Commit 2e0fe9245d6b ("mm/damon/lru_sort: support addr_unit for
DAMON_LRU_SORT") introduced the 'addr_unit' parameter for
DAMON_LRU_SORT.  But the usage document is not updated for that.  Update
the document.

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

diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
index 7b0775d281b4..72a943202676 100644
--- a/Documentation/admin-guide/mm/damon/lru_sort.rst
+++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
@@ -211,6 +211,28 @@ End of target memory region in physical address.
 The end physical address of memory region that DAMON_LRU_SORT will do work
 against.  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_LRU_SORT will work for 10 KiB length of physical address range that
+starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes).
+
+Stat parameters having ``bytes_`` prefix are also in this unit.  For example,
+let's suppose values of ``addr_unit``, ``bytes_lru_sort_tried_hot_regions`` and
+``bytes_lru_sorted_hot_regions`` are ``1024``, ``42``, and ``32``,
+respectively.  Then it means DAMON_LRU_SORT tried to LRU-sort 42 KiB of hot
+memory and successfully LRU-sorted 32 KiB of the memory in total.
+
+If unsure, use only the default value (``1``) and forget about this.
+
 kdamond_pid
 -----------
 
-- 
2.47.3