linux-kernel - Re: [PATCH v2] mm/oom_kill: count global and memory cgroup oom kills

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Message-ID: <alpine.DEB.2.10.1705292129170.9353@chino.kir.corp.google.com>
Date:   Mon, 29 May 2017 21:29:48 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Michal Hocko <mhocko@...nel.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Guschin <guroan@...il.com>
Subject: Re: [PATCH v2] mm/oom_kill: count global and memory cgroup oom
 kills

On Thu, 25 May 2017, Konstantin Khlebnikov wrote:

> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 04c9143a8625..dd30a045ef5b 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -876,6 +876,11 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
>  	/* Get a reference to safely compare mm after task_unlock(victim) */
>  	mm = victim->mm;
>  	mmgrab(mm);
> +
> +	/* Raise event before sending signal: reaper must see this */

How is the oom reaper involved here?

> +	count_vm_event(OOM_KILL);
> +	mem_cgroup_count_vm_event(mm, OOM_KILL);
> +
>  	/*
>  	 * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
>  	 * the OOM victim from depleting the memory reserves from the user