[RFC PATCH 00/10] mm/damon: cleanup code, add test cases, and update guidances in docs

[SJ Park]

Misc cleanup, improvements and updates of code, test, and documents.

Patches 1-3 cleanup DAMON code. Patches 4-8 adds kunit and selftest
test cases for recently fixed bugs and a new feature. Patches 9 and 10
update guidelines for AI review and what document to read, on DAMON
documents.

SJ Park (10):
mm/damon/core: use damon_nr_samples_per_aggr() for max merge threshold
mm/damon/core: remove debug messages
mm/damon/vaddr: remove a debug message
mm/damon/tests/core-kunit: extend set_regions() test for error case
mm/damon/tests/core-kunit: test <=0 size damon_set_regions() inputs
mm/damon/tests/core-kunit: test overlapping ranges for set_regions()
mm/damon/tests/core-kunit: test damon_nr_samples_per_aggr()
selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal
Docs/mm/damon/maintainer-profile: update AI review for Sashiko replies
Docs/ABI/damon: recommend subsystem doc instead of admin-guide

.../ABI/testing/sysfs-kernel-mm-damon | 2 +-
Documentation/mm/damon/maintainer-profile.rst | 19 ++----
mm/damon/core.c | 12 +---
mm/damon/tests/core-kunit.h | 60 ++++++++++++++++---
mm/damon/vaddr.c | 11 +---
tools/testing/selftests/damon/sysfs.sh | 1 +
6 files changed, 61 insertions(+), 44 deletions(-)


base-commit: f5d0a1c210a9bec33ee6cc888f4cc6dd1f56eda7
--
2.47.3

[SJ Park]

damon_test_set_regions_for() is designed to test only success-expected
damon_set_regions() calls. Extend it to cover error-expected calls,
too.

Signed-off-by: SJ Park <s...@kernel.org>
---
mm/damon/tests/core-kunit.h | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 4a536d41cdb2d..befc1196d6d60 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -463,11 +463,12 @@ static void damon_test_set_regions_for(struct kunit *test,
struct damon_addr_range *old_ranges, int sz_old_ranges,
struct damon_addr_range *new_ranges, int sz_new_ranges,
unsigned long min_region_sz,
- struct damon_addr_range *expect_ranges, int sz_expect_ranges)
+ struct damon_addr_range *expect_ranges, int sz_expect_ranges,
+ int expect_err)
{
struct damon_target *t;
struct damon_region *r;
- int i;
+ int i, err;

t = damon_new_target();
if (!t)
@@ -481,7 +482,8 @@ static void damon_test_set_regions_for(struct kunit *test,
damon_add_region(r, t);
}

- damon_set_regions(t, new_ranges, sz_new_ranges, min_region_sz);
+ err = damon_set_regions(t, new_ranges, sz_new_ranges, min_region_sz);
+ KUNIT_EXPECT_EQ(test, err, expect_err);

KUNIT_EXPECT_EQ(test, damon_nr_regions(t), sz_expect_ranges);
if (damon_nr_regions(t) != sz_expect_ranges) {
@@ -510,7 +512,7 @@ static void damon_test_set_regions(struct kunit *test)
(struct damon_addr_range[]){
{.start = 5, .end = 15},
{.start = 15, .end = 25},
- }, 2);
+ }, 2, 0);
/* Un-intersecting regions should be removed. */
damon_test_set_regions_for(test,
(struct damon_addr_range[]){
@@ -523,7 +525,7 @@ static void damon_test_set_regions(struct kunit *test)
1,
(struct damon_addr_range[]){
{.start = 18, .end = 23},
- }, 1);
+ }, 1, 0);
/*
* Holes should be filled up with new regions.
*
@@ -544,7 +546,7 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 8, .end = 16},
{.start = 16, .end = 24},
{.start = 24, .end = 28},
- }, 3);
+ }, 3, 0);
/*
* New regions should be able to be appended.
*
@@ -566,7 +568,7 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 0, .end = 4},
{.start = 4, .end = 15},
{.start = 25, .end = 40},
- }, 3);
+ }, 3, 0);
/*
* New regions should be able to be inserted.
*
@@ -589,7 +591,7 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 0, .end = 15},
{.start = 25, .end = 40},
{.start = 44, .end = 50},
- }, 3);
+ }, 3, 0);
}

static void damon_test_update_monitoring_result(struct kunit *test)
--
2.47.3

[SJ Park]

Commit 1292c0ecb1ca ("mm/damon/core: validate ranges in
damon_set_regions()") disallowed passing zero or negative size input
ranges to damon_set_regions(). Add kunit test cases for those inputs.

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

mm/damon/tests/core-kunit.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index befc1196d6d60..ac15393a7935b 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -592,6 +592,20 @@ static void damon_test_set_regions(struct kunit *test)

{.start = 25, .end = 40},
{.start = 44, .end = 50},

}, 3, 0);
+ /* Zero size regions should return -EINVAL. */
+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){
+ {.start = 42, .end = 42},
+ }, 1, 1,
+ (struct damon_addr_range[]){}, 0, -EINVAL);
+ /* Negative size regions should return -EINVAL. */
+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){
+ {.start = 42, .end = 21},
+ }, 1, 1,
+ (struct damon_addr_range[]){}, 0, -EINVAL);

[SJ Park]

Commit 954157679ec3 ("mm/damon/core: disallow overlapping input ranges
for damon_set_regions()") disallowed passing overlapping input ranges to
damon_set_regions(). Add a kunit test case for the overlapping input.

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

mm/damon/tests/core-kunit.h | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index ac15393a7935b..3041b8288ec26 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -606,6 +606,17 @@ static void damon_test_set_regions(struct kunit *test)

{.start = 42, .end = 21},

}, 1, 1,

(struct damon_addr_range[]){}, 0, -EINVAL);
+ /*

+ * Regions resulting in same region after alingment should return
+ * -EINVAL.
+ */

+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 10, .end = 20},
+ {.start = 20, .end = 30},
+ }, 2, 4096,

[SJ Park]

damon_max_nr_accesses(), which is a previous version of
damon_nr_samples_per_aggr() before the renaming, was wrongly returning
zero or random overflowed values for extreme intervals setup. Commit
35d4a3cf70a8 ("mm/damon/ops-common: handle extreme intervals in
damon_hot_score()") updated the function to return correct or more valid
values. Add a kunit test to ensure it is working as expected.

Signed-off-by: SJ 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 3041b8288ec26..511f2856d343c 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -619,6 +619,22 @@ static void damon_test_set_regions(struct kunit *test)

(struct damon_addr_range[]){}, 0, -EINVAL);
}

+static void damon_test_nr_samples_per_aggr(struct kunit *test)
+{
+ struct damon_attrs attrs = {
+ .sample_interval = 0,
+ .aggr_interval = 0,
+ };
+
+ /* Zero aggregation interval doesn't cause division by zero */
+ KUNIT_EXPECT_EQ(test, damon_nr_samples_per_aggr(&attrs), 1);
+
+ /* Too large aggregation interval doesn't cause overflow */
+ attrs.aggr_interval = (unsigned long)UINT_MAX + 1;
+ KUNIT_EXPECT_GE(test, damon_nr_samples_per_aggr(&attrs), 0);
+ KUNIT_EXPECT_LE(test, damon_nr_samples_per_aggr(&attrs), UINT_MAX);
+}
+

static void damon_test_update_monitoring_result(struct kunit *test)

{
struct damon_attrs old_attrs = {
@@ -1670,6 +1686,7 @@ static struct kunit_case damon_test_cases[] = {
KUNIT_CASE(damon_test_split_above_half_progresses),
KUNIT_CASE(damon_test_ops_registration),
KUNIT_CASE(damon_test_set_regions),
+ KUNIT_CASE(damon_test_nr_samples_per_aggr),
KUNIT_CASE(damon_test_update_monitoring_result),
KUNIT_CASE(damon_test_set_attrs),
KUNIT_CASE(damon_test_mvsum),
--
2.47.3

[SJ Park]

Misc cleanup, improvements and updates of code, test, and documents.

Patches 1-3 cleanup DAMON code. Patches 4-8 adds kunit and selftest
test cases for recently fixed bugs and a new feature. Patches 9 and 10
update guidelines for AI review and what document to read, on DAMON
documents.

Changes from RFC
- RFC: https://lore.kernel.org/2026072805281...@kernel.org
- Remove ctx parameter of __damon_va_init_regions().
- Fix damon_nr_samples_per_aggr() overflow kunit test.
- Rebase to the latest mm-new.

SJ Park (10):
mm/damon/core: use damon_nr_samples_per_aggr() for max merge threshold
mm/damon/core: remove debug messages
mm/damon/vaddr: remove a debug message
mm/damon/tests/core-kunit: extend set_regions() test for error case
mm/damon/tests/core-kunit: test <=0 size damon_set_regions() inputs
mm/damon/tests/core-kunit: test overlapping ranges for set_regions()
mm/damon/tests/core-kunit: test damon_nr_samples_per_aggr()
selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal
Docs/mm/damon/maintainer-profile: update AI review for Sashiko replies
Docs/ABI/damon: recommend subsystem doc instead of admin-guide

.../ABI/testing/sysfs-kernel-mm-damon | 2 +-
Documentation/mm/damon/maintainer-profile.rst | 19 ++----
mm/damon/core.c | 12 +---

mm/damon/tests/core-kunit.h | 65 ++++++++++++++++---
mm/damon/vaddr.c | 16 +----
tools/testing/selftests/damon/sysfs.sh | 1 +
6 files changed, 68 insertions(+), 47 deletions(-)


base-commit: bc87db7fa4d8d45745620150a9487efcb6ebbd51
--
2.47.3

[SJ Park]

damon_test_set_regions_for() is designed to test only success-expected
damon_set_regions() calls. Extend it to cover error-expected calls,
too.

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

mm/damon/tests/core-kunit.h | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 4a536d41cdb2d..befc1196d6d60 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h

@@ -463,11 +463,12 @@ static void damon_test_set_regions_for(struct kunit *test,
struct damon_addr_range *old_ranges, int sz_old_ranges,
struct damon_addr_range *new_ranges, int sz_new_ranges,
unsigned long min_region_sz,
- struct damon_addr_range *expect_ranges, int sz_expect_ranges)
+ struct damon_addr_range *expect_ranges, int sz_expect_ranges,
+ int expect_err)
{
struct damon_target *t;
struct damon_region *r;
- int i;
+ int i, err;

t = damon_new_target();
if (!t)
@@ -481,7 +482,8 @@ static void damon_test_set_regions_for(struct kunit *test,
damon_add_region(r, t);
}

- damon_set_regions(t, new_ranges, sz_new_ranges, min_region_sz);
+ err = damon_set_regions(t, new_ranges, sz_new_ranges, min_region_sz);
+ KUNIT_EXPECT_EQ(test, err, expect_err);

KUNIT_EXPECT_EQ(test, damon_nr_regions(t), sz_expect_ranges);
if (damon_nr_regions(t) != sz_expect_ranges) {

@@ -510,7 +512,7 @@ static void damon_test_set_regions(struct kunit *test)
(struct damon_addr_range[]){

{.start = 25, .end = 40},

- }, 3);
+ }, 3, 0);
/*
* New regions should be able to be inserted.
*
@@ -589,7 +591,7 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 0, .end = 15},

{.start = 25, .end = 40},
{.start = 44, .end = 50},

- }, 3);
+ }, 3, 0);
}

static void damon_test_update_monitoring_result(struct kunit *test)

--
2.47.3

[SJ Park]

Commit 1292c0ecb1ca ("mm/damon/core: validate ranges in
damon_set_regions()") disallowed passing zero or negative size input
ranges to damon_set_regions(). Add kunit test cases for those inputs.

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

mm/damon/tests/core-kunit.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index befc1196d6d60..ac15393a7935b 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -592,6 +592,20 @@ static void damon_test_set_regions(struct kunit *test)

{.start = 25, .end = 40},
{.start = 44, .end = 50},

}, 3, 0);
+ /* Zero size regions should return -EINVAL. */
+ damon_test_set_regions_for(test,

+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 42, .end = 42},
+ }, 1, 1,
+ (struct damon_addr_range[]){}, 0, -EINVAL);
+ /* Negative size regions should return -EINVAL. */
+ damon_test_set_regions_for(test,

+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 42, .end = 21},
+ }, 1, 1,
+ (struct damon_addr_range[]){}, 0, -EINVAL);

[SJ Park]

damon_max_nr_accesses(), which is a previous version of
damon_nr_samples_per_aggr() before the renaming, was wrongly returning
zero or random overflowed values for extreme intervals setup. Commit
35d4a3cf70a8 ("mm/damon/ops-common: handle extreme intervals in
damon_hot_score()") updated the function to return correct or more valid
values. Add a kunit test to ensure it is working as expected.

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

mm/damon/tests/core-kunit.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 3041b8288ec26..0a1882ce6a081 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -619,6 +619,27 @@ static void damon_test_set_regions(struct kunit *test)

(struct damon_addr_range[]){}, 0, -EINVAL);
}

+static void damon_test_nr_samples_per_aggr(struct kunit *test)
+{
+ struct damon_attrs attrs = {
+ .sample_interval = 0,
+ .aggr_interval = 0,
+ };
+
+ /* Zero aggregation interval doesn't cause division by zero */
+ KUNIT_EXPECT_EQ(test, damon_nr_samples_per_aggr(&attrs), 1);
+
+ /*

+ * Too large aggregation interval on 64 bit system doesn't cause
+ * overflow
+ */
+ if (ULONG_MAX > UINT_MAX) {

+ attrs.aggr_interval = (unsigned long)UINT_MAX + 1;

+ KUNIT_EXPECT_EQ(test, damon_nr_samples_per_aggr(&attrs),
+ UINT_MAX);
+ }
+}
+

static void damon_test_update_monitoring_result(struct kunit *test)

{
struct damon_attrs old_attrs = {
@@ -1670,6 +1691,7 @@ static struct kunit_case damon_test_cases[] = {

[SJ Park]

Commit 954157679ec3 ("mm/damon/core: disallow overlapping input ranges
for damon_set_regions()") disallowed passing overlapping input ranges to
damon_set_regions(). Add a kunit test case for the overlapping input.

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

mm/damon/tests/core-kunit.h | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index ac15393a7935b..3041b8288ec26 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -606,6 +606,17 @@ static void damon_test_set_regions(struct kunit *test)

{.start = 42, .end = 21},

}, 1, 1,

(struct damon_addr_range[]){}, 0, -EINVAL);

+ /*
+ * Regions resulting in same region after alingment should return
+ * -EINVAL.
+ */
+ damon_test_set_regions_for(test,

+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 10, .end = 20},
+ {.start = 20, .end = 30},
+ }, 2, 4096,

+ (struct damon_addr_range[]){}, 0, -EINVAL);

}

static void damon_test_update_monitoring_result(struct kunit *test)

--
2.47.3

[SJ Park]

damon_test_set_regions_for() is designed to test only success-expected
damon_set_regions() calls. Extend it to cover error-expected calls,
too.

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

mm/damon/tests/core-kunit.h | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 4a536d41cdb2d..befc1196d6d60 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h

{.start = 25, .end = 40},

- }, 3);
+ }, 3, 0);
/*
* New regions should be able to be inserted.
*
@@ -589,7 +591,7 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 0, .end = 15},

{.start = 25, .end = 40},
{.start = 44, .end = 50},

- }, 3);
+ }, 3, 0);
}

[SJ Park]

Misc cleanup, improvements and updates of code, test, and documents.

Patches 1-5 cleanup DAMON code. Patches 6-10 adds kunit and selftest
test cases for recently fixed bugs and a new feature. Patches 11 and 12

update guidelines for AI review and what document to read, on DAMON
documents.

Changes from RFC v1.1
- RFC v1.1: https://lore.kernel.org/2026072903375...@kernel.org
- Fix a typo: s/alingment/alignment/.
- Add damon probes parameter validation cleanup (patches 4 and 5).

Changes from RFC
- RFC: https://lore.kernel.org/2026072805281...@kernel.org
- Remove ctx parameter of __damon_va_init_regions().
- Fix damon_nr_samples_per_aggr() overflow kunit test.
- Rebase to the latest mm-new.

SJ Park (12):

mm/damon/core: use damon_nr_samples_per_aggr() for max merge threshold
mm/damon/core: remove debug messages
mm/damon/vaddr: remove a debug message

mm/damon/core: validate number of probes in valid_probe_params()
mm/damon/sysfs: remove probes number validation

mm/damon/tests/core-kunit: extend set_regions() test for error case
mm/damon/tests/core-kunit: test <=0 size damon_set_regions() inputs
mm/damon/tests/core-kunit: test overlapping ranges for set_regions()
mm/damon/tests/core-kunit: test damon_nr_samples_per_aggr()
selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal
Docs/mm/damon/maintainer-profile: update AI review for Sashiko replies
Docs/ABI/damon: recommend subsystem doc instead of admin-guide

.../ABI/testing/sysfs-kernel-mm-damon | 2 +-
Documentation/mm/damon/maintainer-profile.rst | 19 ++----

mm/damon/core.c | 19 +++---
mm/damon/sysfs.c | 2 +-

mm/damon/tests/core-kunit.h | 65 ++++++++++++++++---
mm/damon/vaddr.c | 16 +----
tools/testing/selftests/damon/sysfs.sh | 1 +

7 files changed, 76 insertions(+), 48 deletions(-)


base-commit: a8aa6f3b608c8c9119a7978f5f4eb083c53ea56b
--
2.47.3

[SJ Park]

Commit 954157679ec3 ("mm/damon/core: disallow overlapping input ranges
for damon_set_regions()") disallowed passing overlapping input ranges to
damon_set_regions(). Add a kunit test case for the overlapping input.

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

mm/damon/tests/core-kunit.h | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index ac15393a7935b..252d81c30d6f1 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h

@@ -606,6 +606,17 @@ static void damon_test_set_regions(struct kunit *test)
{.start = 42, .end = 21},
}, 1, 1,
(struct damon_addr_range[]){}, 0, -EINVAL);
+ /*

+ * Regions resulting in same region after alignment should return

+ * -EINVAL.
+ */
+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){
+ {.start = 10, .end = 20},
+ {.start = 20, .end = 30},
+ }, 2, 4096,
+ (struct damon_addr_range[]){}, 0, -EINVAL);
}

[SJ Park]

Commit 1292c0ecb1ca ("mm/damon/core: validate ranges in
damon_set_regions()") disallowed passing zero or negative size input
ranges to damon_set_regions(). Add kunit test cases for those inputs.

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

mm/damon/tests/core-kunit.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index befc1196d6d60..ac15393a7935b 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -592,6 +592,20 @@ static void damon_test_set_regions(struct kunit *test)

{.start = 25, .end = 40},
{.start = 44, .end = 50},

}, 3, 0);
+ /* Zero size regions should return -EINVAL. */

+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 42, .end = 42},
+ }, 1, 1,

+ (struct damon_addr_range[]){}, 0, -EINVAL);

+ /* Negative size regions should return -EINVAL. */

+ damon_test_set_regions_for(test,
+ (struct damon_addr_range[]){}, 0,
+ (struct damon_addr_range[]){

+ {.start = 42, .end = 21},
+ }, 1, 1,

[SJ Park]

damon_max_nr_accesses(), which is a previous version of
damon_nr_samples_per_aggr() before the renaming, was wrongly returning
zero or random overflowed values for extreme intervals setup. Commit
35d4a3cf70a8 ("mm/damon/ops-common: handle extreme intervals in
damon_hot_score()") updated the function to return correct or more valid
values. Add a kunit test to ensure it is working as expected.

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

mm/damon/tests/core-kunit.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 252d81c30d6f1..c7bda8aadef3f 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -619,6 +619,27 @@ static void damon_test_set_regions(struct kunit *test)

(struct damon_addr_range[]){}, 0, -EINVAL);
}

+static void damon_test_nr_samples_per_aggr(struct kunit *test)
+{
+ struct damon_attrs attrs = {
+ .sample_interval = 0,
+ .aggr_interval = 0,
+ };
+
+ /* Zero aggregation interval doesn't cause division by zero */
+ KUNIT_EXPECT_EQ(test, damon_nr_samples_per_aggr(&attrs), 1);
+
+ /*
+ * Too large aggregation interval on 64 bit system doesn't cause
+ * overflow
+ */
+ if (ULONG_MAX > UINT_MAX) {
+ attrs.aggr_interval = (unsigned long)UINT_MAX + 1;
+ KUNIT_EXPECT_EQ(test, damon_nr_samples_per_aggr(&attrs),
+ UINT_MAX);
+ }
+}
+

static void damon_test_update_monitoring_result(struct kunit *test)