From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-225.mta1.migadu.com [95.215.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2E2A31F9A4 for ; Mon, 28 Sep 2026 08:03:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.225 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790582592; cv=none; b=D9jWO0KGp8fAxpJIdmJFP0NGs2K9OMBIJOCBkMcAL1YCJ0m6mwwo0ngm3Nwt4M89fqEpSmk8Mu0JlJ0K3FqDtEVmwXtMr2O+2nc8Sd2lGvN2WZ2oCFkwv1/MUYm3wBTlhc9ELLq8L01LeHAAUqWcl6b2pl6FmfC6zKecnNNECJQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790582592; c=relaxed/simple; bh=u6pM4Q2lirOQrXvVOmhw6eCdvf86YRNbjnR3yNkFQzk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QoUT+xlKuiixZN3ed6AR+UdBIxID6qiXwxl60jxHeITlCwDGU89AFJ0TAloXp+W4RcznsOt6B/1C60aD5xB4Exe1NYMMTM+zNukvaX/yOImI7gjDAEpGBeBfwVo3L/56LfsSCFlJDG9EiI6moS0YKmysyJp21j/6OYyTapcG5uI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=C+V5Fg7y; arc=none smtp.client-ip=95.215.58.225 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="C+V5Fg7y" X-Envelope-To: linux-kernel@vger.kernel.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: linux-kernel@vger.kernel.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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <655c509e-318f-48bc-8183-2b1274dd05ac@kernel.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