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Biederman" , avagin@virtuozzo.com, gorcunov@virtuozzo.com References: <151066759055.14465.9783879083192000862.stgit@localhost.localdomain> From: Kirill Tkhai Message-ID: <88152c11-a5b5-90f8-be46-99ed6c722064@virtuozzo.com> Date: Tue, 14 Nov 2017 22:58:15 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [89.178.236.212] X-ClientProxiedBy: HE1PR1001CA0005.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:3:f7::15) To AM5PR0801MB1329.eurprd08.prod.outlook.com (2603:10a6:203:1f::7) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 1ccc79d3-3174-4903-5a16-08d52b9a1c89 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(4534020)(4602075)(4627115)(201703031133081)(201702281549075)(2017052603199);SRVR:AM5PR0801MB1329; X-Microsoft-Exchange-Diagnostics: 1;AM5PR0801MB1329;3:DD0he+2KIIP79ssQMqaxEirkjVE7tq+RPy2NZb4JCNoiTTY/6DHFOwpspj+VKoHbiXaJM0GteX3F07V+WJPuutapEYIaG6MPUAlUWDoPeycAszepHVYcXsh9IO87gtg35aN8iSEpIFtWrBVpT4FWkoRij9dYw8b3N6pEzZgf/udtHHDYI4ahDfmSFJG0km3Opmlj1m0RweYQ51lAQMqCXmoel6MMmbzJCyAnQGVxypEf55olCB6Tt+kQ4amcLRo5;25:WjGMFkFavsFMJvY3fJipPucCEOZcKQpepSkDuTMgBuF8uLYqeXI4+gBAptSUFBqbDfTQwXqJr6gHYmKTcZPhMsHlUfKTVtwDMMbw+r5GhAdXwxbmxhN0akmVajFhgv1PaUolo495PhuO2wdvaJUIdPxGGopRywaDBpikl7GbMCBuTfgPo1arYftL9cvvH6I3IdvS3hfTzsxySBJ2nlzjBcotUggJ54NZb8jfaNtr+kcPPDl3qH1udbZSpHR5P6TGLkMk/VBJO+yaZuKQrjAqSNiDU+sheWUy24LwlsBGJiH2bTG/3z6ET60uBRZYjki+qG5K7/3HNgIvIjnmKdzUdQ==;31:MpQWmsQ/J/cWsPNYr5YbuDx3nzZbDhDM7tUvDioR5TRppBy1ftMHRmFYh57J6r7eh9V8n6on3Ct1K5RRG2nAo8K330MGMkN48N+1koEicce3oDX9wru3YFn0KbspelTl6UFb4HYWbx8Yf5nxGix46j9JdNVrihdsvtdsgZPRgZYQjgVpIb/DNhj0lHTRuYmcRKvG0QkTElS1k9Kcn73dvcEMdnziqyR1WQhMk6aaAY8= X-MS-TrafficTypeDiagnostic: AM5PR0801MB1329: X-Microsoft-Exchange-Diagnostics: 1;AM5PR0801MB1329;20:ygi+wW+WB7+h/wmnp4OW2pE1piqHpiwSoE7y70s96YycmvBrXcxTR7aBouIFjYqFsazk3yeF2CEDMZuD5Ywy0nygRmapG7scxgkVm0I0w5TvkYljDfg0d6twKcK3veVo8QASUp2wQqit5miZ2K+OfubMa60SDPBFL4OQeb35ru3C0JO8fwPpmbXBy5q7GIxEq4UrXiodBO/X28qZXpVstB/x0I6RkfjEQLpn61F6XV+6rh+Hmu1G0MwqL76NKhdnTI/ZJJayvsYY23784e2n0eHbIak0SF2DTF3wY7h55k7chKj86QSFPRdbvH6B/OIG3br74oBAixl3+zG/em7TLFMuP0dM8SRLXsCiEgPQrBp7+sTfN3a5V+zr1TbPKElCO4KJnZnjmPoKowY5XG5KgrqkAaoi1gsPUw4Bp+/ejP0=;4:FeCtUmqVCI8gvp1ip4+e5FX9FYLr6nwf3CHYv4AH21nX0WJzbCl4t78ZWqySI1+IdRR379VeZm76JdCEoZMAMCMq68i6PydHmFL9QuqN4x6YxmRhy92hcONwGFuaYOFKGl/zYBZmR6zQsE0FccHd8nvG856D/Nm33/7wRnpV5RvVnNxKLUpkR0PY7cUyenQev6CKYrdQ5SGyrLXvYL9ROJnxudmjxaAHy8utUlr21qETQS48Pt7hEjfiRXFiQ8SQOpuEXKskEFLra3BRtGl3Uw== X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; 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>> >> - rv = mutex_lock_killable(&net_mutex); >> + rv = down_read_killable(&net_sem); >> if (rv < 0) { >> net_free(net); >> dec_net_namespaces(ucounts); >> @@ -421,7 +421,7 @@ struct net *copy_net_ns(unsigned long flags, >> list_add_tail_rcu(&net->list, &net_namespace_list); >> rtnl_unlock(); >> } >> - mutex_unlock(&net_mutex); >> + up_read(&net_sem); >> if (rv < 0) { >> dec_net_namespaces(ucounts); >> put_user_ns(user_ns); >> @@ -446,7 +446,7 @@ static void cleanup_net(struct work_struct *work) >> list_replace_init(&cleanup_list, &net_kill_list); >> spin_unlock_irq(&cleanup_list_lock); >> >> - mutex_lock(&net_mutex); >> + down_read(&net_sem); >> >> /* Don't let anyone else find us. */ >> rtnl_lock(); >> @@ -486,7 +486,7 @@ static void cleanup_net(struct work_struct *work) >> list_for_each_entry_reverse(ops, &pernet_list, list) >> ops_free_list(ops, &net_exit_list); >> >> - mutex_unlock(&net_mutex); >> + up_read(&net_sem); > > After your patch setup_net() could run concurrently with cleanup_net(), > given that ops_exit_list() is called on error path of setup_net() too, > it means ops->exit() now could run concurrently if it doesn't have its > own lock. Not sure if this breaks any existing user. Yes, there will be possible concurrent ops->init() for a net namespace, and ops->exit() for another one. I hadn't found pernet operations, which have a problem with that. If they exist, they are hidden and not clear seen. The pernet operations in general do not touch someone else's memory. If suddenly there is one, KASAN should show it after a while.