Date: Sun, 4 Jun 2017 22:30:02 +0300
From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Roman Gushchin <guro@fb.com>
Cc: linux-mm@kvack.org, Tejun Heo <tj@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Li Zefan <lizefan@huawei.com>,
        Michal Hocko <mhocko@kernel.org>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, kernel-team@fb.com,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 4/7] mm, oom: introduce oom_kill_all_tasks option
 for memory cgroups
Message-ID: <20170604193002.GB19980@esperanza>
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On Thu, Jun 01, 2017 at 07:35:12PM +0100, Roman Gushchin wrote:
> This option defines whether a cgroup should be treated
> as a single entity by the OOM killer.
> 
> If set, the OOM killer will compare the whole cgroup with other
> memory consumers (other cgroups and tasks in the root cgroup),
> and in case of an OOM will kill all belonging tasks.
> 
> Disabled by default.
> 
...
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> @@ -5265,6 +5292,12 @@ static struct cftype memory_files[] = {
>  		.write = memory_max_write,
>  	},
>  	{
> +		.name = "oom_kill_all_tasks",
> +		.flags = CFTYPE_NOT_ON_ROOT,
> +		.seq_show = memory_oom_kill_all_tasks_show,
> +		.write = memory_oom_kill_all_tasks_write,
> +	},
> +	{
>  		.name = "events",
>  		.flags = CFTYPE_NOT_ON_ROOT,
>  		.file_offset = offsetof(struct mem_cgroup, events_file),

I don't really like the name of the new knob, but can't come up with
anything better :-( May be, drop '_tasks' suffix and call it just
'oom_kill_all'? Or perhaps we should emphasize the fact that this
cgroup is treated as a single entity by the OOM killer by calling it
'oom_entity' or 'oom_unit'? Dunno...