[RFC PATCH v2 00/10] mm/damon: improve readability, clarity and test coverage

[SJ Park]

Yet another batch of miscellaneous DAMON minor improvements. Mostly
focused on readability and clarity of code and document, and unit/self
test coverage. No user-visible behavioral change is intended.

Changes from RFC
- RFC: https://lore.kernel.org/2026091220081...@kernel.org
- Fix a typo in the selftest warning message.
- Collect A-b: from Randy.
- Split out damos_adjust_quota() fix to an individual hotfix patch.
- Add a patch for initializing walk_control_obsolete in damon_new_ctx().
- Add a patch for probe_hits_wsum damos filter commit kunit test.
- Trivial patch sequence update.
- Rebase to the latest mm-new.

SJ Park (10):
mm/damon/api: remove NR_DAMOS_FILTER_TYPES
mm/damon/core: use abs_diff() in damon_feed_loop_next_input()
mm/damon/core: use mult_frac() in damon_feed_loop_next_input()
mm/damon/core: set damon_ctx->walk_control_obsolete in damon_new_ctx()
mm/damon/core: document damon_call()/damon_start() race hang issue
mm/damon/paddr: remove pa parameter from damon_pa_filter_pass()
mm/damon/tests/core-kunit: test eligible_mem_bp commitment
mm/damon/tests/core-kunit: add probe_hits_wsum damos filter commit
test
selftests/damon/sysfs_memcg_path_leak: fail only for real DAMON leak
Docs/mm/damon/design: clarify bp is basis point

Documentation/mm/damon/design.rst | 5 ++--
include/linux/damon.h | 2 --
mm/damon/core.c | 19 ++++--------
mm/damon/paddr.c | 5 ++--
mm/damon/tests/core-kunit.h | 30 +++++++++++++++++++
.../selftests/damon/sysfs_memcg_path_leak.sh | 7 +++++
6 files changed, 48 insertions(+), 20 deletions(-)


base-commit: b7c76a308c2afda7cfc2ce98be3eed466be71337
--
2.47.3

[SJ Park]

DAMOS filter commit kunit test lacks test cases for probe_hits_wsum
filter type. Add test cases for probe_hits_wsum type DAMOS filter
commit.

Signed-off-by: SJ Park <s...@kernel.org>
---
mm/damon/tests/core-kunit.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 1244cfeae5e70..df84d9cc7d204 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -1166,6 +1166,10 @@ static void damos_test_commit_filter_for(struct kunit *test,
KUNIT_EXPECT_EQ(test, dst->sz_range.min, src->sz_range.min);
KUNIT_EXPECT_EQ(test, dst->sz_range.max, src->sz_range.max);
break;
+ case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
+ KUNIT_EXPECT_EQ(test, dst->range_min, src->range_min);
+ KUNIT_EXPECT_EQ(test, dst->range_max, src->range_max);
+ break;
default:
break;
}
@@ -1239,6 +1243,22 @@ static void damos_test_commit_filter(struct kunit *test)
.allow = true,
.target_idx = 6,
}, false);
+ damos_test_commit_filter_for(test, &dst,
+ &(struct damos_filter){
+ .type = DAMOS_FILTER_TYPE_PROBE_HITS_WSUM,
+ .matching = false,
+ .allow = true,
+ .range_min = 12,
+ .range_max = 34,
+ }, false);
+ damos_test_commit_filter_for(test, &dst,
+ &(struct damos_filter){
+ .type = DAMOS_FILTER_TYPE_PROBE_HITS_WSUM,
+ .matching = false,
+ .allow = true,
+ .range_min = 34,
+ .range_max = 12,
+ }, true);
}

static void damos_test_help_initailize_scheme(struct damos *scheme)
--
2.47.3

[SJ Park]

There was a DAMOS quota goal commit bug [1] that doesn't update the nid
field for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP metric goal. Add a kunit
test case for confirming nid commitment.

[1] https://lore.kkernel.org/202608270450...@kernel.org

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

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

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 82c542afaa60e..1244cfeae5e70 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -835,6 +835,9 @@ static void damos_test_commit_quota_goal_for(struct kunit *test,
KUNIT_EXPECT_EQ(test, dst->nid, src->nid);
KUNIT_EXPECT_EQ(test, dst->memcg_id, src->memcg_id);
break;
+ case DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP:
+ KUNIT_EXPECT_EQ(test, dst->nid, src->nid);
+ break;
default:
break;
}
@@ -898,6 +901,13 @@ static void damos_test_commit_quota_goal(struct kunit *test)
.current_value = 345,
.last_psi_total = 567,
});
+ damos_test_commit_quota_goal_for(test, &dst,
+ &(struct damos_quota_goal){
+ .metric = DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP,
+ .target_value = 12,
+ .current_value = 345,
+ .nid = 6,
+ });
}

static void damos_test_commit_quota_goals_for(struct kunit *test,
--
2.47.3

[SJ Park]

There was a DAMOS quota goal commit bug [1] that doesn't update the nid
field for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP metric goal. Add a kunit
test case for confirming nid commitment.

[1] https://lore.kkernel.org/202608270450...@kernel.org

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

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

index 5da84caf4124d..1f19fefdd98c3 100644

[SJ Park]

Yet another batch of miscellaneous DAMON minor improvements. Mostly
focused on readability and clarity of code and document, and unit/self
test coverage. No user-visible behavioral change is intended.

Changes from RFC v2
- RFC v2: https://lore.kernel.org/2026091704053...@kernel.org
- Drop RFC tag.

base-commit: 942682790e570c9422a389bf34097e74c4777fe9
--
2.47.3

[SJ Park]

DAMOS filter commit kunit test lacks test cases for probe_hits_wsum
filter type. Add test cases for probe_hits_wsum type DAMOS filter
commit.

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

mm/damon/tests/core-kunit.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 1f19fefdd98c3..5ff0436c58441 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h

@@ -1166,6 +1166,10 @@ static void damos_test_commit_filter_for(struct kunit *test,
KUNIT_EXPECT_EQ(test, dst->sz_range.min, src->sz_range.min);
KUNIT_EXPECT_EQ(test, dst->sz_range.max, src->sz_range.max);
break;
+ case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
+ KUNIT_EXPECT_EQ(test, dst->range_min, src->range_min);
+ KUNIT_EXPECT_EQ(test, dst->range_max, src->range_max);

+ break;
default:
break;
}

[SJ Park]

On Thu, 17 Sep 2026 07:21:58 -0700 SJ Park <s...@kernel.org> wrote:

> Yet another batch of miscellaneous DAMON minor improvements. Mostly
> focused on readability and clarity of code and document, and unit/self
> test coverage. No user-visible behavioral change is intended.

Sashiko found no blocker for this series. Sashiko send its findings to damon@
mailing list [1], and I reply those if anything needs to be clarified. Please
refer to those for details.

[1] https://lore.kernel.org/damon/


Thanks,
SJ

[Andrew Morton]

On Thu, 17 Sep 2026 07:21:58 -0700 SJ Park <s...@kernel.org> wrote:

> Yet another batch of miscellaneous DAMON minor improvements. Mostly
> focused on readability and clarity of code and document, and unit/self
> test coverage. No user-visible behavioral change is intended.

Thanks, all queued up in mm-new.