Description of problem:
- Freshly deployed RHEL5.5 instances have one 6GB partition only used for / (instead of 10GB previously).
- It is impossible to resize it without rebooting (/ being mounted, partitions cannot be reloaded by the kernel, and one cannot grow a filesystem beyond the partition limit anymore)

Version-Release number of selected component (if applicable):
RHEL5.5 EC2 images

How reproducible:
100%

Steps to Reproduce:
1. Install the RHEL5.5 AMIs on a 10GB block device
2. Try to repartition using fdisk/parted/sfdisk
3. Optionally try to reload the partition table using partprobe
4. Try to resize2fs
  
Actual results:
Operations 2-3 fail, operation 4 is therefore impossible.


Expected results:
No need for the steps 2-3

Additional info:

# strace kpartx -a /dev/sda
stat("/dev/sda", {st_mode=S_IFBLK|0640, st_rdev=makedev(8, 0), ...}) = 0
ioctl(3, DM_DEV_STATUS, 0x42bae60)      = -1 ENXIO (No such device or address)

# strace partprobe /dev/sda
ioctl(3, CDROMAUDIOBUFSIZ or SCSI_IOCTL_GET_IDLUN, 0x7fff3ecac5b0) = -1 EINVAL (Invalid argument)
write(2, "Error: ", 7Error: )                  = 7
write(2, "Error initialising SCSI device /"..., 59Error initialising SCSI device /dev/sda - Invalid argument
) = 59