> So if there's some userspace process with a broken NFS server and it > does umount(MNT_DETACH) it will end up hanging every other > umount(MNT_DETACH) on the system because the dealyed_mntput_work > workqueue (to my understanding) cannot make progress. Ok, "to my understanding" has been updated after going back and reading the delayed work code. Luckily it's not as bad as I thought it is because it's queued on system_wq which is multi-threaded so it's at least not causing everyone with MNT_DETACH to get stuck. I'm still skeptical how safe this all is.
