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 266B5FED3E6 for ; Fri, 24 Apr 2026 18:51:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 914B66B008C; Fri, 24 Apr 2026 14:51:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8EA5A6B0092; Fri, 24 Apr 2026 14:51:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8004B6B0093; Fri, 24 Apr 2026 14:51:41 -0400 (EDT) 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 6F0886B008C for ; Fri, 24 Apr 2026 14:51:41 -0400 (EDT) Received: from smtpin05.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 106068A43A for ; Fri, 24 Apr 2026 18:51:41 +0000 (UTC) X-FDA: 84694343202.05.1649295 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf04.hostedemail.com (Postfix) with ESMTP id 22D274000B for ; Fri, 24 Apr 2026 18:51:38 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="I73QB/Yo"; spf=pass (imf04.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=1777056699; 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=1MORKsTImeIr4TjVhGEtdBn2NHX8NEyxGoKMvYtvEHs=; b=zFuWEw659/4DAcf+JN2gPUTmYfOONFU6fzOmE/PxP2gs0Zpr9HgMwhaLHPvYuSVLqHXj1S ljrmH0XrSdaNxvab/pQW8bS41l1ennijM1j7hu07Cg5yfn1l1xZNA0A33FDGqJPxntGvAH SqlUbjDRMoZmv12d0yl79VHSg52dgaA= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="I73QB/Yo"; spf=pass (imf04.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; s=arc-20220608; d=hostedemail.com; t=1777056699; a=rsa-sha256; cv=none; b=Qphu0+ChMeK7pL1WD+sKdpNYk1ZBcaNZrdrJ31yz38LL5xRSoA6UQ9sUF0Y+xKZFbiMYFq X0dMxeX9Ct/I9XXlgjDhWS1NCw0Delz/0KAQ9ee2CjvxBfNedde4i2V7gnbGj0mAfUt3pS Yq3npNIwFeU3M9uwpm+iZ/S+0qUVfsQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id EAC4E41B6B; Fri, 24 Apr 2026 18:51:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07EC2C19425; Fri, 24 Apr 2026 18:51:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777056697; bh=+gfjjzK2HjGlwyfcUBpjGFMM8VknhFJmUXv7rsRO1Tw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=I73QB/YoKiHDxTJYDQAZJJqd6DpiWso0Fv34A29QLEdUDh4e/9DIMBxEx6bjkHaME eSOcJ/kr8JheEFprhBsRAIYwP8ui81DS4Ec2MhWcAb3LTduz/Mw0tHH74Ypekkq31f tWzmRP1hbVGBek3ZImYupzEnyAgFtJkj8scXdz6NeXJZg3Emc4SM0scKvVwyE5Yvn8 q6eVKd8YZlneyt/S+2klo8xFuk/s+iumOQMZw7M0YDjTBpq/xwQiLotDxKofUq2cRB aBUac+XxaFCMgRvSsJ+dlJnmUsVyLaWjS4/TIqP4CQ5v7roQrj8+LPbMHANxYsjaaB wpq3Yb5wx3O0g== Message-ID: Date: Fri, 24 Apr 2026 20:51:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v3 01/19] mm: thread user_addr through page allocator for cache-friendly zeroing To: Matthew Wilcox , "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , Gregory Price , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Muchun Song , Oscar Salvador , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Hugh Dickins , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , linux-fsdevel@vger.kernel.org References: <9dd9deabd42801f3c344326991d1431c3d8db39d.1776808210.git.mst@redhat.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 22D274000B X-Stat-Signature: cw9ah5cwjzgq8cfsx9519g6tftkdw8ex X-HE-Tag: 1777056698-438829 X-HE-Meta: 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 oRafPir4 apNswa0xaLrz5KnZ16qWv86K100sQRgZQ+DmkfnvPxg78L4SYfm7oRZvAeyw9ByTslBbcieZ5dG1lFgF9AiH4y5ckBmRUHfkbNsy+90U1stzQ+8o6iXE9daF0c+TMqxzDORRWfFulyENGbZdeSwnlXTR1mPyySddEA7x9UpDT0xHUpD9ba7JYe9CjXLR1LtMaYvC0kUWfkLX6pndCMcDnKGtwI/LxDoM/P5MWhD0Hf8jsf+JWQL7Af8eUmBqSQyoYpyB3HzQGZ1HYkshmOwjzjIIyTDcwkVMkccwwuNfTSXdSA7p+gP176uI2qcNhCWzUzluVhI7XOyBNqxxhYHZEff0d6EsZ1lq+K76b2qxYUDagkter2BfKBc7CR8K3mz97TRT8 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/24/26 20:41, Matthew Wilcox wrote: > On Tue, Apr 21, 2026 at 06:01:10PM -0400, Michael S. Tsirkin wrote: >> Thread a user virtual address from vma_alloc_folio() down through >> the page allocator to post_alloc_hook(). This is plumbing preparation >> for a subsequent patch that will use user_addr to call folio_zero_user() >> for cache-friendly zeroing of user pages. >> >> The user_addr is stored in struct alloc_context and flows through: >> vma_alloc_folio -> folio_alloc_mpol -> __alloc_pages_mpol -> >> __alloc_frozen_pages -> get_page_from_freelist -> prep_new_page -> >> post_alloc_hook > > I don't like this. I think we should instead lift the zeroing from > post_alloc_hook() to the callers of __alloc_frozen_pages(). I don't think so. In particular how zeroing optimizations are related to buddy details (tag zeroing, kasan unpoisoning, init_on_alloc/init_on_free, now pre-zeroing). > > I don't understand why you want to remove the double-zeroing of memory > when the user has asked for zero_on_alloc. They asked for stupid things, > let them bear the cost. That's not how the world works :) -- Cheers, David