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Date: Wed, 30 Sep 2015 15:50:51 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Kyle Walker <kwalker@redhat.com>, Michal Hocko <mhocko@kernel.org>,
        Stanislav Kozina <skozina@redhat.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm 3/3] mm/oom_kill: fix the wrong task->mm == mm
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Message-ID: <20150930135051.GD32263@redhat.com>
References: <20150929141822.GA10962@redhat.com> <alpine.DEB.2.10.1509291541010.3375@chino.kir.corp.google.com>
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On 09/29, David Rientjes wrote:
>
> On Tue, 29 Sep 2015, Oleg Nesterov wrote:
>
> > Both "child->mm == mm" and "p->mm != mm" checks in oom_kill_process()
> > are wrong. ->mm can be if task is the exited group leader. This means
> > in particular that "kill sharing same memory" loop can miss a process
> > with a zombie leader which uses the same ->mm.
> >
> > Note: the process_has_mm(child, p->mm) check is still not 100% correct,
> > p->mm can be NULL too. This is minor, but probably deserves a fix or a
> > comment anyway.
> >
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> Acked-by: David Rientjes <rientjes@google.com>
>
> I like this and I don't want to hold up a fix for a personal preference,
> but I find process_has_mm() to simply imply the process has a non-NULL mm.

Hmm, yes ;)

> Maybe process_shares_mm()?  Something to consider.

Agreed, will rename in v2.

Oleg.