linux-kernel - Re: [PATCH RFC] mm: don't raise MEMCG_OOM event due to failed high-order allocation

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Message-ID: <20180911124737.GV10951@dhcp22.suse.cz>
Date:   Tue, 11 Sep 2018 14:47:37 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     peter enderborg <peter.enderborg@...y.com>
Cc:     Roman Gushchin <guro@...com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-team@...com,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: [PATCH RFC] mm: don't raise MEMCG_OOM event due to failed
 high-order allocation

On Tue 11-09-18 14:41:04, peter enderborg wrote:
> On 09/11/2018 02:11 PM, Michal Hocko wrote:
> > Why is this a problem though? IIRC this event was deliberately placed
> > outside of the oom path because we wanted to count allocation failures
> > and this is also documented that way
> >
> >           oom
> >                 The number of time the cgroup's memory usage was
> >                 reached the limit and allocation was about to fail.
> >
> >                 Depending on context result could be invocation of OOM
> >                 killer and retrying allocation or failing a
> >
> > One could argue that we do not apply the same logic to GFP_NOWAIT
> > requests but in general I would like to see a good reason to change
> > the behavior and if it is really the right thing to do then we need to
> > update the documentation as well.
> >
> 
> Why not introduce a MEMCG_ALLOC_FAIL in to memcg_memory_event?

My understanding is that this is what the oom event is about.

-- 
Michal Hocko
SUSE Labs