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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-Stat-Signature: qstxqwthe31c6457xz9g3fx4wbpgb8fx X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5DDCA140003 X-HE-Tag: 1790585423-929042 X-HE-Meta: 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 E9inF2wn yGQGhHOk7+ZJHTZ3eU7Ci/uNhAa+e1yEHoBXuwWgsPc5vIDVkVcUdxLNZHg+on2XZpAEbFVPKUliqSMtU9CCjW+Zfpi19BRRowX+nJP5Ac6vxT/88xp1MX0YxnkLvKGN31gL4u8owR4lIQY9Pw87ldJRJqqeKKhjfkb+LKtcoL4pxqVsJCssTd0dXvErLc3qEOlip2ROqC2PbkZqpP0WvmUIuClDpFydTQGYR4zoGMUP2e5d6SczRkSRH4Qa891a1VbuW2njIrbsvaajoehacrRx0Ggx6POoiupRMtfo5Pz5TgWNszE7JSEbmB2x/p59HnrjvNPUXV61CjM95TysXmc7qKttmjANr+roG Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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