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 5C733606A31A for ; Wed, 28 Oct 2026 20:58:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WpZXmrJh Received: by kanga.kvack.org (Postfix) id 7A3046B05B4; Wed, 28 Oct 2026 16:58:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 72CB86B05B5; Wed, 28 Oct 2026 16:58:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F54F6B05B6; Wed, 28 Oct 2026 16:58:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 335EC6B05B4 for ; Wed, 28 Oct 2026 16:58:17 -0400 (EDT) Received: from smtpin25.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B347712019D for ; Wed, 28 Oct 2026 20:58:16 +0000 (UTC) X-FDA: 85373247792.25.E9A711B Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf05.hostedemail.com (Postfix) with ESMTP id 07A19100009 for ; Wed, 28 Oct 2026 20:58:14 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=WpZXmrJh; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf05.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1793221095; 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=OkkxJXamG/EOg1fXbdxdVy//NPlViTUZPyzdPBS0XNI=; b=RIRwEaSlYk9Q799gn1PgJA7daffRDkbq9Xwufn5yJ4ZLzDGiSo7XEwFJi98XAvs0PmX6tX uCw2OuzCTV6GX6EgZnnxIsoEI1J2INcybiUAguoe6J8YI9UD00bfbkTRB+OC/LMkro62nG BIn/9SdVg0toUkLEYeNh6YDCqAqqnwA= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=WpZXmrJh; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf05.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793221095; b=ngq+RKlLIIR6LtmTSEnfCuDSfMvk84rNvTBP9Uf46+NpY/MUcDhT8NweeWll5xs2Dta8Fb ossq87/Q6wartWM2FIW5zZYm3yrtgmd06BllpOOgZ1NsUdjw6xyWRXOC0EIEGi4bdxLavg 3tXJbsUmstoxWRyJ8aFjjOcro02Gg/Q= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 6BF55601FE; Wed, 28 Oct 2026 20:58:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 385F51F031E1; Wed, 28 Oct 2026 20:57:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793221094; bh=OkkxJXamG/EOg1fXbdxdVy//NPlViTUZPyzdPBS0XNI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=WpZXmrJhfZ4oFqEjPk/JBXWd575607dk5zGyo1rvpwVg3yy5YfXeNqH5w4vNIuQ0d ktOBD8dQNFzWnH3XPl6qzKMN2hP2/vyEl+46oFkRGa6BZf7drUChBa82kCuH/c0DUS 4CdKqDnR8j5WZaqwqSM2nFlx0ftJBuLWGr4Lbh/2VrlOFq7ZhO68etuPzFcaxVfO9F ZsFMFRIJFcw/2vEWbBe/tqJrUBZIpK95m9X3L3KY24CdVU5OCiwKZO7X6MQczUDuDg AGEl/ld/sByznq2EWDJP+O/uKfdSVS5eGuApV6Jdg6Ibbm/bAgkmLKnbgUaCwCgLH9 zwTicYTUGAKpQ== Message-ID: Date: Wed, 28 Oct 2026 21:57:56 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 20/46] mm/gup: fix clearing folios in memfd_pin_folios() To: Pratyush Yadav Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Chris Mason , stable@vger.kernel.org References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-20-6f74bec9a5bb@kernel.org> <2vxzbj8fp4sn.fsf@kernel.org> <2vxzld7injcv.fsf@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: <2vxzld7injcv.fsf@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 07A19100009 X-Stat-Signature: xqftjunk4qdqqdckq6nq4zf6qq43aor6 X-Rspamd-Server: rspam04 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-Rspam-User: X-HE-Tag: 1793221094-264581 X-HE-Meta: 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 a50/2KOC QWhfkx6jFQS6FUR77G7ZWYhJE6pgf59doh5wkfGUT93LA4DANZMFMviz/D7LZefwaFzWqyZrmrYxfqrk4uWGAkQ1XmiShbwcD3qXHkq8zEh7nVmxhj6uvuMH0WErIlR6n6H68q3wh8W+DqFoSmmgNYRjK9GTjfOgrNc+RE/jxKDw2EqbLaEtXXW9GiZPgOh707rtN2hDZEgAA4UlKSv3fsJQM3KEs22rS07uOAbYCXTfGVEkCmDyYQU/Xlt+k7kM9r3SkecMLyRhPyjnxNYAufRqYHFAua8XzC1MwovokfSSFSplziHFgpRSGlWC/FYps5AEvWlSZZlto+joIDrMzv1eIAZbhbD9WwGBHnBq9MySHnh95P2E9d2AueWUXNIC4z9zs 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 10/28/26 12:40, Pratyush Yadav wrote: > On Tue, Oct 27 2026, David Hildenbrand (Arm) wrote: > >> On 10/27/26 16:00, Pratyush Yadav wrote: >>> >>> >>> Nit: this logic is repeated in a couple places in shmem.c and in >>> memfd_luo.c. Perhaps it deserves a helper? >>> >>> Anyway, sounds like an important fix so don't make my nitpick stop you >>> from landing this if you don't want to bother. >> >> Thanks! yeah, I had the same thought when trying to improve this. We should have >> an easier way to just not hand out unzeroed folios outside of shmem core >> functions in the first place ... > > Normally this should use shmem_read_folio() to get all the folios, which > does zero the folios before handing them out. I guess memfd_pin_folios() > uses filemap_get_folios_contig() for performance reasons. That is my recollection from back then, yes. > It does the > lookup under RCU and doesn't need to take the folio lock. Perhaps we > need a shmem_get_folios_contig()? That sounds like a reasonable cleanup I think, without looking into some of the nasty details. :) -- Cheers, David