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

Eric W. Biederman
2012-11-02T08:54:26Z

> 于 2012年11月02日 15:02, Eric W. Biederman 写道:
>> Gao feng <gaofeng@cn.fujitsu.com> 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?

Eric