linux-kernel - Re: [PATCH -mm 1/3] mm/oom_kill: remove the wrong fatal_signal

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Message-ID: <20150930134321.GA32263@redhat.com>
Date:	Wed, 30 Sep 2015 15:43:21 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Kyle Walker <kwalker@...hat.com>,
	Michal Hocko <mhocko@...nel.org>,
	Stanislav Kozina <skozina@...hat.com>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -mm 1/3] mm/oom_kill: remove the wrong
	fatal_signal_pending()

On 09/29, David Rientjes wrote:
>
> On Tue, 29 Sep 2015, Oleg Nesterov wrote:
>
> > The fatal_signal_pending() was added to suppress unnecessary "sharing
> > same memory" message, but it can't 100% help anyway because it can be
> > false-negative; SIGKILL can be already dequeued.
> >
> > And worse, it can be false-positive due to exec or coredump. exec is
> > mostly fine, but coredump is not. It is possible that the group leader
> > has the pending SIGKILL because its sub-thread originated the coredump,
> > in this case we must not skip this process.
> >
> > We could probably add the additional ->group_exit_task check but this
> > pach just removes fatal_signal_pending(), the extra "Kill process" is
> > unlikely and doesn't really hurt.
> >
> > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
>
> Acked-by: David Rientjes <rientjes@...gle.com>

Thanks!

> In addition, I'm really debating whether we need the "sharing same memory"
> line or not.  In the past, it has been helpful because there is no other
> way to determine what the kernel has killed other than to leave an
> artifact behind in the kernel log.  I can imagine that this could easily
> spam the kernel log, though, accompanied by oom killer messages that are
> already very verbose.  I wouldn't mind if it the printk were removed
> entirely.

Yes, me too... let me reply to Tetsuo's email.

Oleg.

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