Docs/mm/damon: move the list of DAMOS actions to design doc

DAMOS operation actions are explained nearly twice on the DAMON usage
document, once for the sysfs interface, and then again for the debugfs
interface.  Duplication is bad.  Also it would better to keep this kind of
concept level details in design document and keep the usage document small
and focus on only the usage.  Move the list to design document and update
usage document to reference it.

Link: https://lkml.kernel.org/r/20240217005842.87348-3-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/admin-guide/mm/damon/usage.rst

@@ -302,27 +302,8 @@ In each scheme directory, five directories (``access_pattern``, ``quotas``,
 
 The ``action`` file is for setting and getting the scheme's :ref:`action
 <damon_design_damos_action>`.  The keywords that can be written to and read
-from the file and their meaning are as below.
-
-Note that support of each action depends on the running DAMON operations set
-:ref:`implementation <sysfs_context>`.
-
- - ``willneed``: Call ``madvise()`` for the region with ``MADV_WILLNEED``.
-   Supported by ``vaddr`` and ``fvaddr`` operations set.
- - ``cold``: Call ``madvise()`` for the region with ``MADV_COLD``.
-   Supported by ``vaddr`` and ``fvaddr`` operations set.
- - ``pageout``: Call ``madvise()`` for the region with ``MADV_PAGEOUT``.
-   Supported by ``vaddr``, ``fvaddr`` and ``paddr`` operations set.
- - ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``.
-   Supported by ``vaddr`` and ``fvaddr`` operations set.
- - ``nohugepage``: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``.
-   Supported by ``vaddr`` and ``fvaddr`` operations set.
- - ``lru_prio``: Prioritize the region on its LRU lists.
-   Supported by ``paddr`` operations set.
- - ``lru_deprio``: Deprioritize the region on its LRU lists.
-   Supported by ``paddr`` operations set.
- - ``stat``: Do nothing but count the statistics.
-   Supported by all operations sets.
+from the file and their meaning are same to those of the list on
+:ref:`design doc <damon_design_damos_action>`.
 
 The ``apply_interval_us`` file is for setting and getting the scheme's
 :ref:`apply_interval <damon_design_damos>` in microseconds.
@@ -763,19 +744,17 @@ Action
 ~~~~~~
 
 The ``<action>`` is a predefined integer for memory management :ref:`actions
-<damon_design_damos_action>`.  The supported numbers and their meanings are as
-below.
-
- - 0: Call ``madvise()`` for the region with ``MADV_WILLNEED``.  Ignored if
-   ``target`` is ``paddr``.
- - 1: Call ``madvise()`` for the region with ``MADV_COLD``.  Ignored if
-   ``target`` is ``paddr``.
- - 2: Call ``madvise()`` for the region with ``MADV_PAGEOUT``.
- - 3: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``.  Ignored if
-   ``target`` is ``paddr``.
- - 4: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``.  Ignored if
-   ``target`` is ``paddr``.
- - 5: Do nothing but count the statistics
+<damon_design_damos_action>`.  The mapping between the ``<action>`` values and
+the memory management actions is as below.  For the detailed meaning of the
+action and DAMON operations set supporting each action, please refer to the
+list on :ref:`design doc <damon_design_damos_action>`.
+
+ - 0: ``willneed``
+ - 1: ``cold``
+ - 2: ``pageout``
+ - 3: ``hugepage``
+ - 4: ``nohugepage``
+ - 5: ``stat``
 
 Quota
 ~~~~~

Documentation/mm/damon/design.rst

@@ -294,9 +294,29 @@ not mandated to support all actions of the list.  Hence, the availability of
 specific DAMOS action depends on what operations set is selected to be used
 together.
 
-Applying an action to a region is considered as changing the region's
-characteristics.  Hence, DAMOS resets the age of regions when an action is
-applied to those.
+The list of the supported actions, their meaning, and DAMON operations sets
+that supports each action are as below.
+
+ - ``willneed``: Call ``madvise()`` for the region with ``MADV_WILLNEED``.
+   Supported by ``vaddr`` and ``fvaddr`` operations set.
+ - ``cold``: Call ``madvise()`` for the region with ``MADV_COLD``.
+   Supported by ``vaddr`` and ``fvaddr`` operations set.
+ - ``pageout``: Call ``madvise()`` for the region with ``MADV_PAGEOUT``.
+   Supported by ``vaddr``, ``fvaddr`` and ``paddr`` operations set.
+ - ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``.
+   Supported by ``vaddr`` and ``fvaddr`` operations set.
+ - ``nohugepage``: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``.
+   Supported by ``vaddr`` and ``fvaddr`` operations set.
+ - ``lru_prio``: Prioritize the region on its LRU lists.
+   Supported by ``paddr`` operations set.
+ - ``lru_deprio``: Deprioritize the region on its LRU lists.
+   Supported by ``paddr`` operations set.
+ - ``stat``: Do nothing but count the statistics.
+   Supported by all operations sets.
+
+Applying the actions except ``stat`` to a region is considered as changing the
+region's characteristics.  Hence, DAMOS resets the age of regions when any such
+actions are applied to those.
 
 
 .. _damon_design_damos_access_pattern: