Some low bits might have been set by the driver, causing
a message like this to come out:

 [   13.288062] ------------[ cut here ]------------
 [   13.293211] WARNING: at lib/dma-debug.c:803 check_unmap+0x1a1/0x654()
 [   13.300387] Hardware name: ProLiant DL180 G6
 [   13.305335] hpsa 0000:06:00.0: DMA-API: device driver tries to free
 DMA memory it has not allocated [device address=0x000000007f81e001]
 [size=640 bytes]
Signed-off-by: NStephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>