From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BD577F483EC for ; Mon, 23 Mar 2026 19:53:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0AD686B0005; Mon, 23 Mar 2026 15:53:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 05EA76B0088; Mon, 23 Mar 2026 15:53:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB6486B008A; Mon, 23 Mar 2026 15:53:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D7C326B0005 for ; Mon, 23 Mar 2026 15:53:16 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 8C09D1EF8F for ; Mon, 23 Mar 2026 19:53:16 +0000 (UTC) X-FDA: 84578376792.19.93DA75D Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf23.hostedemail.com (Postfix) with ESMTP id 189D4140003 for ; Mon, 23 Mar 2026 19:53:13 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=cVO0umbP; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf23.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774295594; 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=Uh47nTI4m1Lhkiqy2yEiFdYsiaJ447ZvNYpdEMrlqpk=; b=SPzEVWKD0jqncbUyc88jsJ0U8D7HuVruT/Zx9J9/DLpgq2/rPK+Dgl9OeCBucrO1q+Cv0Q wa6NcFV2DYvx535p1B0PSLYKrM3VDHA2ttOovVAvLIAv+6V6wGTUXTh8URzIcVqFYm7o5X PousmOkfp3M1FHmzpx6ZayO7uumtUuo= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774295594; a=rsa-sha256; cv=none; b=wr//+w9CHhFsd0wByeqbW3gbb6VYKQN729P2m0jw10qwQuGa4mr2/otHPMSVQd0ZWPBH8e ZkSCfq5F+D/4YGxHehTDNRTptnbJ9GIgrZ3mYEF8jPgtTY8QoziIpHaY9L5uyTcKtZ0YU7 FSPJNhpepwVU8YHXkFEYUCI7XBoirxs= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=cVO0umbP; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf23.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 1539943834; Mon, 23 Mar 2026 19:53:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FB00C4CEF7; Mon, 23 Mar 2026 19:53:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774295592; bh=Wu3kjDSNkN5FVjTb4kqzvVi628241DvvruskNz7eyNU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cVO0umbPLG2GPAWshF09LgIS68Q0JPofvRWldFefm3OIfXXa2ENAGmD664zeOlBIS +IpW8DdlJeEWx9sTAzsmsgA8dxMoxvaczbfZJUjMN3GzF4m31/WLnpGHJUAdbchFlb 00B/1LzGj7FXCzEXzhoROtvSzH+htOToA2vGsVw/fq2j2HTcy8dj5EQRonGrdasuXO 47wD7dYqszZ+y4ITQFUelkZJWAwVIHMXvnVgEjSNF5fxESxld3qU4dizX58Cud6Zkn 1Jkr2cjEuMxiX4y0qg1t1uBVJ/zR7xMEpYpvZbsv4qDcci8BmqeawwfmPAA/jU3ET6 dyLEP6SCw7vsw== Message-ID: Date: Mon, 23 Mar 2026 20:53:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 02/11] mm/khugepaged: remove READ_ONLY_THP_FOR_FS code in collapse_file() To: Zi Yan Cc: "Matthew Wilcox (Oracle)" , Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org References: <20260323190644.1714379-1-ziy@nvidia.com> <20260323190644.1714379-3-ziy@nvidia.com> <7382046f-7c58-4a3e-ab34-b2704355b7d5@kernel.org> 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-Rspamd-Queue-Id: 189D4140003 X-Stat-Signature: 5w4hf47tepscf7ydpz3e1ba96pjrxuoa X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774295593-759467 X-HE-Meta: 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 tkUnHrhx nlg7/jTj1oacOso6mvMRKVinDfqZKaV+lamghTFQygDH+12iuNrjxdf3AobYZ9ADgFo4PqxXO5P7fTSDRmvh0lqugPEcFBt29j4aBPfvNheOJnauXtlXaBgY/GCwaWsRrmparO3qwuHKs3xXRjI1x0mVcmkWOST8tJNtmqkXl81mQQu9CrfGD/Du/5/tQFjeqf+7JHIVbS5btqRDmyWiAWpWerYh3iZwCu0/pwTrFGOv8Fi3yl7OVK39rJMuzszQh/VpOys8lDBf/rT0MCUeE8bgIvetKIlTQx+p5hC/zG5bQaqamfT77QGOL5I+FQ4mNiFmKJmTeosqhF2U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/23/26 20:47, Zi Yan wrote: > On 23 Mar 2026, at 15:41, David Hildenbrand (Arm) wrote: > >> On 3/23/26 20:06, Zi Yan wrote: >>> READ_ONLY_THP_FOR_FS is no longer present, remove corresponding code. >>> >>> Signed-off-by: Zi Yan >>> --- >>> mm/khugepaged.c | 159 +++++++++++------------------------------------- >>> 1 file changed, 34 insertions(+), 125 deletions(-) >>> >>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >>> index b2ac28ddd480..39f0b8959535 100644 >>> --- a/mm/khugepaged.c >>> +++ b/mm/khugepaged.c >>> @@ -1899,7 +1899,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, >>> int nr_none = 0; >>> bool is_shmem = shmem_file(file); >>> >>> - VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); >>> + VM_WARN_ON_ONCE(!is_shmem); >> >> Oh, but if that means that khugepaged cannot collapse large folios in >> FSes anymore, then this is the wrong approach I suppose? >> >> I would have assumed that we would now collapse for any files that >> support large folios (in PMD size), not stopping to collapse entirely. > > My understanding is that collapse_file() is only used for > READ_ONLY_THP_FOR_FS. If FSes with large folio support also use it, > I can replace IS_ENABLE with mapping_large_folio_support(). Otherwise we'd be losing support for THP collapse in files? We'd have to cross fingers that readahead gives us some. So we have to be a bit careful here. We want khugepaged to collapse THPs in filesystems that support large folios even without READ_ONLY_THP_FOR_FS. -- Cheers, David