Fix a bug introduced with the CLFLUSH changes: we must always flush pages
changed in cpa(), not just when they are reverted.
Reenable CLFLUSH usage with that now (it was temporarily disabled
for .22)
Add some BUG_ONs
Contains fixes from Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>