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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B8E4DC9833E for ; Mon, 28 Sep 2026 08:50:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Xux5ZPoLqrz1mbftErEicTW9loRDj4oR9SfIqryQVFI=; b=dM0tc63ammd2URMAnHq+s2dl6v IuiVRu8WiXWzOqSxwt5ZnYE9GQmJmj2kyzaqByRRmucsF8vH9YGP4oglxa3HXBMM5Vcj26OwfrZK0 TnosEKxuUXucJaHOATCxG8/7C28oy+DVq/Pw2ZEjQq4Qffj/7fNnd/TekSPwgNGlt16paGicl3XEX 83SEbVVcq0IsEyDrOYrnLUVdDhDJrjmOb80zCQI0221yNeyb3SfAyP7iBbMlfummWmeVMeTICW4vb +jaZIeAIZdp5pAxsYhkk3IQ80/GNk1pz/ebCjexZnuasKr/n7gimr92qjKiQDMQKea4iODuv787/9 P7+AV7ng==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB745-0000000092U-1eK1; Mon, 28 Sep 2026 08:50:25 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB743-0000000092E-0fo4 for kexec@lists.infradead.org; Mon, 28 Sep 2026 08:50:23 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 8DE9A43C8E; Mon, 28 Sep 2026 08:50:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07EE51F000FF; Mon, 28 Sep 2026 08:50:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790585422; bh=Xux5ZPoLqrz1mbftErEicTW9loRDj4oR9SfIqryQVFI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=iEK97vavCrO6FGamvL6w7E2I1MX2GZCebpDkO0cMSJDvo5xQ2vNNjADjci6TP8N29 b8f5WsNIuHiiAVePejbUiD2f14ejjCMal/GCUjIpIQcT74Gun81v7NHdK2Qm42IMCn 7yrkD2JQqZC3M8VbYDcqxuGS8IbhDUEdbAyK4k0BgbhaG1CS5D+9XqaUVVL7X0I6o7 fReqiFglUmaWiN2BlAbXClfp2HnuyMig/dz67ReP7rtvxpERkOiDkfJTJ/t/SPpeS1 7uKDXsEYc3REZnADw9w8J+97lG7Kzs/sY9a6AjOEiFY2bkpohtKyBzjjxopxg2+1jP x6teGcrUOIaqg== Message-ID: <9009312f-0ffb-4425-ab82-1eb7e52a4646@kernel.org> Date: Mon, 28 Sep 2026 10:50:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 10/13] mm/sparse: remove SECTION_MARKED_PRESENT To: Dave Young Cc: David Carlier , akpm@linux-foundation.org, axelrasmussen@google.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, baoquan.he@linux.dev, brendan.jackman@linux.dev, dakr@kernel.org, driver-core@lists.linux.dev, gregkh@linuxfoundation.org, hannes@cmpxchg.org, jan.kiszka@siemens.com, kasong@tencent.com, kbingham@kernel.org, liam@infradead.org, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, mhocko@suse.com, osalvador@suse.de, qi.zheng@linux.dev, rafael@kernel.org, rppt@kernel.org, shakeel.butt@linux.dev, surenb@google.com, vbabka@kernel.org, weixugc@google.com, yuanchu@google.com, ziy@nvidia.com, devel@lists.crash-utility.osci.io, kexec@lists.infradead.org, Baoquan He References: <20260921-b4-sparsemem_cleanups-v2-10-54d81d65e125@kernel.org> <20260927192013.144672-1-devnexen@gmail.com> <655c509e-318f-48bc-8183-2b1274dd05ac@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 9/28/26 10:01, Dave Young wrote: > Cced kexec list. > > On Mon, Sep 28, 2026 at 09:28:08AM +0200, David Hildenbrand (Arm) wrote: >> On 9/27/26 21:20, David Carlier wrote: >>> >>> Hi David, >> >> Hi! >> >>> >>> It seems dropping SECTION_MARKED_PRESENT_BIT shifts the other section flags down >>> one bit. crash hardcodes SECTION_HAS_MEM_MAP as (1UL << 1) in >>> pfn_to_map(), so it now tests SECTION_IS_ONLINE: offline and >>> ZONE_DEVICE sections no longer resolve to a struct page. makedumpfile >>> only checks bit 0 and is fine. >> >> Thanks. To be expected when relying on kernel internals. >> >> Which makes me wonder why makedumpfile >> (https://github.com/makedumpfile/makedumpfile) not require any such information. >> >>> >>> Keep bit 0 reserved, or export the bits via vmcoreinfo? >> We could export it, or crash can simply detect the change based on the kernel >> version. I remember the latter was done in makedumpfile in the past (although we >> export it). >> >> I can send a separate patch to export it. > > Thanks David. Checking kernel internals via kernel version is not a good idea > due to the downstream kernels. Patch at: https://lore.kernel.org/r/20260928-section_has_mem_map-v1-1-4129f6ba2838@kernel.org -- Cheers, David