The current link http://kernel.dk/blk-mq.pdf leads to a 404 error page.
https://www.kernel.dk/blk-mq.pdf leads to the correct document.

Signed-off-by: Jenson Johnathon Reggentin <mail@jregg.de>
---
 Documentation/block/blk-mq.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/block/blk-mq.rst b/Documentation/block/blk-mq.rst
index fc06761b6ea9..c2af39f14d6d 100644
--- a/Documentation/block/blk-mq.rst
+++ b/Documentation/block/blk-mq.rst
@@ -139,7 +139,7 @@ completed.
 Further reading
 ---------------
 
-- `Linux Block IO: Introducing Multi-queue SSD Access on Multi-core Systems <http://kernel.dk/blk-mq.pdf>`_
+- `Linux Block IO: Introducing Multi-queue SSD Access on Multi-core Systems <https://kernel.dk/blk-mq.pdf>`_
 
 - `NOOP scheduler <https://en.wikipedia.org/wiki/Noop_scheduler>`_
 
-- 
2.54.0