , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org On Mon, Aug 23, 2021 at 8:10 AM Mike Rapoport wrote: > > On Mon, Aug 23, 2021 at 12:17:50PM +0200, Geert Uytterhoeven wrote: > > Hi Mike, > > > > On Mon, Aug 16, 2021 at 7:52 AM Mike Rapoport wrote: > > > On Wed, Aug 11, 2021 at 10:50:59AM +0200, Geert Uytterhoeven wrote: > > > > Prepare for early_init_fdt_scan_reserved_mem() reserving the memory > > > > occupied by an elf core header described in the device tree. > > > > As arch_mem_init() calls early_init_fdt_scan_reserved_mem() before > > > > mips_reserve_vmcore(), the latter needs to check if the memory has > > > > already been reserved before. > > > > > > Doing memblock_reserve() for the same region is usually fine, did you > > > encounter any issues without this patch? > > > > Does it also work if the same region is part of an earlier larger > > reservation? I am no memblock expert, so I don't know. > > I didn't run into any issues, as my MIPS platform is non-DT, but I > > assume arch/arm64/mm/init.c:reserve_elfcorehdr() had the check for > > a reason. > > The memory will be reserved regardless of the earlier reservation, the > issue may appear when the reservations are made for different purpose. E.g. > if there was crash kernel allocation before the reservation of elfcorehdr. > > The check in such case will prevent the second reservation, but, at least > in arch/arm64/mm/init.c:reserve_elfcorehdr() it does not seem to prevent > different users of the overlapping regions to step on each others toes. If the kernel has been passed in overlapping regions, is there anything you can do other than hope to get a message out? > Moreover, arm64::reserve_elfcorehdr() seems buggy to me, because of there > is only a partial overlap of the elfcorehdr with the previous reservation, > the non-overlapping part of elfcorehdr won't get reserved at all. What do you suggest as the arm64 version is not the common version? Rob