Fedora :: F12 Yum Locks During "Running Transaction Test"?

I spent some time on this issue and I just wanted to share a resolution that was difficult to find (at least for me).Yum was working fine for me for a long time on my Fedora 12 installation x64, when suddenly it stopped during transaction checks. It didn't matter which package I was installing, or if I performed an update or anything. Always in the same place, and it always required a kill -9 to stop the process. Even with debugging turned on in yum (-d 10 -e 10 --rpmverbosity=10) it would not display an error...just hang during the transaction check. I tried the following to no avail:

Code:
# rm -f /var/lib/rpm/__db.*
# yum clean all
# rpm -v -v rebuilddb

Still, it would lock after the transaction test. The only thing that solved my issue was running:

Code:
# strace yum -y update This showed me that I had a stale NFS mount that was in a hung state. I tried umount but it just showed that the device was busy and would not unmount. The only way to fix it was to perform:

Code:
# umount -l /mnt/data which allowed the stale mount to be removed. Once that was cleaned up, everything worked. I struggled with this because there were no debugging messages, and I had no idea the transaction check would go through all of my mounted drives. However I just wanted others to know about this, because it was a rare issue, and I had trouble finding the solution.