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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55119E7716F for ; Wed, 4 Dec 2024 21:21:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C67976B0082; Wed, 4 Dec 2024 16:21:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BF0DA6B0083; Wed, 4 Dec 2024 16:21:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A1C3F6B0085; Wed, 4 Dec 2024 16:21:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7BC3D6B0082 for ; Wed, 4 Dec 2024 16:21:19 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 2FA231A11F8 for ; Wed, 4 Dec 2024 21:21:19 +0000 (UTC) X-FDA: 82858547310.02.91615D7 Received: from NAM04-MW2-obe.outbound.protection.outlook.com (mail-mw2nam04on2049.outbound.protection.outlook.com [40.107.101.49]) by imf02.hostedemail.com (Postfix) with ESMTP id 0E0F280017 for ; Wed, 4 Dec 2024 21:20:47 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=XzzER9Q9; spf=pass (imf02.hostedemail.com: domain of ziy@nvidia.com designates 40.107.101.49 as permitted sender) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1733347269; 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=WsYuWKLSKFONDOYYcVUa3mmUdxnlFRmrkln8M14C7BA=; b=cEe/DjWBww46l5b8VmuptSLKEn0D8JoEgZhYp+yym3oE2vTEzeSOIgXBDvPrDUxA3b4odR oCohgouRbFxGghv0+wQKU34T0TaUQtnilkiO/oZ5kIrilkqslRvfEmKQNF1G8PPZ9LQcBA AON7WqTov0kH5m5MyM/sxDwHdpvLVpY= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1733347269; a=rsa-sha256; cv=pass; b=3S8lw7Ukt+MyJGmtcSp29pdY+7MznOasij3MBodf1ydEkfbKdHqqR4dDL6YxOgkvpdpTHS SETaNl6UOpGm1FnAt6sv4rdbimVAbGETWZwrJrNxjH7eAbmjiVq/hX8zYR9LHmdBiGX3To o/WzxYgJljkpPhAlersP7L5p3Dx5IvA= ARC-Authentication-Results: i=2; imf02.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=XzzER9Q9; spf=pass (imf02.hostedemail.com: domain of ziy@nvidia.com designates 40.107.101.49 as permitted sender) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Dcu6NIvKaeMrY3VJdQjY+GXfffi0Nw8M/feCBIQBprJc1jtC3+ceRzgMtTXFAdMQU+xjKEAlaNrLWihGsibWsASvyJEIt08jdTcLoWGFtZkfxcfd4hhAUEbXfQsVugHR+go5swCUipKV8Vx9aZYrGwCy6bgb7kJ6K08iHdYWivhtxYCg32h4yYZgpEO857ifbkfTHm3M9+W2FMjG8zaV+LJloQqXzh+23/4sIOBIdv1Q61lWBXVy8gRi2B6ascdvUhhzJmqfn2JEvPV90VmEwXRL6rujXXKwVjDdev6KeDznvoEPuqqh/RXb7xaI7TJi0PZd0IlnuIcO1XUmu1RNCg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=WsYuWKLSKFONDOYYcVUa3mmUdxnlFRmrkln8M14C7BA=; b=ARe9llk/E63Z3wOM/2Ppu+T+c/QLiOJUvzK3uM4h2r7iySguda/yQ1Pp1EE84TonlBzQWvhVjXuUszS8Orsk+5umxwjMnWV/nUb+REqrzmrHjqzI0P8hAXgpe7BNVtA1Uaqqu33EiPHNEmFzRcxc8PMRbRo1z+5Cd6mVTLfzwU48i4jP9b3Z8J/niSaS3VvQObOpeFWDQfF1WUGMLHcR+44z2Lr9l7hAVoMgp8dGFDukoR9OFJjB3miqPjK1VYEzPajlbOXr7npDgPqgg6K97sTXtsfuwHWfBx0vdJLUs0zseXrMd87G0TucuiT5Tz/H3Dbdpcs3AWSZaZj8/K/Klg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=WsYuWKLSKFONDOYYcVUa3mmUdxnlFRmrkln8M14C7BA=; b=XzzER9Q9Vdf9M+76HORyBV02MF3UN5UjKXGWVaXftLhweRP9Ioy5Yb23iWw8mk52Gc1bGeIaDAQe/nSU2EvzBFcqwW+q2YBZO3QaYU1GwYlTtCOi8TMszMktUWbUn2WDAfSXK/kRv/Ug1I6YxuDZP+wT27WHeSPu25Kna1tR6LZW4D3lD7MblGCpUre3VnRly2z/aw+HXSFIGW4rXNTq61RkDE1HD2Te9LTQyQFfULMwhKWnPUEc7UxDG9s7cdspITsSUF/oyoYPmB/6LpWOwMAXiiZVKA1Fo3/bVsgg4v8vSbHFC8mPLTsF5witvvTb/2lJIXaewmuRHw3BElSxhQ== Received: from DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) by BL3PR12MB6452.namprd12.prod.outlook.com (2603:10b6:208:3bb::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8207.18; Wed, 4 Dec 2024 21:21:11 +0000 Received: from DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a]) by DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a%7]) with mapi id 15.20.8207.017; Wed, 4 Dec 2024 21:21:11 +0000 From: Zi Yan To: Vlastimil Babka , Kees Cook , Alexander Potapenko Cc: Matthew Wilcox , Geert Uytterhoeven , linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Miaohe Lin , Kefeng Wang , John Hubbard , "Huang, Ying" , Ryan Roberts , linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org Subject: Re: [PATCH] mm: avoid zeroing user movable page twice with init_on_alloc=1 Date: Wed, 04 Dec 2024 16:21:08 -0500 X-Mailer: MailMate (1.14r6065) Message-ID: In-Reply-To: <2D6F1B31-A261-4983-B0AA-D45C07E21CFB@nvidia.com> References: <20241011150304.709590-1-ziy@nvidia.com> <9942C08D-C188-461C-B731-F08DE294CD2B@nvidia.com> <09B2AB6A-B122-4287-B97E-F800E511097E@nvidia.com> <2390F919-D502-4428-B8CE-5154D30112C4@nvidia.com> <2D6F1B31-A261-4983-B0AA-D45C07E21CFB@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BL1PR13CA0315.namprd13.prod.outlook.com (2603:10b6:208:2c1::20) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|BL3PR12MB6452:EE_ X-MS-Office365-Filtering-Correlation-Id: 0c47519e-733c-4de8-0d9b-08dd14a99366 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?UkpXRG02N0ZUUWhZQnhjOUxEeG9QRUE4R2M2NnNOYU9SWmZkL3IzNGNZTFhU?= =?utf-8?B?MjlISWgxOWJ5RzdTZG1ycTdweE1CcHM2M3lVZDNrRmM1dkNQNkIyWlFuVERO?= =?utf-8?B?MHFuSUpXdkYzV1FObXF6NVdyNlFrdlQ1bG9IdDU0L3pnSGhXWCt4czI0U1VI?= =?utf-8?B?UkRWaE45N1g3NW9FZjIwRm1yVXJjWlcyaFdMNlBuOTZtS1hDRTEvU3NNZDFN?= =?utf-8?B?aGRheTBpaTkrdTZFTktuQm5abVpOUS9nTjV0eFdja2dITVRLVktvOVpYMlYv?= =?utf-8?B?aUc0TEdNMWtUTkdRVHFwdG1ieGNwT2hWMW1ON2IyS0FOZFExUzBLOWM3Tncx?= =?utf-8?B?UlVRWjBBaUJUUmNJZzYrNzZuN1IzUUNhQWVXbmhTZlBGQzBCMHViQVRSZEgv?= =?utf-8?B?ZnV6MTZqclFzVFRNVGpWV1BXWlJJODN2QTJ3MzlKTndBMTBYd0VIcFJrQit2?= =?utf-8?B?ZEF5NDZiODd2VlZTWVhOaG9NVGd5WjRpQi9UTXRuc1ArSHpqcE14ejcrWlJj?= =?utf-8?B?Uk5lNWlrNHY1cGxGZ2JLeERGQjhOSEhJMCt3RVlsT3h5eE1oV3dub0hKTlRl?= =?utf-8?B?M3JFMldKMzI4dk0vSHM2N050anJnaVo2L3NEOStvRW1lZEhOVjhQQSthc2lM?= =?utf-8?B?U3Z6RENaenBGQnorZ283ODNNcnd3alZuNVhBZGwxTmh3WmpSeC9LYit4M1lW?= =?utf-8?B?djNoK1dnVnY3Zkh6MXNXemQxa3FiNFQ4MjFobnJBVlk3RkxiSDdpODdCYnVh?= =?utf-8?B?V1NWTWFjaFY2NGRXZ1JsQlhrc2lDc2FoOGJvVVpVbytZeXZpaGJ6NFdvK3VW?= =?utf-8?B?YnFWWTkzTC95V1VubHpzb2UxWFVMZE9OTnVPWjUvRGxuWEdvWWVsQW1VQzRw?= =?utf-8?B?V3Z6RXA3OGZOSnkxSlNzZ29mY0ZaMjVubmFERnYvL2dWWDN0MkFiZWhudEw1?= =?utf-8?B?dUQ0SnBHY1Y1Z0p4QTBIQnRLVFdCbkN6dVNlS285K1hJbW5vTUp4NUhUK2ts?= =?utf-8?B?OS9CSnNoc1U1ZWh3Sm1BWjlSOWNFRk9oN0NwNjF3NkRIaEFvVUpIYU9uRFJo?= =?utf-8?B?MGRiTXNYRSs1VzNPREFHL3p1ZzZrTXZDRkM4QUJidVhlTnpwa0xOcEhwRWVC?= =?utf-8?B?MHJ1TVRDTFNIK1N1VWVkUnBsdFVaU21mMWNZSnEyWHN0eUh5akl2OFRoMDRO?= =?utf-8?B?bmQ5QTA4bFNuc3JGMDhKWmZ1eDlJeld3RUxJZDYzU01NWGZwOXBRbHg1eHVS?= =?utf-8?B?dUdzNnpEZ2hLaUFZSE9YMFk4UlppZ0MrK0JQNUxWbEJpdDEwdWw5aDVZeU9j?= =?utf-8?B?aSt5N2JTV2VrVXUyeGNCN0NINjFKdk5BcVgvSGt0TzRyejltVVFXSXZ4Y2dK?= =?utf-8?B?SHBYQ0s2M0dXVytadmdSK0lmWjdjU2xWNllaS01yRnNVKzY4SVRDRFoxaUdM?= =?utf-8?B?TFp3YVBUV2N6bm5kU05vVWIvODRXWEMwRnFpdGVMdVBxV2NIUW9mTlA4Yzdn?= =?utf-8?B?NnI3RlpsZ0dONG9URkc4bzBteWlESk5Pd0pFL01PRDM3M0lJN2hiaDdlRnFX?= =?utf-8?B?ZS9leFhkVDBBc1ltd2lzcDVYSWNobVF3NFlzeU13dGQyandRUXZtTFZKdlps?= =?utf-8?B?WDcrTjYyNXhmME5XaVF3WXl0U2cyUzFKNmdUck41UFRKamRaeVVPYkcxL2xk?= =?utf-8?B?WnlnZTRUN0lDWlFWa1BRaXplbjBUNHM0ck0xeFM4WURkVmhlRHo0NFdoNGFV?= =?utf-8?B?MHRxdWhUVnFnNlBJVkRrZ1hqVWsxcG1zdWhtbC9oWjdvT0NtVHl2dHNLa2pr?= =?utf-8?B?SEhVbXptdjhoa0IvQmZ3dz09?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR12MB9473.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(376014)(366016)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?S2hNYzBwZlVtRjlsYkgzNFdOOUFnNTVhVldwckpzUDN6ekJPbXI1RURHLzVL?= =?utf-8?B?S0I3blFzbzdJSWl3RGNzckNhQ1JMa3JvVFJKTDZGNDRURmpvZE8wdWRMeVhS?= =?utf-8?B?MGNpdkJJR2ZsUkNGQmxBN1ZQNndDc0pRYjRmc3I2ZWtLY0dONVMyVGhxWUE0?= =?utf-8?B?bmVNYlhEdXRHa3dNa053QzhkdmZLSlFGZ2Y5NkdVcWhXR1ZjdHlKZDQ4UzF3?= =?utf-8?B?VHcvNEpFWVZNRG9La1JhSlRNSUJhQ2FjeVV3bEpYZjZKZmVQRnNLNFRMTFdi?= =?utf-8?B?OWFaejRGcm9HZ0pneFhqV21hU1AzTm5ibVcrQWo1NjZ3OTRadDFsK2VGaEVr?= =?utf-8?B?UkJKL3hvOERKMnRtS1ZPbzR3ZzdKdE9OMzhrYStmQUlZby9pWnZzWjhmNVJj?= =?utf-8?B?QzcwREZFL2JyS3gzOFhyeGsveDNQWWc1R0FCd3hxSlFHWk1zaFlpcmxyMm1O?= =?utf-8?B?dDczeWp1ZHBadnQ4d1hTbEEyc0w0aEVHQ3FuV1MzdFg1VTM1VlNzVjI5Y2Rq?= =?utf-8?B?bXBheXBpNkF0cmg4MjhXZCtHME0yV1ZxVDR5NWNJY3dxOUtmMUNHN3NwUzJn?= =?utf-8?B?eXFOenlkTFQ1V3IrZ0hDc0YxbEwyUWlNdFFyUTlyS0hKbE1KL0Jia0VPSFBV?= =?utf-8?B?RFhVeTBYQ1V2R01jUk80dStLdmhqZ3hLQjhMd3hUU2FXL1hSU3hHbFNacjBv?= =?utf-8?B?UEpjWWRpaFBqbmpNbmtLVGhTc1MveHVrcFBZWFl5bCtReXEveklLbm1Ya0k4?= =?utf-8?B?emhMVks2WENaRGtMZXpJaGF0TURYanZqbjBxbCtMZlJ4VGVGRHpNKzRlekdB?= =?utf-8?B?UWRINTVVVU5jSVdRdk9oWUNRMGVXS0FkVy9DVklVa1BqVloybHpBSFp1cGgv?= =?utf-8?B?c3krRkM3ZVdmZFVLZTN2SUNSeWVnYnZXSzRUVWgyYlRsbGswcHpTczAzZnIx?= =?utf-8?B?Nm5aUFZxajYyU0FGSUJZMGo0NklHUGdsWktFc1BCQTdUb096TEhacjlONzJQ?= =?utf-8?B?OXVJaVU4TkpiOTZJN3BCT0VzenEvOUZncDhvRVkyM0Q0WjJCTHBlanNjUUc0?= =?utf-8?B?ODVlcm11dHM1Y05LNzB4TmhXVThyQ2wzN2QxL3pzUnFjVjR3MDc3NFBrL2J4?= =?utf-8?B?MFMwMUNjeE13b2pQSFNpeVhXL1FuaGhFODZsc3ZUaG1IR0FxeXp1S2YxRmFG?= =?utf-8?B?SGxsR1dSYlVZeXJ2SlZNeDZBVXNROHl3MzdrOVZHK3ZRMW5SZlNxbXpycld1?= =?utf-8?B?R3Y5dXgwRXpmZ2JpWlBtVG9Iak81NEsyb1RJdE5jcU5NUnlhc2ViNTErbnAv?= =?utf-8?B?VUR6SlA1UUZuaWdqYUNDb1lFdm9HdHB3YjJtQUlwRk5CeENvS1hjWUlCeFdC?= =?utf-8?B?cndLcVNqRE1UVS9ZZWdoek13Q1VKdGY5UUFYYWsyeHhWZEFleTBFdndHWi9O?= =?utf-8?B?em91eU02WjY3bE4yYURHOGovUEhsdkdsQldVTkZUNm1hUlh2RXdLMlBocmpz?= =?utf-8?B?TGJwWUZydHg0K2Ewc2NJeGNKKzUySVpwazk2WHhtbUNkemI5MU9lYVVENENh?= =?utf-8?B?UmhtSGlwUFQ5RnZiZWxRalh2YXFkQ0pBNU1ubE52dFJEOUVIbVFqMW1yNkdK?= =?utf-8?B?UDJsSlNlWUh2b0d2R1lLM241QmwzcmordkcxYytLaDRVQ3R0YkJJQW9wNklh?= =?utf-8?B?ZTJiWVFRTWlLdDc4ZUxsWmFWd2liZ1ZPdlJ5WlJkUUpLTlZ3OU1RTEZYUFpX?= =?utf-8?B?REhHakRjcnc4OWFvejIreDhzZDhzRDRxdEtNSlhHTlRjWlJsWUpWMzdwZFcr?= =?utf-8?B?RVFaS2lkcDNuNDZNZ0dWcFRZczJLcG9wR3AwNlZSTHpQdDluK3dsbm1jTDhi?= =?utf-8?B?M3JtSW1pOXdNUDFlZUhqRnFMVFNUOGgwV3N1YVRlbWxmU2JSM1lia3NpNkd0?= =?utf-8?B?YnRiUXlBWFdVdVRwdXV3Myt6M2xFM29zMEl6SnNqK2gwSlpQdUdvMEFQdWNO?= =?utf-8?B?WWtudDRvMW5XMjdNRGtldUxWc2RzeE4wYWJ5UEpST0ppbzRkNGI4U1oxZGlS?= =?utf-8?B?dnU5ejArd2tTVTNtZXZIMG41Uy9OWjFVY0d0WnQ0bVpSNHBLT21YV0E3dE4r?= =?utf-8?Q?uq5bUs8Uylz6KpNhgM1Hk873j?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0c47519e-733c-4de8-0d9b-08dd14a99366 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Dec 2024 21:21:11.3030 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: EG6SWCfRrMxet/rpkYJLlNsoo/xMD8S+a5Wz2QQ6/gDR5ED7BAtli2lz+HgQbiOz X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6452 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0E0F280017 X-Stat-Signature: auptjks1qsqypobpno3muufcymcefafd X-Rspam-User: X-HE-Tag: 1733347247-120022 X-HE-Meta: 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 SV7cRSBA 1LhXrodTa+D1WrJOlUCOMSElLk2Y5/OoBluKpaSwoUqIQ5msqhxUcJgFBJZp98fgXCw98C4w61YGZTP68hmKVfTAhjhMba6BvD3vglSdn7ojIVUrwdWJ2HfYGTKBWqCF1XRLQrhnPTmYaEEBrJWBh3/ANN736I7NBM0rfflHcJP4UP/9oGYehDeIPwQoUe7h8zCfmWOJHJbm/U7vX3WXbjDvXwDm6jmS6WNWK7LGa2Qycfy7ZfzlySvMCeUksdmr9M9O/mvYeB1FZEZfRigTMmN0aJA+QPJL+Hd7J7HFbvUj6lk1TaSn9h/sLyKdONqpkcZPGokFErcoh9eAf6aRixAYfA02kSx0IRSciDTD05tPJOQftQLNMZNgRZoEgOHpDnUFx X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4 Dec 2024, at 13:16, Zi Yan wrote: > On 4 Dec 2024, at 13:13, Zi Yan wrote: > >> On 4 Dec 2024, at 12:46, Vlastimil Babka wrote: >> >>> On 12/4/24 18:33, Zi Yan wrote: >>>> On 4 Dec 2024, at 11:29, Matthew Wilcox wrote: >>>> >>>>> On Wed, Dec 04, 2024 at 11:16:51AM -0500, Zi Yan wrote: >>>>>>> So maybe the clearing done as part of page allocator isn't enough h= ere. >>>>>>> >>>>>> Basically, mips needs to flush data cache if kmap address is aliased= to >>>>> >>>>> People use "aliased" in contronym ways. Do you mean "has a >>>>> non-congruent alias" or "has a congruent alias"? >>>>> >>>>>> userspace address. This means when mips has THP on, the patch below >>>>>> is not enough to fix the issue. >>>>>> >>>>>> In post_alloc_hook(), it does not make sense to pass userspace addre= ss >>>>>> in to determine whether to flush dcache or not. >>>>>> >>>>>> One way to fix it is to add something like arch_userpage_post_alloc(= ) >>>>>> to flush dcache if kmap address is aliased to userspace address. >>>>>> But my questions are that >>>>>> 1) if kmap address will always be the same for two separate kmap_loc= al() calls, >>>>> >>>>> No. It just takes the next address in the stack. >>>> >>>> Hmm, if kmap_local() gives different addresses, wouldn=E2=80=99t init_= on_alloc be >>>> causing issues before my patch? In the page allocator, the page is zer= oed >>>> from one kmap address without flush, then clear_user_highpage() clears >>>> it again with another kmap address with flush. After returning to user= space, >>>> the user application works on the page but when the cache line used by >>>> init_on_alloc is written back (with 0s) at eviction, user data is corr= upted. >>>> Am I missing anything? Or all arch with cache aliasing never enables >>>> init_on_alloc? >>> >>> Maybe the arch also defines some hooks like arch_kmap_local_post_unmap(= ) ? >> >> But this does not solve the possible init_on_alloc issue, since init_on_= alloc >> is done in mm/page_alloc.c without userspace address and has no knowledg= e of >> whether the zeroed page will be used in userspace nor the cache line wil= l >> be the same as the userspace page cache line. If dcache is flushed >> unconditionally for kmap_local, that could degrade performance. >> >>> As for the fix, could it rely on e.g. __HAVE_ARCH_COPY_USER_HIGHPAGE in= stead >>> of CONFIG_MIPS? That affects more arches, I don't know if we broke only= mips >>> or others too. >> >> Yes, this is much better, since this issue affects any arch with cache a= liasing. >> Let me update my fix. Thanks. > > I notice that arm64 has __HAVE_ARCH_COPY_USER_HIGHPAGE defined, so I will > need to look for an alternative. It turns out sh, sparc, arm, xtensa, nios2, m68k, parisc, csky, and powerpc= all have cache flush operations in clear_user_page() compared to clear_pag= e() and arc clears PG_dc_clean bit in addition to clear_page(). So __GFP_ZERO cannot simply replace clear_user_page()/clear_user_highpage()= . I can add ARCH_REQUIRE_CLEAR_USER_PAGE for these arch and use it to decide whether clear_user_page()/clear_user_highpage() needs to be used regardless= of the presence of init_on_alloc. I also wonder if INIT_ON_ALLOC_DEFAULT_ON works on these arch or not. Best Regards, Yan, Zi