[0/8] mm/damon: add sysfs dirs for managing DAMOS filters based on handling layers

Message

SeongJae Park March 5, 2025, 10:27 p.m. UTC

DAMOS filters are categorized into two groups based on their handling
layers, namely core and operations layers.  The categorization affects
when each filter is evaluated.  Core layer handled filters are evaluated
first.  The order meant nothing before, but introduction of allow
filters changed that.

DAMOS sysfs interface provides single directory for filters, namely
'filters'.  Users can install any filters in any order there.  DAMON
will internally categorize those into core and operations layer handled
ones, and apply the evaluation order rule.  The ordering rule is clearly
documented.  But the interface could still confuse users since it is
allowed to install filters on the directory in mixed ways.

Add two sysfs directories for managing filters by handling layers,
namely 'core_filters' and 'ops_filters' for filters that handled by core
and operations layer, respectively.  Those are avoided to be used for
installing filters that not handled by the assumed layers.

For backward compatibility, keep 'filters' directory with its curernt
behavior.  Filters installed in the directory will be added to DAMON
after those of 'core_filters' and 'ops_filters' directories, with the
automatic categorizations.  Also recommend users to use the new
directories while noticing 'filters' directory could be deprecated in
future on the usage documents.

Note that new directories provide all features that were provided with
'filters', but just in a more clear way.  Deprecating 'filters' in
future will hence not make an irreversal feature loss.

Changes from RFC
(https://lore.kernel.org/[e-mail])
- Fix sphinx error on usage doc change
- Wrodsmith commit messages
- Rebase on latest mm-unstable

SeongJae Park (8):
  mm/damon/sysfs-schemes: let damon_sysfs_scheme_set_filters() be used
    for different named directories
  mm/damon/sysfs-schemes: implement core_filters and ops_filters
    directories
  mm/damon/sysfs-schemes: commit filters in {core,ops}_filters
    directories
  mm/damon/core: expose damos_filter_for_ops() to DAMON kernel API
    callers
  mm/damon/sysfs-schemes: record filters of which layer should be added
    to the given filters directory
  mm/damon/sysfs-schemes: return error when for attempts to install
    filters on wrong sysfs directory
  Docs/ABI/damon: document {core,ops}_filters directories
  Docs/admin-guide/mm/damon/usage: update for {core,ops}_filters
    directories

 .../ABI/testing/sysfs-kernel-mm-damon         |  16 +++
 Documentation/admin-guide/mm/damon/usage.rst  |  31 +++--
 include/linux/damon.h                         |   1 +
 mm/damon/core.c                               |   9 +-
 mm/damon/sysfs-schemes.c                      | 119 ++++++++++++++++--
 5 files changed, 153 insertions(+), 23 deletions(-)


base-commit: d5ce0f2fd108557fb138adccb203441d0d70f1c4