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 F25BCC79F99 for ; Tue, 8 Sep 2026 16:56:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CBFCC6B008A; Tue, 8 Sep 2026 12:56:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C495E6B008C; Tue, 8 Sep 2026 12:56:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE94E6B0092; Tue, 8 Sep 2026 12:56:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 7D1E86B008A for ; Tue, 8 Sep 2026 12:56:57 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 12341140671 for ; Tue, 8 Sep 2026 16:56:57 +0000 (UTC) X-FDA: 85191199674.08.D952395 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf11.hostedemail.com (Postfix) with ESMTP id 453194000A for ; Tue, 8 Sep 2026 16:56:55 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=oaCiuBJH; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788886615; 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=7HFhd4KDSfD7wKAluuKwUfaCYQwrDIt/d+mkB/YfLSk=; b=tbZYc+gdfx2WlvDF8sl4DQE2ppTba7ApVpe0ugvv/doKfXqeQ1tEtwBc+t5Ho2LYGJ1nGn kVXwNVPzfwaHLx5EVa2UzgbfFLMm0iZ4mzJot1u9lwv7Hb0AGLvFhU02c5NaadrNWG3DNV DGbmI29p5RNBvnKL7GSHhN+2iAH7Q+w= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788886615; b=R8RWU2GkgO1HeJKtDr8G/+TjkJ94Np7qpt/b7jB/IUVSNxvZhylXYFmPpTmn/E9kHy3GS6 oRya52uEMfeq/BtD2jMP6HayoLi3FSgj4dAE+IHzS1BOZ26mt1jlD1C+7hpSvT8KMu62L+ z/oUufvL8s2zRbDrnPFSCP4+UTJEQW4= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=oaCiuBJH; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 58A4843CE3; Tue, 8 Sep 2026 16:56:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E39A1F00A3D; Tue, 8 Sep 2026 16:56:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788886614; bh=7HFhd4KDSfD7wKAluuKwUfaCYQwrDIt/d+mkB/YfLSk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=oaCiuBJHcKgdnJXHuF42Gzn0lhaqMVP/UkFfIBAUqBxb807yLavtvcGoPz6cRuN6G Gz9iTzi01MNzkULWuYzsM222rtvW8VlUZsqcufeVph6urpPk1fq7jq+DD1dw4nk/7o z5o9hGwvA0pLqg0VTxIpay5TpKTE2KrpHOap8FxcJCTa/boF8eOrk3WXzh2hSkhBvd mwvUhIhsgTgjsSXbJWaZcRSbTgrCrB/nPCczcKQokivuwdrYgXoEJj6JidRCMzOuNE C0XjaiTLaVLDiOD6roe2m8oNg3/4w7dtuyMQ2SjWxQoBAZRvpcNzsLJOKeXMuzgb3U N+I5lEnfyJ+xQ== Message-ID: <9395aac2-af01-42cf-92ea-4e3d5e7eec6d@kernel.org> Date: Tue, 8 Sep 2026 18:56:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 09/14] mm/page-flags: check page/folio->private instead of PG_private To: Zi Yan , "Matthew Wilcox (Oracle)" , Andrew Morton , Muchun Song , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Gregory Price , Ying Huang , Alistair Popple , Johannes Weiner , Qi Zheng , Shakeel Butt , Kairui Song Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Steven Rostedt , Masami Hiramatsu , Jan Kara , Mathieu Desnoyers , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Axel Rasmussen , Yuanchu Xie , Wei Xu , linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20260907-remove-pg_private-v3-0-6ae22f9d9272@nvidia.com> <20260907-remove-pg_private-v3-9-6ae22f9d9272@nvidia.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: <20260907-remove-pg_private-v3-9-6ae22f9d9272@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 1duzs94weugnejfwfz9nj6stkqtd7cyg X-Rspam-User: X-Rspamd-Queue-Id: 453194000A X-Rspamd-Server: rspam03 X-HE-Tag: 1788886615-52188 X-HE-Meta: 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 xhZxnqEY 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 cHlwS69n 8jCg2A/kuQw0bq1+ktwc9CgA+o9FZbRs+gFDvp7ADNmHi0gGPcl6V/mAgTJ224NClnmM1Tx/d42gjSBAGt4HvvsQ4rFtYYaHWTzutQ8bRc2VB35oyISK3zCveZLcnawEw5Ut/kROcsZooGtPrrwMGwBEYBqBnEHv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/8/26 04:56, Zi Yan wrote: > After the changes of the prior commits, page/folio->private != NULL is now > equivalent to checking PG_private. > > Stop checking PG_private on pages and folios and use page/folio->private > instead, except swapcache and hugetlb folios, because the former uses a > field (swp_entry_t swap) overlapping with ->private and the latter sets its > flags in ->private. Exclude swapcache and hugetlb when the code is meant to > check PG_private only. PG_swapcache and folio->swap.val cannot be set/clear > as a whole, so excluding swapcache with folio_test_swapcache() is not > reliable. Instead, use folio_test_swapbacked(), since PG_swapbacked is > stable when a folio is added to/removed from swapcache. > > folio_expected_ref_count() can be called without folio lock, so annotate > folio_test_private() with data_race() to avoid triggering race condition > checks. While at it, annotate folio->mapping too. Add data_race() > annotation for other lockless callers too. > > folio_set/clear_private() and Set/ClearPagePrivate() become no-ops. > PG_private is no longer checked at page free time. > > Remove KPF_PRIVATE since PG_private is no longer used. > > Assisted-by: Claude:claude-opus-4-8 > Assisted-by: Codex:gpt-5 > Signed-off-by: Zi Yan > To: Andrew Morton > To: David Hildenbrand > To: Steven Rostedt > To: Masami Hiramatsu > To: Lorenzo Stoakes > To: "Matthew Wilcox (Oracle)" > To: Jan Kara > To: Johannes Weiner > Cc: "Liam R. Howlett" > Cc: Vlastimil Babka > Cc: Mike Rapoport > Cc: Suren Baghdasaryan > Cc: Michal Hocko > Cc: Mathieu Desnoyers > Cc: Zi Yan > Cc: Baolin Wang > Cc: Nico Pache > Cc: Ryan Roberts > Cc: Dev Jain > Cc: Barry Song > Cc: Lance Yang > Cc: Usama Arif > Cc: Matthew Brost > Cc: Joshua Hahn > Cc: Rakie Kim > Cc: Byungchul Park > Cc: Gregory Price > Cc: Ying Huang > Cc: Alistair Popple > Cc: Qi Zheng > Cc: Shakeel Butt > Cc: Kairui Song > Cc: Axel Rasmussen > Cc: Yuanchu Xie > Cc: Wei Xu > Cc: linux-kernel@vger.kernel.org > Cc: linux-fsdevel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-trace-kernel@vger.kernel.org > --- [...] > /* !PageAnon && !swapper_space */ > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 40d3f1b48a74c..9348ebf9de882 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -978,7 +978,8 @@ static void folio_check_dirty_writeback(struct folio *folio, > *writeback = folio_test_writeback(folio); > > /* Verify dirty/writeback state if the filesystem supports it */ > - if (!folio_test_private(folio)) > + if (!(folio_test_private(folio) && !folio_test_swapbacked(folio) && > + !folio_test_hugetlb(folio))) Now that I read that check ... a fourth time? a fifth? I stopped counting :) Should we have a (in light of folio_attach_private()): static inline bool folio_has_attached_private(const struct folio *folio) { /* Careful, we might get called on unlocked folios. */ if (!data_race(folio->private)) return false; /* On some folios ->private is used for different purposes. */ return !folio_test_swapbacked(folio) && !folio_test_hugetlb(folio); } Of course, adding some nice documentation what having attached private means? -- Cheers, David