On 06/05/2012 12:00 PM, Glauber Costa wrote: > On 06/05/2012 01:37 PM, Glauber Costa wrote: >> On 06/05/2012 01:36 PM, Daniel Lezcano wrote: >>> On 06/04/2012 03:33 PM, Glauber Costa wrote: >>>> Currently, it is possible for a process to join existing >>>> net, uts and ipc namespaces. This patch allows a process to join an >>>> existing pid namespace as well. >>>> >>>> For that to remain sane, some restrictions are made in the calling >>>> process: >>>> >>>> * It needs to be in the parent namespace of the namespace it wants to >>>> jump to >>>> * It needs to sit in its own session and group as a leader. >>>> >>>> The rationale for that, is that people want to trigger actions in a >>>> Container >>>> from the outside. For instance, mainstream linux recently gained the >>>> ability >>>> to safely reboot a container. It would be desirable, however, that >>>> this >>>> action is triggered from an admin in the outside world, very much >>>> like a >>>> power switch in a physical box. >>>> >>>> This would also allow us to connect a console to the container, >>>> provide a >>>> repair mode for setups without networking (or with a broken one), etc. >>> >>> Hi Glauber, >>> >>> I am in favor of this patch but I think the pidns support won't be >>> complete and some corner-cases are not handled. >>> >>> May be you can look at Eric's patchset [1] where, IMO, everything is >>> taken into account. Some of the patches may be already upstream. >>> >>> Thanks >>> -- Daniel >> >> I don't remember seeing such patchset in the mailing lists, but that >> might be my fault, due to traffic... >> >> I'll take a look. If it does what I need, I can just drop this. >> > > Ok. In a quick look, it does not seem to go all the way. This is just > by reading, but your reboot patch, for instance, is unlikely to work > with that, since if it doesn't alter pid->level, things like task > ns_of_pid won't work. > > Running the test scripts I wrote for my testing of that patch also > doesn't seem to produce the expected result: > > after doing setns, the pid won't show up in that namespace. Yes, AFAIR, pid won't show up, you have to do fork-exec. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
