[RFC PATCH v1.1 00/11] mm/damon: update, optimize, and clean up doc, tests, and code

[RFC PATCH v1.1 00/11] mm/damon: update, optimize, and clean up doc, tests, and code

[SeongJae Park]

Patches 1 and 2 update the design and ABI documents for recently added
DAMON features.  Patches 3-7 add or update more unit and self tests for
DAMON to cover recently changed or added functions and sysfs files.
Patch 8 optimizes damon_commit_target_regions() to skip unnecessary
adjacent ranges setup.  Patches 9-11 clean and fix up recently added
DAMON sysfs interface code for readability.

Changes from RFC
- RFC: https://lore.kernel.org/20260624142008.87180-1-sj@kernel.org
- Rebase directly to latest mm-new.

SeongJae Park (11):
  Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP
  Docs/ABI/damon: document probe files
  mm/damon/tests/core-kunit: test damon_rand()
  selftests/damon/sysfs.sh: test multiple probe dirs creation
  selftests/damon/sysfs.sh: test {core,ops}_filters/ directories
  selftests/damon/sysfs.sh: test dests dir
  selftests/damon/sysfs.sh: test all files in quota goal dir
  mm/damon/core: reduce range setup in damon_commit_target_regions()
  mm/damon/sysfs: split probe setup function out
  mm/damon/sysfs: split out filters setup function
  mm/damon/sysfs: fix typos in probe_{add,rm}_dirs: s/attr/probe/

 .../ABI/testing/sysfs-kernel-mm-damon         |  40 +++++++
 Documentation/mm/damon/design.rst             |   2 +
 mm/damon/core.c                               |  22 +++-
 mm/damon/sysfs.c                              | 102 ++++++++++--------
 mm/damon/tests/core-kunit.h                   |  21 ++++
 tools/testing/selftests/damon/sysfs.sh        |  70 +++++++++++-
 6 files changed, 206 insertions(+), 51 deletions(-)


base-commit: 09ff70563340c38d31012044b9c6c18f225f4fbf
-- 
2.47.3

[RFC PATCH v1.1 01/11] Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP

[SeongJae Park]

Commit 9138e27a3bc3 ("mm/damon: add node_eligible_mem_bp goal metric")
introduced DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP but forgot updating the
DAMON design document for that.  Update.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 2da7ca0d3d17a..1ed02f2280790 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -686,6 +686,8 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to
   (1/10,000).
 - ``inactive_mem_bp``: Inactive to active + inactive (LRU) memory size ratio in
   bp (1/10,000).
+- ``node_eligible_mem_bp``: Scheme target access pattern-eligible memory ratio
+  of a node in bp (1/10,000).
 
 ``nid`` is optionally required for only ``node_mem_used_bp``,
 ``node_mem_free_bp``, ``node_memcg_used_bp`` and ``node_memcg_free_bp`` to
-- 
2.47.3

[RFC PATCH v1.1 02/11] Docs/ABI/damon: document probe files

[SeongJae Park]

DAMON ABI document is not updated for the DAMON probe sysfs files.
Update.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 .../ABI/testing/sysfs-kernel-mm-damon         | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index b73e6bc28ea5f..2815f6bc05c18 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -157,6 +157,46 @@ Description:	Writing a value to this file sets the maximum number of
 		monitoring regions of the DAMON context as the value.  Reading
 		this file returns the value.
 
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/nr_probes
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for each DAMON probe named '0' to 'N-1' under the
+		probes/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/nr_filters
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for each DAMON probe filter named '0' to 'N-1'
+		under the filters/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/type
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the type of
+		the memory of the interest.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/path
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	If 'memmcg' is written to the 'type' file, writing to and
+		reading from this file sets and geets the path to the memory
+		cgroup of the interest.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/matching
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing 'Y' or 'N' to this file sets whether the filter is for
+		the memory of the 'type', or all except the 'type'.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/allow
+Date:		May 2026
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing 'Y' or 'N' to this file sets whether to allow or reject
+		hitting the probe for the memory that satisfies the 'type' and
+		the 'matching' of the directory.
+
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/nr_targets
 Date:		Mar 2022
 Contact:	SeongJae Park <sj@kernel.org>
-- 
2.47.3

[RFC PATCH v1.1 03/11] mm/damon/tests/core-kunit: test damon_rand()

[SeongJae Park]

Commit 9012c4e647df ("mm/damon: replace damon_rand() with a per-ctx
lockless PRNG") optimized DAMON for better performance.  Add a kunit
test for ensuring the pseudo randomness quality.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/tests/core-kunit.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 1cfb8c176b873..756f3b9e2ed3b 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1460,6 +1460,26 @@ static void damon_test_is_last_region(struct kunit *test)
 	damon_free_target(t);
 }
 
+static void damon_test_rand(struct kunit *test)
+{
+	struct damon_ctx ctx;
+	int counts[10] = {};
+	int i;
+
+	prandom_seed_state(&ctx.rnd_state, get_random_u64());
+	for (i = 0; i < 10000; i++) {
+		unsigned long rnd = damon_rand(&ctx, 0, 10);
+
+		KUNIT_EXPECT_GE(test, rnd, 0);
+		KUNIT_EXPECT_LE(test, rnd, 9);
+		counts[rnd]++;
+	}
+	for (i = 0; i < 10; i++) {
+		KUNIT_EXPECT_GE(test, counts[i], 900);
+		KUNIT_EXPECT_LE(test, counts[i], 1100);
+	}
+}
+
 static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_target),
 	KUNIT_CASE(damon_test_regions),
@@ -1489,6 +1509,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_set_filters_default_reject),
 	KUNIT_CASE(damon_test_apply_min_nr_regions),
 	KUNIT_CASE(damon_test_is_last_region),
+	KUNIT_CASE(damon_test_rand),
 	{},
 };
 
-- 
2.47.3

[RFC PATCH v1.1 04/11] selftests/damon/sysfs.sh: test multiple probe dirs creation

[SeongJae Park]

DAMON sysfs essential file operations test (sysfs.sh) was extended to
test DAMON probes sysfs directory, by commit 14885da09b0f
("selftests/damon/sysfs.sh: test probes dir").  Unlike other DAMON sysfs
files, it is testing only a single directory case.  Extend it for
multiple directories.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.sh | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index 78f4badb5bebb..0f2ef462a6b6a 100755
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -346,8 +346,13 @@ test_probes()
 	ensure_write_succ "$probes_dir/nr_probes" "1" "valid input"
 	test_probe "$probes_dir/0"
 
+	ensure_write_succ "$probes_dir/nr_probes" "2" "valid input"
+	test_probe "$probes_dir/0"
+	test_probe "$probes_dir/1"
+
 	ensure_write_succ "$probes_dir/nr_probes" "0" "valid input"
 	ensure_dir "$probes_dir/0" "not_exist"
+	ensure_dir "$probes_dir/1" "not_exist"
 }
 
 test_monitoring_attrs()
-- 
2.47.3

[RFC PATCH v1.1 05/11] selftests/damon/sysfs.sh: test {core,ops}_filters/ directories

[SeongJae Park]

DAMON sysfs interface essential file operations test (sysf.sh) is not
testing DAMOS {core,ops}_filters directories.  Add the tests.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.sh | 28 ++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index 0f2ef462a6b6a..07a33995be852 100755
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -103,10 +103,28 @@ test_filter()
 {
 	filter_dir=$1
 	ensure_file "$filter_dir/type" "exist" "600"
-	ensure_write_succ "$filter_dir/type" "anon" "valid input"
-	ensure_write_succ "$filter_dir/type" "memcg" "valid input"
-	ensure_write_succ "$filter_dir/type" "addr" "valid input"
-	ensure_write_succ "$filter_dir/type" "target" "valid input"
+
+	local dir_name=$(basename "$(dirname "$filter_dir")")
+	if  [ "$dir_name" = "filters" ] || [ "$dir_name" = "ops_filters" ]
+	then
+		ensure_write_succ "$filter_dir/type" "anon" "valid input"
+		ensure_write_succ "$filter_dir/type" "memcg" "valid input"
+	fi
+	if  [ "$dir_name" = "filters" ] || [ "$dir_name" = "core_filters" ]
+	then
+		ensure_write_succ "$filter_dir/type" "addr" "valid input"
+		ensure_write_succ "$filter_dir/type" "target" "valid input"
+	fi
+	if [ "$dir_name" = "core_filters" ]
+	then
+		ensure_write_fail "$filter_dir/type" "anon" "ops type"
+		ensure_write_fail "$filter_dir/type" "memcg" "ops type"
+	fi
+	if [ "$dir_name"  = "ops_filters" ]
+	then
+		ensure_write_fail "$filter_dir/type" "addr" "core type"
+		ensure_write_fail "$filter_dir/type" "target" "core type"
+	fi
 	ensure_write_fail "$filter_dir/type" "foo" "invalid input"
 	ensure_file "$filter_dir/matching" "exist" "600"
 	ensure_file "$filter_dir/memcg_path" "exist" "600"
@@ -208,6 +226,8 @@ test_scheme()
 	test_quotas "$scheme_dir/quotas"
 	test_watermarks "$scheme_dir/watermarks"
 	test_filters "$scheme_dir/filters"
+	test_filters "$scheme_dir/core_filters"
+	test_filters "$scheme_dir/ops_filters"
 	test_stats "$scheme_dir/stats"
 	test_tried_regions "$scheme_dir/tried_regions"
 }
-- 
2.47.3

[RFC PATCH v1.1 06/11] selftests/damon/sysfs.sh: test dests dir

[SeongJae Park]

DAMON selftest interface essential file operations test (sysfs.sh) is
not testing DAMOS dests/ directory.  Add the test.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.sh | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index 07a33995be852..ffa8413b5ab3d 100755
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -99,6 +99,29 @@ test_stats()
 	done
 }
 
+test_dest()
+{
+	dest_dir=$1
+	ensure_file "$dest_dir/id" "exist"
+	ensure_file "$dest_dir/weight" "exist"
+}
+
+test_dests()
+{
+	dests_dir=$1
+	ensure_file "$dests_dir/nr_dests" "exist" "600"
+	ensure_write_succ "$dests_dir/nr_dests" "1" "valid input"
+	test_dest "$dests_dir/0"
+
+	ensure_write_succ "$dests_dir/nr_dests" "2" "valid input"
+	test_dest "$dests_dir/0"
+	test_dest "$dests_dir/1"
+
+	ensure_write_succ "$dests_dir/nr_dests" "0" "valid input"
+	ensure_dir "$dests_dir/0" "not_exist"
+	ensure_dir "$dests_dir/1" "not_exist"
+}
+
 test_filter()
 {
 	filter_dir=$1
-- 
2.47.3

[RFC PATCH v1.1 07/11] selftests/damon/sysfs.sh: test all files in quota goal dir

[SeongJae Park]

DAMON sysfs interface for DAMOS quota has quite extended since its
initial introduction.  The test case for that in DAMON sysfs interface
essential file operations test (sysfs.sh) has not accordingly extended,
though.  Extend the test case to test all existing files.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.sh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index ffa8413b5ab3d..15fb9df928818 100755
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -199,6 +199,20 @@ test_goal()
 	ensure_dir "$goal_dir" "exist"
 	ensure_file "$goal_dir/target_value" "exist" "600"
 	ensure_file "$goal_dir/current_value" "exist" "600"
+	ensure_file "$goal_dir/target_metric" "exist" "600"
+	local fpath="$goal_dir/target_metric"
+	ensure_write_succ "$fpath" "user_input" "valid input"
+	ensure_write_succ "$fpath" "some_mem_psi_us" "valid input"
+	ensure_write_succ "$fpath" "node_mem_used_bp" "valid input"
+	ensure_write_succ "$fpath" "node_mem_free_bp" "valid input"
+	ensure_write_succ "$fpath" "node_memcg_used_bp" "valid input"
+	ensure_write_succ "$fpath" "node_memcg_free_bp" "valid input"
+	ensure_write_succ "$fpath" "active_mem_bp" "valid input"
+	ensure_write_succ "$fpath" "inactive_mem_bp" "valid input"
+	ensure_write_succ "$fpath" "node_eligible_mem_bp" "valid input"
+	ensure_write_fail "$fpath" "foo" "invalid input"
+	ensure_file "$goal_dir/nid" "exist" "600"
+	ensure_file "$goal_dir/path" "exist" "600"
 }
 
 test_goals()
-- 
2.47.3

[RFC PATCH v1.1 08/11] mm/damon/core: reduce range setup in damon_commit_target_regions()

[SeongJae Park]

damon_commit_target_regions() calls damon_set_regions() for updating the
destination target's monitoring target region boundaries.  It sets the
boundaries same to source target's monitoring regions, even if they are
adjacent.  Meanwhile, damon_set_region() sets the destination target
regions exactly the same to the source, only when the target regions are
empty.  When there are existing target regions, only a few regions are
expanded or shrunk to fit on only the boundaries for disjoint regions in
the source.  Hence the adjacent source ranges mean nothing in common
cases.  When there are many regions, such adjacent range setup is only a
waste of time and space.  We recently found [1] it is actually causing
memory overhead.  Setup the ranges for only distinct ranges.

[1] https://lore.kernel.org/20260603112306.58490-1-akinobu.mita@gmail.com

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 7e4b9affc5b06..ce5294cb1b4f3 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1349,21 +1349,33 @@ static struct damon_target *damon_nth_target(int n, struct damon_ctx *ctx)
 static int damon_commit_target_regions(struct damon_target *dst,
 		struct damon_target *src, unsigned long src_min_region_sz)
 {
-	struct damon_region *src_region;
+	struct damon_region *src_region, *prev = NULL;
 	struct damon_addr_range *ranges;
 	int i = 0, err;
 
-	damon_for_each_region(src_region, src)
-		i++;
+	damon_for_each_region(src_region, src) {
+		if (!prev || prev->ar.end != src_region->ar.start)
+			i++;
+		prev = src_region;
+	}
 	if (!i)
 		return 0;
 
 	ranges = kmalloc_objs(*ranges, i, GFP_KERNEL | __GFP_NOWARN);
 	if (!ranges)
 		return -ENOMEM;
+	prev = NULL;
 	i = 0;
-	damon_for_each_region(src_region, src)
-		ranges[i++] = src_region->ar;
+	damon_for_each_region(src_region, src) {
+		if (!prev) {
+			ranges[i].start = src_region->ar.start;
+		} else if (prev->ar.end != src_region->ar.start) {
+			ranges[i++].end = prev->ar.end;
+			ranges[i].start = src_region->ar.start;
+		}
+		prev = src_region;
+	}
+	ranges[i++].end = damon_last_region(src)->ar.end;
 	err = damon_set_regions(dst, ranges, i, src_min_region_sz);
 	kfree(ranges);
 	return err;
-- 
2.47.3

[RFC PATCH v1.1 09/11] mm/damon/sysfs: split probe setup function out

[SeongJae Park]

damon_sysfs_set_probes() function is relatively long.  It has two nested
loop for setting two nested entities, namely probe and filter.  Split
out the probe level setup for readability.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 80 ++++++++++++++++++++++++++++--------------------
 1 file changed, 46 insertions(+), 34 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 2e95e3bac774d..982d824f63c21 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1899,47 +1899,59 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
 	return damon_set_attrs(ctx, &attrs);
 }
 
-static int damon_sysfs_set_probes(struct damon_ctx *ctx,
-		struct damon_sysfs_probes *sys_probes)
+static int damon_sysfs_set_probe(struct damon_probe *probe,
+		struct damon_sysfs_probe *sys_probe)
 {
+	struct damon_sysfs_filters *sys_filters;
 	int i;
 
-	for (i = 0; i < sys_probes->nr; i++) {
-		struct damon_sysfs_filters *sys_filters =
-			sys_probes->probes_arr[i]->filters;
-		struct damon_probe *c;
-		int j;
+	sys_filters = sys_probe->filters;
+	if (!sys_filters)
+		return 0;
 
-		if (!sys_filters)
-			continue;
-		c = damon_new_probe();
-		if (!c)
+	for (i = 0; i < sys_filters->nr; i++) {
+		struct damon_sysfs_filter *sys_filter =
+			sys_filters->filters_arr[i];
+		struct damon_filter *filter;
+
+		filter = damon_new_filter(sys_filter->type,
+				sys_filter->matching,
+				sys_filter->allow);
+		if (!filter)
 			return -ENOMEM;
-		damon_add_probe(ctx, c);
-
-		for (j = 0; j < sys_filters->nr; j++) {
-			struct damon_sysfs_filter *sys_filter =
-				sys_filters->filters_arr[j];
-			struct damon_filter *filter;
-
-			filter = damon_new_filter(sys_filter->type,
-					sys_filter->matching,
-					sys_filter->allow);
-			if (!filter)
-				return -ENOMEM;
-			if (filter->type == DAMON_FILTER_TYPE_MEMCG) {
-				int err;
-
-				err = damon_sysfs_memcg_path_to_id(
-						sys_filter->path,
-						&filter->memcg_id);
-				if (err) {
-					damon_destroy_filter(filter);
-					return err;
-				}
+		if (filter->type == DAMON_FILTER_TYPE_MEMCG) {
+			int err;
+
+			err = damon_sysfs_memcg_path_to_id(
+					sys_filter->path,
+					&filter->memcg_id);
+			if (err) {
+				damon_destroy_filter(filter);
+				return err;
 			}
-			damon_add_filter(c, filter);
 		}
+		damon_add_filter(probe, filter);
+	}
+	return 0;
+}
+
+static int damon_sysfs_set_probes(struct damon_ctx *ctx,
+		struct damon_sysfs_probes *sys_probes)
+{
+	int i, err;
+
+	for (i = 0; i < sys_probes->nr; i++) {
+		struct damon_sysfs_probe *sys_probe;
+		struct damon_probe *p;
+
+		p = damon_new_probe();
+		if (!p)
+			return -ENOMEM;
+		damon_add_probe(ctx, p);
+		sys_probe = sys_probes->probes_arr[i];
+		err = damon_sysfs_set_probe(p, sys_probe);
+		if (err)
+			return err;
 	}
 	return 0;
 }
-- 
2.47.3

[RFC PATCH v1.1 10/11] mm/damon/sysfs: split out filters setup function

[SeongJae Park]

damon_sysfs_set_probe() is doing not only probe setup but also filters
setup.  Split out filters setup for readability.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 982d824f63c21..f3bb146b204df 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1899,16 +1899,11 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
 	return damon_set_attrs(ctx, &attrs);
 }
 
-static int damon_sysfs_set_probe(struct damon_probe *probe,
-		struct damon_sysfs_probe *sys_probe)
+static int damon_sysfs_set_filters(struct damon_probe *probe,
+		struct damon_sysfs_filters *sys_filters)
 {
-	struct damon_sysfs_filters *sys_filters;
 	int i;
 
-	sys_filters = sys_probe->filters;
-	if (!sys_filters)
-		return 0;
-
 	for (i = 0; i < sys_filters->nr; i++) {
 		struct damon_sysfs_filter *sys_filter =
 			sys_filters->filters_arr[i];
@@ -1935,6 +1930,17 @@ static int damon_sysfs_set_probe(struct damon_probe *probe,
 	return 0;
 }
 
+static int damon_sysfs_set_probe(struct damon_probe *probe,
+		struct damon_sysfs_probe *sys_probe)
+{
+	struct damon_sysfs_filters *sys_filters;
+
+	sys_filters = sys_probe->filters;
+	if (!sys_filters)
+		return 0;
+	return damon_sysfs_set_filters(probe, sys_filters);
+}
+
 static int damon_sysfs_set_probes(struct damon_ctx *ctx,
 		struct damon_sysfs_probes *sys_probes)
 {
-- 
2.47.3

[RFC PATCH v1.1 11/11] mm/damon/sysfs: fix typos in probe_{add,rm}_dirs: s/attr/probe/

[SeongJae Park]

damon_sysfs_probe_{add,rm}_dirs names a variable for damon_sysf_probe
as 'attr'.  Probably a trivial copy-pasta error, but it makes the code
not pleasant to read.  Fix those.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index f3bb146b204df..36d71f1675426 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1068,7 +1068,7 @@ static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
 	return kzalloc_obj(struct damon_sysfs_probe);
 }
 
-static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *attr)
+static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *probe)
 {
 	struct damon_sysfs_filters *filters;
 	int err;
@@ -1076,22 +1076,22 @@ static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *attr)
 	filters = damon_sysfs_filters_alloc();
 	if (!filters)
 		return -ENOMEM;
-	attr->filters = filters;
+	probe->filters = filters;
 
 	err = kobject_init_and_add(&filters->kobj, &damon_sysfs_filters_ktype,
-			&attr->kobj, "filters");
+			&probe->kobj, "filters");
 	if (err) {
 		kobject_put(&filters->kobj);
-		attr->filters = NULL;
+		probe->filters = NULL;
 	}
 	return err;
 }
 
-static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *attr)
+static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *probe)
 {
-	if (attr->filters) {
-		damon_sysfs_filters_rm_dirs(attr->filters);
-		kobject_put(&attr->filters->kobj);
+	if (probe->filters) {
+		damon_sysfs_filters_rm_dirs(probe->filters);
+		kobject_put(&probe->filters->kobj);
 	}
 }
 
-- 
2.47.3

Re: [RFC PATCH v1.1 01/11] Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The patch introduces an internal inconsistency in the design document by documenting the `node_eligible_mem_bp` metric but failing to update the adjacent sentence that lists which metrics require the `nid` parameter.
--

commit 77a1ee91d398d22fd9a42b16bbf085e55f72a94a
Author: SeongJae Park <sj@kernel.org>
Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP

This commit updates the DAMON design document to include the
node_eligible_mem_bp goal metric that was introduced in an earlier commit.

> diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
> --- a/Documentation/mm/damon/design.rst
> +++ b/Documentation/mm/damon/design.rst
> @@ -686,6 +686,8 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to
>    (1/10,000).
>  - ``inactive_mem_bp``: Inactive to active + inactive (LRU) memory size ratio in
>    bp (1/10,000).
> +- ``node_eligible_mem_bp``: Scheme target access pattern-eligible memory ratio
> +  of a node in bp (1/10,000).
>  
>  ``nid`` is optionally required for only ``node_mem_used_bp``,
>  ``node_mem_free_bp``, ``node_memcg_used_bp`` and ``node_memcg_free_bp`` to

[Severity: Low]
Since node_eligible_mem_bp is a node-specific metric, should it also be
added to this list of metrics that optionally require nid? As currently
written, the use of the word "only" implies that node_eligible_mem_bp does
not use an nid parameter, which could be misleading for users trying to
configure this metric.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625050756.91115-1-sj@kernel.org?part=1

Re: [RFC PATCH v1.1 03/11] mm/damon/tests/core-kunit: test damon_rand()

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The KUnit test uses a non-deterministic seed with tight probability bounds, which will cause sporadic test failures.
--

commit bc9f1073820b74c3fbb6ac52d5ca363629f99f3d
Author: SeongJae Park <sj@kernel.org>

mm/damon/tests/core-kunit: test damon_rand()

Commit 9012c4e647df ("mm/damon: replace damon_rand() with a per-ctx
lockless PRNG") optimized DAMON for better performance.  Add a kunit
test for ensuring the pseudo randomness quality.

> diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
> index 1cfb8c176b873..756f3b9e2ed3b 100644
> --- a/mm/damon/tests/core-kunit.h
> +++ b/mm/damon/tests/core-kunit.h

[ ... ]

> @@ -1460,6 +1460,26 @@ static void damon_test_is_last_region(struct kunit *test)
>  	damon_free_target(t);
>  }
>  
> +static void damon_test_rand(struct kunit *test)
> +{
> +	struct damon_ctx ctx;
> +	int counts[10] = {};
> +	int i;
> +
> +	prandom_seed_state(&ctx.rnd_state, get_random_u64());
> +	for (i = 0; i < 10000; i++) {
> +		unsigned long rnd = damon_rand(&ctx, 0, 10);
> +
> +		KUNIT_EXPECT_GE(test, rnd, 0);
> +		KUNIT_EXPECT_LE(test, rnd, 9);
> +		counts[rnd]++;
> +	}
> +	for (i = 0; i < 10; i++) {
> +		KUNIT_EXPECT_GE(test, counts[i], 900);
> +		KUNIT_EXPECT_LE(test, counts[i], 1100);

[Severity: Medium]
The test uses a true random seed to initialize the PRNG state, making the
test output non-deterministic. Is it possible that these tight expectation
bounds will cause sporadic test failures in automated CI environments?

Statistically, a binomial distribution with n=10,000 and p=0.1 has a
standard deviation of 30. The allowed variation of +/- 100 is roughly
+/- 3.33 standard deviations. The probability of any single bin falling
outside this range is around 0.086%.

Over 10 bins, does this mean the test could spuriously fail about 0.86%
of the time (roughly 1 in 117 runs)?

> +	}
> +}
> +
>  static struct kunit_case damon_test_cases[] = {
>  	KUNIT_CASE(damon_test_target),

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625050756.91115-1-sj@kernel.org?part=3

Re: [RFC PATCH v1.1 02/11] Docs/ABI/damon: document probe files

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Incorrect sysfs value 'memmcg' and typographical errors in DAMON probe ABI documentation.
--

commit 0777dacf66fdc3cce9315b7348cc989aa1d048f8
Author: SeongJae Park <sj@kernel.org>

Docs/ABI/damon: document probe files

This commit updates the DAMON ABI documentation to include the new DAMON
probe sysfs files, defining directories for probes, filters, and attributes.

> diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
> index b73e6bc28ea5f..2815f6bc05c18 100644
> --- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
> +++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
[ ... ]
> +What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/path
> +Date:		May 2026
> +Contact:	SeongJae Park <sj@kernel.org>
> +Description:	If 'memmcg' is written to the 'type' file, writing to and
> +		reading from this file sets and geets the path to the memory
> +		cgroup of the interest.

[Severity: Medium]
Is the expected type value documented correctly here? The documentation
instructs users to write 'memmcg' to the type file, but the underlying kernel
code strictly expects 'memcg'. If userspace follows this documentation, will
the kernel reject the input with an -EINVAL error?

Also, this isn't a bug, but there is a typo in this sentence where "geets"
is written instead of "gets".

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625050756.91115-1-sj@kernel.org?part=2

Re: [RFC PATCH v1.1 06/11] selftests/damon/sysfs.sh: test dests dir

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The newly added `test_dests()` function is never invoked, and its helper `test_dest()` omits a required argument, causing the test to be both unexercised and structurally broken.
--

commit 53579293376a979c6b9c9914d1d77ffa57418d36
Author: SeongJae Park <sj@kernel.org>

selftests/damon/sysfs.sh: test dests dir

DAMON selftest interface essential file operations test (sysfs.sh) is
not testing DAMOS dests/ directory. This commit adds a test for the
dests directory.

> diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
> index 07a33995be852..ffa8413b5ab3d 100755
> --- a/tools/testing/selftests/damon/sysfs.sh
> +++ b/tools/testing/selftests/damon/sysfs.sh
> @@ -99,6 +99,29 @@ test_stats()
>  	done
>  }
>  
> +test_dest()
> +{
> +	dest_dir=$1
> +	ensure_file "$dest_dir/id" "exist"
> +	ensure_file "$dest_dir/weight" "exist"

[Severity: Medium]
Does ensure_file() require a third argument for the expected permission?
Without it, the underlying check might evaluate the file's permission against
an empty string and unconditionally fail the test.

> +}
> +
> +test_dests()
> +{

[Severity: Medium]
Is test_dests() ever invoked? It looks like this function is defined here
but remains unreferenced in the script. Should it be called from
test_scheme() to verify the directory under each scheme?

> +	dests_dir=$1
> +	ensure_file "$dests_dir/nr_dests" "exist" "600"
> +	ensure_write_succ "$dests_dir/nr_dests" "1" "valid input"
> +	test_dest "$dests_dir/0"

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625050756.91115-1-sj@kernel.org?part=6

Re: [RFC PATCH v1.1 01/11] Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP

[SeongJae Park]

On Thu, 25 Jun 2026 05:13:50 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Low] The patch introduces an internal inconsistency in the design document by documenting the `node_eligible_mem_bp` metric but failing to update the adjacent sentence that lists which metrics require the `nid` parameter.
> --
> 
> commit 77a1ee91d398d22fd9a42b16bbf085e55f72a94a
> Author: SeongJae Park <sj@kernel.org>
> Docs/mm/damon/design: update for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP
> 
> This commit updates the DAMON design document to include the
> node_eligible_mem_bp goal metric that was introduced in an earlier commit.
> 
> > diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
> > --- a/Documentation/mm/damon/design.rst
> > +++ b/Documentation/mm/damon/design.rst
> > @@ -686,6 +686,8 @@ mechanism tries to make ``current_value`` of ``target_metric`` be same to
> >    (1/10,000).
> >  - ``inactive_mem_bp``: Inactive to active + inactive (LRU) memory size ratio in
> >    bp (1/10,000).
> > +- ``node_eligible_mem_bp``: Scheme target access pattern-eligible memory ratio
> > +  of a node in bp (1/10,000).
> >  
> >  ``nid`` is optionally required for only ``node_mem_used_bp``,
> >  ``node_mem_free_bp``, ``node_memcg_used_bp`` and ``node_memcg_free_bp`` to
> 
> [Severity: Low]
> Since node_eligible_mem_bp is a node-specific metric, should it also be
> added to this list of metrics that optionally require nid? As currently
> written, the use of the word "only" implies that node_eligible_mem_bp does
> not use an nid parameter, which could be misleading for users trying to
> configure this metric.

Good catch!  I will do so in the next revision.


Thanks,
SJ

[...]

Re: [RFC PATCH v1.1 02/11] Docs/ABI/damon: document probe files

[SeongJae Park]

On Thu, 25 Jun 2026 05:14:13 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Incorrect sysfs value 'memmcg' and typographical errors in DAMON probe ABI documentation.
> --
> 
> commit 0777dacf66fdc3cce9315b7348cc989aa1d048f8
> Author: SeongJae Park <sj@kernel.org>
> 
> Docs/ABI/damon: document probe files
> 
> This commit updates the DAMON ABI documentation to include the new DAMON
> probe sysfs files, defining directories for probes, filters, and attributes.
> 
> > diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
> > index b73e6bc28ea5f..2815f6bc05c18 100644
> > --- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
> > +++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
> [ ... ]
> > +What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/probes/<P>/filters/<F>/path
> > +Date:		May 2026
> > +Contact:	SeongJae Park <sj@kernel.org>
> > +Description:	If 'memmcg' is written to the 'type' file, writing to and
> > +		reading from this file sets and geets the path to the memory
> > +		cgroup of the interest.
> 
> [Severity: Medium]
> Is the expected type value documented correctly here? The documentation
> instructs users to write 'memmcg' to the type file, but the underlying kernel
> code strictly expects 'memcg'. If userspace follows this documentation, will
> the kernel reject the input with an -EINVAL error?
> 
> Also, this isn't a bug, but there is a typo in this sentence where "geets"
> is written instead of "gets".

Good catches.  Those are typos.  Somehow nowadays my computer shows lags at
multiple things including BT keyboard input catch...

I will fix these in the next revision.



Thanks,
SJ

[...]

Re: [RFC PATCH v1.1 03/11] mm/damon/tests/core-kunit: test damon_rand()

[SeongJae Park]

On Thu, 25 Jun 2026 05:13:51 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The KUnit test uses a non-deterministic seed with tight probability bounds, which will cause sporadic test failures.
> --
> 
> commit bc9f1073820b74c3fbb6ac52d5ca363629f99f3d
> Author: SeongJae Park <sj@kernel.org>
> 
> mm/damon/tests/core-kunit: test damon_rand()
> 
> Commit 9012c4e647df ("mm/damon: replace damon_rand() with a per-ctx
> lockless PRNG") optimized DAMON for better performance.  Add a kunit
> test for ensuring the pseudo randomness quality.
> 
> > diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
> > index 1cfb8c176b873..756f3b9e2ed3b 100644
> > --- a/mm/damon/tests/core-kunit.h
> > +++ b/mm/damon/tests/core-kunit.h
> 
> [ ... ]
> 
> > @@ -1460,6 +1460,26 @@ static void damon_test_is_last_region(struct kunit *test)
> >  	damon_free_target(t);
> >  }
> >  
> > +static void damon_test_rand(struct kunit *test)
> > +{
> > +	struct damon_ctx ctx;
> > +	int counts[10] = {};
> > +	int i;
> > +
> > +	prandom_seed_state(&ctx.rnd_state, get_random_u64());
> > +	for (i = 0; i < 10000; i++) {
> > +		unsigned long rnd = damon_rand(&ctx, 0, 10);
> > +
> > +		KUNIT_EXPECT_GE(test, rnd, 0);
> > +		KUNIT_EXPECT_LE(test, rnd, 9);
> > +		counts[rnd]++;
> > +	}
> > +	for (i = 0; i < 10; i++) {
> > +		KUNIT_EXPECT_GE(test, counts[i], 900);
> > +		KUNIT_EXPECT_LE(test, counts[i], 1100);
> 
> [Severity: Medium]
> The test uses a true random seed to initialize the PRNG state, making the
> test output non-deterministic. Is it possible that these tight expectation
> bounds will cause sporadic test failures in automated CI environments?
> 
> Statistically, a binomial distribution with n=10,000 and p=0.1 has a
> standard deviation of 30. The allowed variation of +/- 100 is roughly
> +/- 3.33 standard deviations. The probability of any single bin falling
> outside this range is around 0.086%.
> 
> Over 10 bins, does this mean the test could spuriously fail about 0.86%
> of the time (roughly 1 in 117 runs)?

Good catch.  I will modify the test to widen the bound to [800, 1200].


Thanks,
SJ

[...]

Re: [RFC PATCH v1.1 06/11] selftests/damon/sysfs.sh: test dests dir

[SeongJae Park]

On Thu, 25 Jun 2026 05:14:49 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The newly added `test_dests()` function is never invoked, and its helper `test_dest()` omits a required argument, causing the test to be both unexercised and structurally broken.
> --
> 
> commit 53579293376a979c6b9c9914d1d77ffa57418d36
> Author: SeongJae Park <sj@kernel.org>
> 
> selftests/damon/sysfs.sh: test dests dir
> 
> DAMON selftest interface essential file operations test (sysfs.sh) is
> not testing DAMOS dests/ directory. This commit adds a test for the
> dests directory.
> 
> > diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
> > index 07a33995be852..ffa8413b5ab3d 100755
> > --- a/tools/testing/selftests/damon/sysfs.sh
> > +++ b/tools/testing/selftests/damon/sysfs.sh
> > @@ -99,6 +99,29 @@ test_stats()
> >  	done
> >  }
> >  
> > +test_dest()
> > +{
> > +	dest_dir=$1
> > +	ensure_file "$dest_dir/id" "exist"
> > +	ensure_file "$dest_dir/weight" "exist"
> 
> [Severity: Medium]
> Does ensure_file() require a third argument for the expected permission?
> Without it, the underlying check might evaluate the file's permission against
> an empty string and unconditionally fail the test.
> 
> > +}
> > +
> > +test_dests()
> > +{
> 
> [Severity: Medium]
> Is test_dests() ever invoked? It looks like this function is defined here
> but remains unreferenced in the script. Should it be called from
> test_scheme() to verify the directory under each scheme?

Good findings!  I will fix those in the next revision.


Thanks,
SJ

[...]