From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/6] proc, oom: drop bogus task_lock and mm check
Date: Wed, 1 Jun 2016 00:53:03 +0200 [thread overview]
Message-ID: <20160531225303.GE26582@redhat.com> (raw)
In-Reply-To: <20160531073227.GA26128@dhcp22.suse.cz>
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.
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 ;)
Oleg.
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WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/6] proc, oom: drop bogus task_lock and mm check
Date: Wed, 1 Jun 2016 00:53:03 +0200 [thread overview]
Message-ID: <20160531225303.GE26582@redhat.com> (raw)
In-Reply-To: <20160531073227.GA26128@dhcp22.suse.cz>
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.
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 ;)
Oleg.
next prev parent reply other threads:[~2016-05-31 22:53 UTC|newest]
Thread overview: 68+ 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 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 1/6] proc, oom: drop bogus task_lock and mm check Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-31 7:32 ` Michal Hocko
2016-05-31 7:32 ` Michal Hocko
2016-05-31 22:53 ` Oleg Nesterov [this message]
2016-05-31 22:53 ` Oleg Nesterov
2016-06-01 6:53 ` Michal Hocko
2016-06-01 6:53 ` Michal Hocko
2016-06-01 10:41 ` Tetsuo Handa
2016-06-01 10:41 ` Tetsuo Handa
2016-06-01 10:48 ` Michal Hocko
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 ` 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
2016-05-30 13:05 ` Michal Hocko
2016-05-31 7:41 ` 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 13:05 ` Michal Hocko
2016-05-30 19:28 ` Oleg Nesterov
2016-05-30 19:28 ` Oleg Nesterov
2016-05-31 7:42 ` Michal Hocko
2016-05-31 7:42 ` Michal Hocko
2016-05-31 21:43 ` Oleg Nesterov
2016-05-31 21:43 ` Oleg Nesterov
2016-06-01 7:09 ` Michal Hocko
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 13:05 ` Michal Hocko
2016-05-30 18:18 ` Oleg Nesterov
2016-05-30 18:18 ` Oleg Nesterov
2016-05-31 7:43 ` Michal Hocko
2016-05-31 7:43 ` Michal Hocko
2016-05-31 21:48 ` Oleg Nesterov
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 13:05 ` Michal Hocko
2016-05-30 17:35 ` Oleg Nesterov
2016-05-30 17:35 ` Oleg Nesterov
2016-05-31 7:46 ` Michal Hocko
2016-05-31 7:46 ` Michal Hocko
2016-05-31 22:29 ` Oleg Nesterov
2016-05-31 22:29 ` Oleg Nesterov
2016-06-01 7:03 ` Michal Hocko
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 14:03 ` Michal Hocko
2016-06-02 15:24 ` Tetsuo Handa
2016-06-02 15:50 ` Michal Hocko
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