ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
pagefault_disable();
ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
pagefault_disable();