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McKenney" References: <20200818162408.836759-1-yhs@fb.com> <20200818162408.836816-1-yhs@fb.com> From: Yonghong Song Message-ID: Date: Tue, 18 Aug 2020 10:13:58 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MN2PR15CA0007.namprd15.prod.outlook.com (2603:10b6:208:1b4::20) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c0a8:11e8::10d3] (2620:10d:c091:480::1:a06c) by MN2PR15CA0007.namprd15.prod.outlook.com (2603:10b6:208:1b4::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3305.24 via Frontend Transport; Tue, 18 Aug 2020 17:14:01 +0000 X-Originating-IP: [2620:10d:c091:480::1:a06c] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 26800ad1-5849-4050-a293-08d8439a1ae2 X-MS-TrafficTypeDiagnostic: BYAPR15MB2488: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:7691; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: b+rYV7KibL0l/aYGWXMfmTpjfVt5q3sNwEHYkzSEOPka00cxdCQPSk92QJkLFGdWTBmQZGlf561HHqeZlxWC05P0vyimHs8vsLM3Osa+H3yc/HHebNR3dfjWoQuz7DlGRCq18YLNpxUeZTcMIzaBnjXQjZ/R/udxqDpa4d5DnUVV1ncWl6jXbS/wZ2Ln7yLp2YZJWKkfY2ZVlhYikilSFIW6K0fq6exQGYtWzL4LQi/kJcWEGqO6ba2MzWjn/BWLuyTt/d7gMVZxCgEIRoVBeVYy08AlheafdIvWIRwHnKm8qKuL3KIK9xFfSJt6edJpqtWUkE22gmoQIny14DK6KDnJAGFpgxAm6nUZwH1Xnbj7aoM8GHFvQJiTNkFLVl9I X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB4088.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(366004)(136003)(346002)(396003)(39860400002)(376002)(83380400001)(31686004)(36756003)(86362001)(5660300002)(52116002)(2906002)(66946007)(53546011)(66556008)(31696002)(54906003)(66476007)(6916009)(16526019)(6666004)(186003)(8676002)(478600001)(8936002)(6486002)(316002)(2616005)(4326008)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: Cw2tiUcEIVDh8A9DvBY7NujKfdQpF/mT/Xsy/zeBj4c8oHq6VAAZxeUEuvgcwFCQzGKk8fOiniLcSBQ4PScBMEAnUcRtC97Qk/lHqJvIzazlnJeFaBqgctepfozVvjvyeKQbo7+3LRbGdSSWUPUNNjfvj2MWtHffhHsIPU7ksCvFMTNTTc4NPihgOveQsh1osPKzOr8YHP5zkUceIAbpqCLqiJnqoym85KTUBv3sUC6NaANe6IdQG47ij+QnG+/d15npxBlgyOCChNKWcS1jKXkmqCkRggai8ezskm2E2Sr2o+QUaB8HtMousBPurdq2FEuzEEAjEbJtNuUt9W+51caZblyNQkLZ0W4ifdQE9yw8x7Ws/t1CNNANVQwJ7wWo/P4/uwvSNSSwUY4BiQuwnYKiq1tp1XLWmwN/9zZMNSCGQRaaqnsouAssffMn5SBRsAipFzCvTfR3zDX9do6RbDCGhjwo/p1+Pz5ugdJ8hhckRI64sO4Ke1nedPfXkFQQrcwYACoHeQ5Xo6RE6VrlADYOG4EV7Q0c8/myR3V0NGGiTp8L4DGH1bpdW8wgztQ/E/s2ajR9dq3uLYa+GD+wBQf5igc1NVa9VXFjbqeNAYewtStKeJG3gD1eB03DkXgcFIB3PkioOSSSbelPKq4oKZMuqMldHIbHk1aM2NIQ+dAp2EitaTyziB+iR387BIAz X-MS-Exchange-CrossTenant-Network-Message-Id: 26800ad1-5849-4050-a293-08d8439a1ae2 X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4088.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2020 17:14:02.9779 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: zlXIxp4A4XFX8hoLTg73rkRQcnPK29uij1SxrpMWquOfLQG41etPTPp7cg1Lh0vQ X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2488 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-18_11:2020-08-18,2020-08-18 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=999 spamscore=0 mlxscore=0 clxscore=1015 suspectscore=0 adultscore=0 bulkscore=0 impostorscore=0 phishscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008180121 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8/18/20 10:06 AM, Alexei Starovoitov wrote: > On Tue, Aug 18, 2020 at 9:24 AM Yonghong Song wrote: >> index f21b5e1e4540..885b14cab2c0 100644 >> --- a/kernel/bpf/task_iter.c >> +++ b/kernel/bpf/task_iter.c >> @@ -27,6 +27,8 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, >> struct task_struct *task = NULL; >> struct pid *pid; >> >> + cond_resched(); >> + >> rcu_read_lock(); >> retry: >> pid = idr_get_next(&ns->idr, tid); >> @@ -137,6 +139,8 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info, >> struct task_struct *curr_task; >> int curr_fd = info->fd; >> >> + cond_resched(); >> + > > Instead of adding it to every *seq_get_next() it probably should be in > bpf_seq_read(). Yes, we can add cond_resched() to bpf_seq_read(). This should cover both cases. Will make the change. > If cond_resched() is needed in task_file_seq_get_next() it should > probably be after 'again:'. We probably do not need here unless all tasks have zero files or each file just closed with f->f_count == 0 but the file pointer still there.