linux-kernel - Re: [RFC] Per file OOM badness

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Message-ID: <381a868c-78fd-d0d1-029e-a2cf4ab06d37@gmail.com>
Date:   Wed, 24 Jan 2018 13:11:09 +0100
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Michel Dänzer <michel@...nzer.net>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Christian.Koenig@....com, linux-mm@...ck.org,
        amd-gfx@...ts.freedesktop.org, Roman Gushchin <guro@...com>
Subject: Re: [RFC] Per file OOM badness

Am 24.01.2018 um 12:50 schrieb Michal Hocko:
> On Wed 24-01-18 12:23:10, Michel Dänzer wrote:
>> On 2018-01-24 12:01 PM, Michal Hocko wrote:
>>> On Wed 24-01-18 11:27:15, Michel Dänzer wrote:
> [...]
>>>> 2. If the OOM killer kills a process which is sharing BOs with another
>>>> process, this should result in the other process dropping its references
>>>> to the BOs as well, at which point the memory is released.
>>> OK. How exactly are those BOs mapped to the userspace?
>> I'm not sure what you're asking. Userspace mostly uses a GEM handle to
>> refer to a BO. There can also be userspace CPU mappings of the BO's
>> memory, but userspace doesn't need CPU mappings for all BOs and only
>> creates them as needed.
> OK, I guess you have to bear with me some more. This whole stack is a
> complete uknonwn. I am mostly after finding a boundary where you can
> charge the allocated memory to the process so that the oom killer can
> consider it. Is there anything like that? Except for the proposed file
> handle hack?

Not that I knew of.

As I said before we need some kind of callback that a process now starts 
to use a file descriptor, but without anything from that file descriptor 
mapped into the address space.

Regards,
Christian.