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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783496821; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xnyQ+PHT+3eNwL4WaZUpFwQj5QvjLSiiyEcci+5680M=; b=X/t84kLISTmiVJPCQs4yoTMaLcmLnKB9dtaBgRn1X03iCJ4lD888gXcjvw+5KbZlVg4uyt jwsSIjlEGJK9KwkNCE7Y17qeBvDRoC487jsP7aO6EnrIXki52kBRpVQxr/mselizV071qg 5Syh2gsXI/FTT2mK3br/GPSXgoynHQE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 7D59141860; Wed, 8 Jul 2026 07:47:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACB9A1F00A3A; Wed, 8 Jul 2026 07:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783496820; bh=xnyQ+PHT+3eNwL4WaZUpFwQj5QvjLSiiyEcci+5680M=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Tq0udb3O/Y9T5qnEC8H++LRf8y4Zc8mrOdGACzi9BjbXQYJSAXNBhJSdbu6IN0QRt Vl++O0GIH59JskKPG6pUkT/ls6L7BMcwdVHGy10AqTHQEeiNeyzCl/UoR1S3mgb88F qVR9okijsk5wGLVjo4plGelA5kTJr86x3ltmCiZCZz1uZMzAiWJM9/wD32/H5tOlZd kABS48CVXsyQSPNaKy0SyMtppbYYCQu824UximWMfOD9UUdp9FMMHIzxqcQ6sb6i9r +DZsikgFOHtsb78F/7Tu1WiCpFXTvxxq3eWfTwB75m/Ac6nEyf49IBeMwgkR81UxT6 SUmE/ldoco4Jw== Message-ID: Date: Wed, 8 Jul 2026 09:46:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 0/2] mm: split underused anonymous mTHP folios To: Joanne Koong , akpm@linux-foundation.org, ljs@kernel.org Cc: usama.arif@linux.dev, alex@ghiti.fr, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, willy@infradead.org, linux-mm@kvack.org References: <20260707201735.4113107-1-joannelkoong@gmail.com> 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: <20260707201735.4113107-1-joannelkoong@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 3269940006 X-Rspam-User: X-Stat-Signature: s9c3igxwo6j8mmsbofuw95homw14p6h3 X-Rspamd-Server: rspam03 X-HE-Tag: 1783496821-514385 X-HE-Meta: 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 pV6b0BCp VLqqOZOJp5a3sea0KVxDm/k8KTlh22+mX6tt3GAafvPrGVTCYeW0aNQYwj0EIvmPWuI+rujActT3YxEvUP+imSFRc8J2CcZPEHIGB/B59hh9kminWgqb7ib6OH17kGIGmMV7u1OqG8mgkjR2kOiLhc8a1gFKZvNVGxaD3cMp6qHX59rRG+bxdHgWSvJYXXA2bxEGFfr3Lp0zoYc2xN1P2Ku8/ftelQ4nQgNiogbzCdlFTAkeisgscFHuCqmkYXAiB9cMg Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/7/26 22:17, Joanne Koong wrote: > PMD-sized THPs that are mostly zero-filled are reclaimed under memory pressure > by the deferred split shrinker, but this is not done for mTHP folios. At Meta, > we would like to deploy 2M THP=always on ARM (with 64k base pages), as 2M > provides contpte benefits and 512M is too big. However, 2M THP=always will > result in a memory regression unless the extra unused portions of THPs can be > broken down and reclaimed. > > This series has two patches: > Patch 1 - makes thp_underused() work for non-PMD-sized folios by scaling > khugepaged_max_ptes_none proportionally to the folio size and using that > as the threshold for how many zero-filled pages a folio can contain before > it's considered underused. Did you look at the khugepaged side, and how we handle it there? -- Cheers, David