From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D7D72606A331 for ; Thu, 12 Nov 2026 12:32:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=c7b2RtdT Received: by kanga.kvack.org (Postfix) id F32526B05C3; Thu, 12 Nov 2026 07:32:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE1CF6B05DA; Thu, 12 Nov 2026 07:32:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DAAB26B05DB; Thu, 12 Nov 2026 07:32:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AB5326B05C3 for ; Thu, 12 Nov 2026 07:32:20 -0500 (EST) Received: from smtpin22.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 3C0AA160252 for ; Thu, 12 Nov 2026 12:32:20 +0000 (UTC) X-FDA: 85426404840.22.0C66B03 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf03.hostedemail.com (Postfix) with ESMTP id 7223320007 for ; Thu, 12 Nov 2026 12:32:18 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=c7b2RtdT; spf=pass (imf03.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-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794486738; b=cxv7wvJfjxgxSDgz3jfFTV09Pa5bia5Hw/SI2iNdDGM5uDeYiowItfdwjIGvGlf6trITlw LFUtEwjq3Dga/Ay+eG7xMCzEV3rwMOKI5ACqeMj1kojx5MNPVGJFuApiDYg0xuqr68TaLf y3ZRrmaHJQwiVKVaYShKE9N0sS9eLRE= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=c7b2RtdT; spf=pass (imf03.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=1794486738; 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=/0Nn7OA0YlSzxRYVQPnJYHdM+16KC7XB/f6ArytZHYI=; b=NQcQDDkVPfinR0SW05jjKqLoYCpuq49Lk29jz34Ny7Hae0s3JSqcV7HGnqq+mPtyzEoVAb t0Lzx4Dvvs8USfTMjdM9LXD9saE4sNrpF9SP4BA4QySmW5AxADpLpODDrRrHpKWOAZrKDT anVYuIGpIJI71k80bs/G9+tjQIok1gY= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9E57D47038; Thu, 12 Nov 2026 12:32:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 925A91F00A07; Thu, 12 Nov 2026 12:32:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794486737; bh=/0Nn7OA0YlSzxRYVQPnJYHdM+16KC7XB/f6ArytZHYI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=c7b2RtdTLtIz0vkgbAYrym+dG29Wb2E4K0rNtFnrkYrU7U6fWrjEz23dl6OtszE3b SOmtdAoZsy5KeKOC+/VgMAibVVUnSLCsG/PCeEvrEIGROultdLtfMDoMUL3i7GnApO Yn+9d3ZYvpy2IeNC/EQHse0nkLDcQ+M4G2h17s9JOyv9HNtR1VkRgNXvGKZXsxZQt3 DN+pN2kYgktqaiCUbPuFjYjGbtBNIaeKQJEN6JuzuaeH5P+HGpIYYIxJgfMg+XUtDc bA2KtlhkNmPnQwEwbuwByZeYSjJOW7Vm7cpwCJ7Zdr1B0890spWvDOK3UsCv9zQk6v Zk+px+/0oaslg== Message-ID: Date: Thu, 12 Nov 2026 13:32:02 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 01/18] mm: free PG_rcu_free folios only after an RCU grace period To: Kiryl Shutsemau Cc: Linus Torvalds , Andrew Morton , Matthew Wilcox , Vlastimil Babka , Lorenzo Stoakes , Jan Kara , Hugh Dickins , Christian Brauner , Alexander Viro , Harry Yoo , Miklos Szeredi , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kairui Song , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , "Paul E. McKenney" , Pedro Falcato , Luis Chamberlain , Ilya Gladyshev , Jaegeuk Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev, kernel-team@meta.com References: <20261104130118.2507513-1-kas@kernel.org> <20261104130118.2507513-2-kas@kernel.org> <8504e28f-faeb-41e3-842e-0cb74d1a25ad@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-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7223320007 X-Stat-Signature: gcr8rj5dn8798j3chidjrjox6pn7yorw X-Rspam-User: X-HE-Tag: 1794486738-182932 X-HE-Meta: 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 CH8QqMyt 42ZQTf3y5PLmPn7mp/B0iKuNCB0k1HTBSXsTg0N6DSI7WnKk88AfAb0Q2afzSy5vgH2SohwaQgnm12mtXXPuD/iJyYTtvvbjHRQuBEq9Kuy2xO/iDReU8gX2U4+rEUIs/QgvrsBrMbYHUCzBRVPRvIBLtSf1Ruz7b7NFLGVTAwtcfWrpa9XhFHKPf4+KkO5D/OlU8YPj/2Z7ZqDuJDve8pW1/9/hzcq2AcfX7NRuBTlLDfDQbgvyqr2iTNW5hjf4tKSnY9jUHwyAReBFJ39u44y+beftXOQQnXCoIZOQ3SSYLLjb09Bjr7/GT8hgDj+goAGHU27TQSrIuW1wu/nNCXdUhSmREoFcwzYWe6OMmwbjFO0D7LZMoiCcPH76GswjD1iwY Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/12/26 13:26, Kiryl Shutsemau wrote: > On Wed, Nov 11, 2026 at 11:03:38AM +0100, David Hildenbrand (Arm) wrote: >> So I might be completely off, but what I imagine is that the memdescs will get >> RCU-freed (these are not pages), and once they are then getting freed, they will >> probably take the physical page with them. >> >> And freeing memdescs through RCU will likely be memdesc specific. >> >> I really don't know, Willy might know more about these plans. > > Right: once the folio is allocated separately, the lockless read > dereferences it too, so it has to wait for the grace period along with > its pages. The per-CPU batching and the waits in the allocator later > in the series do not depend on where the check sits. > > Until then the folio is the struct page, and __free_pages_prepare() is > the one place every page cache folio passes, so v3 keeps the check > there. If we go that way, don't make it effectively folio-centric in the implementation. That's what triggered my response in the first place. -- Cheers, David