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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [Patch 0/2] iscsit/isert deadlock prevention under heavy I/O Content-Language: en-US To: David Jeffery Cc: linux-rdma@vger.kernel.org, target-devel@vger.kernel.org, Sagi Grimberg , Laurence Oberman References: <20220311175713.2344960-1-djeffery@redhat.com> From: Max Gurtovoy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AM6P193CA0092.EURP193.PROD.OUTLOOK.COM (2603:10a6:209:88::33) To DM4PR12MB5040.namprd12.prod.outlook.com (2603:10b6:5:38b::19) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 8638ecb7-4c70-4fa0-86a1-08da05ca4414 X-MS-TrafficTypeDiagnostic: DM6PR12MB2761:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: c7hPt8xRWL/sRkcLOQRTmUClRCke0xTFnHBriyI/nCxxVWDVJQZpDtne07ZeB+4mUDvlum+McwGLsJSCjLYeMtfM9WrYJ2ahRffJieYWIy6Ws0jSUzJVPaRWuwM2OqvSvMXdASldsp/WZEwkYBLkj9ymhvBISLQNQ7c/o8gM9Mb/jdDm54NDHuYl7yTbtpgDkyfp4R8oQ/w0qFsrmbHGGxmuKGwT9uHXbgN3QslVKk3SRFqhAIKJBwzcu6wAIC+ZOWhdV9+8v/QjmpluNBDjgD1S+e9IHwPyI6nMq97b6LCrkChHRU9z+GFp3ntSJUvslqXKrFPxEirRd+NCBOsRhVv5mzYJG1FU83eYcgzJCRtExrrNovkUY+pP7bL5uBI8yi9ptW1gTJYtJdYVawTyK3NccHMi1k/GqTOPlQBgqvXGNDgrx7hn4DsfH2SeDmzppxdl4zTpOWn6jQBkKko1RLVLOjltv560WqzcOmewHk24IJWcDlHMGWIyBRUazBcK/6efVu2828L5hHWUbjGz0cbiA09r2qHYA+q90pUDdSsGW3uN9d8CcmhUEYoMtA7eQmuhBLY18fWWdc8R7dmUGeRmn9El7jPaycdb+7GHBYR+Qwyx9RVG/RXxXxWyqDP38OAREkXIz7OjE+4y4+HxwCEK0jp0TPFcHEGpjtboPZl4fJQzmfRmd/meUBRDe/MTdaFTHWzJ2qYnjwQFVWqf61xAjGSJ8pPpqZSssDbZuQA= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM4PR12MB5040.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(4636009)(366004)(316002)(4326008)(6666004)(6512007)(38100700002)(86362001)(31696002)(6506007)(53546011)(2906002)(8676002)(66476007)(54906003)(66556008)(36756003)(66946007)(6916009)(31686004)(6486002)(508600001)(8936002)(5660300002)(2616005)(186003)(26005)(45980500001)(43740500002);DIR:OUT;SFP:1101; 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Is there a particular reason you don't want > to do anything to modify max_cmd_sn behavior? according to the description the command was parsed successful and sent to the initiator. Why do we need to change the window ? it's just a race of putting the context back to the pool. And this race is rare. > > I didn't do something like this as it seems to me to go against the > intent of the design. It makes the iscsi window mostly meaningless in > some conditions and complicates any allocation path since it now must > gracefully and sanely handle an iscsi_cmd/isert_cmd not existing. I > assume special commands like task-management, logouts, and pings would > need a separate allocation source to keep from being dropped under > memory load. it won't be dropped. It would be allocated dynamically and freed (instead of putting it back to the pool). > David Jeffery >