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Date: Wed, 27 Jan 2021 12:02:08 +0100
From: Michal Hocko <mhocko@suse.com>
To: Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>
Subject: Re: [PATCH] procfs/dmabuf: Add /proc/<pid>/task/<tid>/dmabuf_fds
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On Wed 27-01-21 11:53:55, Christian K=F6nig wrote:
[...]
> In general processes are currently not held accountable for memory they
> reference through their file descriptors. DMA-buf is just one special cas=
e.

True

> In other words you can currently do something like this
> =

> fd =3D memfd_create("test", 0);
> while (1)
> =A0=A0=A0 write(fd, buf, 1024);
> =

> and the OOM killer will terminate random processes, but never the one
> holding the memfd reference.

memfd is just shmem under cover, no? And that means that the memory gets
accounted to MM_SHMEMPAGES. But you are right that this in its own
doesn't help much if the fd is shared and the memory stays behind a
killed victim.

But I do agree with you that there are resources which are bound to a
process life time but the oom killer has no idea about those as they are
not accounted on a per process level and/or oom_badness doesn't take
them into consideration.
-- =

Michal Hocko
SUSE Labs
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