Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [RFC] Per file OOM badness
To:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Michal Hocko <mhocko@kernel.org>, Roman Gushchin <guro@fb.com>
Cc:     dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org
References: <20180118170006.GG6584@dhcp22.suse.cz>
 <20180123152659.GA21817@castle.DHCP.thefacebook.com>
 <20180123153631.GR1526@dhcp22.suse.cz>
 <ccac4870-ced3-f169-17df-2ab5da468bf0@daenzer.net>
 <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>
From:   =?UTF-8?Q?Michel_D=c3=a4nzer?= <michel@daenzer.net>
Message-ID: <445628d3-677c-a9f8-171f-7d74a603c61d@daenzer.net>
Date:   Tue, 30 Jan 2018 12:02:26 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <3026d8c5-9313-cb8b-91ef-09c02baf27db@amd.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-CA
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2018-01-30 11:40 AM, Christian König wrote:
> Am 30.01.2018 um 10:43 schrieb Michel Dänzer:
>> [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?


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?


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer