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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 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; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: g48tgooipdkkrsky4w7wcy84jddzqk33 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4401B20004 X-HE-Tag: 1790586854-736614 X-HE-Meta: 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 Ten+OZSo bC8VxnQ+H87PsyYLwfRwUUnqJkA4YlHTbSfEHnBIPO1sbvogvIjDpfyslPRe3sALf5p9iPqgsqCUx7b9mSzKfF4ZNKJz4ZkrBPYiE4cVJ22l3zEPLKMdSxn/GpuOE5D8jKuXEUX0gvpMZEa3jJc11lx2Am+qTnM3yNGC0pHYADvOXtI02yd20PasF3ipGDBLOPxvAg5XBKczEeYoGkfPMAdWyq55Umw/+fywrQxD9rNIct8fTyeLQtkUOmIjYAT01DnMDiSrOr/ZbdYY7nUGiCDwJvgGgROljTilVczjwU91JrM0t2z6hB6YNar3Pv4I9RphRHBynsGP4ufw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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