From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C648648A2D8 for ; Mon, 28 Sep 2026 09:14:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790586854; cv=none; b=hER158yvPgGgL2/KquLgO3Zq8ghelzEFTpCY8Hpwy1S3TEo6A/Q1Zw4zLde8X5KQKGUlndyhm/H77bAOcQlKckzi+TeYF2Kt4r/OlnjUxaqNIEiEvVfdUt0y/4vJRs9LP3O88u914A9ZMx/aLJfHULyd9xGYhY5TSNnUxtVl65o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790586854; c=relaxed/simple; bh=1/BRcfIJFa/qC7oqq6HsmjAP7pPrWxTpVEek1viLASI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=scImHV6e/9v1cUs6TS8me5qORGloU6G94vaj9SvGh8ZXbAUiLPtBlP3nbQIbXASo2tWU84RpRolIZbWhdXOGyzO8ypB2wv1ueBCTyAtQkbOpTDDdFAYNneQNbRc98xzy6DGxp+yKbpy92rpSCtdfNwTXXTNSnwy8TYS5ilhOPsE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UCN9NmS3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UCN9NmS3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7BE7B1F000FF; Mon, 28 Sep 2026 09:14:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790586853; bh=ojbopmmPdRq/zC/UNBXyGoZ8LTFlDLR7fEeeqgcm29E=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=UCN9NmS3qDbL/ypLkWhgpQEUgaZ4gIGG221Wvzif/dNp8eyiOSruzJowP8cP4pGFM 14MqP4+FI2MUDZPI3gOzpTrMdGAkfw2O+19mcqK3Seb3Eo0jFpe80JS8YW1c6x8aXC u1k7LD3qLH/vDSBkX8kvu4uevFpj9agKp4H7WHYVUcsjAUFa+i/y3n1U5qpSNXMb4l XaLBkmIHOZ9IDkwYn39br9fJBSdvYc/8HtRZcFJoiS28pFCpghc2b7EJYOlKx73fbN RfATo7vhTs5x24kuA9ETBFJATiCEaWFvbYQvDJoSr34yiscNvuPtVduFQZKAdPcxCm szeHHvmBGEIEA== Message-ID: <21abd60c-e71b-40ed-9506-853d4485cf4b@kernel.org> Date: Mon, 28 Sep 2026 11:14:08 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] vmcoreinfo: export SECTION_HAS_MEM_MAP To: Baoquan He Cc: Andrew Morton , David Carlier , Dave Young , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260928-section_has_mem_map-v1-1-4129f6ba2838@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 On 9/28/26 11:11, Baoquan He wrote: > On 09/28/26 at 10:48am, David Hildenbrand (Arm) wrote: >> The crash tool currently hardcodes SECTION_HAS_MEM_MAP, and makedumpfile >> needs similar information (although still relying on >> SECTION_MARKED_PRESENT, it should switch to SECTION_HAS_MEM_MAP). >> >> Let's just export the value instead, so tools that work on vmcoreinfo >> will not have to guess. >> >> Signed-off-by: David Hildenbrand (Arm) >> --- >> Result of the discussion in reply to "[PATCH v2 00/13] mm/sparse: remove >> SECTION_MARKED_PRESENT and further cleanups" [1] >> >> This patch can go in independently. It would be preferable if both >> go into the same kernel release ;) >> >> [1] https://lore.kernel.org/r/20260921-b4-sparsemem_cleanups-v2-0-54d81d65e125@kernel.org >> --- >> kernel/vmcore_info.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c >> index 5a417f8a922a..7833a36064a8 100644 >> --- a/kernel/vmcore_info.c >> +++ b/kernel/vmcore_info.c >> @@ -182,6 +182,7 @@ static int __init crash_save_vmcoreinfo_init(void) >> VMCOREINFO_STRUCT_SIZE(mem_section); >> VMCOREINFO_OFFSET(mem_section, section_mem_map); >> VMCOREINFO_NUMBER(SECTION_SIZE_BITS); >> + VMCOREINFO_NUMBER(SECTION_HAS_MEM_MAP); >> VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); >> #endif >> VMCOREINFO_STRUCT_SIZE(page); > > It would be good to add one section in > Documentation/admin-guide/kdump/vmcoreinfo.rst, e.g > > SECTION_HAS_MEM_MAP > ------------------- > > Indicates a memory section has struct page array (mem_map). User-space > tools should read this value but not hardcode it since the bit position > could change between kernel versions. I'm not particularly happy about having core-kernel defines documented in kdump/vmcoreinfo.rst, though? If it would be something vmcoreinfo special, sure. But not for basic defines. "See the kernel source code" is really what anybody using this should be doing? -- Cheers, David