On the docker image debian:stretch-slim, couldn't delete a specific folder on a NFS drive, using rm -rf /folder-name as root (or rm-rf * after entering the folder-name).
Got the following error back:
rm: cannot remove 'test-ikmgfjhv/dev/.nfse47cf31c6b1dd52500000009': Device or resource busy
After a lot of searching, eventually got to the following link:
https://uisapp2.iu.edu/confluence-prd/pages/viewpage.action?pageId=123962105
Which Describes exactly why those files exist in NFS and how to handle them. As I wasn't using the same machine the process runs on (another container), so in my case, I had to work around that and first make sure the process using the file is being killed on the first machine, then try to delete it on the second one, according to the project's needs.