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 871F9C9833E for ; Mon, 28 Sep 2026 08:03:20 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=O6oX7WoY9qy+38lv9uTWDEFP6iRKHKXco4d1bWNWC4k=; b=L7Tn0AQRR/dB3+nuMm4WdbuUj0 KsFLd2iKj4bDbFNF6OLXWVKEAnfbJCjiYFRol+p3CJffbGksM+LX56SSU2c9L/XExpmHl5VDv6AJb 0OkiTAd/HFurtlOlxA2I6bLvwgO+htBOOjHTVaxxTYrqOnIxgZNbNw/PbEdmSvKuDAnrjkXkHSkSR uaC9in1/d4rIYZ1hukaXPtwvP2V3Ty2D5jG0AUYQJ81KRpafhuAtgP+H4bQQ5pUDBqEvGBuXUpTEe fZWE9UbsWBIrfMrYVFWdE488+BKRezeSTIiNBs4JMNrRxH/9qJVnY+so5oNOejX0CV8bzJJ2T+EAc NYfABd4A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB6KT-0000000007Z-1ppS; Mon, 28 Sep 2026 08:03:17 +0000 Received: from out-160.mta0.migadu.com ([2001:41d0:1004:224b::a0] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB6KN-0000000006w-3vaj for kexec@lists.infradead.org; Mon, 28 Sep 2026 08:03:13 +0000 X-Envelope-To: kexec@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=u6pM4Q2lirOQrXvVOmhw6eCdvf86YRNbjnR3yNkFQzk=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790582588; v=1; x=1791187388; b=C+V5Fg7yUDtnG95PdYyQlpKrqN/I0S/X42BAIMYGwTLCGzp4vAUZid0wtjsNCaEZFEsjqFB+ y46+C0Knmw9IqwGouFl4z0q9eUZEllrBPQRgyYhcIQKi9YaOwn5MwUkGYSVRKEaW8FzJnOV8jZZ PolBC5842VTOJPZssiW6x/6g= X-Envelope-To: kexec@lists.infradead.org Received: by smtp.migadu.com with ESMTPS id 6cea94b206c11561; Mon, 28 Sep 2026 08:03:07 +0000 X-Mizu-Trace-ID: 6cea94b206c11561 X-Migadu-Flow: FLOW_OUT Date: Mon, 28 Sep 2026 16:01:16 +0800 From: Dave Young To: "David Hildenbrand (Arm)" 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 Subject: Re: [PATCH v2 10/13] mm/sparse: remove SECTION_MARKED_PRESENT Message-ID: References: <20260921-b4-sparsemem_cleanups-v2-10-54d81d65e125@kernel.org> <20260927192013.144672-1-devnexen@gmail.com> <655c509e-318f-48bc-8183-2b1274dd05ac@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <655c509e-318f-48bc-8183-2b1274dd05ac@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260928_010312_118653_5970F018 X-CRM114-Status: GOOD ( 17.50 ) 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 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: > > On Mon, Sep 21, 2026 at 09:59:02PM +0200, David Hildenbrand (Arm) wrote: > >> enum { > >> - SECTION_MARKED_PRESENT_BIT, > >> SECTION_HAS_MEM_MAP_BIT, > >> SECTION_IS_ONLINE_BIT, > >> SECTION_IS_EARLY_BIT, > > > > 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. > > -- > Cheers, > > David