Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_nsfailed

From: Gao feng
Date: Fri Nov 02 2012 - 05:02:40 EST


ä 2012å11æ02æ 16:54, Eric W. Biederman åé:
> Gao feng <gaofeng@xxxxxxxxxxxxxx> writes:
>
>> ä 2012å11æ02æ 15:02, Eric W. Biederman åé:
>>> Gao feng <gaofeng@xxxxxxxxxxxxxx> writes:
>>>
>>>> we should call pid_ns_release_proc to unmount pid_namespace's
>>>> proc_mnt when copy_net_ns failed in function create_new_namespaces.
>>>>
>>>> otherwise,the proc_mnt will not be freed and because the super_block
>>>> of proc_mnt also add the reference of the pid_namespace,so this
>>>> pid_namespace will never be released too.
>>>
>>> Ouch!
>>>
>>> Have you encountered this failure in practice or is this just from
>>> review?
>>
>> I add some printk in pid_ns_release_proc,it's not called in above case.
>> when copy_net_ns failed,this pid_namespace is not used by any task,
>> so proc_flush_task can't call pid_ns_release_proc to umount this pidns->proc_mnt.
>> it's the only chance we can unmount this pindns->proc_mnt.
>>
>> With this patch,everything runs well.
>
> I have reviewed the code and I don't doubt that this is necessary.
>
> What caused you to look into this failure? Is there some semi-practical
> real world case that someone is hitting?
>

So far,there is no case hitting this problem.
Thanks

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