linux-kernel - Re: [PATCH] mm/oom_kill: wake futex waiters before annihilating victim shared mutex

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Message-ID: <YbG1mu0CLONo+Z7l@dhcp22.suse.cz>
Date:   Thu, 9 Dec 2021 08:51:54 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Joel Savitz <jsavitz@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Waiman Long <longman@...hat.com>, linux-mm@...ck.org,
        Nico Pache <npache@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Darren Hart <dvhart@...radead.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        André Almeida <andrealmeid@...labora.com>
Subject: Re: [PATCH] mm/oom_kill: wake futex waiters before annihilating
 victim shared mutex

On Wed 08-12-21 21:59:29, Joel Savitz wrote:
> On Wed, Dec 8, 2021 at 11:05 AM Michal Hocko <mhocko@...e.com> wrote:
[...]
> > I have had a closer look and I guess I can see what you are trying to
> > achieve. futex_exit_release is normally called from exit_mm context. You
> > are likely seeing a situation when the oom victim is blocked and cannot
> > exit. That is certainly possible but it shouldn't be a permanent state.
> > So I would be more interested about your particular issue and how long
> > the task has been stuck unable to exit.
> 
> Before applying this patch I never saw a task eventually exit during
> the reproduction of this system state.

What has happened to the oom victim and why it has never exited?

Side note. I have noticed that you have sent v2 with minor changes. It
is usualy better to resolve review feedback before posting a new
version. Discussion gets rather hard to follow otherwise.

Thanks!
-- 
Michal Hocko
SUSE Labs