From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754535AbeALImo (ORCPT + 1 other); Fri, 12 Jan 2018 03:42:44 -0500 Received: from mail-eopbgr60129.outbound.protection.outlook.com ([40.107.6.129]:61128 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754273AbeALIml (ORCPT ); Fri, 12 Jan 2018 03:42:41 -0500 Subject: Re: [PATCH 3/4] tty: Iterate only thread group leaders in __do_SAK() To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, jslaby@suse.com, viro@zeniv.linux.org.uk, keescook@chromium.org, serge@hallyn.com, james.l.morris@oracle.com, luto@kernel.org, john.johansen@canonical.com, mingo@kernel.org, akpm@linux-foundation.org, mhocko@suse.com, peterz@infradead.org References: <151568564127.6090.3546718160925256054.stgit@localhost.localdomain> <151568582337.6090.931248807289363396.stgit@localhost.localdomain> <20180111183412.GA18725@redhat.com> From: Kirill Tkhai Message-ID: <9a854275-7a72-fc54-99fa-66161732fbf9@virtuozzo.com> Date: Fri, 12 Jan 2018 11:42:30 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20180111183412.GA18725@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [195.214.232.6] X-ClientProxiedBy: DB6P193CA0013.EURP193.PROD.OUTLOOK.COM (2603:10a6:6:29::23) To AM5PR0801MB1332.eurprd08.prod.outlook.com (2603:10a6:203:1f::10) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: c708f5b6-cdd5-4e2e-f7af-08d559986d81 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020079)(4652020)(5600026)(4604075)(2017052603307)(7153060)(7193020);SRVR:AM5PR0801MB1332; X-Microsoft-Exchange-Diagnostics: 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X-Microsoft-Exchange-Diagnostics: 1;AM5PR0801MB1332;20:omBb7dZNbQff6kR6HSIg8AAgEE1EcKtiMea9JquXDNOb67LCCyc6mql6j76rSEJgGSeGIDe6tZBTQoeaKRkRWkulbGUOnt5o/WpBV78MnX86CtrpHIYaFlCjORZN16T9AhI+uCO8RW1aNxErdgb1Yg5HUhWg5lJNZNz3UeXNk8k= X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Jan 2018 08:42:33.6177 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c708f5b6-cdd5-4e2e-f7af-08d559986d81 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM5PR0801MB1332 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 11.01.2018 21:34, Oleg Nesterov wrote: > On 01/11, Kirill Tkhai wrote: >> >> Since threads can't have additional fd in comparison >> to thread group leader > ... >> as they definitely have the same >> files struct, as thread group leader. > > Hmm. Why? Iirc CLONE_THREAD doesn't require CLONE_FILES? Oh, it's really so. Surprise. Thanks for pointing that. I'll try to find a way, how we can iterate threads fds using rcu. > Also. The group leader can exit, in this case its ->files == NULL > but other threads can be alive. Sure, thanks, Oleg. Kirill