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 46AEFC25B08 for ; Thu, 18 Aug 2022 01:15:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BCA976B0073; Wed, 17 Aug 2022 21:14:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B53288D0005; Wed, 17 Aug 2022 21:14:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 980098D0003; Wed, 17 Aug 2022 21:14:59 -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 81DCC6B0073 for ; Wed, 17 Aug 2022 21:14:59 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 582531A18C2 for ; Thu, 18 Aug 2022 01:14:59 +0000 (UTC) X-FDA: 79810944318.03.3E6BFFA Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by imf07.hostedemail.com (Postfix) with ESMTP id 8FD034005C for ; Thu, 18 Aug 2022 01:14:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660785298; x=1692321298; h=message-id:date:subject:to:cc:references:from: in-reply-to:content-transfer-encoding:mime-version; bh=hexIbovqNWWqwIVrlyEFfh/snr7S//BKbmFdQ9KSzjE=; b=QZrjGfEQ+K5OcROxMf+605qqgD+xKpVs5EY9NT4f3auoS5JYCOX3ScqF VZ8rMRu6br9xYRMGi1bYa0LJMr4GgOlr4JDDs5ZygWjnrqVs3DbHcmYr7 oL6IQiXhmzC7Kpo8l89apDv01sfaEfG8/lu/vTdv7HirolOTdnC4+L9x+ /W9Fo35NKk7Wa4USoiKZvLLkU3d5DJjwJzijIaOfEs6xPsAzqO2q4Rrv6 0dRzxNQTZMfwA6iMqN/D7Lhhku4JkaNvcwas7k/60HTexLsoePf+oaTF3 hwo147Knvzo5GQgUbdL+ht8BS7qsUxmXYBhkw9PfiQViTueAtGchVxPRu A==; X-IronPort-AV: E=McAfee;i="6500,9779,10442"; a="275689130" X-IronPort-AV: E=Sophos;i="5.93,244,1654585200"; d="scan'208";a="275689130" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2022 18:14:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,244,1654585200"; d="scan'208";a="636609203" Received: from fmsmsx603.amr.corp.intel.com ([10.18.126.83]) by orsmga008.jf.intel.com with ESMTP; 17 Aug 2022 18:14:56 -0700 Received: from fmsmsx612.amr.corp.intel.com (10.18.126.92) by fmsmsx603.amr.corp.intel.com (10.18.126.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 17 Aug 2022 18:14:56 -0700 Received: from fmsmsx608.amr.corp.intel.com (10.18.126.88) by fmsmsx612.amr.corp.intel.com (10.18.126.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 17 Aug 2022 18:14:56 -0700 Received: from fmsedg601.ED.cps.intel.com (10.1.192.135) by fmsmsx608.amr.corp.intel.com (10.18.126.88) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28 via Frontend Transport; Wed, 17 Aug 2022 18:14:56 -0700 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (104.47.57.177) by edgegateway.intel.com (192.55.55.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2375.28; Wed, 17 Aug 2022 18:14:56 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=I6wN4uNK9W7V98Vr4kioSy2DsKs3gI0pPjNTjWf8PFozrLxgcc/4r42L4gzKrkmEK5+mbFTH3XDASGv1fmqSwVZMLEbr6O2wbciNSQBSkeXfGCN8IalZjxms0XVMknpMZOkZZXq9bi+lJDhzeOSJrOaIyhmqjTXYtU6oLPGHtwSDcOpJX1g6z9cU9gZD6TMAb26AeWyLmERMIA6Y1pvAxBhBxT+JffI0CWqa0WKUttXJY4I3lWDAEqnBcUeBIPb3lH6kDoDUf+K8uDg/Ou/0MnRZKgnaWrAGyj6otMT5sJihtTHmaTzM7Rco4V+32af6iVZda42S5Uez7c1xaQP1DA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=jiKOIW0WQ5qlh8qfB5EzOMle2sMoqwVC4T1RKJ4uitk=; b=VhWvMedrahcdcQ/rdhVwhSGRuwVB8wz5+5lVU82kinQr3gWdnLmGnQY+mXXramdvDF6Bdzjhu8QUo5Jk54Rjp7DAIOTAQisX7goFrqInGP0JVYjTVXXxDsM3ka0pfFgzW7AIk7rcHhzYJgvWtjy1wTbyeU4rnUjMB6xn4pgVSx887E6iZR5yavU/yyeA13joJ5StaiXBpjb23KA61ZEHt0mLDdROX/WwNcTMUnOvIWkUstCTSmIKEpSd244bmVYryZCClnPi0CO2PVgjfBWrMbCdMXhvCScV9FqGCp4P5NdgNjYAAEUhbcUGnuZJbYIpFwsbsMg04puwej/c/QK46A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Received: from CO1PR11MB4820.namprd11.prod.outlook.com (2603:10b6:303:6f::8) by BYAPR11MB3573.namprd11.prod.outlook.com (2603:10b6:a03:fe::33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5504.17; Thu, 18 Aug 2022 01:14:49 +0000 Received: from CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::fcda:4c77:5786:209c]) by CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::fcda:4c77:5786:209c%4]) with mapi id 15.20.5525.019; Thu, 18 Aug 2022 01:14:49 +0000 Message-ID: <019c1272-9d01-9d51-91a0-2d656b25c318@intel.com> Date: Thu, 18 Aug 2022 09:14:41 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.12.0 Subject: Re: [PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at() Content-Language: en-US To: Muchun Song , Miaohe Lin CC: Andrew Morton , Mike Kravetz , Muchun Song , Linux MM , References: <20220816130553.31406-1-linmiaohe@huawei.com> <20220816130553.31406-5-linmiaohe@huawei.com> <0EAF1279-6A1C-41FA-9A32-414C36B3792A@linux.dev> From: "Yin, Fengwei" In-Reply-To: <0EAF1279-6A1C-41FA-9A32-414C36B3792A@linux.dev> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SGBP274CA0003.SGPP274.PROD.OUTLOOK.COM (2603:1096:4:b0::15) To CO1PR11MB4820.namprd11.prod.outlook.com (2603:10b6:303:6f::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9efa2c4a-ad55-4c03-3c79-08da80b70bb8 X-MS-TrafficTypeDiagnostic: BYAPR11MB3573:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO1PR11MB4820.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(396003)(346002)(366004)(136003)(39860400002)(376002)(5660300002)(38100700002)(8676002)(31686004)(66476007)(4326008)(66556008)(66946007)(36756003)(8936002)(2616005)(186003)(6506007)(478600001)(26005)(6512007)(82960400001)(86362001)(31696002)(2906002)(53546011)(41300700001)(54906003)(6666004)(316002)(83380400001)(110136005)(6486002)(45980500001)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cVBoSWNzdjMwMnMySmQzcG90blpkeEtLSThndlFiVFY4SENQNEpPb05wQVBx?= =?utf-8?B?VEhPamxTZDNwbEdOVnd0QzFUd1JZdDByVzNMNVJheDhTMllCN0R0c2JLdXlX?= =?utf-8?B?STI4a2RaeWplcWNGOXBNWGt0MmJWdlVVMG16cXJoZkVZcS9mT2lQUGVwcW00?= =?utf-8?B?VGdMa3F2RjVJc2dKbUFuaVlDb2tLb2oyR3R0dDczaHNNb2NRTytsbEk3cEZl?= =?utf-8?B?WkpweEt6S1hxZUhkbm5xeXNDcXN3eTMxejhjMjl0RGRYK3l5bGtCSTZCM0s2?= =?utf-8?B?a3ZKYXRWN1FNU2JFQVY1VWttaTlMZEJHQTFsUVdjaDg0STNDbnlpSHZRcWpV?= =?utf-8?B?YWtJM1V3TmtSUXZyK1VBa2dyZzFteTBBZzMrYWZJMXlVSVg3bUg1eDlkZ3E4?= =?utf-8?B?THBSK3A4d2w4dFdhamVOa0R4VFBQeGs5MG9zZFZVcnM3ejViamNrVEt3TzVw?= =?utf-8?B?TFc2czhFVFN0TThBQXllLzU3TVUvTG5NUy9helU5TVVSVUJhQ3FsUVdLcVdS?= =?utf-8?B?c1dRZGZDRlpIR3JMUDhidkQ2Z0tpS01EemFUMUw2SXhwQzdSYmNOcVpNVGNJ?= =?utf-8?B?V1JVODJTV1FYSnlMTUtkZllxRlRMck4xWmhBMy9oNjV6M1ROTEZWRW5HTjl0?= =?utf-8?B?WUsxWXZ4TTE5dW1od1puUVk1RG5TNzlOWHBsRlk3TllmaCtwZHRKcnA0S0hk?= =?utf-8?B?WmJEVnN1aEljQ0p2dUtzeFJqK3BVREx2VDV5b1REL09ESlVnWGo4VFhYOUlU?= =?utf-8?B?VmV3L1o1Tjh3aThJWE1hcVhvS0FXQnVNZk5udkJVbWhkWHMzS0tIK00vRUZ6?= =?utf-8?B?R01GY0pUSHU5UDVOalJTak52aW1NMXVwRlNhM1IvVnNCd2lVMStwNDFHc245?= =?utf-8?B?eHZGaUNiRGx4UDFTaTluNDB0cVhMK3dac0tZVHFyUzFYb001NnArVS9oRXJz?= =?utf-8?B?b2xWcTBEOXlUeXlORDZxbmtJUUN2TjNObEtzQ3czS2NiYVVqOHE1WWtnNHpN?= =?utf-8?B?dDBFelcxdDhub2lSd1lYdFZ2Wlk4UHRReGVsSHNUVlZyaXc5TWxXQmNFOEtM?= =?utf-8?B?Zjk3MmRRWm5zK2R0eXRlcmV5V1Q1ZjM4RzlJMVVOZVVCYkhXUWQvN1RIY1BL?= =?utf-8?B?bjdFd3UzelBMZ0ZLVGVSUjVCZ3M5My9XdndjbHNpQ3hUWkNhMU9UbHA3bHhB?= =?utf-8?B?M0EwQjA3d29seENlem5uRjJSU2V1dkh2WDVFaU1VTVZIRUthOTZ2aTJkYXVn?= =?utf-8?B?Z1hRMGU5L25pdE9IMXFLcEJtVnluQ2lObG9laklxS0FGR3hPdDIrVjFVUmNw?= =?utf-8?B?ckd6VUtFUkw5Nmh0MVVVcElwSzVMRWtaWURmT3pKZWhxc1Y1Wi9sUW9WZlVT?= =?utf-8?B?M3llU1lzdWZHdFlTNndXVEozaG5HeVVEcHNSL0tBcmFibmNubWhMZXpOajc5?= =?utf-8?B?T0Mya0JqZm1tM0JCUXlKVUo1bThOQXVKWE1pUjEweUN1bHAyS2VYblBxWTNM?= =?utf-8?B?UDVmeWszSzBwRnhIcGZaTVdxK20xUFRxUmlVMGtMTU9SVjR2bSt4aFBwbFdE?= =?utf-8?B?Skk3TjZ6Rkd1RitVZmo3Sm5xUllTUXMzVEZaTExlRzlxcVI1eTBaN081YUlH?= =?utf-8?B?dmNobk9kekFrMjByRk5SQjN6Vi9aaVJ3Uy9oK2ozNHZhNHBvenVYWUFSREo1?= =?utf-8?B?elMwTldCVWxQWDVENXFMbldpcHROOFVoeFVSNCtUMEFBOXVkOW9FSXhTUjg4?= =?utf-8?B?cUl6ZDc1bVhzSG5pTVZqZXJIVEtCMm5pMzJCNGdaMmJiZ3RLQ21oaDlMZGJ1?= =?utf-8?B?UmdTREI4VTY2K0pKemo1N3poVnFrZXQvUEVlMUFlalNGVjgxQ2tJcUlIZk1C?= =?utf-8?B?bXhiSW1XTkd4TGdaQWp1R0QyUHZ5UzNYTDEyUmkzZFJETktYUWVWekhva040?= =?utf-8?B?L3cxQlZxcDVlNngwMm1DTjdYcm0rd0lYWDIxeExMdFNwRFZxRkFSdjZ0ZjJS?= =?utf-8?B?YVVrdEpsUkxxdUpxWUdDbFZrMnFLMzBGMC83L1VaNVFJTGNRL2NJQ3dDZU8x?= =?utf-8?B?OFNocFdQbk1Maldsc0ZRdGE4WXdoVElIamV4YmhWb3FabVJYcXo3ekQ4OWlj?= =?utf-8?Q?BXHYQxTdXQort4KiZyWdSvYCS?= X-MS-Exchange-CrossTenant-Network-Message-Id: 9efa2c4a-ad55-4c03-3c79-08da80b70bb8 X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4820.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2022 01:14:49.3309 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: aW5syODNNLQalUcFdOn9lE0lF0vKfBW0yQdtiIiYf4cHHDutv4LuhYc5ndYKMP4r21xkmM0gTucsTC67Vs1rBQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR11MB3573 X-OriginatorOrg: intel.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1660785298; a=rsa-sha256; cv=fail; b=3X778UfJsZTZSqnrGtFknCDP2GC8/wFmX8Gsl6M2wJkAwB1xJ3aFgZBLA/H3INmPg/++rE 4zxVb5kANVihAvPC7giYBFouEkNqjBb9HnYDH6UrJpNfjcUp/YQXB9DrmJbDVSZkUAN9aY xRlmlRvQ8/E61gCtZ+VS3j3EoparF+4= ARC-Authentication-Results: i=2; imf07.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=QZrjGfEQ; spf=pass (imf07.hostedemail.com: domain of fengwei.yin@intel.com designates 134.134.136.126 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com; dmarc=pass (policy=none) header.from=intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660785298; 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=jiKOIW0WQ5qlh8qfB5EzOMle2sMoqwVC4T1RKJ4uitk=; b=Brw/xFCD3Y9kS+OxtWWH4muoOlKbT0LeA3OJ/ryxImkfpSptryG+jUu9oALNzQRNJq01I2 QQZ4OkEOyQeULqgq5wCk0vC7T9JdZHVv8zFgyHEfXupZMORX3grXhBxG+6AWrDEb7+C/wl Ne89isZsSFsIvXOA4JcRd3hfdOPzfQA= X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: i1i8w9ubrb4aca5euuecijxyux4opthz X-Rspamd-Queue-Id: 8FD034005C Authentication-Results: imf07.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=QZrjGfEQ; spf=pass (imf07.hostedemail.com: domain of fengwei.yin@intel.com designates 134.134.136.126 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com; dmarc=pass (policy=none) header.from=intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") X-HE-Tag: 1660785298-419105 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: On 8/17/2022 7:21 PM, Muchun Song wrote: > > >> On Aug 17, 2022, at 16:41, Miaohe Lin wrote: >> >> On 2022/8/17 10:53, Muchun Song wrote: >>> >>> >>>> On Aug 16, 2022, at 21:05, Miaohe Lin wrote: >>>> >>>> The memory barrier smp_wmb() is needed to make sure that preceding stores >>>> to the page contents become visible before the below set_pte_at() write. >>> >>> I’m not sure if you are right. I think it is set_pte_at()’s responsibility. >> >> Maybe not. There're many call sites do the similar things: >> >> hugetlb_mcopy_atomic_pte >> __do_huge_pmd_anonymous_page >> collapse_huge_page >> do_anonymous_page >> migrate_vma_insert_page >> mcopy_atomic_pte >> >> Take do_anonymous_page as an example: >> >> /* >> * The memory barrier inside __SetPageUptodate makes sure that >> * preceding stores to the page contents become visible before >> * the set_pte_at() write. >> */ >> __SetPageUptodate(page); > > IIUC, the case here we should make sure others (CPUs) can see new page’s > contents after they have saw PG_uptodate is set. I think commit 0ed361dec369 > can tell us more details. > > I also looked at commit 52f37629fd3c to see why we need a barrier before > set_pte_at(), but I didn’t find any info to explain why. I guess we want > to make sure the order between the page’s contents and subsequent memory > accesses using the corresponding virtual address, do you agree with this? This is my understanding also. Thanks. Regards Yin, Fengwei > > Thanks. > >> >> So I think a memory barrier is needed before the set_pte_at() write. Or am I miss something? >> >> Thanks, >> Miaohe Lin >> >>> Take arm64 (since it is a Relaxed Memory Order model) as an example (the >>> following code snippet is set_pte()), I see a barrier guarantee. So I am >>> curious what issues you are facing. So I want to know the basis for you to >>> do this change. >>> >>> static inline void set_pte(pte_t *ptep, pte_t pte) >>> { >>> *ptep = pte; >>> >>> /* >>> * Only if the new pte is valid and kernel, otherwise TLB maintenance >>> * or update_mmu_cache() have the necessary barriers. >>> */ >>> if (pte_valid_not_user(pte)) { >>> dsb(ishst); >>> isb(); >>> } >>> } >>> >>> Thanks. >>> > >