[RFC PATCH 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.

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: 197a7eb91f786e5deeb1dfea35076c01ebd37ce0
--
2.47.3

[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 <s...@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 df16cc070eeb0..a1ba807d59a13 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1488,6 +1488,26 @@ static void damon_test_walk_control_obsolete(struct kunit *test)
damon_destroy_ctx(ctx);
}

+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),
@@ -1518,6 +1538,7 @@ static struct kunit_case damon_test_cases[] = {
KUNIT_CASE(damon_test_apply_min_nr_regions),
KUNIT_CASE(damon_test_is_last_region),
KUNIT_CASE(damon_test_walk_control_obsolete),
+ KUNIT_CASE(damon_test_rand),
{},
};

--
2.47.3

[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/202606241420...@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

[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 <s...@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),

[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 v1.1
- RFC v1.1: https://lore.kernel.org/202606250507...@kernel.org
- Document nid requirement for node_eligible_mem_bp.
- Fix typos: s/memmcg/memcg/, s/geets/gets/.
- Drop damon_rnd() randomness test case; test boundness only.
- Fixup dests dir selftest to do real test with correct file permission checks.

Changes from RFC
- RFC: https://lore.kernel.org/202606241420...@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 | 6 +-

mm/damon/core.c | 22 +++-
mm/damon/sysfs.c | 102 ++++++++++--------

mm/damon/tests/core-kunit.h | 17 +++
tools/testing/selftests/damon/sysfs.sh | 71 +++++++++++-
6 files changed, 205 insertions(+), 53 deletions(-)


base-commit: ada7832345164eed1bbca10543b0c46f13738215
--
2.47.3

[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 bounds of the output.

Signed-off-by: SeongJae Park <s...@kernel.org>
---

mm/damon/tests/core-kunit.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 1cfb8c176b873..eec7cb325a431 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1460,6 +1460,22 @@ 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]++;
+ }
+}

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

@@ -1489,6 +1505,7 @@ static struct kunit_case damon_test_cases[] = {

[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 v1.2
- RFC v1.2: https://lore.kernel.org/2026062514235...@kernel.org
- Fix broken sphinx syntax in patch 1.
- Drop unused counts[] for damon_rand() test in patch 3.

mm/damon/tests/core-kunit.h | 15 +++
tools/testing/selftests/damon/sysfs.sh | 71 +++++++++++-
6 files changed, 203 insertions(+), 53 deletions(-)


base-commit: 7221b218afc0bff75d656bb193cb6709737cbbf6
--
2.47.3

[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 bounds of the output.

Signed-off-by: SeongJae Park <s...@kernel.org>
---

mm/damon/tests/core-kunit.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 1cfb8c176b873..282670b0fa908 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1460,6 +1460,20 @@ 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 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);
+ }

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

@@ -1489,6 +1503,7 @@ static struct kunit_case damon_test_cases[] = {

[SJ 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 v1.3
- RFC v1.3: https://lore.kernel.org/202606260016...@kernel.org
- Drop RFC tag.
- Rebase to latest mm-new.

Changes from RFC v1.2
- RFC v1.2: https://lore.kernel.org/2026062514235...@kernel.org
- Fix broken sphinx syntax in patch 1.
- Drop unused counts[] for damon_rand() test in patch 3.
Changes from RFC v1.1
- RFC v1.1: https://lore.kernel.org/202606250507...@kernel.org
- Document nid requirement for node_eligible_mem_bp.
- Fix typos: s/memmcg/memcg/, s/geets/gets/.
- Drop damon_rnd() randomness test case; test boundness only.
- Fixup dests dir selftest to do real test with correct file permission
checks.
Changes from RFC
- RFC: https://lore.kernel.org/202606241420...@kernel.org
- Rebase directly to latest mm-new.

SJ 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 | 6 +-
mm/damon/core.c | 22 +++-
mm/damon/sysfs.c | 102 ++++++++++--------
mm/damon/tests/core-kunit.h | 15 +++
tools/testing/selftests/damon/sysfs.sh | 71 +++++++++++-
6 files changed, 203 insertions(+), 53 deletions(-)

base-commit: bb5dde77be397d614ef968578e3bf6cf9674df3c
--
2.47.3

[SJ 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 bounds of the output.

Signed-off-by: SJ Park <s...@kernel.org>

---
mm/damon/tests/core-kunit.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h

index aef7e0553cba4..0124f83b39b83 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1547,6 +1547,20 @@ static void damon_test_walk_control_obsolete(struct kunit *test)
damon_destroy_ctx(ctx);
}

+static void damon_test_rand(struct kunit *test)
+{
+ struct damon_ctx ctx;
+ 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);
+ }
+}
+
static struct kunit_case damon_test_cases[] = {
KUNIT_CASE(damon_test_target),
KUNIT_CASE(damon_test_regions),

@@ -1578,6 +1592,7 @@ static struct kunit_case damon_test_cases[] = {
KUNIT_CASE(damon_test_apply_min_nr_regions),
KUNIT_CASE(damon_test_is_last_region),
KUNIT_CASE(damon_test_walk_control_obsolete),

[SJ Park]

On Tue, 30 Jun 2026 07:17:14 -0700 SJ Park <s...@kernel.org> wrote:

> 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.

Sashiko found a few things that could be good future works, but none of those
is a blocker of this series, in my opinion. Please read the full thread [1] in
lore.kernel.org if you want more details of Sashiko findings and my replies.

[1] https://lore.kernel.org/202606301417...@kernel.org


THanks,
SJ

[...]