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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3E94C433FE for ; Wed, 5 Oct 2022 13:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229676AbiJEN5d (ORCPT ); Wed, 5 Oct 2022 09:57:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229681AbiJEN5b (ORCPT ); Wed, 5 Oct 2022 09:57:31 -0400 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (mail-mw2nam12on2048.outbound.protection.outlook.com [40.107.244.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE7646567C; Wed, 5 Oct 2022 06:57:30 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=AkumViN9JiSlODspm8nYJFjdymPTTYJmSuKTA+tln/vecaYVPL3GJ+lrGv/riTuzHIneXUgbNp6KjLQShOMpxt2Q2QAdAM2qEPORHWF7aNDWx4L9cgHHLY7ylu3FjsVeEZB3o3drWbdMimTKVb0Q/7nNS2vphOrkHYVm+jPadnSkpxsErY8OlbXKTeUWPpcVxGVIki3aztP3ZfZn1RnVGGo2JGBm2/21c8Yt+SQrX9jCuyAM6Y2FPK+wbNy6RxdHigvHiM8J6Q+fKrsofxZkv1jbYL2lHFEWQIHdLSC0347kcfe996COwQhpn/Q0Nr+Hsswur5EzmMUf8K4PzplUjA== 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=Vk8vJsGPQpGvjhude0+apF7bM3grXm+7pZVMxAzhiqo=; b=aZfUBBTZQt54c1d8HIwVRVIm7k46+t5cenP3UqYwc0rOCf+5gb041NWgCltFtPbgza+qFwFf/G38PRWEeG3H3q4F/+1sRGRi4fpOB6t0ikSZmnToEhK9BhsUlHXjsapGQBVUGBqQST5/souWO5yDrhPILS7SrLcxZiP7D6rBNRcRnjv/d3QSPm3Lmz/FP6kncxFyP/yW1kmWRVnKTuaJ47hgzwr0Y0x+UrumP66c+fn+cwhaEyW+yA/HoOY4McYi5V92RTIP/uYUnlM+IX+56hB4EXKfPHBKYQg6ABD7qOZKbmu7DWXBO0Dc6JnRe4wZaQlLh9Y1lhqBnscsD+1j/g== 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=Vk8vJsGPQpGvjhude0+apF7bM3grXm+7pZVMxAzhiqo=; b=Krda83tUrHZ2jNy0XKYjt2Ok1qHIyinNJyA2m+ndIHPAbkNZePSQTuqs72q8QnyJZn+lkH0XOiMGiIadqpB67MC3Avdtsu65w2ACN0E9ezuRZ0N2M4gr4MWUUQDl0fzVy7nFMhizJJ+cCew/QcxJewc8tgxVgKVp0fnq0UvEMnCcbP0wpSJuJOc+AOlbdCao587tsC0lztrkgtXMWzs+RIOssSiFI6EfC/jGjt152U7ze6dgeDr6WPrcXM/90McfsSwvO4qzIB5oe/hFMhNK4VLsyYOlQ+aMSEbkmREXwK1exInGEWQakqRvO8o2/wauB6MQvuDTQUK7rN74qit2Bw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) by SN7PR12MB7106.namprd12.prod.outlook.com (2603:10b6:806:2a1::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5676.20; Wed, 5 Oct 2022 13:57:29 +0000 Received: from LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::7a81:a4e4:bb9c:d1de]) by LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::7a81:a4e4:bb9c:d1de%5]) with mapi id 15.20.5676.032; Wed, 5 Oct 2022 13:57:29 +0000 Date: Wed, 5 Oct 2022 10:57:28 -0300 From: Jason Gunthorpe To: Matthew Rosato Cc: Christian Borntraeger , Alex Williamson , Tony Krowiak , "Jason J . Herne" , Marc Hartmayer , Eric Farman , Cornelia Huck , kvm@vger.kernel.org, Qian Cai , Joerg Roedel , Marek Szyprowski , linux-s390 Subject: Re: [PATCH v2] vfio: Follow a strict lifetime for struct iommu_group Message-ID: References: <0-v2-a3c5f4429e2a+55-iommu_group_lifetime_jgg@nvidia.com> <4cb6e49e-554e-57b3-e2d3-bc911d99083f@linux.ibm.com> <20220927140541.6f727b01.alex.williamson@redhat.com> <52545d8b-956b-8934-8a7e-212729ea2855@linux.ibm.com> <1aebfa84-8310-5dff-1862-3d143878d9dd@linux.ibm.com> <0a0d7937-316a-a0e2-9d7d-df8f3f8a38e3@linux.ibm.com> <33bc5258-5c95-99ee-a952-5b0b2826da3a@linux.ibm.com> <8982bc22-9afa-dde4-9f4e-38948db58789@linux.ibm.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8982bc22-9afa-dde4-9f4e-38948db58789@linux.ibm.com> X-ClientProxiedBy: BL1PR13CA0136.namprd13.prod.outlook.com (2603:10b6:208:2bb::21) To LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV2PR12MB5869:EE_|SN7PR12MB7106:EE_ X-MS-Office365-Filtering-Correlation-Id: a28648f9-d2a2-42c8-4cde-08daa6d98ab1 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:LV2PR12MB5869.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230022)(4636009)(396003)(136003)(366004)(346002)(376002)(39860400002)(451199015)(7416002)(4744005)(2906002)(8936002)(41300700001)(66946007)(66556008)(66476007)(8676002)(86362001)(4326008)(54906003)(6916009)(316002)(6506007)(38100700002)(2616005)(6486002)(478600001)(186003)(5660300002)(6512007)(26005)(36756003)(83380400001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?min78wBHzIjUmOQ9OZ8+fqRVpeR2n8Q/3S+fp8U+YBvjEdsk0Oaen1ukTeRu?= =?us-ascii?Q?BGKQvUVTt94Nycnk5rdMve4q9cK/WnJ7DCd7K0RVFVKY1h1c6S3zGWD5nkHa?= =?us-ascii?Q?gMUqVADtB72QV23vtd74dAcgvIL7q08XIWkYZu/L33ta7Kcq+B6dkb6SqeeY?= =?us-ascii?Q?tc36TUkHN39A2nwFLlFRqYdC+dsuETxQszr7+a9M0ZmWbLkrUqqfuIFk2eYO?= =?us-ascii?Q?kNbYdH+CsNaiRW6wqKVDUc/beq3SgCFdZs3BJH/wOg2JhbXEu2DK/8PHNOKM?= =?us-ascii?Q?HbYAyRv2hdeyS1oaWZCX1ER2g3sL8vE0OSFQOEMwWvV9bRQ+Xoz4yQaYJirf?= =?us-ascii?Q?GwTeOZXzw1Beam/NGjryp/9lCkXEZxYYIhi9atConBmaGW9yux4PSqbPESAZ?= =?us-ascii?Q?VtkIxe1u36+Z3gSZrmtJ6NXJUR+533nnuOSWqDVvKFrdQeypAXeFE86aMPEZ?= =?us-ascii?Q?W5fxHH97X3uq/L/5HD8TYDguxgnGAosbaIlcb8EOT7SAB7louTF8nG1HMtyx?= =?us-ascii?Q?H88NmNTQfBbIayPhEDWKPZs6So0gZv/xWhSGfMfkaW1NTael8BkiGUW4WnL5?= =?us-ascii?Q?Gf60gWHlCXLgzjIb+HnJrNWYThnaEI0zsDjoWqUc2p7uYw1ToUDj/iDRSey0?= =?us-ascii?Q?tWkYiyRZ77R+Xa0lWi+slkS+f5soX0wKctkUZyGKGnk8/hclwkTdj4du0bZu?= =?us-ascii?Q?iN8hOw+kM4WNCrhkW6yK6/OjlWfnN8oGJRSsFUvAqQBbop3x+nM3GyMHpoga?= =?us-ascii?Q?40xbA1wFlOy7WHsOxWrdJClCCmPpgyRNoZkYDrHpFzUoE6O2I/J4YQFfdtWH?= =?us-ascii?Q?CYQLsaYG+sgrl/2PeYZdm8dzuL3EFWGn7UriouVhUE08Z+NAqjprayiKs+ID?= =?us-ascii?Q?QzbpBmeyF1W734hdp5nRip7i4u7fAhymQ/7i8E87mTHIoH61hKFaP2IgNtkT?= =?us-ascii?Q?PPxClSIMpl/EuyuwGr/RXd9L/fdJgtKXNoxGXgkF/QXzCXQFfh+M3ITPq//z?= =?us-ascii?Q?DlnEwioS1xv+HJ8sQr30FhAfnt4nEpfO6zLTUYod0szoTvqxLTCP0+uMzUFP?= =?us-ascii?Q?KPYxrSpj4Fq/DLp/0KzSQjiYjIeE6uUi6yYd7AThiMn6QP6xna0mjO66dunO?= =?us-ascii?Q?T+Af8B7oribjZfrDkvCAplG649/quNDjnF7g8M1FY7vMuojzvTKvf/1wtfVA?= =?us-ascii?Q?PBTNCUH2FStoMyhN1KV1/T+WzOnhdeDCs/b+AjERtPY84iKz/PfIIekg602r?= =?us-ascii?Q?cPgJSAG3+NoJx1uDR+fXVhnvGkywaFCa8S0x4M+2pJgvKWBqhZc2PWatbcQN?= =?us-ascii?Q?tcWV9DNRmJEqG91ydMeuk2ioBCHCrcUMNOlWhhnwxhV5xuxSa1+wmC2vEdr9?= =?us-ascii?Q?THCxhyEHmVhM64hs/GpvBfE2qmvB/cCW8ymrYScg5tZ9paSQxi0MSTXWQAz1?= =?us-ascii?Q?YTjtRYQ0N9U1PQHWgfumARiAfT4GnyS2SfvqP3EgZqaqyaYP4gcrALCt8zoV?= =?us-ascii?Q?qBvKwAz26jYdFDNapvYHOcVU8IiFhOYxnpJMN+A1NcVlel0B3xv23AiEPh33?= =?us-ascii?Q?BIdlfmKZJoSyHgMo6BU=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: a28648f9-d2a2-42c8-4cde-08daa6d98ab1 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Oct 2022 13:57:29.2741 (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: I4swNtt9DuSL3m06N2225CSp8XR17/6N+SnAW9BWYUimJg5d9Il2FXMn2900FOf4 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7106 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Wed, Oct 05, 2022 at 09:46:45AM -0400, Matthew Rosato wrote: > (again, with the follow-up applied) Besides the panic above I just > noticed there is also this warning that immediately precedes and is > perhaps more useful. Re: what triggers the WARN, both group->owner > and group->owner_cnt are already 0 And this is after the 2nd try that fixes the locking? This shows that vfio_group_detach_container() is called twice (which was my guess), hoever this looks to be impossible as both calls are protected by 'if (group->container)' and the function NULL's group->container and it is all under the proper lock. My guess was that missing locking caused the two cases to race and trigger WARN, but the locking should fix that. So I'm at a loss, can you investigate a bit? Jason