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From: Lance Yang In-Reply-To: <9845ff31-acaf-4a04-86a2-b4104446e966@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2A90C40008 X-Stat-Signature: 7a4i4eyq4znzqmuyzo1ytojhu386grfr X-Rspam-User: X-HE-Tag: 1777540265-300690 X-HE-Meta: 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 q31TmPQ0 go/BoWreqsrOmD+sA6XKSWoFDxCNvhKGA+w1vYNEwchHLJlKwQGshwH6Zx9iVxzKagB0rq2/5uO9VSAXXBkxpiE0lNbU42Pfr8AZfKoQEG8ZOv0En/i2OfzG/Hn5TzfVHamcHFqmdOjNyDnV7FJYTLFUEoBqHKbn9hvGX7AvXPC7LrwYmjKo2fKnEaafi2BW8z+I6XbC1y3TdO5i0H+m1zsdj9HZc1viS8dJc/eullNW/X5fFWUONZu7RhQuXy3++O6EgtxrmbDRlvvQwdwWmLGQkE4M7PGb7GUFIQ/BpgqpBlo8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026/4/30 16:54, David Hildenbrand (Arm) wrote: >>> ... and triggering the VM_WARN_ON_ONE(), although never reported so far. >>> >>> To fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() whether >>> pmd_special/pud_special is actually implemented. >>> >>> Fixes: af38538801c6 ("mm/memory: factor out common code from vm_normal_page_*()") >> >> Agreed. My Fixes tag (where my bisection arrived) was correct for the >> common zap_huge_pmd() symptom I was seeing (Lorenzo's commit removed >> an independent is_huge_zero_pmd() check from it, so it now relies on >> vm_normal_folio_pmd() to give the right answer). But you've chased >> up other usages, and realized it goes back further. You could just as >> well blame the other commit mentioned in this thread, the d82d09e48219 >> ("mm/huge_memory: mark PMD mappings of the huge zero folio special"), >> because in come configs it is not doing what it expects to be doing. >> But af38538801c6 is where effects start appearing, so fine to blame >> it (and both come from the same 6.18 series, do it doesn't matter). >> >>> Signed-off-by: Hugh Dickins > >>> Co-developed-by: David Hildenbrand (Arm) >> >> That's generous, but the patch is not mine at all, and I'll >> happily let you grab my two paragraphs above. Please, just > > Okay, I didn't want to undermine your involvement. > >> Reported-by: Hugh Dickins > > Then, I'd also add a > > Debugged-by: Hugh Dickins Yeah. Thanks to Hugh for the bisection, debugging and detailed analysis! Cheers, Lance