On one of my computers that I upgraded from 11.3 to 11.4 with a SSD HDD, it no longer umounts any disks on reboot or shutdown, there are no errors shown, it goes from sending TERM and KILL to rebooting.
here is my fstab:
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part1 /boot ext4 acl,user_xattr,noatime 1 2
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part5 / ext4 acl,user_xattr,noatime 1 1
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part6 swap swap defaults 0 0
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part7 /var ext4 acl,user_xattr,noatime 1 2
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part8 /usr ext4 acl,user_xattr 1 2
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part9 /opt ext4 acl,user_xattr 1 2
/dev/disk/by-id/ata-OCZ_SOLID_SSD_MK0109030A6100011-part10 /home ext4 acl,user_xattr 1 2
/dev/disk/by-id/ata-SAMSUNG_HD753LJ_S13UJ1KQC05172-part1 /mnt/datadisk ext4 defaults 1 2
/dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246JDWZ209023-part1 /mnt/store xfs defaults 1 2
/dev/cdrom /media/cdrom auto ro,user,noauto 0 0
/dev/disk/by-id/usb-SAMSUNG_HD204UI_FAFFFFF0FDF2FFF1BF8421-0:0-part1 /media/backup auto defaults,user,noauto 1 2
proc /proc proc defaults 0 0
sysfs /sys sysfs noauto 0 0
debugfs /sys/kernel/debug debugfs noauto 0 0
usbfs /proc/bus/usb usbfs noauto 0 0
devpts /dev/pts devpts mode=0620,gid=5 0 0
tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0