diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
index 56690646cf39..a7dea7c75a9b 100644
--- a/Documentation/admin-guide/mm/damon/lru_sort.rst
+++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
@@ -221,6 +221,10 @@ But, setting this too high could result in increased monitoring overhead.
 Please refer to the DAMON documentation (:doc:`usage`) for more detail.  10 by
 default.
 
+Note that this must be 3 or higher. Please refer to the :ref:`Monitoring
+<damon_design_monitoring>` section of the design document for the rationale
+behind this lower bound.
+
 max_nr_regions
 --------------
 
diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
index 442ac5c64795..47854c461706 100644
--- a/Documentation/admin-guide/mm/damon/reclaim.rst
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -204,6 +204,10 @@ monitoring.  This can be used to set lower-bound of the monitoring quality.
 But, setting this too high could result in increased monitoring overhead.
 Please refer to the DAMON documentation (:doc:`usage`) for more detail.
 
+Note that this must be 3 or higher. Please refer to the :ref:`Monitoring
+<damon_design_monitoring>` section of the design document for the rationale
+behind this lower bound.
+
 max_nr_regions
 --------------
 
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 838b14d22519..afc7d52bda2f 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -167,6 +167,13 @@ monitoring attributes, ``sampling interval``, ``aggregation interval``,
 ``update interval``, ``minimum number of regions``, and ``maximum number of
 regions``.
 
+Note that ``minimum number of regions`` must be 3 or higher. This is because the
+virtual address space monitoring is designed to handle at least three regions to
+accommodate two large unmapped areas commonly found in normal virtual address
+spaces. While this restriction might not be strictly necessary for other
+operation sets like ``paddr``, it is currently enforced across all DAMON
+operations for consistency.
+
 To know how user-space can set the attributes via :ref:`DAMON sysfs interface
 <sysfs_interface>`, refer to :ref:`monitoring_attrs <sysfs_monitoring_attrs>`
 part of the documentation.