From: Li Zefan <lizefan@huawei.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>,
Anton Vorontsov <anton.vorontsov@linaro.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
Johannes Weiner <hannes@cmpxchg.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH v2] vmpressure: make sure memcg stays alive until all users are signaled
Date: Fri, 12 Jul 2013 17:54:27 +0800 [thread overview]
Message-ID: <51DFD253.3030501@huawei.com> (raw)
In-Reply-To: <20130712092927.GA15307@dhcp22.suse.cz>
On 2013/7/12 17:29, Michal Hocko wrote:
> On Fri 12-07-13 17:20:09, Li Zefan wrote:
> [...]
>> But if I read the code correctly, even no one registers a vmpressure event,
>> vmpressure() is always running and queue the work item.
>
> True but checking there is somebody is rather impractical. First we
> would have to take a events_lock to check this and then drop it after
> scheduling the work. Which doesn't guarantee that the registered event
> wouldn't go away.
> And even trickier, we would have to do the same for all parents up the
> hierarchy.
>
The thing is, we can forget about eventfd. eventfd is checked in
vmpressure_work_fn(), while vmpressure() is always called no matter what.
vmpressure()
queue_work()
cgroup_diput()
call_rcu(cgroup_free_rcu)
...
queue_work(destroy_cgroup)
...
cgroup_free_fn()
mem_cgroup_destroy()
...
vmpress_work_fn()
There's no guarantee that vmpressure work is run before cgroup destroy
work, I think.
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next prev parent reply other threads:[~2013-07-12 9:55 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130710184254.GA16979@mtj.dyndns.org>
[not found] ` <20130711083110.GC21667@dhcp22.suse.cz>
[not found] ` <51DE701C.6010800@huawei.com>
[not found] ` <20130711092542.GD21667@dhcp22.suse.cz>
[not found] ` <51DE7AAF.6070004@huawei.com>
2013-07-11 9:33 ` [PATCH v2] vmpressure: make sure memcg stays alive until all users are signaled Michal Hocko
2013-07-11 15:44 ` Tejun Heo
2013-07-11 16:22 ` Michal Hocko
2013-07-11 16:32 ` Tejun Heo
2013-07-12 8:40 ` Michal Hocko
2013-07-12 9:20 ` Li Zefan
2013-07-12 9:29 ` Michal Hocko
2013-07-12 9:54 ` Li Zefan [this message]
2013-07-12 10:37 ` Michal Hocko
2013-07-15 3:07 ` Li Zefan
2013-07-15 9:20 ` Michal Hocko
2013-07-15 9:53 ` Li Zefan
2013-07-12 9:24 ` [PATCH 1/3] vmpressure: document why css_get/put is not necessary for work queue based signaling Michal Hocko
2013-07-12 9:24 ` [PATCH 2/3] vmpressure: change vmpressure::sr_lock to spinlock Michal Hocko
2013-07-12 9:24 ` [PATCH 3/3] vmpressure: do not check for pending work to prevent from new work Michal Hocko
2013-07-12 18:48 ` [PATCH 1/3] vmpressure: document why css_get/put is not necessary for work queue based signaling Tejun Heo
2013-07-15 10:27 ` Michal Hocko
2013-07-12 18:34 ` [PATCH v2] vmpressure: make sure memcg stays alive until all users are signaled Tejun Heo
2013-07-12 18:40 ` Tejun Heo
2013-07-12 6:03 ` Li Zefan
2013-07-15 10:30 ` [PATCH v3 1/3] vmpressure: change vmpressure::sr_lock to spinlock Michal Hocko
2013-07-15 10:30 ` [PATCH v3 2/3] vmpressure: do not check for pending work to prevent from new work Michal Hocko
2013-07-15 10:30 ` [PATCH v3 3/3] vmpressure: Make sure there are no events queued after memcg is offlined Michal Hocko
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