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b=Rf3IguUvF83mh9EAP0qqqFrTMbGEZaPXN3nBP7l2StStokf6JxVVAjLnhe2G1vrgj VnTPQYS/66X0dHyu+gAF1ncVkBsOt5nO+Dwuochcah8cNceJukFShKN6tH5/6xAFRq Qw9qbaI+dOGWipyl4dUCm5qay4Tmsh0dAT6b1Rwz2DbWvs/7NTelhSQ4BSRjweZ7j9 y9dAd9vMZ+UlZ+cTHDHWHKLFdfeSEtQVR5GvMPfpkyB4znpi3ecqoitiQbmIcSPd2J SxPdOh4z8uVhH403ZoQh5Q6Q8ipLsbQ0b3+Jge/2cXh4HK0Ebjg3iSncOmQPcq64Ig 0KQbp9FYJk4hw== Message-ID: Date: Thu, 23 Apr 2026 15:20:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Revert "tmpfs: don't enable large folios if not supported" To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, ziy@nvidia.com, ljs@kernel.org, lance.yang@linux.dev, wangkefeng.wang@huawei.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: jigyq414167omur49nrjqtca1r8cdrpn X-Rspamd-Queue-Id: 2D12B1A0014 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1776950443-138594 X-HE-Meta: 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 LEkqPbgv 5Z9w3+BdjfhFvjqBJ+W7/HeswhZytb12AXyf3VWKkiyedTl6DQsUcb3Xcun4I7BZTE5I7YHWq67TTAxdmr5K6ns5k2EpYM+1V0+ApN9i6wWBEt7DH7fHJ1ugfGw1AXpspdh2WnI3qXphLbDj4EmyI32l9nfWIQCohsl0Jn7awm7ov3InmRcRoqeEEfsfMbg6yZLRd3rMeSkJbkgIZMLJZgufrv6H3NzPqU1YkXHuSvoDzQmjg9HNHGDAXQG13ENzjxSZ+jNMR0GBG0cr1JtbT6soMKt5zvI2IayVs1e8NAjA3UbU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/23/26 03:41, Baolin Wang wrote: > This reverts commit 5a90c155defa684f3a21f68c3f8e40c056e6114c. > > Currently, when shmem mounts are initialized, they only use 'sbinfo->huge' to > determine whether the shmem mount supports large folios. However, for anonymous > shmem, whether it supports large folios can be dynamically configured via sysfs > interfaces, so setting or not setting mapping_set_large_folios() during initialization > cannot accurately reflect whether anonymous shmem actually supports large folios, > which has already caused some confusion[1]. > > Moreover, for tmpfs mounts, relying on 'sbinfo->huge' cannot keep the mapping_set_large_folios() > setting consistent across all mappings in the entire tmpfs mount. In other words, > under the same tmpfs mount, after remount, we might end up with some mappings > supporting large folios (calling mapping_set_large_folios()) while others don't. > > After some investigation, I found that the write performance regression addressed > by commit 5a90c155defa has already been fixed by the following commit 665575cff098b > ("filemap: move prefaulting out of hot write path"). See the following test data: > > Base: > dd if=/dev/zero of=/mnt/tmpfs/test bs=400K count=10485 (3.2 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=800K count=5242 (3.2 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=1600K count=2621 (3.1 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=2200K count=1906 (3.0 GB/s ) > dd if=/dev/zero of=/mnt/tmpfs/test bs=3000K count=1398 (3.0 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=4500K count=932 (3.1 GB/s) > > Base + revert 5a90c155defa: > dd if=/dev/zero of=/mnt/tmpfs/test bs=400K count=10485 (3.3 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=800K count=5242 (3.3 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=1600K count=2621 (3.2 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=2200K count=1906 (3.1 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/testbs=3000K count=1398 (3.0 GB/s) > dd if=/dev/zero of=/mnt/tmpfs/test bs=4500K count=932 (3.1 GB/s) > > The data is basically consistent with minor fluctuation noise. So we can now > safely revert commit 5a90c155defa to set mapping_set_large_folios() for all > shmem mounts unconditionally. > > [1] https://lore.kernel.org/all/ec927492-4577-4192-8fad-85eb1bb43121@linux.alibaba.com/ > Signed-off-by: Baolin Wang > --- > Note: for more investigation and test data, see: > https://lore.kernel.org/all/116df9f9-4db7-40d4-a4a4-30a87c0feffa@linux.alibaba.com/ Maybe add that as Link: https://lore.kernel.org/all/116df9f9-4db7-40d4-a4a4-30a87c0feffa@linux.alibaba.com/ above? Acked-by: David Hildenbrand (Arm) -- Cheers, David