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 34DE0C433EF for ; Tue, 18 Jan 2022 19:01:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348580AbiARTBC (ORCPT ); Tue, 18 Jan 2022 14:01:02 -0500 Received: from mx0b-00069f02.pphosted.com ([205.220.177.32]:52370 "EHLO mx0b-00069f02.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244633AbiARTBA (ORCPT ); Tue, 18 Jan 2022 14:01:00 -0500 Received: from pps.filterd (m0246631.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20IHSgCU024410; Tue, 18 Jan 2022 19:00:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : date : subject : from : to : cc : references : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2021-07-09; bh=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=ybLVmXkVN7BtYdFgpwxbO7iBaxGAuXTNrFN+Cewfd64kANUdwGB5ifcSxOKklYXq4Syf Vu74gf8FBJqNnh29g5CMV/p+UBfuGZs8pKUWwXZ1TXvDy+Cxgk7mZq04WKzRxi/a32zT Sss9p/WTqdiwhDvK5fInAl1yTTP8Nvox/VS79nIA+b26bm04M21VxcCNZxTvh66nMC3J K+cvZn2MQX/C6eepRU17yD6cXGhuDGCYWitnvRHQkeYD2DAfHe2TmNkJXnZERiCbgK17 M1gntP05aZF19Lr4YYgutrhIr3tTGaTCYtDKCq4K+dgFnKEzy6s425Y9NuMUHXi+FA11 Vw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by mx0b-00069f02.pphosted.com with ESMTP id 3dnc4q2vr5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Jan 2022 19:00:45 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.1.2/8.16.1.2) with SMTP id 20IJ02mI024246; Tue, 18 Jan 2022 19:00:44 GMT Received: from nam10-dm6-obe.outbound.protection.outlook.com (mail-dm6nam10lp2108.outbound.protection.outlook.com [104.47.58.108]) by userp3020.oracle.com with ESMTP id 3dkqqnwnyp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Jan 2022 19:00:44 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ejGYmpjxx2VnKuTwbEUQmxVLzMRvk+9Q+We2nltCQP1Dve12J0mAj1LC6gMkng/uJbUy5RrlRgWNDrXOU7bJ6LVy2TzITNalX/i1oodrHV2iyKrH5NoLT7nRR2aJyaYJnkpsMf4r25Jiw8FaLFqjKOJwxDEkHHEnAg4muU2Ts6v6LmDfJbfvUbMdbxoeRGoYbN09MHPoa124EtFLEWfmvzgxaARwMy6vLMa7AUph+tym9i+rNUAhqJcq3XQVzMsb5qC1lduY78GoHWV8llNRZAWINIeoj4vJGnZ4ZjR8BUygZ7uWD1vm8/p0OINgwtwlQSlcbYNvTsWDwRd2HEPJHQ== 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=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=FS1E3v0MAfQU/30ea5u+AjzjPe1fvKXyL03J0emMTyX/zYrB/NmDQkKABeQDWi87WUzMysfkhfiSQsJWVN6Ha9MVRIIE95J4Dtm8qpyNYM3ptP7pLZNtDVNBhShOs7xrgu/RJSd+xraa7ef7BeBFB9TdbNvQPZye2hKmRCcY6DXljklWOA9nBxrOAS7c84K6k3Q6VvJQHbcMly4YXAsvHP76vZ0J5e6bEfKvKJUslQRzR/1xPqoTfN3tkM0tc9Vt7dQ38FaQh7EvJ/EAzoiwRZ2i8S3iiIp+L/cQAKHWeTb3QOPejl69LMbELVW+ez4FaYIoK1/3FTuYPYYyO1Od6Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=L4j07e5jieP22kwhkEnj7yaxIj6kFhgH8ZwI6ilxIg9b+QjhOtTQoJCP8F6H2n+u+kqrIwM6lZt+ePyKDMUzLFcX6dlF/Cp3lTHu/v2GKZKa2lBtkwHlJzmg6ThYY0v3gu5LWMcF9HEH7eNb0D03KbqDRhjrDPst5EVipnnXT+0= Received: from DM5PR10MB1466.namprd10.prod.outlook.com (2603:10b6:3:b::7) by PH0PR10MB5795.namprd10.prod.outlook.com (2603:10b6:510:ff::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4909.7; Tue, 18 Jan 2022 19:00:41 +0000 Received: from DM5PR10MB1466.namprd10.prod.outlook.com ([fe80::21b5:910:b965:9e6c]) by DM5PR10MB1466.namprd10.prod.outlook.com ([fe80::21b5:910:b965:9e6c%6]) with mapi id 15.20.4888.014; Tue, 18 Jan 2022 19:00:41 +0000 Message-ID: <201528df-4474-b544-e25a-9746e30df04d@oracle.com> Date: Tue, 18 Jan 2022 13:00:39 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH V6 01/10] Use copy_process in vhost layer Content-Language: en-US From: Mike Christie To: "Eric W. Biederman" Cc: geert@linux-m68k.org, vverma@digitalocean.com, hdanton@sina.com, hch@infradead.org, stefanha@redhat.com, jasowang@redhat.com, mst@redhat.com, sgarzare@redhat.com, virtualization@lists.linux-foundation.org, christian.brauner@ubuntu.com, axboe@kernel.dk, linux-kernel@vger.kernel.org References: <20211129194707.5863-1-michael.christie@oracle.com> <87tuf79gni.fsf@email.froward.int.ebiederm.org> <87tuf11oe6.fsf@email.froward.int.ebiederm.org> <87pmpoxzuf.fsf@email.froward.int.ebiederm.org> <783145b7-243b-b85e-e274-44ef6c0696b9@oracle.com> <874k62b76d.fsf@email.froward.int.ebiederm.org> <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> In-Reply-To: <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: CH2PR15CA0005.namprd15.prod.outlook.com (2603:10b6:610:51::15) To DM5PR10MB1466.namprd10.prod.outlook.com (2603:10b6:3:b::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 8478894c-785d-4e2d-ae22-08d9dab4d2c9 X-MS-TrafficTypeDiagnostic: PH0PR10MB5795:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; 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:DM5PR10MB1466.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(366004)(83380400001)(4326008)(26005)(316002)(186003)(508600001)(6916009)(86362001)(6506007)(53546011)(6486002)(6512007)(2906002)(5660300002)(7416002)(31696002)(2616005)(8936002)(38100700002)(36756003)(66556008)(66476007)(66946007)(31686004)(8676002)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?RGJaYmtIbXk4dmt6M0pkQnhWSElZL24wR1FRQXJxSldvbmZOTTQ3Sm5CbzlN?= =?utf-8?B?STBzaTZwUG9tVVJMbUJhNmI0MjZIdEc2NkdaWWFwSW0vQnpwd0pycTQxcGVE?= =?utf-8?B?WHJlUmN4V0hlcDN3bjc4NEtBOEJ6UjRyVUxGeUl0MFJ3VEkrS2tvVzRpeDEz?= =?utf-8?B?SFl0WHZIR1NXbWhGVUk0ZDBHNXRFU0UxWDIya01pTW5mbDZQMitLOGZ6aUox?= =?utf-8?B?NGVZZFc3SXpwd2lsSW8zLzlaSTFiQlJaeFEvQ05CeXBDY2RKd0tGcEllOExu?= =?utf-8?B?MFhwcmhSZlZIUUk5Z2RDQjlTUUdmUjZ4Q29Rd014cnl4TCtZWktEcVVqdUJX?= =?utf-8?B?NEJ6R1ZUZW5SVXJLWkJpcmJHY2pCU3ZabzNiK2xiUW1ua2YvQWk0L2xwYWFF?= =?utf-8?B?TFhWbkdRaTV1MGozcEY5eWVqQjNicjdMZXNFaXZBcnhJOXkxOWI0RVRsOXky?= =?utf-8?B?SGxMU2VQd1NVMllJQkpDaFRpQlJpc3hYYmNrWmtVclBBMWw4V2M5RHpYaXNR?= =?utf-8?B?djF4emR1MzJ1OFlreGxaVTZuaHAwZEdVSmQxOUlYaW9QT0FzVmQyYUdlMm0r?= =?utf-8?B?b2RzamVINzM0UlM2Y0ZOaXhQWU4yaW9TZHhZSFRWOFlqbnNPWmxPWFltUEJ1?= =?utf-8?B?TThiWTdqRlMrM1g5N0hTMUJ5REF5T1FJbzc5SzlvWlRvZ3QySlM2U25BZ3Zx?= =?utf-8?B?NWhPUWZZUWhXc2pBTTZweEVwTVVTdFFSUzNiUDJBUVFkcDRaU3grRk8zZnhM?= =?utf-8?B?d3U2dFlCc3kxdWhEcU9RQ0t3Zlc3TjNtT0lHcWRmdXRpMHZ2dWk0bnY5NU40?= =?utf-8?B?cmVnbTVYMU8wRm5vNEY2MVU2cmxYNlN0ZWZ2SU5ja2U0cXlxRjQ5Qm11VU1w?= =?utf-8?B?cnNsd0RNak9vMFNuOGVwdURDLzZZelBMYml6Y21mYzhlV3JQKzBHbEVMR2s2?= =?utf-8?B?Rm05OEx2VWI1VEJKYjFzUi9LUm9wSEpPY0lkakpVc09kUEpvMSt5S1FGNml1?= =?utf-8?B?Y055aU9LVzFyWGZ1T2tVUWp3UEJORTNPcXhZaDJYNzdNK2VjVnJFTTNCL3ht?= =?utf-8?B?VDJTbnQ5VzJiUUFyM1Y3UWRLcjVXc21lamJIc3JCT0NsRlNCRWJMQ1dKMXQv?= =?utf-8?B?TzF0bFVCWGVUMURMNWpzM3NZWUNkSGk5bUE5VEVuTDZiaVA2RytVRWtzM3Zj?= =?utf-8?B?eFlBZ2pQcm9TVW53QXJ5OW9hUnVOV0llZFo3ZFp2cDhMditDdXg2Sm5ZelRW?= =?utf-8?B?L0g0M2xzc2VWaTBqL0JGdGxvREdWYWpEcE5lMTgzcDgrTmh4cFNnSGN2aHF0?= =?utf-8?B?TUpRNFBOVWRZUkVlRE5uN0UzZ2Jydm5VdldYNFBscndMaW9ManBVRy9LaEh3?= =?utf-8?B?ZFlxSCtkcm9lQkhma2dKcS9zckEzMkVScUJDN2h5dDllYVFzTE5oQnZkTmtD?= =?utf-8?B?Q3VSUnhqck1waDVoUklLM0dJNUkxR2V6b3NHdHFmdW14WHJRL1kyRFpLSnEy?= =?utf-8?B?d05zK1BsZEsxY1kvSWVoa1lhM1ZoOUpDREpXY2hpc2E5RzVCc05lWnVNM0sv?= =?utf-8?B?L3dvUkJ6cGpvOEVQQzdFQWlWYnYxK3d6QU41dmhOYktKUkZ1b2orYmZWeUhY?= =?utf-8?B?L25yeWJtR210Skg4d3RMdmRGR0FXRGRYWjhINFhldWU2V3J5UFNVU1Jtakly?= =?utf-8?B?MU13L3ZxWThHdDFEZngyMG4xSTJDUTdabTY0QWRaZ2dveFljWExHT2xvVUJa?= =?utf-8?B?TklCOUxJNzdBV1B2ZzJESVpPNThmRlVzelRUU01PMmFLRjBYN3J2c1QvV3Ry?= =?utf-8?B?NzhEUDIwVmJDYU10L2plODFnSTZlNE85dS96aTFHREgxZ2RUaUZUTCtzS0cy?= =?utf-8?B?V2pMUWh0YnZiMTV4TE9hRm9pczBwSWlFRjhUY3hEamhIRytWOTdWd0ZzYWV5?= =?utf-8?B?WWdKZTRuSFlodmNheFI3Y1RVL0EwM0hRNXVSQWZVckMyaVdBeS8yTjZyNDdu?= =?utf-8?B?WEZnT2QwLzNnd1FkWDd4MWx5UHl0bFJNZzZCVXZMZW5hL0c0LzJRUG5oYkVS?= =?utf-8?B?bTdmdE8vajVKNGhJWHdJN2UyclY4SnpUOU9zQ29PczNGREg3NDFaTjk3TVVL?= =?utf-8?B?Qy9BTW05Mi9hb0ViL0IzYmFGd3pJNEFqN0lRbFlpb01aT1BjbE1lNjUzSVhZ?= =?utf-8?B?MGtZZlZQQ05EazZPRlhPSnRvZTdRQWNJbUdpaDdmaTl2MTAwcWU3bUdoK3VN?= =?utf-8?B?T1ovR1VmclZ4dUQwc3R4MXc4Z0FnPT0=?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8478894c-785d-4e2d-ae22-08d9dab4d2c9 X-MS-Exchange-CrossTenant-AuthSource: DM5PR10MB1466.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jan 2022 19:00:41.7224 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: okCPvJgD1Iqd1Aenu/hGT3jZ+4GgPKsdBo9s9hT63FqWsdKuM9dyIDoq5g42z9PFuold88LuTo/rPwF4sUI6Pac0ZiNghr8sI77MWfEZc6A= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR10MB5795 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10231 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 mlxlogscore=999 malwarescore=0 bulkscore=0 suspectscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201180113 X-Proofpoint-GUID: PhsSQegpFunzt2h9r632j-a8CAOOGFmf X-Proofpoint-ORIG-GUID: PhsSQegpFunzt2h9r632j-a8CAOOGFmf Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/18/22 12:51 PM, Mike Christie wrote: > On 1/17/22 11:31 AM, Eric W. Biederman wrote: >> Mike Christie writes: >> >>> On 12/22/21 12:24 PM, Eric W. Biederman wrote: >>>> All I am certain of is that you need to set >>>> "args->exit_signal = -1;". This prevents having to play games with >>>> do_notify_parent. >>> >>> Hi Eric, >>> >>> I have all your review comments handled except this one. It's looking like it's >>> more difficult than just setting the exit_signal=-1, so I wanted to check that >>> I understood you. >> >> [snip problems with exit_signal = -1] >> >>> >>> What do you think? >> >> I was wrong. I appear to have confused the thread and the non-thread >> cases. >> >> Perhaps I meant "args->exit_signal = 0". That looks like >> do_notify_parent won't send it, and thread_group_leader continues to do >> the right thing. > > That doesn't work too. exit_notify will call do_notify_parent but > our parent, qemu, does not ignore SIGCHILD so we will not drop > down in into this chunk: > > psig = tsk->parent->sighand; > spin_lock_irqsave(&psig->siglock, flags); > if (!tsk->ptrace && sig == SIGCHLD && > (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || > (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { > > do_notify_parent will return false and so autoreap in exit_notify will > be false. > > > >> >> Baring any additional confusion on my part that cleanly solves the >> problem of how not to send a signal from a child process cleanly. >> Oh yeah, maybe we are thinking about different things. The issue I am hitting is that the parent, qemu, does not know about these task_structs. And, userspace can add/delete these vhost devices dynamically. So qemu could continue to run, but the vhost device could be deleted. In this case I want to free up the task_struct resources since we are no longer using it. With kthreads do_notify_parent returns true and exit_notify calls release_task, so it's handled for me. I had stuck in the USER/VHOST check in the patch you didn't like to get that behavior. If you prefer not adding the VHOST/USER task check in exit_notify then instead of auto reaping, would another possible alternative be to add a modified kernel_wait like function in the vhost layer to reap the task? 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 smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 DC73AC433F5 for ; Tue, 18 Jan 2022 19:00:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 6E75460E5C; Tue, 18 Jan 2022 19:00:56 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ToLM0gEVBeUJ; Tue, 18 Jan 2022 19:00:55 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTPS id EF8ED60E51; Tue, 18 Jan 2022 19:00:54 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id A91D5C0039; Tue, 18 Jan 2022 19:00:54 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [IPv6:2605:bc80:3010::137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 243E5C002F for ; Tue, 18 Jan 2022 19:00:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 0C63B4091D for ; Tue, 18 Jan 2022 19:00:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp4.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=oracle.com header.b="ybLVmXkV"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.b="L4j07e5j" Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Dv-Y_SHUKmXE for ; Tue, 18 Jan 2022 19:00:52 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by smtp4.osuosl.org (Postfix) with ESMTPS id 1CF1340911 for ; Tue, 18 Jan 2022 19:00:51 +0000 (UTC) Received: from pps.filterd (m0246631.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20IHSgCU024410; Tue, 18 Jan 2022 19:00:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : date : subject : from : to : cc : references : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2021-07-09; bh=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=ybLVmXkVN7BtYdFgpwxbO7iBaxGAuXTNrFN+Cewfd64kANUdwGB5ifcSxOKklYXq4Syf Vu74gf8FBJqNnh29g5CMV/p+UBfuGZs8pKUWwXZ1TXvDy+Cxgk7mZq04WKzRxi/a32zT Sss9p/WTqdiwhDvK5fInAl1yTTP8Nvox/VS79nIA+b26bm04M21VxcCNZxTvh66nMC3J K+cvZn2MQX/C6eepRU17yD6cXGhuDGCYWitnvRHQkeYD2DAfHe2TmNkJXnZERiCbgK17 M1gntP05aZF19Lr4YYgutrhIr3tTGaTCYtDKCq4K+dgFnKEzy6s425Y9NuMUHXi+FA11 Vw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by mx0b-00069f02.pphosted.com with ESMTP id 3dnc4q2vr5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Jan 2022 19:00:45 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.1.2/8.16.1.2) with SMTP id 20IJ02mI024246; Tue, 18 Jan 2022 19:00:44 GMT Received: from nam10-dm6-obe.outbound.protection.outlook.com (mail-dm6nam10lp2108.outbound.protection.outlook.com [104.47.58.108]) by userp3020.oracle.com with ESMTP id 3dkqqnwnyp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Jan 2022 19:00:44 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ejGYmpjxx2VnKuTwbEUQmxVLzMRvk+9Q+We2nltCQP1Dve12J0mAj1LC6gMkng/uJbUy5RrlRgWNDrXOU7bJ6LVy2TzITNalX/i1oodrHV2iyKrH5NoLT7nRR2aJyaYJnkpsMf4r25Jiw8FaLFqjKOJwxDEkHHEnAg4muU2Ts6v6LmDfJbfvUbMdbxoeRGoYbN09MHPoa124EtFLEWfmvzgxaARwMy6vLMa7AUph+tym9i+rNUAhqJcq3XQVzMsb5qC1lduY78GoHWV8llNRZAWINIeoj4vJGnZ4ZjR8BUygZ7uWD1vm8/p0OINgwtwlQSlcbYNvTsWDwRd2HEPJHQ== 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=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=FS1E3v0MAfQU/30ea5u+AjzjPe1fvKXyL03J0emMTyX/zYrB/NmDQkKABeQDWi87WUzMysfkhfiSQsJWVN6Ha9MVRIIE95J4Dtm8qpyNYM3ptP7pLZNtDVNBhShOs7xrgu/RJSd+xraa7ef7BeBFB9TdbNvQPZye2hKmRCcY6DXljklWOA9nBxrOAS7c84K6k3Q6VvJQHbcMly4YXAsvHP76vZ0J5e6bEfKvKJUslQRzR/1xPqoTfN3tkM0tc9Vt7dQ38FaQh7EvJ/EAzoiwRZ2i8S3iiIp+L/cQAKHWeTb3QOPejl69LMbELVW+ez4FaYIoK1/3FTuYPYYyO1Od6Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=xVruDj0UAiKX6qx5/58vjt+11Os6pI3I4rHAc4sg4K8=; b=L4j07e5jieP22kwhkEnj7yaxIj6kFhgH8ZwI6ilxIg9b+QjhOtTQoJCP8F6H2n+u+kqrIwM6lZt+ePyKDMUzLFcX6dlF/Cp3lTHu/v2GKZKa2lBtkwHlJzmg6ThYY0v3gu5LWMcF9HEH7eNb0D03KbqDRhjrDPst5EVipnnXT+0= Received: from DM5PR10MB1466.namprd10.prod.outlook.com (2603:10b6:3:b::7) by PH0PR10MB5795.namprd10.prod.outlook.com (2603:10b6:510:ff::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4909.7; Tue, 18 Jan 2022 19:00:41 +0000 Received: from DM5PR10MB1466.namprd10.prod.outlook.com ([fe80::21b5:910:b965:9e6c]) by DM5PR10MB1466.namprd10.prod.outlook.com ([fe80::21b5:910:b965:9e6c%6]) with mapi id 15.20.4888.014; Tue, 18 Jan 2022 19:00:41 +0000 Message-ID: <201528df-4474-b544-e25a-9746e30df04d@oracle.com> Date: Tue, 18 Jan 2022 13:00:39 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH V6 01/10] Use copy_process in vhost layer Content-Language: en-US From: Mike Christie To: "Eric W. Biederman" References: <20211129194707.5863-1-michael.christie@oracle.com> <87tuf79gni.fsf@email.froward.int.ebiederm.org> <87tuf11oe6.fsf@email.froward.int.ebiederm.org> <87pmpoxzuf.fsf@email.froward.int.ebiederm.org> <783145b7-243b-b85e-e274-44ef6c0696b9@oracle.com> <874k62b76d.fsf@email.froward.int.ebiederm.org> <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> In-Reply-To: <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> X-ClientProxiedBy: CH2PR15CA0005.namprd15.prod.outlook.com (2603:10b6:610:51::15) To DM5PR10MB1466.namprd10.prod.outlook.com (2603:10b6:3:b::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 8478894c-785d-4e2d-ae22-08d9dab4d2c9 X-MS-TrafficTypeDiagnostic: PH0PR10MB5795:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; 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:DM5PR10MB1466.namprd10.prod.outlook.com; PTR:; CAT:NONE; SFS:(366004)(83380400001)(4326008)(26005)(316002)(186003)(508600001)(6916009)(86362001)(6506007)(53546011)(6486002)(6512007)(2906002)(5660300002)(7416002)(31696002)(2616005)(8936002)(38100700002)(36756003)(66556008)(66476007)(66946007)(31686004)(8676002)(43740500002)(45980500001); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?RGJaYmtIbXk4dmt6M0pkQnhWSElZL24wR1FRQXJxSldvbmZOTTQ3Sm5CbzlN?= =?utf-8?B?STBzaTZwUG9tVVJMbUJhNmI0MjZIdEc2NkdaWWFwSW0vQnpwd0pycTQxcGVE?= =?utf-8?B?WHJlUmN4V0hlcDN3bjc4NEtBOEJ6UjRyVUxGeUl0MFJ3VEkrS2tvVzRpeDEz?= =?utf-8?B?SFl0WHZIR1NXbWhGVUk0ZDBHNXRFU0UxWDIya01pTW5mbDZQMitLOGZ6aUox?= =?utf-8?B?NGVZZFc3SXpwd2lsSW8zLzlaSTFiQlJaeFEvQ05CeXBDY2RKd0tGcEllOExu?= =?utf-8?B?MFhwcmhSZlZIUUk5Z2RDQjlTUUdmUjZ4Q29Rd014cnl4TCtZWktEcVVqdUJX?= =?utf-8?B?NEJ6R1ZUZW5SVXJLWkJpcmJHY2pCU3ZabzNiK2xiUW1ua2YvQWk0L2xwYWFF?= =?utf-8?B?TFhWbkdRaTV1MGozcEY5eWVqQjNicjdMZXNFaXZBcnhJOXkxOWI0RVRsOXky?= =?utf-8?B?SGxMU2VQd1NVMllJQkpDaFRpQlJpc3hYYmNrWmtVclBBMWw4V2M5RHpYaXNR?= =?utf-8?B?djF4emR1MzJ1OFlreGxaVTZuaHAwZEdVSmQxOUlYaW9QT0FzVmQyYUdlMm0r?= =?utf-8?B?b2RzamVINzM0UlM2Y0ZOaXhQWU4yaW9TZHhZSFRWOFlqbnNPWmxPWFltUEJ1?= =?utf-8?B?TThiWTdqRlMrM1g5N0hTMUJ5REF5T1FJbzc5SzlvWlRvZ3QySlM2U25BZ3Zx?= =?utf-8?B?NWhPUWZZUWhXc2pBTTZweEVwTVVTdFFSUzNiUDJBUVFkcDRaU3grRk8zZnhM?= =?utf-8?B?d3U2dFlCc3kxdWhEcU9RQ0t3Zlc3TjNtT0lHcWRmdXRpMHZ2dWk0bnY5NU40?= =?utf-8?B?cmVnbTVYMU8wRm5vNEY2MVU2cmxYNlN0ZWZ2SU5ja2U0cXlxRjQ5Qm11VU1w?= =?utf-8?B?cnNsd0RNak9vMFNuOGVwdURDLzZZelBMYml6Y21mYzhlV3JQKzBHbEVMR2s2?= =?utf-8?B?Rm05OEx2VWI1VEJKYjFzUi9LUm9wSEpPY0lkakpVc09kUEpvMSt5S1FGNml1?= =?utf-8?B?Y055aU9LVzFyWGZ1T2tVUWp3UEJORTNPcXhZaDJYNzdNK2VjVnJFTTNCL3ht?= =?utf-8?B?VDJTbnQ5VzJiUUFyM1Y3UWRLcjVXc21lamJIc3JCT0NsRlNCRWJMQ1dKMXQv?= =?utf-8?B?TzF0bFVCWGVUMURMNWpzM3NZWUNkSGk5bUE5VEVuTDZiaVA2RytVRWtzM3Zj?= =?utf-8?B?eFlBZ2pQcm9TVW53QXJ5OW9hUnVOV0llZFo3ZFp2cDhMditDdXg2Sm5ZelRW?= =?utf-8?B?L0g0M2xzc2VWaTBqL0JGdGxvREdWYWpEcE5lMTgzcDgrTmh4cFNnSGN2aHF0?= =?utf-8?B?TUpRNFBOVWRZUkVlRE5uN0UzZ2Jydm5VdldYNFBscndMaW9ManBVRy9LaEh3?= =?utf-8?B?ZFlxSCtkcm9lQkhma2dKcS9zckEzMkVScUJDN2h5dDllYVFzTE5oQnZkTmtD?= =?utf-8?B?Q3VSUnhqck1waDVoUklLM0dJNUkxR2V6b3NHdHFmdW14WHJRL1kyRFpLSnEy?= =?utf-8?B?d05zK1BsZEsxY1kvSWVoa1lhM1ZoOUpDREpXY2hpc2E5RzVCc05lWnVNM0sv?= =?utf-8?B?L3dvUkJ6cGpvOEVQQzdFQWlWYnYxK3d6QU41dmhOYktKUkZ1b2orYmZWeUhY?= =?utf-8?B?L25yeWJtR210Skg4d3RMdmRGR0FXRGRYWjhINFhldWU2V3J5UFNVU1Jtakly?= =?utf-8?B?MU13L3ZxWThHdDFEZngyMG4xSTJDUTdabTY0QWRaZ2dveFljWExHT2xvVUJa?= =?utf-8?B?TklCOUxJNzdBV1B2ZzJESVpPNThmRlVzelRUU01PMmFLRjBYN3J2c1QvV3Ry?= =?utf-8?B?NzhEUDIwVmJDYU10L2plODFnSTZlNE85dS96aTFHREgxZ2RUaUZUTCtzS0cy?= =?utf-8?B?V2pMUWh0YnZiMTV4TE9hRm9pczBwSWlFRjhUY3hEamhIRytWOTdWd0ZzYWV5?= =?utf-8?B?WWdKZTRuSFlodmNheFI3Y1RVL0EwM0hRNXVSQWZVckMyaVdBeS8yTjZyNDdu?= =?utf-8?B?WEZnT2QwLzNnd1FkWDd4MWx5UHl0bFJNZzZCVXZMZW5hL0c0LzJRUG5oYkVS?= =?utf-8?B?bTdmdE8vajVKNGhJWHdJN2UyclY4SnpUOU9zQ29PczNGREg3NDFaTjk3TVVL?= =?utf-8?B?Qy9BTW05Mi9hb0ViL0IzYmFGd3pJNEFqN0lRbFlpb01aT1BjbE1lNjUzSVhZ?= =?utf-8?B?MGtZZlZQQ05EazZPRlhPSnRvZTdRQWNJbUdpaDdmaTl2MTAwcWU3bUdoK3VN?= =?utf-8?B?T1ovR1VmclZ4dUQwc3R4MXc4Z0FnPT0=?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8478894c-785d-4e2d-ae22-08d9dab4d2c9 X-MS-Exchange-CrossTenant-AuthSource: DM5PR10MB1466.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jan 2022 19:00:41.7224 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: okCPvJgD1Iqd1Aenu/hGT3jZ+4GgPKsdBo9s9hT63FqWsdKuM9dyIDoq5g42z9PFuold88LuTo/rPwF4sUI6Pac0ZiNghr8sI77MWfEZc6A= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR10MB5795 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10231 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 mlxlogscore=999 malwarescore=0 bulkscore=0 suspectscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201180113 X-Proofpoint-GUID: PhsSQegpFunzt2h9r632j-a8CAOOGFmf X-Proofpoint-ORIG-GUID: PhsSQegpFunzt2h9r632j-a8CAOOGFmf Cc: axboe@kernel.dk, hdanton@sina.com, mst@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@infradead.org, vverma@digitalocean.com, geert@linux-m68k.org, stefanha@redhat.com, christian.brauner@ubuntu.com X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On 1/18/22 12:51 PM, Mike Christie wrote: > On 1/17/22 11:31 AM, Eric W. Biederman wrote: >> Mike Christie writes: >> >>> On 12/22/21 12:24 PM, Eric W. Biederman wrote: >>>> All I am certain of is that you need to set >>>> "args->exit_signal = -1;". This prevents having to play games with >>>> do_notify_parent. >>> >>> Hi Eric, >>> >>> I have all your review comments handled except this one. It's looking like it's >>> more difficult than just setting the exit_signal=-1, so I wanted to check that >>> I understood you. >> >> [snip problems with exit_signal = -1] >> >>> >>> What do you think? >> >> I was wrong. I appear to have confused the thread and the non-thread >> cases. >> >> Perhaps I meant "args->exit_signal = 0". That looks like >> do_notify_parent won't send it, and thread_group_leader continues to do >> the right thing. > > That doesn't work too. exit_notify will call do_notify_parent but > our parent, qemu, does not ignore SIGCHILD so we will not drop > down in into this chunk: > > psig = tsk->parent->sighand; > spin_lock_irqsave(&psig->siglock, flags); > if (!tsk->ptrace && sig == SIGCHLD && > (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || > (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { > > do_notify_parent will return false and so autoreap in exit_notify will > be false. > > > >> >> Baring any additional confusion on my part that cleanly solves the >> problem of how not to send a signal from a child process cleanly. >> Oh yeah, maybe we are thinking about different things. The issue I am hitting is that the parent, qemu, does not know about these task_structs. And, userspace can add/delete these vhost devices dynamically. So qemu could continue to run, but the vhost device could be deleted. In this case I want to free up the task_struct resources since we are no longer using it. With kthreads do_notify_parent returns true and exit_notify calls release_task, so it's handled for me. I had stuck in the USER/VHOST check in the patch you didn't like to get that behavior. If you prefer not adding the VHOST/USER task check in exit_notify then instead of auto reaping, would another possible alternative be to add a modified kernel_wait like function in the vhost layer to reap the task? _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization