Red Hat Bugzilla – Bug 996785
umount -a causes root file system to become read-only
Last modified: 2015-08-25 09:05:31 EDT
Description of problem:
When doing an umount -a to umount all non-busy file systems in /etc/fstab, the / file system flips to read-only. Command may not actually unmount the file systems. mount -n -o remount.rw / will get the file system back to read-write, but mtab won't update and df -k will not show the mounted file systems that /etc/fstab has configured.
The other local disk file systems (/opt, /var, /boot, /usr) are unaffected.
Version-Release number of selected component (if applicable):
RHEL 6.1, mount from util-linux-ng 2.17.2
Two servers running the same OS, versions, and config show the same problem:
umount -a, / flips to RO, mount -a says the file systems are already mounted, df -k doesn't show the mounted file systems from /etc/ftab apart from the local OS disks.
Steps to Reproduce:
1. verify /etc/fstab /etc/mtab, df -k to see all mounted file systems
2. umount -a ; umounts unused filesystems (NFS mounts, local disk not held up by processes
3. touch /etc/file, can't / has become read-only
expect / to stay read-write, all the file systems in /etc/fstab should remount with mount -a. df -k should show all the mounted file systems
This request was not resolved in time for the current release.
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the next release of Red Hat Enterprise Linux.
The "umount -a" works as expected. It's designed for shutdown and remount root fs read-only is expected feature.
Note that RHEL7 umount provides -R,--recursive option to umount hierarchy of filesystem. It seems better solution than call umount -a.