kernel: Try to clarify why swap is used only by tmpfs in the kernel t…

…o avoid questions

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

slides/kernel-source-code-drivers/kernel-source-code-drivers.tex

@@ -132,7 +132,7 @@ \subsection{Linux kernel source code}
   \item Fixed size stack (8 or 4 KB). Unlike in user space, no mechanism
     was implemented to make it grow. Don't use recursion!
   \item Swapping is not implemented for kernel memory either\\
-    (Exception: {\em tmpfs} filesystem pages)
+    (except {\em tmpfs} which lives completely in the page cache and on swap)
   \end{itemize}
 \end{frame}