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Mon, 28 Sep 2026 09:11:13 +0000 X-Mizu-Trace-ID: 65f31ff16b613622 X-Migadu-Flow: FLOW_OUT Date: Mon, 28 Sep 2026 17:11:08 +0800 From: Baoquan He To: "David Hildenbrand (Arm)" Cc: Andrew Morton , David Carlier , Dave Young , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] vmcoreinfo: export SECTION_HAS_MEM_MAP Message-ID: References: <20260928-section_has_mem_map-v1-1-4129f6ba2838@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260928-section_has_mem_map-v1-1-4129f6ba2838@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 435CC40008 X-Stat-Signature: 5eydztd8znqqgt6f1u1reiq63aotkrgb X-HE-Tag: 1790586676-917023 X-HE-Meta: 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 eW0NkqMX eJ04pccyuSMVR0eqC6L2PCZXZGSX7MiTKUfxKBqyNG1sKBSkuEmBHsykRlt/KZoQYfi30rnBt74s3R0++VyYq4MfqKIobvlzqWQka/vY8G51EfmZogRa+Tq2ixZVjnWNANMY6iCOasjJuPSrgOFg8UotuE5EN4Bq3kWInQEBpGUnqd+POEB9ObSR2EOHgY2XBh0eRSWSLZH1w2DGp20ZdY5BtoptayIe7JO8SW/cDCI4qOL1sn3np+09TU1W+oktJ3YvnoXr4YwNXzS1diAZ7bYRVEeWFGPrLXdSEuQX6QVV65l5pq/6+ijFrhaUvnqlCcARFkUUUtcJNV++4T8sqCw1V3kyDPlVZuOsPsoInD8AB9efWrAMZp1OeLQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. The code change looks good to me. > > --- > > base-commit: 57e4ac91fc62d75d84b5a03827a19ceb4094ecd9 > > change-id: 20260928-section_has_mem_map-6205dc90a09f > > -- > > Cheers, > > David >