On at least arm32, but presumably any arch with highmem, if the
application passes in memory that resides in highmem for the rings,
then we should fail that ring creation. We fail it with -EINVAL, which
is what kernels that don't support IORING_SETUP_NO_MMAP will do as well.

Cc: stable@vger.kernel.org
Fixes: 03d89a2d ("io_uring: support for user allocated memory for rings/sqes")
Signed-off-by: Jens Axboe <axboe@kernel.dk>