From: Roman Gushchin <guro@fb.com>
To: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>,
hannes@cmpxchg.org, David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, akpm@linux-foundation.org,
gthelen@google.com
Subject: Re: cgroup-aware OOM killer, how to move forward
Date: Tue, 24 Jul 2018 08:52:51 -0700 [thread overview]
Message-ID: <20180724155248.GA24429@castle> (raw)
In-Reply-To: <20180724144940.GN1934745@devbig577.frc2.facebook.com>
On Tue, Jul 24, 2018 at 07:49:40AM -0700, Tejun Heo wrote:
> Hello, Michal.
>
> On Tue, Jul 24, 2018 at 04:43:51PM +0200, Michal Hocko wrote:
> > If yes, then I do not see it ;) Mostly because panic_on_oom doesn't have
> > any scope. It is all or nothing thing. You can only control whether
> > memcg OOMs should be considered or not because this is inherently
> > dangerous to be the case by default.
>
> Oh yeah, so, panic_on_oom is like group oom on the root cgroup, right?
> If 1, it treats the whole system as a single unit and kills it no
> matter the oom domain. If 2, it only does so if the oom is not caused
> by restrictions in subdomains.
>
> > oom_group has a scope and that scope is exactly what we are trying to
> > find a proper semantic for. And especially what to do if descendants in
> > the hierarchy disagree with parent(s). While I do not see a sensible
> > configuration where the scope of the OOM should define the workload is
> > indivisible I would like to prevent from "carved in stone" semantic that
> > couldn't be changed later.
>
> And we can scope it down the same way down the cgroup hierarchy.
>
> > So IMHO the best option would be to simply inherit the group_oom to
> > children. This would allow users to do their weird stuff but the default
> > configuration would be consistent.
I think, that the problem occurs because of the default value (0).
Let's imagine we can make default to 1.
It means, that by default we kill the whole sub-tree up to the top-level
cgroup, and it does guarantee consistency.
If on some level userspace _knows_ how to handle OOM, it opts-out
by setting oom.group to 0.
E.g. systemd _knows_ that services working in systems slice are
independent and knows how to detect that they are dead and restart.
So, it sets system.slice/memory.oom.group to 0.
next prev parent reply other threads:[~2018-07-24 15:53 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 22:40 cgroup-aware OOM killer, how to move forward Roman Gushchin
2018-07-12 12:07 ` Michal Hocko
2018-07-12 15:55 ` Roman Gushchin
2018-07-13 21:34 ` David Rientjes
2018-07-13 22:16 ` Roman Gushchin
2018-07-13 22:39 ` David Rientjes
2018-07-13 23:05 ` Roman Gushchin
2018-07-13 23:11 ` David Rientjes
2018-07-13 23:16 ` Roman Gushchin
2018-07-17 4:19 ` David Rientjes
2018-07-17 12:41 ` Michal Hocko
2018-07-17 17:38 ` Roman Gushchin
2018-07-17 19:49 ` Michal Hocko
2018-07-17 20:06 ` Roman Gushchin
2018-07-17 20:41 ` David Rientjes
2018-07-17 20:52 ` Roman Gushchin
2018-07-20 8:30 ` David Rientjes
2018-07-20 11:21 ` Tejun Heo
2018-07-20 16:13 ` Roman Gushchin
2018-07-20 20:28 ` David Rientjes
2018-07-20 20:47 ` Roman Gushchin
2018-07-23 23:06 ` David Rientjes
2018-07-23 14:12 ` Michal Hocko
2018-07-18 8:19 ` Michal Hocko
2018-07-18 8:12 ` Michal Hocko
2018-07-18 15:28 ` Roman Gushchin
2018-07-19 7:38 ` Michal Hocko
2018-07-19 17:05 ` Roman Gushchin
2018-07-20 8:32 ` David Rientjes
2018-07-23 14:17 ` Michal Hocko
2018-07-23 15:09 ` Tejun Heo
2018-07-24 7:32 ` Michal Hocko
2018-07-24 13:08 ` Tejun Heo
2018-07-24 13:26 ` Michal Hocko
2018-07-24 13:31 ` Tejun Heo
2018-07-24 13:50 ` Michal Hocko
2018-07-24 13:55 ` Tejun Heo
2018-07-24 14:25 ` Michal Hocko
2018-07-24 14:28 ` Tejun Heo
2018-07-24 14:35 ` Tejun Heo
2018-07-24 14:43 ` Michal Hocko
2018-07-24 14:49 ` Tejun Heo
2018-07-24 15:52 ` Roman Gushchin [this message]
2018-07-25 12:00 ` Michal Hocko
2018-07-25 11:58 ` Michal Hocko
2018-07-30 8:03 ` Michal Hocko
2018-07-30 14:04 ` Tejun Heo
2018-07-30 15:29 ` Roman Gushchin
2018-07-24 11:59 ` Tetsuo Handa
2018-07-25 0:10 ` Roman Gushchin
2018-07-25 12:23 ` Tetsuo Handa
2018-07-25 13:01 ` Michal Hocko
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