Oleg Nesterov wrote:
On 08/06, Pavel Emelyanov wrote:
Oleg Nesterov wrote:
On 07/26, Pavel Emelyanov wrote:
The reason to release namespaces after reparenting is that when task
exits it may send a signal to its parent (SIGCHLD), but if the parent
has already exited its namespaces there will be no way to decide what
pid to dever to him - parent can be from different namespace.
I almost forgot about this one...
After reading the whole series, I can't understand the above explanation
any longer. The parent can't be from different namespace, either we have
another sub-thread, or we reparent the child to /sbin/init which should
be from the same namespace.
If the child that is a new namespace's init is exiting its parent is from the
different namespace.
In that case it doesn't have childs. The were SIGKILL'ed before exit_notify().
It does not, but it's parent - does :)
Moreover, we will probably want to implement "entering"
the pid namespace, so having tasks with parents from another namespace will
be OK.
Well. I saw this word "entering", but I don't know the meaning. Just curious,
could you explain?
"Entering" means "moving task to arbitrary namespace"
And, if an exiting task has a child which is already from another namespace,
why can't we release our namespace before re-parenting? I guess I need to
know what "entering" means to understand this...
One of the desired actions was the following:
1. task X clones the new namespace with the child Y as this namespace's init;
2. task X waits for SIGCHILD to come informing that the namespace is dead.
In this scenario we need to set the Y's pid as it is seen from X's
namespace in siginfo.
Oleg.
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