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Date:   Fri, 29 Jun 2018 11:59:04 -0700
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 <20180629072132.GA13860@dhcp22.suse.cz>
Subject: Re: [PATCH] memcg, oom: move out_of_memory back to the charge path
From:   Greg Thelen <gthelen@google.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Shakeel Butt <shakeelb@google.com>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>
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Michal Hocko <mhocko@kernel.org> wrote:

> On Thu 28-06-18 16:19:07, Greg Thelen wrote:
>> Michal Hocko <mhocko@kernel.org> wrote:
> [...]
>> > +	if (mem_cgroup_out_of_memory(memcg, mask, order))
>> > +		return OOM_SUCCESS;
>> > +
>> > +	WARN(1,"Memory cgroup charge failed because of no reclaimable memory! "
>> > +		"This looks like a misconfiguration or a kernel bug.");
>> 
>> I'm not sure here if the warning should here or so strongly worded.  It
>> seems like the current task could be oom reaped with MMF_OOM_SKIP and
>> thus mem_cgroup_out_of_memory() will return false.  So there's nothing
>> alarming in that case.
>
> If the task is reaped then its charges should be released as well and
> that means that we should get below the limit. Sure there is some room
> for races but this should be still unlikely. Maybe I am just
> underestimating though.
>
> What would you suggest instead?

I suggest checking MMF_OOM_SKIP or deleting the warning.  But I don't
feel strongly.