The following has be reported by IBM LTC: Cannot umount root mounted --rbind Hardware Environment: VMWare 4.0 Software Environment: RHEL 3 Beta 2 Steps to Reproduce: 1.mkdir /tmp/test 2.mount --rbind / /tmp/test 3.cd /tmp/test 4.ls 5.cd boot 6.ls # this verifies that I can see the contents of another mounted partition 7.cd / 8.umount /tmp/test Actual Results: umount: /tmp/test: device is busy Expected Results: I expected to be able to umount my recursive mount of the system root. Additional Information:Bill - did this happen on RHAS 2.1 ? How about earlier beta versions of RHEL3 ?This feature did not exist in RHAS 2.1 and I did not try the earlier beta release. This appears to be a new feature in this kernel. Actually, it seems as though this feature has been in the kernel since 2.4.18 but this is the first release in which mount had the --rbind switch so I hadn't tried it before. Glen/Greg - please submit this to Red Hat. Thanks.
(from discussion with Al Viro) this is not a bug; with rbind, proc and others are mounted on TOP of the new mount point, so it is indeed busy. If you want to umount it anyway, you need to use umount -l which will recursive umount this again.