[PATCH v3 00/11] mm/damon: support ARM32 with LPAE

[PATCH v3 00/11] mm/damon: support ARM32 with LPAE

[SeongJae Park]

Previously, DAMON's physical address space monitoring only supported
memory ranges below 4GB on LPAE-enabled systems. This was due to
the use of 'unsigned long' in 'struct damon_addr_range', which is
32-bit on ARM32 even with LPAE enabled[1].

To add DAMON support for ARM32 with LPAE enabled, a new core layer
parameter called 'addr_unit' was introduced[2]. Operations set layer
can translate a core layer address to the real address by multiplying
the parameter value to the core layer address. Support of the parameter
is up to each operations layer implementation, though. For example,
operations set implementations for virtual address space can simply
ignore the parameter. Add the support on paddr, which is the DAMON
operations set implementation for the physical address space, as we have
a clear use case for that.

[1]https://lore.kernel.org/all/20250408075553.959388-1-zuoze1@huawei.com/
[2]https://lore.kernel.org/all/20250416042551.158131-1-sj@kernel.org/

Changes from v2
(https://lore.kernel.org/20250822093420.2103803-1-yanquanmin1@huawei.com)
- Fix 64bit division linking errors on certain 32bit arch configs.
- Re-posted by SJ.

Changes from v1
(https://lore.kernel.org/all/20250821105159.2503894-1-yanquanmin1@huawei.com/)
- Set dst->min_sz_region as src->min_sz_region in damon_commit_ctx().
- Fixed the incorrect 'min_region' in the commit message.

Changes from RFC v2
(https://lore.kernel.org/all/20250820080623.3799131-1-yanquanmin1@huawei.com/)
- Rename 'min_region' to 'min_sz_region'.
- Separate the overflow prevention in damos_set_effective_quota() from
  this series.
- Drop RFC tag.

Changes from RFC v1
(https://lore.kernel.org/all/20250813050706.1564229-1-yanquanmin1@huawei.com/)
- Set DAMOS_PAGEOUT, DAMOS_LRU_[DE]PRIO, DAMOS_MIGRATE_{HOT,COLD} and
  DAMOS_STAT stat in core address unit.
- Pass ctx->min_region value to replace the original synchronization.
- Drop the DAMOS stats type changes, keep them as 'unsigned long' type.
- Separate add addr_unit support for DAMON_RECLAIM and LRU_SORT from
  this patch series.

Quanmin Yan (1):
  mm/damon: add damon_ctx->min_sz_region

SeongJae Park (10):
  mm/damon/core: add damon_ctx->addr_unit
  mm/damon/paddr: support addr_unit for access monitoring
  mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT
  mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO
  mm/damon/paddr: support addr_unit for MIGRATE_{HOT,COLD}
  mm/damon/paddr: support addr_unit for DAMOS_STAT
  mm/damon/sysfs: implement addr_unit file under context dir
  Docs/mm/damon/design: document 'address unit' parameter
  Docs/admin-guide/mm/damon/usage: document addr_unit file
  Docs/ABI/damon: document addr_unit file

 .../ABI/testing/sysfs-kernel-mm-damon         |   7 ++
 Documentation/admin-guide/mm/damon/usage.rst  |  11 +-
 Documentation/mm/damon/design.rst             |  16 ++-
 include/linux/damon.h                         |   7 +-
 mm/damon/core.c                               |  70 ++++++-----
 mm/damon/paddr.c                              | 119 +++++++++++-------
 mm/damon/sysfs.c                              |  41 +++++-
 mm/damon/tests/core-kunit.h                   |  21 ++--
 mm/damon/tests/vaddr-kunit.h                  |   2 +-
 mm/damon/vaddr.c                              |   2 +-
 10 files changed, 204 insertions(+), 92 deletions(-)


base-commit: 398a6e2cbd43b92d9a5fa6b4020be72c2441babd
-- 
2.39.5

[PATCH v3 08/11] Docs/mm/damon/design: document 'address unit' parameter

[SeongJae Park]

Add 'addr_unit' parameter description on DAMON design document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 2f6ba5c7f4c7..d9d5baa1ec87 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -67,7 +67,7 @@ processes, NUMA nodes, files, and backing memory devices would be supportable.
 Also, if some architectures or devices support special optimized access check
 features, those will be easily configurable.
 
-DAMON currently provides below three operation sets.  Below two subsections
+DAMON currently provides below three operation sets.  Below three subsections
 describe how those work.
 
  - vaddr: Monitor virtual address spaces of specific processes
@@ -135,6 +135,18 @@ the interference is the responsibility of sysadmins.  However, it solves the
 conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags,
 as Idle page tracking does.
 
+Address Unit
+------------
+
+DAMON core layer uses ``unsinged long`` type for monitoring target address
+ranges.  In some cases, the address space for a given operations set could be
+too large to be handled with the type.  ARM (32-bit) with large physical
+address extension is an example.  For such cases, a per-operations set
+parameter called ``address unit`` is provided.  It represents the scale factor
+that need to be multiplied to the core layer's address for calculating real
+address on the given address space.  Support of ``address unit`` parameter is
+up to each operations set implementation.  ``paddr`` is the only operations set
+implementation that supports the parameter.
 
 .. _damon_core_logic:
 
-- 
2.39.5

[PATCH v3 09/11] Docs/admin-guide/mm/damon/usage: document addr_unit file

[SeongJae Park]

Document addr_unit DAMON sysfs file on DAMON usage document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 11 +++++++----
 Documentation/mm/damon/design.rst            |  2 ++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index ff3a2dda1f02..2cae60b6f3ca 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -61,7 +61,7 @@ comma (",").
     │ :ref:`kdamonds <sysfs_kdamonds>`/nr_kdamonds
     │ │ :ref:`0 <sysfs_kdamond>`/state,pid,refresh_ms
     │ │ │ :ref:`contexts <sysfs_contexts>`/nr_contexts
-    │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations
+    │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations,addr_unit
     │ │ │ │ │ :ref:`monitoring_attrs <sysfs_monitoring_attrs>`/
     │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
     │ │ │ │ │ │ │ intervals_goal/access_bp,aggrs,min_sample_us,max_sample_us
@@ -188,9 +188,9 @@ details).  At the moment, only one context per kdamond is supported, so only
 contexts/<N>/
 -------------
 
-In each context directory, two files (``avail_operations`` and ``operations``)
-and three directories (``monitoring_attrs``, ``targets``, and ``schemes``)
-exist.
+In each context directory, three files (``avail_operations``, ``operations``
+and ``addr_unit``) and three directories (``monitoring_attrs``, ``targets``,
+and ``schemes``) exist.
 
 DAMON supports multiple types of :ref:`monitoring operations
 <damon_design_configurable_operations_set>`, including those for virtual address
@@ -205,6 +205,9 @@ You can set and get what type of monitoring operations DAMON will use for the
 context by writing one of the keywords listed in ``avail_operations`` file and
 reading from the ``operations`` file.
 
+``addr_unit`` file is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the operations set.
+
 .. _sysfs_monitoring_attrs:
 
 contexts/<N>/monitoring_attrs/
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index d9d5baa1ec87..80354f4f42ba 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -135,6 +135,8 @@ the interference is the responsibility of sysadmins.  However, it solves the
 conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags,
 as Idle page tracking does.
 
+.. _damon_design_addr_unit:
+
 Address Unit
 ------------
 
-- 
2.39.5