[RFC PATCH 0/2] mm/damon/sysfs: document filters/ directory as deprecated

[RFC PATCH 0/2] mm/damon/sysfs: document filters/ directory as deprecated

[SeongJae Park]

Commit ab71d2d30121 ("mm/damon/sysfs-schemes: let
damon_sysfs_scheme_set_filters() be used for different named
directories") introduced alternatives of 'filters' directory, namely
core_filters/ and 'ops_filters/ directories.  Now the alternatives are
well stabilized and ready for all users.  All filters/ directory use
cases are expected to be able to be migrated to the alternatives.  An
LTS kernel having the alternatives, namely 6.18.y, is also released.
Existence of filters/ directory is only confusing.

It would be better not immediately removing the directory, though.
There could be users that need time before migrating to the
alternatives. There might be unexpected use cases that the alternatives
cannot support.  Doing the deprecation step by step across multiple
years like DAMON debugfs deprecation would be safer.  Start the
deprecation changes by announcing the deprecation on the documents.

Every year, one more action for completely removing the directory will
be followed, like DAMON debugfs deprecation did.  Following yearly
actions are currently expected.  In 2027, deprecation warning kernel
messages will be printed once, for use of filters/ directory.  In 2028,
filters/ directory will be renamed to filters_DEPRECATED/.  In 2029,
filters_DEPRECATED/ directory will be removed.

SeongJae Park (2):
  Docs/admin-guide/mm/damon/usage: mark scheme filters sysfs dir as
    deprecated
  Docs/ABI/damon: mark schemes/<S>/filters/ deprecated

 .../ABI/testing/sysfs-kernel-mm-damon         | 62 ++++++++++---------
 Documentation/admin-guide/mm/damon/usage.rst  |  7 ++-
 2 files changed, 38 insertions(+), 31 deletions(-)


base-commit: 68f9cad2eca9a05a70ec47a90f2ae97aa2363a9c
-- 
2.47.3

[RFC PATCH 1/2] Docs/admin-guide/mm/damon/usage: mark scheme filters sysfs dir as deprecated

[SeongJae Park]

The alternatives of 'filters/' directory, namely 'core_filters/' and
'ops_filters/', can fully support all the features 'filters/' directory
can do, and provide better user experience.   Having 'filters/'
directory is only confusing to users.  Announce it as deprecated on the
usage document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index d5548e460857c..918c14a8e852b 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -486,9 +486,10 @@ layers.  Filters that requested by ``core_filters`` and ``ops_filters`` will be
 installed before those of ``filters``.  All three directories have same files.
 
 Use of ``filters`` directory can make expecting evaluation orders of given
-filters with the files under directory bit confusing.  Users are hence
-recommended to use ``core_filters`` and ``ops_filters`` directories.  The
-``filters`` directory could be deprecated in future.
+filters with the files under directory bit confusing.  For the reason,
+``filters`` directory is deprecated.  It is still functioning, but it will be
+broken and eventually removed in near future.  Users should use
+``core_filters`` and ``ops_filters`` directories instead.
 
 In the beginning, the directory has only one file, ``nr_filters``.  Writing a
 number (``N``) to the file creates the number of child directories named ``0``
-- 
2.47.3