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b=GBit5RGATOfbr5x1B8Iah9ZKcHyEC4nw1LQkzGQ1ljV+PUlp0sDeFbRMge8ndkD2N 5hbxQmyDKoxzBT2A2WOm3msxhnQSIeFA1rxJEhBh1tS5fsrRP34troIl8gB8dwVSSy n7incecVx0eMXZzVx1M2WyuUX2wzl1KEGQyLqwcbXO5cLbzciDNnFyGrRMSJQ6Iv3u in+lJV5CbLbY5Vjz8OaHzoxOFZhQr3IBXF8Ojv4ugrXTIjR/CA64ZAImWeduGj97uq OswYEX7Pt1D2sTAFTHfmYgA4cGgJINi19f3moklhfuUcALrBsmn1Fmc4GXGXoVGWPL o6612VYwIJr7A== Message-ID: Date: Fri, 22 May 2026 23:51:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable v18 07/14] mm/khugepaged: skip collapsing mTHP to smaller orders To: Nico Pache , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, jackmanb@google.com, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, liam@infradead.org, ljs@kernel.org, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com, Usama Arif References: <20260522150009.121603-1-npache@redhat.com> <20260522150009.121603-8-npache@redhat.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: <20260522150009.121603-8-npache@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 19B1A8000A X-Rspam-User: X-Stat-Signature: 5mzgrdmnjq1dj9hh1zfpft1ghucz6b6k X-HE-Tag: 1779486729-949265 X-HE-Meta: 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 BQVRq60c 3ke40vkZVHrfZb6HLiEJFQNAQ8u75tgPdzOWyurNkz6O7+8WE7xLnw1qegLbTHAwzpUfyO79yNjLfnLPlqUe2WlixGjN5e3UU9Is8wuW4L3Tz4y88zJGCxsP0y3qN1q00bgJof93Py4JQRS8egL2vqlcTaCM5rB2Lsm1yaWHMgLies4PF+JC00zImz1rMwxLL14mcAHrGNsWfBnhDbvhFBkQXe0RRU4m7ejGq+uNn1NJYHLWoCj60O4WCjJGOaRJaw2oLssRR+nvZcwy6/2wxsv6GYWAtVe4ijFKFobW6TozzpRr6zzNoAeKbn/hSv/E69UQnNBUOZHmTZB8E0HqEFlnwKGC1aKgZL2AU Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/22/26 17:00, Nico Pache wrote: > khugepaged may try to collapse a mTHP to a smaller mTHP, resulting in > some pages being unmapped. The "some pages being unmapped" part is unclear. I assume what you mean is "possibly resulting in a partially mapped source folio, which is undesired." But there is also the problem that we could try collapsing a folio to a same-sized folio, which doesn't make sense (assuming the folio is fully mapped). Clarify all that, please. Acked-by: David Hildenbrand (arm) -- Cheers, David