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 804BCC3DA7D for ; Tue, 3 Jan 2023 19:20:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0E11F8E0005; Tue, 3 Jan 2023 14:20:21 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0907A8E0001; Tue, 3 Jan 2023 14:20:21 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E4BCB8E0005; Tue, 3 Jan 2023 14:20:20 -0500 (EST) 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 D7B008E0001 for ; Tue, 3 Jan 2023 14:20:20 -0500 (EST) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A24C1160C0E for ; Tue, 3 Jan 2023 19:20:20 +0000 (UTC) X-FDA: 80314453800.13.9DCA56F Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf23.hostedemail.com (Postfix) with ESMTP id 9502D140007 for ; Tue, 3 Jan 2023 19:20:16 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=mxOTopUi; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf23.hostedemail.com: domain of fenghua.yu@intel.com designates 134.134.136.65 as permitted sender) smtp.mailfrom=fenghua.yu@intel.com; arc=pass ("microsoft.com:s=arcselector9901:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1672773617; 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=4zGM3TnPy5FpDM2G7Fd777uhj1G8RvnQpAAjZGa6few=; b=w4GJ5DuERf50bP89MbUWrJdnc5houiEo08iAwIU5+IdRlmIqAD2fPaxWgbJoV8ndD46zlr xUTWTPrLpxS/g23TVK+lPVZxN1+Uo07S+rtSF7e32M00qHFb9XLZKf1L1hanhebJHkEnaY NgWDmh/N3CinklxnKHi6LFI7t/NhWpk= ARC-Authentication-Results: i=2; imf23.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=mxOTopUi; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf23.hostedemail.com: domain of fenghua.yu@intel.com designates 134.134.136.65 as permitted sender) smtp.mailfrom=fenghua.yu@intel.com; arc=pass ("microsoft.com:s=arcselector9901:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1672773617; a=rsa-sha256; cv=pass; b=p8pfnqoi2gVUYRbfXKvNOAKXVw3cOTz3ECXLexeMcKpezXt2yu6XVLrXT+zciX2eVlnIWQ ke2NvIWOqWqI4cy+EOwqnXycBJGhnoC3ZqbuYDiCD+IqowmMWDiXitgexSaZUHhYdIkzbp KnEeYybjCK2knqCpbZ9UE5AkrDdG7kg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672773616; x=1704309616; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=4zGM3TnPy5FpDM2G7Fd777uhj1G8RvnQpAAjZGa6few=; b=mxOTopUirFJDeTUMP049fbnpnI5HfgTW4uJBjl+qzjwR5nJfZRWXNZka cWGfzvson47MgGi9zbugWJSw3e/U9d/BD394I3cnQWbzUmQddj+cMd6Ai +LtSTvxfyBw8uomyRbQiknBZ8Gcq7MGmP2O23KDGcwOWv+WnreHVKZDAG RDL27NJaWd6xKcO7FjyUFPUsarHagBCA+KmEvJwgdufDekj6bfWWdVZuy ME0oGbT32+C9XaLpaZ8GPnhfrdobfSl4g25VFuQ992tkFEv6w0MwAUop/ 1Lba+rPfnQa1V2hWJy1Hpv+a3uXS7Q6SxYd8skb+xf+qgoitIfpqosuvI g==; X-IronPort-AV: E=McAfee;i="6500,9779,10579"; a="323729880" X-IronPort-AV: E=Sophos;i="5.96,297,1665471600"; d="scan'208";a="323729880" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jan 2023 11:20:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10579"; a="778972862" X-IronPort-AV: E=Sophos;i="5.96,297,1665471600"; d="scan'208";a="778972862" Received: from orsmsx603.amr.corp.intel.com ([10.22.229.16]) by orsmga004.jf.intel.com with ESMTP; 03 Jan 2023 11:20:14 -0800 Received: from orsmsx610.amr.corp.intel.com (10.22.229.23) by ORSMSX603.amr.corp.intel.com (10.22.229.16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.16; Tue, 3 Jan 2023 11:20:14 -0800 Received: from orsedg603.ED.cps.intel.com (10.7.248.4) by orsmsx610.amr.corp.intel.com (10.22.229.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.16 via Frontend Transport; Tue, 3 Jan 2023 11:20:14 -0800 Received: from NAM12-BN8-obe.outbound.protection.outlook.com (104.47.55.168) by edgegateway.intel.com (134.134.137.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.16; Tue, 3 Jan 2023 11:20:13 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=A8lPY67GbIzonJVzph37YrhKybhDvaaXn412BqsTcZ3qwuieU/dx9zC0m+EvaWiLirHC7T2Hrv7BHoZrcRiD0dZtjKiRoqapfl9KD5rQFDv7yfErUe68r4nnqVmuQ0ale5a6vfrq4T2/t1zmAk5niPekzsuwKQ1eEf+KIABrylbuM+HhaGT998QOKZXFZFFFVG7PMKbYvP721S4e4gFhvmJzI9Qa/tFJYtD19YgyY3koJXR0K/J3Lgl3ONJm4WT7dd5EM5tD9izdNGImCby+y6DjAehTLa+JtsoDWmrNrP8mN8JGzK1Ac0DeY+8BcdfpyzpidzDLzdIK1fMmXdNUKA== 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=4zGM3TnPy5FpDM2G7Fd777uhj1G8RvnQpAAjZGa6few=; b=OeVoDzNIvAglzn/ioHFiDEIc/PXkkYkuuhRTSh9n2MVHsmVjKN5WR2QMG5g9rhABPK5NkLB2fSp3a6k27SLJb0Dp6D3KKLF2Pkit78jCOFCbzAIJUu+hEkZK90UawBHpucaUC5C3M0e88OfqKMYc3Bj1u/5R3m626Dc4oNCt5VveZ/jugsA6rforrGmnNIuei7lm7BW6ONa/yZnEGn2qFGh6ApVwQ+hdFI2YxJpzRLsLtcgduzyf7mQyU4ONqchL/txrXGeyx3HXb9CUHVQdhlWO+8s2nR/SINt54rcM6Ir5rzv/U/+4yAdnhftk9EBibf3bkWoYXYCIerz1svVqQA== 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 IA1PR11MB6097.namprd11.prod.outlook.com (2603:10b6:208:3d7::17) by CO6PR11MB5650.namprd11.prod.outlook.com (2603:10b6:5:35a::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5944.19; Tue, 3 Jan 2023 19:20:12 +0000 Received: from IA1PR11MB6097.namprd11.prod.outlook.com ([fe80::16c0:1ae3:13ee:c40e]) by IA1PR11MB6097.namprd11.prod.outlook.com ([fe80::16c0:1ae3:13ee:c40e%3]) with mapi id 15.20.5944.019; Tue, 3 Jan 2023 19:20:11 +0000 From: "Yu, Fenghua" To: Lorenzo Stoakes CC: Vinod Koul , "Jiang, Dave" , "dmaengine@vger.kernel.org" , "Zhu, Tony" , Andrew Morton , "linux-mm@kvack.org" , Christoph Hellwig Subject: RE: [PATCH 09/17] mm: export access_remote_vm() symbol Thread-Topic: [PATCH 09/17] mm: export access_remote_vm() symbol Thread-Index: AQHZH5FkNhHM4hOH50a42EHT2Acr4K6M9zQAgAABTYCAAA0YkA== Date: Tue, 3 Jan 2023 19:20:11 +0000 Message-ID: References: <20230103163505.1569356-1-fenghua.yu@intel.com> <20230103163505.1569356-10-fenghua.yu@intel.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-publictraffictype: Email x-ms-traffictypediagnostic: IA1PR11MB6097:EE_|CO6PR11MB5650:EE_ x-ms-office365-filtering-correlation-id: 0e466f6b-f16f-411e-c40d-08daedbf88f9 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:IA1PR11MB6097.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230022)(376002)(366004)(136003)(346002)(396003)(39860400002)(451199015)(5660300002)(52536014)(2906002)(8936002)(8676002)(4326008)(41300700001)(478600001)(316002)(66476007)(76116006)(66946007)(64756008)(66446008)(6916009)(54906003)(66556008)(71200400001)(26005)(9686003)(6506007)(33656002)(7696005)(55016003)(83380400001)(82960400001)(122000001)(186003)(38100700002)(38070700005)(86362001)(22166006);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata-chunkcount: 1 x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?y9hOLY0G5PH0zCKnm9eY68EwxfjkV+nAuIZizqALMTP8opu85cee8CMXwwlw?= =?us-ascii?Q?5f1DwRtadaCMpRNZMbf3J9zuZ9vtjhfhBkEgrGRlA/39CINpCAzPrKQp1iAg?= =?us-ascii?Q?dNztCOmouGZ525DfLBIwtxVFzE54mTFdl4xSrCP3tHm55vaXYiX7MV5VUktb?= =?us-ascii?Q?SVoAoQGQ5uLdvwLXha7ofbT6oU//8h8gP827Tjoa0Qnxro/ElSDWI36EFWuU?= =?us-ascii?Q?DPGITC1ScUAnfLXLt3nhpZ7qTldktDYagYzKxlvm8jigxgy5f0TUUvYEMOB4?= =?us-ascii?Q?fRPqR5CzwUU+Wp10QXy0RqyOQKQ6Zu+e0+JdYkXen943IO5YcMOmv2SEcD+f?= =?us-ascii?Q?f+DHjlKmmNgwfhLS4pfuIBGQiEXTbDQJ71zCFz4jRkLW3VCG/7fLB8RPG6hE?= =?us-ascii?Q?ryNVOf2leCss830mFPoF7l7BbqLynT84wfXEp5bi3vU7OzGfnja6lhKVDNWJ?= =?us-ascii?Q?lH9Xbt6LCosfFaHE0w/BOdUTVHG0phxAZ7MPJGe2bv0eKtMkD66ZfnIE7mOq?= =?us-ascii?Q?03jVRqL02Gh3CzRMA2cDpGa7NGs2ppxRfIrMwa2/xgsHttW4J2tcImEg6f3Y?= =?us-ascii?Q?u/g72GCSjduhhCh4ruxU/tkW4zOQTgFx939lg4e7TBz6qKSMZssx4y4OCpk3?= =?us-ascii?Q?JOW21cfN7V8i9RKKQsCx85yT8+w6q+uQeTd/aNPkE7RD9AF1m88Y8ivjdB2R?= =?us-ascii?Q?WkCR/cQ6/Yq6i9KaWOzF11ka6IHXN3YWJCvqw+hAWe44dUdGmANAkxaTiyn4?= =?us-ascii?Q?3HX3fVj06nwdUkH46x2bVBuNQANR9P3eAmxXsIcHffDbZzKDKoN9OMj1+ULg?= =?us-ascii?Q?6C95BuxYE3Zg3IAZkY5JT2G9P5DejmficLBWtjRwo3M/uaGkBraThS9k8Yek?= =?us-ascii?Q?9Sdw3IaVrrv5eVBDQfX92VAp6t6pheMrzQlQDSckYFOjpgzBuveJdEcB5MAV?= =?us-ascii?Q?hC62T4yYsL8FQIG7ioYG4OH0uaPhE1S0rbv6EaKlSS5C0JcZ9D18Qu1uj6up?= =?us-ascii?Q?1uiGYkLB06Imgg4L77KSM/gXzf5c/NHj5SHMjHXBdj2dr4c2jT7QoFh0A6xe?= =?us-ascii?Q?5pUORemxq9u+lvK5qhYrbw0yfttjxdOEIJQj+lXVAjX81YqySa5EErbDj6EI?= =?us-ascii?Q?YBcFyxhAxO9RPxaUDiqCi+kmbQUE2chamZVf7/hsdivlymR/Aykyc9s8uudG?= =?us-ascii?Q?ISLhzjrAj8fayk4aYY7nXLHCxL8siW2pqeJptvIixkR5ZR9kA6GFeFZ5fMx5?= =?us-ascii?Q?/ayrf4GOCIhJkW6c5ajt2IHWfZKQUOwFAN/w98Hhs3NGGQmVc3CYr2xYWnIu?= =?us-ascii?Q?xdWbDGOCkllZ+4dSgF2PTv2SshTRkdI1nCqPXByWhCMWkH56LKZ9qmunY11o?= =?us-ascii?Q?EtSZHwEXkUb/oxhlUD3pLdGD1bV3wIe+ACqqp9G53IYqt6LpxKsbKqDt7/a8?= =?us-ascii?Q?/O3Fnlde8aVLgR5DaFZbOowFnIhfJWn2KIAzqolJTnYAyoF22cRtucCawME4?= =?us-ascii?Q?DU0l6Nt/pRlZNjPbsA4SVK9UUYEjbDD2FxiHkwcqRzxAMmeGh+ypNXb8+Xgi?= =?us-ascii?Q?qSRFpm88q24SoIN9DCpE0/dwV4fTwEDFZb697jzM?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: IA1PR11MB6097.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0e466f6b-f16f-411e-c40d-08daedbf88f9 X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Jan 2023 19:20:11.8328 (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: HazeXrxZA33EpwKm8vZrDqM8mna/iLgW8RYAyNLb6EMyTNnyYwHdySKEly1jnvrkUo6JekiQ0r3x0pBqGEkkqA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO6PR11MB5650 X-OriginatorOrg: intel.com X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9502D140007 X-Stat-Signature: k6hk5yhws44q94b6zdy9kgcp4ukqh31r X-HE-Tag: 1672773616-657894 X-HE-Meta: U2FsdGVkX19x+LRj0VLmlCW1M5E1v1uSwwHg7OCllbsTPHS4Qv0GvrqIYjQcBV4Y4mdE4tkF9srPoDQIuxGgP8Z+Vqm9JwcX7VCr2BWx1CNZqYwfKERi9gyQkgHdR6KKGx9nUdZThxjqzzh5GVICtVmrG8WkwcMpl26w2vJEf4Ja0ib3l544MKot4E/P5o+U4mNkFD3R0symMA0aPUK1ZN+FVq0ZpR3D2DukGNRhO7AKyoaQ/7/mLarh9Ydp6X2ZmdEeE8aCBRE3wNYZbVAkvnYCsVtoKsDFVJbjXIFyxmvxj25UOuOzpCa46hYxLctK3NPLxAq7d/eIBqofaYo8DJV9WLkkfeEgO5cFcPhPo3eCRpNAaUU6mObOMpXa1ybg9kfmMaf/gukp0tSWObPxCueLckdjlPnsVuOiYXVhrq8razokqN/5BJEaKletW19NB/+UUj/JJlnaqplZjhnj9lXPL0AiLhyDC4ZQHnB7qJ8xQpPzYQBijgYQmxw0QLvpJ4WL02+n32YpDBRUTg/R2Qq1dtKNyd/Qu954JB7GpkOm3WMzm77hf5SKJ3IPhnERvH9u2wEkTDnal3OV+r0ki0Ik7cspTz0sq+73FJnY4V6UaBhrFffDEHZjmZW+BaZZtRKukG5/JiSznnE+SDuRDH1EbSPFFQA/7bsPVt/DvsmaSP35Cj6zshRc153+2hoSOc8Dyg+TFA44tgsbeUi3nGWVXPgbaGUJBT5kC7fOSsRZV5+oQ4WOWSAfUuY/JHNFd5EMWkC1/BMIUYkw9LpwvG7KvPTdRukYEDjiuOvab3OmSrBdyAbEquVvR9q6GrAXcPvR077HNnY256f/O+sncZO9g7Q28jCMqK2Gk9iYO5ZrYspX5MQiKDL8P66iQ9bdXJ9ki+eRaZbzmTdXxIQXxtSbEEcKTEC0XY6fyg7aEBMl77ghkQeZP8wLNZ4MUZfY31h/Vn55vxiG6mjNhzn jxoJ/5CB 7MeSCQKymKT+40F52obyiPmUtWexObIhjjV12UCouNpe95CAQsnXLkPTE636/nJYj8AKWQQ8hq7XgY8s= 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: Hi, Lorenzo, > On Tue, Jan 03, 2023 at 09:46:00AM -0800, Lorenzo Stoakes wrote: > On Tue, Jan 03, 2023 at 05:45:30PM +0000, Lorenzo Stoakes wrote: > > Can you explain what use case you have for exporting this? Currently > > this is only used by procfs. > > >=20 > Ugh I hit send too soon ! I see you've explained the _why_ (i.e. idxd). T= he other > two points remain, however. >=20 > > Additionally, it relies on a reference count being held on the mm > > which seems a little risky exposing to a driver. access_remote_vm(mm) directly call __access_remote_vm(mm). access_process_vm(tsk) calls mm=3Dget_task_mm() then __access_remote_vm(mm)= . So instead of access_remote_vm(mm), it's access_process_vm(tsk) that holds a reference count on the mm, right? > > > > Is there a reason you can't use access_process_vm() which is exported > > and additionally handles the refrencing? IDXD interrupt handler starts a work which needs to access remote vm. The remote mm is found by PASID which is saved in device event log. In the work, it's hard to get the remote mm from a task because mm->owner c= ould be NULL but the mm is still existing. Thanks. -Fenghua