From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@kernel.org, oleg@redhat.com
Cc: linux-mm@kvack.org, rientjes@google.com, vdavydov@parallels.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] proc, oom: drop bogus task_lock and mm check
Date: Wed, 1 Jun 2016 19:41:09 +0900 [thread overview]
Message-ID: <201606011941.DJJ09369.FSFtQVMLFOJOOH@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20160601065339.GA26601@dhcp22.suse.cz>
Michal Hocko wrote:
> On Wed 01-06-16 00:53:03, Oleg Nesterov wrote:
> > On 05/31, Michal Hocko wrote:
> > >
> > > Oleg has pointed out that can simplify both oom_adj_write and
> > > oom_score_adj_write even further and drop the sighand lock. The only
> > > purpose of the lock was to protect p->signal from going away but this
> > > will not happen since ea6d290ca34c ("signals: make task_struct->signal
> > > immutable/refcountable").
> >
> > Sorry for confusion, I meant oom_adj_read() and oom_score_adj_read().
> >
> > As for oom_adj_write/oom_score_adj_write we can remove it too, but then
> > we need to ensure (say, using cmpxchg) that unpriviliged user can not
> > not decrease signal->oom_score_adj_min if its oom_score_adj_write()
> > races with someone else (say, admin) which tries to increase the same
> > oom_score_adj_min.
>
> I am introducing oom_adj_mutex in a later patch so I will move it here.
Can't we reuse oom_lock like
if (mutex_lock_killable(&oom_lock))
return -EINTR;
? I think that updating oom_score_adj unlikely races with OOM killer
invocation, and updating oom_score_adj should be a killable operation.
>
> > If you think this is not a problem - I am fine with this change. But
> > please also update oom_adj_read/oom_score_adj_read ;)
>
> will do. It stayed in the blind spot... Thanks for pointing that out
>
> Thanks!
> --
> Michal Hocko
> SUSE Labs
>
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next prev parent reply other threads:[~2016-06-01 10:41 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-30 13:05 [PATCH 0/6 -v2] Handle oom bypass more gracefully Michal Hocko
2016-05-30 13:05 ` [PATCH 1/6] proc, oom: drop bogus task_lock and mm check Michal Hocko
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-31 7:32 ` Michal Hocko
2016-05-31 22:53 ` Oleg Nesterov
2016-06-01 6:53 ` Michal Hocko
2016-06-01 10:41 ` Tetsuo Handa [this message]
2016-06-01 10:48 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 2/6] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko
2016-05-30 13:05 ` [PATCH 3/6] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko
2016-05-31 7:41 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 4/6] mm, oom: skip vforked tasks from being selected Michal Hocko
2016-05-30 19:28 ` Oleg Nesterov
2016-05-31 7:42 ` Michal Hocko
2016-05-31 21:43 ` Oleg Nesterov
2016-06-01 7:09 ` Michal Hocko
2016-06-01 14:12 ` Tetsuo Handa
2016-06-01 14:25 ` Michal Hocko
2016-06-02 10:45 ` Tetsuo Handa
2016-06-02 11:20 ` Michal Hocko
2016-06-02 11:31 ` Tetsuo Handa
2016-06-02 12:55 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 5/6] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-05-30 18:18 ` Oleg Nesterov
2016-05-31 7:43 ` Michal Hocko
2016-05-31 21:48 ` Oleg Nesterov
2016-05-30 13:05 ` [PATCH 6/6] mm, oom: fortify task_will_free_mem Michal Hocko
2016-05-30 17:35 ` Oleg Nesterov
2016-05-31 7:46 ` Michal Hocko
2016-05-31 22:29 ` Oleg Nesterov
2016-06-01 7:03 ` Michal Hocko
2016-05-31 15:03 ` Tetsuo Handa
2016-05-31 15:10 ` Michal Hocko
2016-05-31 15:29 ` Tetsuo Handa
2016-06-01 7:25 ` Michal Hocko
2016-06-01 12:04 ` Tetsuo Handa
2016-06-01 12:43 ` Michal Hocko
2016-06-02 14:03 ` [PATCH 7/6] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-02 15:24 ` Tetsuo Handa
2016-06-02 15:50 ` Michal Hocko
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