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From: Yafang Shao <laoar.shao@gmail.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH] mm, memcg: clear page protection when memcg oom group happens
Date: Mon, 25 Nov 2019 22:45:18 +0800	[thread overview]
Message-ID: <CALOAHbD9RPM-Xvbnm0p_QEU9SEtYKfs_u-y3wFxhMO2s1OBVVw@mail.gmail.com> (raw)
In-Reply-To: <20191125144213.GB602168@cmpxchg.org>

On Mon, Nov 25, 2019 at 10:42 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> On Mon, Nov 25, 2019 at 03:21:50PM +0100, Michal Hocko wrote:
> > On Mon 25-11-19 22:11:15, Yafang Shao wrote:
> > > When there're no processes, we don't need to protect the pages. You
> > > can consider it as 'fault tolerance' .
> >
> > I have already tried to explain why this is a bold statement that
> > doesn't really hold universally and that the kernel doesn't really have
> > enough information to make an educated guess.
>
> I agree, this is not obviously true. And the kernel shouldn't try to
> guess whether the explicit userspace configuration is still desirable
> to userspace or not. Should we also delete the cgroup when it becomes
> empty for example?
>
> It's better to implement these kinds of policy decisions from
> userspace.
>
> There is a cgroup.events file that can be polled, and its "populated"
> field shows conveniently whether there are tasks in a subtree or
> not. You can use that to clear protection settings.

Thanks for you information. I will take a look at it.

Thanks
Yafang


  reply	other threads:[~2019-11-25 14:45 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-25 10:14 [PATCH] mm, memcg: clear page protection when memcg oom group happens Yafang Shao
2019-11-25 11:08 ` Michal Hocko
2019-11-25 11:37   ` Yafang Shao
2019-11-25 11:54     ` Michal Hocko
2019-11-25 12:17       ` Yafang Shao
2019-11-25 12:31         ` Michal Hocko
2019-11-25 12:37           ` Yafang Shao
2019-11-25 12:45             ` Michal Hocko
2019-11-25 14:11               ` Yafang Shao
2019-11-25 14:21                 ` Michal Hocko
2019-11-25 14:42                   ` Johannes Weiner
2019-11-25 14:45                     ` Yafang Shao [this message]
2019-11-26  3:52                     ` Yafang Shao
2019-11-26  7:31                       ` Michal Hocko
2019-11-26  9:35                         ` Yafang Shao
2019-11-26  9:50                           ` Michal Hocko
2019-11-26 10:02                             ` Yafang Shao
2019-11-26 10:22                               ` Michal Hocko
2019-11-26 10:56                                 ` Yafang Shao
2019-11-25 14:44                   ` Yafang Shao

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