Re: + hugetlb-cgroup-simplify-pre_destroy-callback.patch added to -mm tree

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

(2012/07/20 17:01), Michal Hocko wrote:
> On Fri 20-07-12 10:20:29, KAMEZAWA Hiroyuki wrote:
> [...]
>> Hmm, can't cgroup_lock() be implemented as
>>
>>
>> void cgroup_lock()
>> {
>> 	get_online_cpus()
>> 	lock_memory_hotplug()
>> 	mutex_lock(&cgroup_mutex);
>> }
>
> This is really ugly and it wouldn't help much anyway. Notifier which
> takes the cgroup_lock is called when cpu_hotplug.lock is held already.

Hm ? IIUC, notifer will not work until put_online_cpu() is called.

> You would need to call cgroup_lock() before taking the cpu_hotplug.lock
> and remove it from notifiers. I think this should be doable but I didn't
> have too much time to look deeper into it.
>



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