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

[PATCH 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 v2
- RFC v2: https://lore.kernel.org/20260917040537.107341-1-sj@kernel.org
- Drop RFC tag.
- Rebase to the latest mm-new.
Changes from RFC
- RFC: https://lore.kernel.org/20260912200814.145612-1-sj@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: 942682790e570c9422a389bf34097e74c4777fe9
-- 
2.47.3

[PATCH 07/10] mm/damon/tests/core-kunit: test eligible_mem_bp commitment

[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/20260827045035.94611-1-sj@kernel.org

Signed-off-by: SJ Park <sj@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
--- 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

[PATCH 08/10] mm/damon/tests/core-kunit: add probe_hits_wsum damos filter commit test

[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 <sj@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;
 	}
@@ -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

[PATCH 09/10] selftests/damon/sysfs_memcg_path_leak: fail only for real DAMON leak

[SJ Park]

The selftest can fail for any leak if it happens while the test is
running.  Remove the false positive test failures by further checking if
the expected leaking function is called out on the report.

Signed-off-by: SJ Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs_memcg_path_leak.sh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh b/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
index 33a7ff43ed6cc..34c37129c49fe 100755
--- a/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
+++ b/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
@@ -41,5 +41,12 @@ if [ "$kmemleak_report" = "" ]
 then
 	exit 0
 fi
+if ! echo "$kmemleak_report" | grep "memcg_path_store" --quiet
+then
+	echo "[WARN] memleak found; apparently not from DAMON, though"
+	echo "$kmemleak_report"
+	exit 0
+fi
+
 echo "$kmemleak_report"
 exit 1
-- 
2.47.3

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

[SJ Park]

On Thu, 17 Sep 2026 07:21:58 -0700 SJ Park <sj@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

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

[Andrew Morton]

On Thu, 17 Sep 2026 07:21:58 -0700 SJ Park <sj@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.