From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754628AbeDYOVy (ORCPT ); Wed, 25 Apr 2018 10:21:54 -0400 Received: from mail-co1nam03on0080.outbound.protection.outlook.com ([104.47.40.80]:19536 "EHLO NAM03-CO1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753283AbeDYOVw (ORCPT ); Wed, 25 Apr 2018 10:21:52 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Andrey.Grodzovsky@amd.com; Subject: Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for signaled process. To: Oleg Nesterov , "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Alexander.Deucher@amd.com, Christian.Koenig@amd.com, David.Panariti@amd.com, akpm@linux-foundation.org References: <1524583836-12130-1-git-send-email-andrey.grodzovsky@amd.com> <1524583836-12130-3-git-send-email-andrey.grodzovsky@amd.com> <87muxsbmkp.fsf@xmission.com> <8840ac96-50c4-f94d-eb7c-f007940163f3@amd.com> <877eowa5qh.fsf@xmission.com> <20180425135552.GD7592@redhat.com> From: Andrey Grodzovsky Message-ID: Date: Wed, 25 Apr 2018 10:21:45 -0400 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: <20180425135552.GD7592@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [165.204.55.251] X-ClientProxiedBy: YQBPR0101CA0058.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c00:1::35) To CY4PR1201MB0120.namprd12.prod.outlook.com (2603:10b6:910:1c::14) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7153060)(7193020);SRVR:CY4PR1201MB0120; 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Biederman wrote: >> Let me respectfully suggest that the wait_event_killable on that code >> path is wrong. > I tend to agree even if I don't know this code. > > But if it can be called from f_op->release() then any usage of "current" or > signals looks suspicious. Simply because "current" can be completely irrelevant > task which does the last fput(), say, cat /proc/pid/fdinfo/... or even a kernel > thread. > > Oleg. So what you say is that switching to current->PF_EXITING as indication of a reason why I am here (drm_sched_entity_fini) is also a bad idea, but we still want to be able to exit immediately and not wait for GPU jobs completion when the reason for reaching this code is because of KILL signal to the user process who opened the device file. With termination from fput   it seems impossible... But thinking more about it, any task still referencing this file and putting down the reference and is not exiting due to SIGKILL will just have to go through the  slow path - wait for jobs completion on GPU (with some TO). Andrey >