Commit 7db551fcfb2a ("mm/damon/reclaim: support addr_unit for
DAMON_RECLAIM") introduced the 'addr_unit' parameter for DAMON_RECLAIM.
But the usage document is not updated for that.  Update the document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 .../admin-guide/mm/damon/reclaim.rst          | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
index 92bb7cf1b558..552a7786b082 100644
--- a/Documentation/admin-guide/mm/damon/reclaim.rst
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -232,6 +232,28 @@ The end physical address of memory region that DAMON_RECLAIM will do work
 against.  That is, DAMON_RECLAIM will find cold memory regions in this region
 and reclaims.  By default, biggest System RAM is used as the region.
 
+addr_unit
+---------
+
+A scale factor for memory addresses and bytes.
+
+This parameter is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM.
+
+``monitor_region_start`` and ``monitor_region_end`` should be provided in this
+unit.  For example, let's suppose ``addr_unit``, ``monitor_region_start`` and
+``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively.
+Then DAMON_RECLAIM will work for 10 KiB length of physical address range that
+starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes).
+
+``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are also in
+this unit.  For example, let's suppose values of ``addr_unit``,
+``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are ``1024``,
+``42``, and ``32``, respectively.  Then it means DAMON_RECLAIM tried to reclaim
+42 KiB memory and successfully reclaimed 32 KiB memory in total.
+
+If unsure, use only the default value (``1``) and forget about this.
+
 skip_anon
 ---------
 
-- 
2.47.3