From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id C0F796B0005 for ; Tue, 30 Jan 2018 06:34:22 -0500 (EST) Received: by mail-lf0-f69.google.com with SMTP id m79so4079385lfm.17 for ; Tue, 30 Jan 2018 03:34:22 -0800 (PST) Received: from netline-mail3.netline.ch (mail.netline.ch. [148.251.143.178]) by mx.google.com with ESMTP id r11si985029ljd.357.2018.01.30.03.34.20 for ; Tue, 30 Jan 2018 03:34:21 -0800 (PST) Subject: Re: [RFC] Per file OOM badness References: <20180118170006.GG6584@dhcp22.suse.cz> <20180123152659.GA21817@castle.DHCP.thefacebook.com> <20180123153631.GR1526@dhcp22.suse.cz> <20180124092847.GI1526@dhcp22.suse.cz> <583f328e-ff46-c6a4-8548-064259995766@daenzer.net> <20180124110141.GA28465@dhcp22.suse.cz> <36b49523-792d-45f9-8617-32b6d9d77418@daenzer.net> <20180124115059.GC28465@dhcp22.suse.cz> <381a868c-78fd-d0d1-029e-a2cf4ab06d37@gmail.com> <20180130093145.GE25930@phenom.ffwll.local> <3db43c1a-59b8-af86-2b87-c783c629f512@daenzer.net> <3026d8c5-9313-cb8b-91ef-09c02baf27db@amd.com> <445628d3-677c-a9f8-171f-7d74a603c61d@daenzer.net> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= Message-ID: Date: Tue, 30 Jan 2018 12:34:18 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: christian.koenig@amd.com, Michal Hocko , Roman Gushchin Cc: linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org On 2018-01-30 12:28 PM, Christian KA?nig wrote: > Am 30.01.2018 um 12:02 schrieb Michel DA?nzer: >> On 2018-01-30 11:40 AM, Christian KA?nig wrote: >>> Am 30.01.2018 um 10:43 schrieb Michel DA?nzer: >>>> [SNIP] >>>>> Would it be ok to hang onto potentially arbitrary mmget references >>>>> essentially forever? If that's ok I think we can do your process based >>>>> account (minus a few minor inaccuracies for shared stuff perhaps, >>>>> but no >>>>> one cares about that). >>>> Honestly, I think you and Christian are overthinking this. Let's try >>>> charging the memory to every process which shares a buffer, and go from >>>> there. >>> My problem is that this needs to be bullet prove. >>> >>> For example imagine an application which allocates a lot of BOs, then >>> calls fork() and let the parent process die. The file descriptor lives >>> on in the child process, but the memory is not accounted against the >>> child. >> What exactly are you referring to by "the file descriptor" here? > > The file descriptor used to identify the connection to the driver. In > other words our drm_file structure in the kernel. > >> What happens to BO handles in general in this case? If both parent and >> child process keep the same handle for the same BO, one of them >> destroying the handle will result in the other one not being able to use >> it anymore either, won't it? > Correct. > > That usage is actually not useful at all, but we already had > applications which did exactly that by accident. > > Not to mention that somebody could do it on purpose. Can we just prevent child processes from using their parent's DRM file descriptors altogether? Allowing it seems like a bad idea all around. -- Earthling Michel DA?nzer | http://www.amd.com Libre software enthusiast | Mesa and X developer -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org