On Wed, Jul 25, 2018 at 01:22:47PM +0200, Christoph Hellwig wrote:

quoted

+			pmap = kmap_atomic(iv.bv_page) + iv.bv_offset;
+			p = pmap;

Maybe:

			pmap = p = kmap_atomic(iv.bv_page) + iv.bv_offset;

Max pointed out that even with this, we're still calling kunmap_atomic()
with an address potentially at an offset from the page that was kmap'ed.
While currently harmless, perhaps for correctness:

 			pmap = kmap_atomic(iv.bv_page);
			p = pmap + iv.bv_offset;