unshare() pid ns

unshare() pid ns

[sukadev-r/Jw6+rmf7HQT0dZR+AlfA]

Pavel,

unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
I thought we supported it in the earlier patchsets.  I guess
I missed that in the review of recent patchsets.

Did we remove/disable it on purpose ? I am not particular that we
support it though. Just want to make sure.

Suka

Re: unshare() pid ns

[Pavel Emelyanov]

sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
> Pavel,
> 
> unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
> I thought we supported it in the earlier patchsets.  I guess
> I missed that in the review of recent patchsets.

I disabled unsharing of pid namespaces because it's almost
impossible. Look - you have to reattach all the pids to the
task with saving its ids as seen in previous namespaces.

> Did we remove/disable it on purpose ? I am not particular that we
> support it though. Just want to make sure.
> 
> Suka
> 

Re: unshare() pid ns

[Serge E. Hallyn]

Quoting Pavel Emelyanov (xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org):
> sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
>> Pavel,
>> unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
>> I thought we supported it in the earlier patchsets.  I guess
>> I missed that in the review of recent patchsets.
>
> I disabled unsharing of pid namespaces because it's almost
> impossible. Look - you have to reattach all the pids to the
> task with saving its ids as seen in previous namespaces.

We agree, but thought you for some perverse reason preferred unshare to
clone for pidns :)

Thanks for clarifying.

-serge

Re: unshare() pid ns

[Pavel Emelyanov]

Serge E. Hallyn wrote:
> Quoting Pavel Emelyanov (xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org):
>> sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
>>> Pavel,
>>> unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
>>> I thought we supported it in the earlier patchsets.  I guess
>>> I missed that in the review of recent patchsets.
>> I disabled unsharing of pid namespaces because it's almost
>> impossible. Look - you have to reattach all the pids to the
>> task with saving its ids as seen in previous namespaces.
> 
> We agree, but thought you for some perverse reason preferred unshare to
> clone for pidns :)

I did that in my first version of patches, but then realized
that such problem (the need in reattaching pids) makes the
unsharing ugly.

BTW, unsharing of a pid namespace is a valid operation, so I
think I will enable it in the nearest future. I have some
thought on how to make such a reattach ;)

> Thanks for clarifying.
> 
> -serge
> 

Re: unshare() pid ns

[Serge E. Hallyn]

Quoting Pavel Emelyanov (xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org):
> Serge E. Hallyn wrote:
> > Quoting Pavel Emelyanov (xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org):
> >> sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
> >>> Pavel,
> >>> unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
> >>> I thought we supported it in the earlier patchsets.  I guess
> >>> I missed that in the review of recent patchsets.
> >> I disabled unsharing of pid namespaces because it's almost
> >> impossible. Look - you have to reattach all the pids to the
> >> task with saving its ids as seen in previous namespaces.
> > 
> > We agree, but thought you for some perverse reason preferred unshare to
> > clone for pidns :)
> 
> I did that in my first version of patches, but then realized
> that such problem (the need in reattaching pids) makes the
> unsharing ugly.
> 
> BTW, unsharing of a pid namespace is a valid operation, so I
> think I will enable it in the nearest future. I have some
> thought on how to make such a reattach ;)

Alrighty  :)

Of course it's not just the kernel ugliness, but also the userspace
ugliness, for instance the rumored (I haven't looked to confirm) caching
of pids by glibc.

But in the end if we can achieve symmetry between all the CLONE_NEW*
flags all the better.

-serge

Re: unshare() pid ns

[Cedric Le Goater]

Hello Pavel ! 

Pavel Emelyanov wrote:
> Serge E. Hallyn wrote:
>> Quoting Pavel Emelyanov (xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org):
>>> sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
>>>> Pavel,
>>>> unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
>>>> I thought we supported it in the earlier patchsets.  I guess
>>>> I missed that in the review of recent patchsets.
>>> I disabled unsharing of pid namespaces because it's almost
>>> impossible. Look - you have to reattach all the pids to the
>>> task with saving its ids as seen in previous namespaces.
>> We agree, but thought you for some perverse reason preferred unshare to
>> clone for pidns :)
> 
> I did that in my first version of patches, but then realized
> that such problem (the need in reattaching pids) makes the
> unsharing ugly.
> 
> BTW, unsharing of a pid namespace is a valid operation, so I
> think I will enable it in the nearest future. I have some
> thought on how to make such a reattach ;)

that would be also very useful to 'enter' such a namespace.

BTW, did you take a look at the sys_hijack() serge sent ? 

Thanks,

C.

Re: unshare() pid ns

[sukadev-r/Jw6+rmf7HQT0dZR+AlfA]

Pavel Emelianov [xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org] wrote:
| sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
| >Pavel,
| >
| >unshare() of pid ns seems to fail with -EINVAL in 2.6.23-rc3-mm1.
| >I thought we supported it in the earlier patchsets.  I guess
| >I missed that in the review of recent patchsets.
| 
| I disabled unsharing of pid namespaces because it's almost
| impossible. Look - you have to reattach all the pids to the
| task with saving its ids as seen in previous namespaces.

Agree. Eric pointed that out early on.
| 
| >Did we remove/disable it on purpose ? I am not particular that we
| >support it though. Just want to make sure.
| >
| >Suka
| >