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 B91D9C9830E for ; Thu, 24 Sep 2026 18:52:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BBECB6B00A7; Thu, 24 Sep 2026 14:52:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B966D6B00A9; Thu, 24 Sep 2026 14:52:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A85516B00AA; Thu, 24 Sep 2026 14:52:01 -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 880AE6B00A7 for ; Thu, 24 Sep 2026 14:52:01 -0400 (EDT) Received: from smtpin20.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 2F65A1C2D68 for ; Thu, 24 Sep 2026 18:52:01 +0000 (UTC) X-FDA: 85249550442.20.04987BD Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf14.hostedemail.com (Postfix) with ESMTP id 5DEC7100003 for ; Thu, 24 Sep 2026 18:51:59 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gWev+vg3; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.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=1790275919; 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=POlX+wONx1gCTE6Vq8TjSNhvRxCbSmUHbAHjJxxduJA=; b=gb4ZI2mEoD7c5hEGYdxtuO9DILVTbtGBAJEzd4UPm4omalelDlltCHib5mA6MgtBelv+ba XAokN9L9Bmtm+dX4oDPGhCTejKFqX77PnfbWXgjDthVA0zN2tpgGWhL680ID/SpNxFsMgx 3pcoA9m7ex+SgRfPgI69xTWSzFEzrow= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gWev+vg3; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790275919; b=UQtdkewyC8b8CrgxGWgJBISTOIbPZccFjJDCV+4q04eWkwFAtgXlTnYE55QcekYkgLIbHA IWrAIqQQ3ghGYfIJqBTUeXkmep1dRy2UuCZEkayTt0kj0vcut7DJ9WtLruUGJPwYFReg0d 5XNzOoLjZy04jsfs/Dim/d8gAgyqnu0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C9E4343D84; Thu, 24 Sep 2026 18:51:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23D9F1F000FF; Thu, 24 Sep 2026 18:51:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790275917; bh=POlX+wONx1gCTE6Vq8TjSNhvRxCbSmUHbAHjJxxduJA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=gWev+vg3aOUbjtwtT3U2+C2VyN7eOtcfSBJs3s8YonBNI/+ZZ7xc1mf6k3ukzx0PH Nb814Zy6qTVPFJpgHeTrhLWHbWJXlGYju1D2NrpmJPctR+FCbAJDal4gVTwnWwW2xI /MFTvB3yrPrnMGBOFMN4O88mm0HjIb4cEaoDuj+UNT4EqcaMrg/MKzFJ8w/H78bLVm fw9oOITb653B8XboMh1yPGGCS3ctD7pEsjXS9288YTGJolEMdjEWCUs65za7t3JhlA tImKWiPpv8xP/PxYxxQlkz6Rpt893lRL4IjOhyugIHB+gp0xVjpO+tnRCf3dnynPqs aEjtLEJvNH9Nw== Message-ID: <16d3f4da-cc35-4d1a-99c2-270fad68728e@kernel.org> Date: Thu, 24 Sep 2026 20:47:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: don't schedule deferred kernel page table freeing while booting To: Dave Hansen , Mikhail Gavrilov , Andrew Morton , Dave Hansen Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Vishal Moola , Ingo Molnar , Lu Baolu , Jason Gunthorpe , Steven Rostedt , x86@kernel.org, linux-mm@kvack.org, regressions@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260924092307.22813-1-mikhail.v.gavrilov@gmail.com> <6a0c2fd9-b2e1-40d2-b7a1-ba93cb3c53a3@intel.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: <6a0c2fd9-b2e1-40d2-b7a1-ba93cb3c53a3@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 5DEC7100003 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: p5uu5qbwhr3ok1zhk7s5pi7etbip8r51 X-HE-Tag: 1790275919-236334 X-HE-Meta: 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 eFRddcKz nXI5Ti/UVGT/iBI2W1Mdf3q954uiqZnPRR4+v4gOoAjlIpexnbyR4B7OYLc05IUUBkZP9w9XNkj5IuXQqU93l9xbFfWiP53s9Y0lJM1izdIE07jmDA1/sgYmK29zphqceUbMLQMNoDAyF4nNVON150OhkuhMYgoQJj3rNWLgzH3A1oDjC+m1eoWDoo52DdIVlzhen2OjLxqNTcVk/SorNoKhPVaRMHzco9e+v9omu17YNVYlaOLPAy5xhHaOteGG/az0klLoNP4/y3v0faGuQA+aFH91hdWNw5FUyugjkX9JB6ppDCD0PB1Yaw0bGFyZRYS2LiVyxwRQoqcNJAj3/FZtZMw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/24/26 19:57, Dave Hansen wrote: > On 9/24/26 02:23, Mikhail Gavrilov wrote: >> Keep putting the table on the list, but don't schedule the work while >> the system is still booting. The next kernel page table freed after >> boot schedules it, and the work then frees the early table too, after >> the same IOMMU flush as any other. If no kernel page table is freed >> after boot, the ones freed during boot stay on the list. > > There seems to be an awful lot of chit chat about how and when the > boot-time tables might get freed. Like: > >> So on this box the early tables wait until the first module is >> loaded, and no separate drain is needed. > Wouldn't a "separate drain" be all of 5 lines of code? > > /* Take care of deferred freeing from boot: */ > static __init int free_boot_kernel_pgtables(void) > { > schedule_work(&kernel_pgtable_work.work); > } > late_initcall(free_boot_kernel_pgtables); > > Then we don't have to reason about it at all. Jup, that's what I hinted at in v1 and what Lorenzo replied to v2 as well. (late_initcall vs. core_initcall) -- Cheers, David