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Date:   Thu, 10 May 2018 13:41:47 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Roman Gushchin <guro@fb.com>
Cc:     kernel-team@fb.com, Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH v2] mm: fix oom_kill event handling
Message-ID: <20180510114147.GB5325@dhcp22.suse.cz>
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On Tue 08-05-18 13:46:37, Roman Gushchin wrote:
> Commit e27be240df53 ("mm: memcg: make sure memory.events is
> uptodate when waking pollers") converted most of memcg event
> counters to per-memcg atomics, which made them less confusing
> for a user. The "oom_kill" counter remained untouched, so now
> it behaves differently than other counters (including "oom").
> This adds nothing but confusion.
> 
> Let's fix this by adding the MEMCG_OOM_KILL event, and follow
> the MEMCG_OOM approach. This also removes a hack from
> count_memcg_event_mm(), introduced earlier specially for the
> OOM_KILL counter.

I agree that the current OOM_KILL is confusing. But do we really need
another memcg_memory_event_mm helper used for only one counter rather
than reuse memcg_memory_event. __oom_kill_process doesn't have the memcg
but nothing should really prevent us from adding the context
(oom_control) there, no?

[...]
-- 
Michal Hocko
SUSE Labs