From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Nicolai_H=c3=a4hnle?= Subject: Re: [RFC] Per file OOM badness Date: Tue, 30 Jan 2018 12:35:20 +0100 Message-ID: References: <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> <20180130104216.GR25930@phenom.ffwll.local> <5c3f8061-d2d2-fa33-faac-cb95e0b2d44b@daenzer.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <5c3f8061-d2d2-fa33-faac-cb95e0b2d44b@daenzer.net> Content-Language: en-US Sender: owner-linux-mm@kvack.org To: =?UTF-8?Q?Michel_D=c3=a4nzer?= , christian.koenig@amd.com, Michal Hocko , Roman Gushchin Cc: linux-mm@kvack.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On 30.01.2018 11:48, Michel Dänzer wrote: > On 2018-01-30 11:42 AM, Daniel Vetter wrote: >> On Tue, Jan 30, 2018 at 10:43:10AM +0100, Michel Dänzer wrote: >>> On 2018-01-30 10:31 AM, Daniel Vetter wrote: >>> >>>> I guess a good first order approximation would be if we simply charge any >>>> newly allocated buffers to the process that created them, but that means >>>> hanging onto lots of mm_struct pointers since we want to make sure we then >>>> release those pages to the right mm again (since the process that drops >>>> the last ref might be a totally different one, depending upon how the >>>> buffers or DRM fd have been shared). >>>> >>>> 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. >> >> I'm not concerned about wrongly accounting shared buffers (they don't >> matter), but imbalanced accounting. I.e. allocate a buffer in the client, >> share it, but then the compositor drops the last reference. > > I don't think the order matters. The memory is "uncharged" in each > process when it drops its reference. Daniel made a fair point about passing DRM fds between processes, though. It's not a problem with how the fds are currently used, but somebody could do the following: 1. Create a DRM fd in process A, allocate lots of buffers. 2. Pass the fd to process B via some IPC mechanism. 3. Exit process A. There needs to be some assurance that the BOs are accounted as belonging to process B in the end. Cheers, Nicolai -- Lerne, wie die Welt wirklich ist, Aber vergiss niemals, wie sie sein sollte. -- 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