Interesting. I don't have access to the code I was talking about anymore, but I'm pretty sure that I did have different threads in different mount namespaces.

Interesting. I don't have access to the code I was talking about anymore, but I'm pretty sure that I did have different threads in different mount namespaces. Looking at the man-page briefly it looks like the restriction you are talking about applies only to user namespaces. Interesting to know that there are even more situations to be considered.