Re: [PATCH 09/11] pidns: Add setns support

[Eric W. Biederman]

Gao feng <gaofeng@xxxxxxxxxxxxxx> writes:

> ä 2012å11æ17æ 00:35, Eric W. Biederman åé:
>> From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
>> 
>> - Pid namespaces are designed to be inescapable so verify that the
>>   passed in pid namespace is a child of the currently active
>>   pid namespace or the currently active pid namespace itself.
>> 
>>   Allowing the currently active pid namespace is important so
>>   the effects of an earlier setns can be cancelled.
>> 
>> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>> ---
>
> Hi Eric
>
> I noticed that,after we call setns to change task's pidns to container A's pidns.
> we can't see this task in container A's proc filesystem.
>
> Is this what we expected?

Only children move to the new pid namespace so yes.

Any other semantic requires ugly races with changing the pid of an
existing process.

Eric

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