Re: [RFC] Per file OOM badness

Michal Hocko
2018-01-23T15:36:34Z

On Tue 23-01-18 15:27:00, Roman Gushchin wrote:
> On Thu, Jan 18, 2018 at 06:00:06PM +0100, Michal Hocko wrote:
> > On Thu 18-01-18 11:47:48, Andrey Grodzovsky wrote:
> > > Hi, this series is a revised version of an RFC sent by Christian Konig
> > > a few years ago. The original RFC can be found at
> > > https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.freedesktop.org_archives_dri-2Ddevel_2015-2DSeptember_089778.html&d=DwIDAw&c=5VD0RTtNlTh3ycd41b3MUw&r=jJYgtDM7QT-W-Fz_d29HYQ&m=R-JIQjy8rqmH5qD581_VYL0Q7cpWSITKOnBCE-3LI8U&s=QZGqKpKuJ2BtioFGSy8_721owcWJ0J6c6d4jywOwN4w&
> > Here is the origin cover letter text
> > : I'm currently working on the issue that when device drivers allocate memory on
> > : behalf of an application the OOM killer usually doesn't knew about that unless
> > : the application also get this memory mapped into their address space.
> > :
> > : This is especially annoying for graphics drivers where a lot of the VRAM
> > : usually isn't CPU accessible and so doesn't make sense to map into the
> > : address space of the process using it.
> > :
> > : The problem now is that when an application starts to use a lot of VRAM those
> > : buffers objects sooner or later get swapped out to system memory, but when we
> > : now run into an out of memory situation the OOM killer obviously doesn't knew
> > : anything about that memory and so usually kills the wrong process.
> > :
> > : The following set of patches tries to address this problem by introducing a per
> > : file OOM badness score, which device drivers can use to give the OOM killer a
> > : hint how many resources are bound to a file descriptor so that it can make
> > : better decisions which process to kill.
> > :
> > : So question at every one: What do you think about this approach?
> > :
> > : My biggest concern right now is the patches are messing with a core kernel
> > : structure (adding a field to struct file). Any better idea? I'm considering
> > : to put a callback into file_ops instead.
>
> Hello!
>
> I wonder if groupoom (aka cgroup-aware OOM killer) can work for you?

I do not think so. The problem is that the allocating context is not
identical with the end consumer.
--
Michal Hocko
SUSE Labs