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b=J1RRaJsjFoPPzLLr+uhbPsnz4s6HEiGtDUliOig0I6SGfRKOs6wSvlzLJb4/GiJhD O87gKny2z+59fQSrPq0OpUbuXNOz2YjE+3mJ8tXxiuvSKRaG9x4hYFcAjcX8aKOq8W +KOuL/Lnlo6fJKFqOw5ouWYPRW1vccwAW9VyGXFoFV+PF98W9TEHARAXUiTcqhiaJp 2eynJFn5+FPYRGCrD3lTK2oWYT1Lb6D2CjwpquUhL7AYCnK52bv49oSzW/pzMXI0j8 t2k414mb6oDPC8cJb/Ivs5I8kOhx+bHIC8miqqFrQJUOTr8l9DuiaI/FzvE+dgtkH+ kXI+vX0aZe5Tg== Message-ID: <92376758-5bb5-4391-8904-cd0e2f72acf8@kernel.org> Date: Mon, 9 Mar 2026 15:39:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 6/6] arm64: mm: implement the architecture-specific test_and_clear_young_ptes() To: Baolin Wang , akpm@linux-foundation.org Cc: catalin.marinas@arm.com, will@kernel.org, lorenzo.stoakes@oracle.com, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, dev.jain@arm.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <7f891d42a720cc2e57862f3b79e4f774404f313c.1772778858.git.baolin.wang@linux.alibaba.com> <6305e05e-2911-42b0-b6f5-7fdde787b778@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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Since the folio_pte_batch() > will group consecutive !cont PTEs into one batch and consecutive cont > PTEs into another (assume all PTEs belong to a single large folio), > because their PTE entries have different CONT bits. Interesting, thanks. I thought that folio_pte_batch() would be able to batch that. But yes, pte_batch_hint() relies on the CONT bit still being set after a ptep_get(). I wonder whether we should document somewhere that the arm implementation depends on that. This might be something to look into in the future. (make folio_pte_batch() ignore cont information when comparing and make the arm implementation be able to deal with that). Assume we unmapped the last page of a large folio. Ideally, we'd be able to process the remaining THP pieces (all ptes) in a single operation. I guess right now it would be two. -- Cheers, David