On 01/04/2011 11:04 AM, Daniel Lezcano wrote: > On 01/04/2011 12:02 AM, Mike Heffner wrote: >> Hi, >> >> Is it possible for a process running in a parent PID namespace to map >> the PID of a process running in a child's namespace from the >> parent->child's namespace? For example, if I span the process "myproc" >> with CLONE_NEWPID then a call to getpid() inside myproc will return "1" >> whereas in the parent's namespace that process could actually be PID >> "23495". I'd like to be able to know that 23495 maps to 1 in the new NS. >> Obviously, just mapping the first PID is straightforward since I can >> just look at the result of clone(). However, mapping the PIDs of >> processes subsequently forked from "myproc" -- in this example -- I >> haven't been able to figure out. > > AFAIK, it is not possible. > > That would be very nice to show the pid<-> vpid association. > > The procfs is a good candidate to show these informations. > > That would makes sense to show the content of /proc/<pid>/status with > the pid relatively to the namespace. > > Let me give an example: > > Assuming the process '1234' creates a new pid namespace, and the child > which is '1' in the new namespace has the real pid '4321'. This one > mounts its /proc. > > If the process '1234' looks at /proc/4321/root/proc/1/status, it sees: > > ... > Tgid: 1 > Pid: 1 > PPid: 0 > ... > > > It could be: > > ... > Tgid: 4321 > Pid: 4321 > PPid: 1234 > ... > > as the file is inspected from the parent namespace. Of course, if the > file is looked from the child namespace context, we will see '1', '1' > and '0'. > > I suppose the patch in the kernel should very small also. > > Thoughts ? Would that mean that finding the pid->vpid association for a real PID X requires checking all files /proc/<X>/root/proc/<Y>/status where Y is all vpids until you find the one where Pid == X? It would be nice to have a have a way to check a single file for the association where vpid is not known beforehand -- unless I'm misunderstanding your solution. Cheers, Mike _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
