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 9112DF89256 for ; Tue, 21 Apr 2026 10:58:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F2A0E6B008A; Tue, 21 Apr 2026 06:58:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F01CE6B008C; Tue, 21 Apr 2026 06:58:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E18126B0092; Tue, 21 Apr 2026 06:58:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D1BA66B008A for ; Tue, 21 Apr 2026 06:58:19 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 9A3D3E5D3C for ; Tue, 21 Apr 2026 10:58:19 +0000 (UTC) X-FDA: 84682263918.05.639A848 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf19.hostedemail.com (Postfix) with ESMTP id E15BE1A000E for ; Tue, 21 Apr 2026 10:58:17 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=GfPX7xO7; spf=pass (imf19.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1776769097; 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=zEyZM8/rbDUleahj5R0RBPr/fsqgnIZU7DeBLPbpmwI=; b=Y+ORd6xxXdhaFafvdox+c1fPQYIBGKzD1YNTpTvUUieB0xVKZJ8103Qe1EdE6RqgCOzglI YP4oxHPM5Y4bEQv3+gOA4mNlq23WRapDhFnyKl2XPGYsbEhoSr/u/DWVCZWrDklzanMPeX lL6LqDoLGNUWKRkqIJ+tekrivHz/SX4= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=GfPX7xO7; spf=pass (imf19.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1776769097; a=rsa-sha256; cv=none; b=kW3oklPcTNYcbll1UxzE/sqJEASfvz5u0PkSrdc5p4AEEvnB9Msb1Wceopm+gWQUQrwobU NzPT7NBXf+zLJ6CIng2LUjrz+15BoxSfMvbdfKtKsvBi6efaOcHLMdE8fMSN68YrAhw/WR /GLQsVUxOHa4kQ807EJnsobbcnqf33o= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 3E6A160125; Tue, 21 Apr 2026 10:58:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1815AC2BCB0; Tue, 21 Apr 2026 10:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776769096; bh=t8tGhKLq59XKo8MiSyis/w2Xu/nbZ8LJlkNLeDD7oDc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GfPX7xO7qWEA3W1FaagrkCuVWqO23hvMOk/g5VXvc3tyPCglgVtA2SVovEMpppYO1 jlNzP7iEpJBeMl0CDcK4ofJcqaATpxK037YKBke/Sv37LACFY+KZYnJjsatfUO/WgI 8IdCDbg/RNL5BSkkhpmqwFKf3TU8UuYSXiICT0AwHy0H9xYorZctt0/kruvi0DbFjv 3Hn/IpIz1463zxI/Gm2gffBNZa18PvqdMZ1Ey5AtjQeTp9wAI2d9cfIo+OqCTuZJ5A CbOwayf52P5Kc6tGuN5OzyiHF1/9mTITm7P21YNJy7dYgRgn0YjOkFg9+zXYIjUQcH MSGcwB3DC1LSQ== Message-ID: Date: Tue, 21 Apr 2026 12:58:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 11/18] mm: skip zeroing in vma_alloc_zeroed_movable_folio for pre-zeroed pages To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport References: <39c3c8e647fc4c8e3dcb5c9d12f2e29b5404e8f2.1776689093.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: <39c3c8e647fc4c8e3dcb5c9d12f2e29b5404e8f2.1776689093.git.mst@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: tkojpxzg7ugww1pwb7r5yna7zxokgdo3 X-Rspamd-Queue-Id: E15BE1A000E X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1776769097-670370 X-HE-Meta: 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 +/CuAUZt hMYLj9xIPJpzqSSUm0SoIbZ2ibfp/ustLMjewWhGkGglKcNiC+KAcWlrKQtIJ0g8c/7JwIigGwR1xMomLj7SjEkJKd3CBGjjdJ36QraZrWeUKsrfFFreqOpsn3A3qgZzT1j1nX2d8mmNb+S5XGe4MSt98CVtSCk58N5opeecflFRG+aOs4Q/KzZAOVjN2GbG4kT4yGaHf8ZLMw85bPT24KGy8Ihz5+fM14szwY+xFI/Ka2iceXfrfmGSlO2gNZecAFiq7n3WEcAqjU+4eDYmopim+bJnwDjWYaExYxF5AAoM5Ptnm/AFNCTZvQq84y9VI1EWnsbw0kqkU3BrIhz8Lj3x5Ao7o57Qe4j3ZBdV7Qr4zwL8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/20/26 14:50, Michael S. Tsirkin wrote: > Use vma_alloc_folio_hints() and check PGHINT_ZEROED to skip > clear_user_highpage() when the page is already zeroed. > > On x86, vma_alloc_zeroed_movable_folio is overridden by a macro > that uses __GFP_ZERO directly, so this change has no effect there. > > Signed-off-by: Michael S. Tsirkin > Assisted-by: Claude:claude-opus-4-6 > Assisted-by: cursor-agent:GPT-5.4-xhigh > --- > include/linux/highmem.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index af03db851a1d..8bb67772c1cb 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -321,9 +321,11 @@ struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, > unsigned long vaddr) > { > struct folio *folio; > + pghint_t hints; > > - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); > - if (folio && user_alloc_needs_zeroing()) > + folio = vma_alloc_folio_hints(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr, > + &hints); > + if (folio && user_alloc_needs_zeroing() && !(hints & PGHINT_ZEROED)) > clear_user_highpage(&folio->page, vaddr); > > return folio; For others reading along, the variant on your other branch: diff --git a/include/linux/highmem.h b/include/linux/highmem.h index af03db851a1d9..ffa683f64f1d1 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -320,13 +320,8 @@ static inline struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, unsigned long vaddr) { - struct folio *folio; - - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); - if (folio && user_alloc_needs_zeroing()) - clear_user_highpage(&folio->page, vaddr); - - return folio; + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, + 0, vma, vaddr); } #endif Looks like an extremely clean interface. -- Cheers, David