If swap is on a UAS device, we could recurse into the driver by using
GFP_KERNEL.  Using GFP_NOIO ensures we won't.
Reported-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>