sd 4:0:0:0: [sda] 390721968 512-byte hardware sectors (200050 MB)
Your disk reports one size
sda: rw=0, want=532056072, limit=390721968
Buffer I/O error on device sda3, logical block 0
but your partition table thinks the disk is an entirely different size
I striped two 200GB HDD to a 400GB HDD (hardware RAID).
The partition table claims that there is a 400GB HDD, but LINUX assumes
two separate 200GB HDD's
I replaced the first HDD by a different HDD, turned RAID off and booted
without libata.dma=1, and the problem occured again.
Then, I booted using libata.dma=1, and the problem disappeared!!!
A thousand thanks to Alan Cox!!!!
If some developer is interested, then I can provide more information and
make some more experiments.
Best regards, Daniel