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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7ADA9CA0ED1 for ; Mon, 18 Aug 2025 14:28:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To: Content-Type:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=bzd4Y932ys/rq1Lye5ykuPXV31VL1tYr/K62MmB90ro=; b=OmJVpMvQyMAGEdmDvXY7x5tLTT p5FrEc7ADzt19b3uS240OdEotwH0znf2kKY/LYmuIlUK/4ox4mOWtjkNTxP9iEksbTo8fd0WQ1hj+ KveEHW73QlpFffRqdW6rO+VrzCYR/aAfQjRBg1i6/9U5LGUcaJXqwJTQ85sxo8vfuEaxKHxr1qS6Y EZ9FnUCjwMvakZ2T9sUTlpFdlnz5VQ1NBXa7lrDjF0jV+qmPsz8jJeQnYMuJNYjwmsGGJAMttDfKg 6E5JHHHYtveUM/ISfZ1+sT5Flv1MzmSJ8bPY9NQ994Cn0PRhS3TVSzpaFAdpCUUReBQkSMm48yWIq 9w2MlHPQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uo0qH-00000007kTU-1r79; Mon, 18 Aug 2025 14:28:09 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uo0gY-00000007imR-0LNl; Mon, 18 Aug 2025 14:18:06 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=MIME-Version:In-Reply-To:Content-Type: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bzd4Y932ys/rq1Lye5ykuPXV31VL1tYr/K62MmB90ro=; b=JJOuJJHXl+07j5l7wSZj8E8uLL /w7LEnV7waVtMm1Mb2/AMjdp/bFfZvrzBksqA9dRgqpnaXo1lE3E92Qs4FhJ7E+fNY+kXrP+Zc9Jv dZLR256ITcJm8MhOdc6Ls8SLHCqPv8DFX6Xikedwmig4TJSA9hfxU22AHBaM8X1siMYBlZFSUG5xf b8/Ao4PEloaqEyXj9xy28JIokE1ubYQMZa+Mw50+lBerou4iAw7IDZCuMVRL3K4FokPfiVd4ABwzz 3wOWUe30VMfw63q0HYkUwxamFe+XMrK6glCmbC1mU+KvIskeoXXlsXEtv/7fXvBcmxZQGVpRXlIru dlfjLxYA==; Received: from mail-bn8nam11on20625.outbound.protection.outlook.com ([2a01:111:f403:2414::625] helo=NAM11-BN8-obe.outbound.protection.outlook.com) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uo0gV-0000000HPVw-0IZh; Mon, 18 Aug 2025 14:18:04 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=G4yBWWx0fNBL0CRuBMYaYuxYuWLjjD2uV+B+wTAdE8t4YskzNeibhs5uZjjYU4SAZDx9wXv7IMjI0pEe2igeoYUS69OOx4DLoQDY0XS2Uk3lmsXSX8gYFqAmPOrDrEFF5nVhJQ7Gq143clpmtw/JS3snDyidvMf2QJjmcD+No80nu4mTuLk2S9/51XXPGoZUjaKunL79bCiIpJXqmHrWhuitycOVtmoEcltXDAEeAnADzBjJy4OpF2CoPzdWJ57skqshxtegTG03G9zMez27vXYacNIZpeK7KH8XFsMhYr64TVTmHJIbUvhPsWZ5MGXmVSWgtU2NyiPp5LJFHQTVxw== 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=bzd4Y932ys/rq1Lye5ykuPXV31VL1tYr/K62MmB90ro=; b=s/DKoyCDq+BMn9C7ozurjkl65Q/MAFDFLq8bTZk5f2Gf/mvZY3Zsp6u3Ji0Tq8Aa4z9bd+cctlyzPz/Ha5ODsIhItfvJylDnPuc3rz4WfDUqFP+2jvhyrFTDRsvktaK+Eqcmg0BrntPh8bnSFm1I6DStoqcc1azKsCbWXLkcydTkDBVwo8EfnGzpitUPQ7V8jpSjUveU1QQ6HhYv8n8DrNuJ3Bbtoek/BYa806ywFuNfYY6DGqSvHE2MYal7lS2Z6oLijPGaoanDDq+AD9Pz+PAA1TgFej72BIy7LywnXmIlIsrgnZ6xQKibOThrfFy7hILXoEdswyaQIbdgqB8Ufg== 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=bzd4Y932ys/rq1Lye5ykuPXV31VL1tYr/K62MmB90ro=; b=H5noVzdTpeksDx1OgQRKPi4GwNTX8+TdYKpzBnG1/iK6yu9/zQOVlz8q5+E3+V2/N+PvthXX+fB2sSu1HfwHx/UBYGlS+Sb0cXSd9BKzP5hv04lGsK+CC2yh0eFZqYXeN9p3FYqPAGl8NWmmelBOFgDHcZaWSTy4GFRCgDbLMENrcW4PokDJBIl590sESX6ujYokJGSqA8xVo86I57qzHxUvznBjfFaxdZhOOzRc1zfbOXiz1RnO/KdqxHGUHLKy317F9i5ClvkDgbV97MYQOViAzizQuRj3NjXsg5AYWE9PJwXs6Chli9X69qmG30JBltFcDlQE6EqNgUaWGmD1bQ== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) by SJ2PR12MB8832.namprd12.prod.outlook.com (2603:10b6:a03:4d0::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9031.19; Mon, 18 Aug 2025 14:17:54 +0000 Received: from CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732]) by CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732%4]) with mapi id 15.20.9031.023; Mon, 18 Aug 2025 14:17:54 +0000 Date: Mon, 18 Aug 2025 11:17:51 -0300 From: Jason Gunthorpe To: "Tian, Kevin" Cc: Nicolin Chen , "robin.murphy@arm.com" , "joro@8bytes.org" , "bhelgaas@google.com" , "will@kernel.org" , "robin.clark@oss.qualcomm.com" , "yong.wu@mediatek.com" , "matthias.bgg@gmail.com" , "angelogioacchino.delregno@collabora.com" , "thierry.reding@gmail.com" , "vdumpa@nvidia.com" , "jonathanh@nvidia.com" , "rafael@kernel.org" , "lenb@kernel.org" , "Liu, Yi L" , "baolu.lu@linux.intel.com" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , "linux-tegra@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-pci@vger.kernel.org" , "patches@lists.linux.dev" , "Jaroszynski, Piotr" , "Sethi, Vikram" , "helgaas@kernel.org" , "etzhao1900@gmail.com" Subject: Re: [PATCH v3 1/5] iommu: Lock group->mutex in iommu_deferred_attach Message-ID: <20250818141751.GN802098@nvidia.com> References: <44783ca52e17a9ca0ce7acfe8daae3edc3d7b45b.1754952762.git.nicolinc@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SN6PR05CA0004.namprd05.prod.outlook.com (2603:10b6:805:de::17) To CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8659:EE_|SJ2PR12MB8832:EE_ X-MS-Office365-Filtering-Correlation-Id: 53c22fbe-1ea5-4523-6413-08ddde62057b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014|7416014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?WNVPTHA9lOiOTWvNoLMvmg6PeV5anA7qq3t7KmvI3TYJMWCVhyGG2L9oWvP+?= =?us-ascii?Q?rJJzvfCRQHtVoyhpI7y76qpVVomAy1dvb6PO3rVSjMuPK2/JpSYURiFtMwD7?= =?us-ascii?Q?ufc77T4RkQdlsvnll0OyxM2+vL28MQ8ti2Rg+AHsZVuA51Iz3B7CfMozo9DW?= =?us-ascii?Q?JVaY343PDTzOY2w3y6KxPg/H8+Oo+9kFqy6sW0fjuvAzDcn3G7Xp5+zjISf6?= =?us-ascii?Q?vlsZ6JBSG814efavJu+YN/HsiN+v+rIXT/4JI27/zUwDyrI+QqlbTJ4j0MKe?= =?us-ascii?Q?adazJg2YYHKh8YAbARAHs90qKEG1Jd90Ae4Y9b7nuPUe3jSbt4FLh+yBAGWx?= =?us-ascii?Q?mJwb/OtMBjmRQ8sqiaaU6/heMP1D8pKWGeSaPczDZgRP/9PIZ2jCoRqf1KZx?= =?us-ascii?Q?JPgXYx+OCfJTJw1HoWFdkkLsf+NykwN0nw/RIDDD8Ouv+K81s8NYGmDe5ZSG?= =?us-ascii?Q?61SXQSFAjAu5KF3kNOxWxJlUBdxj/3/r/NMJiHbJ8WftPPVA1IVU3jQ6ukBM?= =?us-ascii?Q?lcXbXKCOWCHeFaaeobXmSRWWr+HYRMiNRFUCDC1g3cxHo1Hpoeowp+S87z0H?= =?us-ascii?Q?KyojkcVbAsL9yqj3EB7szMfRcVDQVP0WSGwPBg1BC6ZfLWxPYw00jkv9q2/b?= =?us-ascii?Q?v6zxKI2ZJYcuNZlVZJjUoHcHnBidca/BQZnphCQyfmJ3WnTALI1ndVio/ZS6?= =?us-ascii?Q?y1jrOxJLEPBE7BmCI8twQe+rhkf0WKJIn27ZD8J8NpO1uVH088o8TIRaOsCW?= =?us-ascii?Q?wQS2hGRjmQoAyTfRsjPgLpK1mohxU++HUVuTb2aN7hj25QaFNf1CwMx1HC90?= =?us-ascii?Q?8NT8ELaUm1jFX/KvrifHzn6bv3HwUfWc96SAvwB2iO0zo1Ei5GYlcao5Mxtn?= =?us-ascii?Q?W8B6odTPgnh04c8+c/3RIhj8Cy3fkHui91516wyeI7hmttBfsu1TTHmMIGL1?= =?us-ascii?Q?CLRmkBWM5eRolHOR5nnHWUJ77dPsD4k+8hlRb03kxVw2pAttAs/xHu93OypS?= =?us-ascii?Q?OJLHepS2rBNmharUKQUpyc2UNhboO2OTGr9Xw3nk2cP0YaU6WtB3pv2qLY5g?= =?us-ascii?Q?KoLwIYnDOmOLwYtKPE7ZUm5N9T8hZsQq3ZgZx0rBhO4OC08xLVNhaQXYW6AZ?= =?us-ascii?Q?AobivY4r5Ejvk4jgHPxiMvfHcmLJPc+m3QlSnFlmvV4Og4w28/Y6fZayUAHa?= =?us-ascii?Q?5jRrZkrOFbfiPoiCeA5yZmUJDsSKycQafniuIPVuU+BP/rRMP8roI2lnnvLm?= =?us-ascii?Q?11DMaZXuSj70ryQ7hxNNgw9xu5T5m4rC3GWUjVHO8NXkNkqG6/ZYRDY6TMjn?= =?us-ascii?Q?ONT3qYw8vt6ZtKcfcfE0ZAjob2iq74U+DxsJ8yq0HAfS8DpTWs3aaWOpHxei?= =?us-ascii?Q?A/aLNpxRIQEOMPw0NFoYXRvdphQC8xTb6i7ObML58/5U+jXU1RWNUBe0kWdU?= =?us-ascii?Q?5/vh1dPCM/M=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR12MB8659.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(376014)(7416014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?7nRaFKqyJ1AxM/hcmvI2CWjbR39D8YrLsrjHdMzHe97ygodaJTHEDM3DeSL4?= =?us-ascii?Q?eTDW7ZtZDs0H/AYlarTPcP6kJMJRmpvMXRAK5hyYfUbiUWYXhHrsl+u0hdcx?= =?us-ascii?Q?IfoIbKB6ckm8jOBFf07tosotisIdgkGMS1U1RD92ikgWlj5TH/8vKuJwTt5e?= =?us-ascii?Q?pFMXgkRzOpfs/44Pzr2N3yFlzpo+fPyg6pM+WsMX787KA0FfE+ybFloS3Tde?= =?us-ascii?Q?ZRBin/RYeKAC0xO9QHXJelZjhTerxQfHDmFY3nhSqhnoGSAeDXUdlemKwhiM?= =?us-ascii?Q?S9pJmyN3Te9Hh8yNHkyJkftNRhKimYtdXeFUVn15OePGDwXo7/6N51VB6MmP?= =?us-ascii?Q?epzeOcq2FWDtrZxUG8W4i323+g3bx/L8vpvty78JCvwB+2LmlrhmHUk1Mkbt?= =?us-ascii?Q?XB7WQx047UeIGxJ+oNWa3t87o9weUs+UyKY6Z2JUcFjwy6Wv4tWQrmbutisz?= =?us-ascii?Q?tg/MZ1e+UQQW+kNthlDODyOdvgBLSJIprPz5sU9dc1hom+QKq6GJO/ujvfx/?= =?us-ascii?Q?kD4gUhByDqrlYmabZV+qOa4SvKsSpbfX+IZT9yUJ6EqYretiuxk0lrJpO6LK?= =?us-ascii?Q?d2g5W9E4TL3vBb/79kxO1zVQxpbdI5ELhpfI+9HMQNnkSo2xOJGMsaxeqWQB?= =?us-ascii?Q?58cX+vydMj2ARUaIefOlY4o+tbuyRX3mgzoyijLbS/OgUxdoXCRd7eSFOtB/?= =?us-ascii?Q?d5bTOkVonse1Y3h2W0Zg2Drt0oeK4iSrG8Z+zWNSJMK6UcLmeKsAv09glLXd?= =?us-ascii?Q?8vIZtQzt8w8IxSQAaT+Ad3RnSN8h3gzEX0NfgtiUgceF/YfYFSdlefSVvFgV?= =?us-ascii?Q?szDldG33V7jZ8xLy9ddJKQr7yU8nn2+NsmzIk8/OVcds/ryV4ohO36fKoZvz?= =?us-ascii?Q?aeKtKsBqnBzK2dQju19O/FjdAdN9vYwJ7WuVGCKuXUjd1hh0KwIRcl9OuvC0?= =?us-ascii?Q?M9S+Jor+7pxVubgfB3ba3mrE9GQSzvgV8w7ZdH7QWpqm3o7bE1JKggoyXlCH?= =?us-ascii?Q?wYbqCe1gfv5S2YAW9LBKNaABLnMpceaUB0CWGPOVuiX4p+AHM4Yhi7xsqf9V?= =?us-ascii?Q?OWef8gJaZZbY7ZA9sgsF0/Sp82vZn2LhxqXWLpPXo2I0IHwizIG+q0rkgqx2?= =?us-ascii?Q?hiUizrbjfK2CmZmSnCADJctrW9OMxQs/W20S75A+T+l5mOW7XRZbc8+WpURO?= =?us-ascii?Q?AMNDIM+0WPHCaa1e7/mg2FL4tbJB51NoFMAxrWEBsGhvIy9qgn67t4DYVOrC?= =?us-ascii?Q?XZ/m8/wtW+XrRPcE8RYY6sxWR+5sDlQWiaScogXzp1wBTtsAaXjDYt4JfqcX?= =?us-ascii?Q?SyW64B/od8DWoCxuRyrCuZV3C/1mqPqjYvXKTcrxj0jphEAOQwgitrWgxdri?= =?us-ascii?Q?CS3ZkcVepZad8n3AEwLdqT0xizil9zj7SUdP3l7mUAfpS6q4yFLjjRYISJwe?= =?us-ascii?Q?/tRnrNi4KVPCAx0f/fzwxiIJORu5xiRz3fCR70UqKztgN1zSvWk4t20tXqNl?= =?us-ascii?Q?hQX1T3oXSIizAb3TfAYQ1g712T4ISbOUzODHEn9a52oNFxkduki10c6T9zWv?= =?us-ascii?Q?8ji5NSpdpkitlJ4V9EAN2RKHhnbwCEuQ7vZmytd7?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 53c22fbe-1ea5-4523-6413-08ddde62057b X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2025 14:17:53.8915 (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: ZG/dwyIC+4KKlmOJmQIzyUCc6TN0S83NZPd3854cq+LhtFLLKm/ThwcjUnJVTOsj X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8832 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250818_151803_235878_5AA613FA X-CRM114-Status: GOOD ( 11.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 15, 2025 at 08:24:57AM +0000, Tian, Kevin wrote: > > From: Nicolin Chen > > Sent: Tuesday, August 12, 2025 6:59 AM > > > > The iommu_deferred_attach() is a runtime asynchronous function called by > > iommu-dma function, which could race against other attach functions if it > > accesses something in the dev->iommu_group. > > Is there a real racing scenario being observed or more theoretical? I think the commit message should explain the actual reason this is being done, which AFAICT because the new lockdeps added in following patches will fail on this path otherwise. Jason