Quoting Cedric Le Goater (legoater@xxxxxxx): > > > No, what you're suggesting does not suffice. > > probably. I'm still trying to understand what you mean below :) > > Man, I hate these hierarchicals pid_ns. one level would have been enough, > just one vpid attribute in 'struct pid*' Well I don't mind - temporarily - saying that nested pid namespaces are not checkpointable. It's just that if we're going to need a new syscall anyway, then why not go ahead and address the whole problem? It's not hugely more complicated, and seems worth it. > > Call > > (5591,3,1) the task knows as 5591 in the init_pid_ns, 3 in a child pid > > ns, and 1 in grandchild pid_ns created from there. Now assume we are > > checkpointing tasks T1=(5592,1), and T2=(5594,3,1). > > > > We don't care about the first number in the tuples, so they will be > > random numbers after the recreate. > > yes. > > > But we do care about the second numbers. > > yes very much and we need a way set these numbers in alloc_pid() > > > But specifying CLONE_NEWPID while recreating the process tree > > in userspace does not allow you to specify the 3 in (5594,3,1). > > I haven't looked closely at hierarchical pid namespaces but as we're > using a an array of pid indexed but the pidns level, i don't see why > it shouldn't be possible. you might be right. > > anyway, I think that some CLONE_NEW* should be forbidden. Daniel should > send soon a little patch for the ns_cgroup restricting the clone flags > being used in a container. Uh, that feels a bit over the top. We want to make this uncheckpointable (if it remains so), not prevent the whole action. After all I may be running a container which I don't plan on ever checkpointing, and inside that container running a job which i do want to migrate. So depending on if we're doing the Dave or the rest-of-the-world way :), we either clear_bit(pidns->may_checkpoint) on the parent pid_ns when a child is created, or we walk every task being checkpointed and make sure they each are in the same pid_ns. Doesn't that suffice? -serge _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers