Upgrading stock 6.2 glibc to: glibc-2.1.3-19.i386.rpm glibc-devel-2.1.3-19.i386.rpm causes a strange problem that I'm able to duplicate on similar machines. After doing the upgrade with rpm -Fvh, rebooting the system causes: Unmounting file systems umount2: Device or resource busy umount: /: device is busy mount: / is busy Unmounting proc file system mount: / is busy The system is then rebooted, and an fsck is run at next bootup. Rebooting again causes no problems.
That's because init was still using the old glibc at reboot time. Run telinit u after upgrading glibc if you want clean reboots after glibc upgrade. I have already coded a program which will take care of doing telinit u on upgrades (it is tricky because of package dependencies), it will appear in the next glibc 2.1.93+ build.