linux-kernel - Re: [v7 2/5] mm, oom: cgroup-aware OOM killer

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Message-ID: <20170906083413.4nzwc27fk3bu2ye4@dhcp22.suse.cz>
Date:   Wed, 6 Sep 2017 10:34:13 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Roman Gushchin <guro@...com>
Cc:     linux-mm@...ck.org, Vladimir Davydov <vdavydov.dev@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        David Rientjes <rientjes@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>, kernel-team@...com,
        cgroups@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [v7 2/5] mm, oom: cgroup-aware OOM killer

On Tue 05-09-17 21:23:57, Roman Gushchin wrote:
> On Tue, Sep 05, 2017 at 04:57:00PM +0200, Michal Hocko wrote:
[...]
> > > @@ -810,6 +810,9 @@ static void __oom_kill_process(struct task_struct *victim)
> > >  	struct mm_struct *mm;
> > >  	bool can_oom_reap = true;
> > >  
> > > +	if (is_global_init(victim) || (victim->flags & PF_KTHREAD))
> > > +		return;
> > > +
> > 
> > This will leak a reference to the victim AFACS
> 
> Good catch!
> I didn't fix this after moving reference dropping into __oom_kill_process().
> Fixed.

Btw. didn't you want to check
victim->signal->oom_score_adj == OOM_SCORE_ADJ_MIN

here as well? Maybe I've missed something but you still can kill a task
which is oom disabled which I thought we agreed is the wrong thing to
do.
-- 
Michal Hocko
SUSE Labs