[PATCH v2 0/3] selftests/damon: misc fixes for test bugs

[PATCH v2 0/3] selftests/damon: misc fixes for test bugs

[Kunwu Chan]

From: Kunwu Chan <chentao@kylinos.cn>

This series fixes several bugs in the DAMON selftests.  Most are
trivial but cause tests to silently pass when they shouldn't, or
fail prematurely on slow machines.

Patch 1 fixes mutable default arguments in DamonCtx.__init__()
that cause state to leak between test instances.

Patch 2 fixes wrong operator precedence and join TypeError in
damos_tried_regions.py.

Patch 3 fixes several wrong strings that produce dead elif
branches, skipped file existence checks, and broken dict key
lookups.

Based on next-20260529.
base-commit: 7da7f07112610a520567421dd2ffcb51beaefbcc
---
Changes in v2:
- Fix From:/Signed-off-by mismatch.
- Add Reviewed-by tags from SeongJae Park.
- Drop the duplicate memcg_path fix.
- Drop the empty aggregation-cycle retry fix pending root-cause
  investigation.
- No code change


Kunwu Chan (3):
  selftests/damon: prevent cross-context state pollution in DamonCtx
  selftests/damon/damos_tried_regions: fix expectation output and join
    TypeError
  selftests/damon: fix dead code, skipped checks, and broken lookups

 tools/testing/selftests/damon/_damon_sysfs.py        | 12 +++++++++---
 .../testing/selftests/damon/damos_apply_interval.py  |  2 +-
 tools/testing/selftests/damon/damos_quota_goal.py    |  2 +-
 tools/testing/selftests/damon/damos_tried_regions.py |  4 ++--
 .../selftests/damon/drgn_dump_damon_status.py        |  2 +-
 tools/testing/selftests/damon/sysfs.py               |  4 ++--
 tools/testing/selftests/damon/sysfs.sh               |  6 +++---
 ...fs_update_schemes_tried_regions_wss_estimation.py |  2 +-
 8 files changed, 20 insertions(+), 14 deletions(-)

-- 
2.43.0

[PATCH v2 1/3] selftests/damon: prevent cross-context state pollution in DamonCtx

[Kunwu Chan]

From: Kunwu Chan <chentao@kylinos.cn>

DamonCtx.__init__() uses mutable default values for
monitoring_attrs, targets, and schemes.  In Python these are
evaluated once at function definition time, so multiple
DamonCtx instances can unintentionally share the same lists
and DamonAttrs instance.

Replace the mutable defaults with None sentinels and
initialize the objects when needed.

Co-developed-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/_damon_sysfs.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/selftests/damon/_damon_sysfs.py
index 8b12cc048440..2f6f2699db25 100644
--- a/tools/testing/selftests/damon/_damon_sysfs.py
+++ b/tools/testing/selftests/damon/_damon_sysfs.py
@@ -624,17 +624,23 @@ class DamonCtx:
     pause = None
     idx = None
 
-    def __init__(self, ops='paddr', monitoring_attrs=DamonAttrs(), targets=[],
-            schemes=[], pause=False):
+    def __init__(self, ops='paddr', monitoring_attrs=None, targets=None,
+            schemes=None, pause=False):
         self.ops = ops
+        if monitoring_attrs is None:
+            monitoring_attrs = DamonAttrs()
         self.monitoring_attrs = monitoring_attrs
         self.monitoring_attrs.context = self
 
+        if targets is None:
+            targets = []
         self.targets = targets
         for idx, target in enumerate(self.targets):
             target.idx = idx
             target.context = self
 
+        if schemes is None:
+            schemes = []
         self.schemes = schemes
         for idx, scheme in enumerate(self.schemes):
             scheme.idx = idx
-- 
2.43.0

[PATCH v2 2/3] selftests/damon/damos_tried_regions: fix expectation output and join TypeError

[Kunwu Chan]

From: Kunwu Chan <chentao@kylinos.cn>

The expectation print has wrong operator precedence: '%' binds
before the conditional expression, so the else branch prints
'not met' without the prefix 'expectation (>= 14) is'.  Add
parentheses to fix it.

Also, '\n'.join() on the list of ints raises TypeError;
convert to str in the list comprehension.

Co-developed-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/damos_tried_regions.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/damon/damos_tried_regions.py b/tools/testing/selftests/damon/damos_tried_regions.py
index 3b347eb28bd2..d6472e6a6e08 100755
--- a/tools/testing/selftests/damon/damos_tried_regions.py
+++ b/tools/testing/selftests/damon/damos_tried_regions.py
@@ -55,10 +55,10 @@ def main():
     collected_nr_regions.sort()
     sample = collected_nr_regions[4]
     print('50-th percentile nr_regions: %d' % sample)
-    print('expectation (>= 14) is %s' % 'met' if sample >= 14 else 'not met')
+    print('expectation (>= 14) is %s' % ('met' if sample >= 14 else 'not met'))
     if collected_nr_regions[4] < 14:
         print('full nr_regions:')
-        print('\n'.join(collected_nr_regions))
+        print('\n'.join(['%d' % x for x in collected_nr_regions]))
         exit(1)
 
 if __name__ == '__main__':
-- 
2.43.0

[PATCH v2 3/3] selftests/damon: fix dead code, skipped checks, and broken lookups

[Kunwu Chan]

From: Kunwu Chan <chentao@kylinos.cn>

'hugeapge_size' in drgn_dump_damon_status.py was a dead elif branch.
$fail_reason in sysfs.sh was undefined, silently emptying the error
message.  'exit' instead of 'exist' in sysfs.sh skipped a file
existence check.  'nohugeapge' in sysfs.py broke an action dict
lookup.

Fix other wrong strings in the same files.

Co-developed-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/_damon_sysfs.py               | 2 +-
 tools/testing/selftests/damon/damos_apply_interval.py       | 2 +-
 tools/testing/selftests/damon/damos_quota_goal.py           | 2 +-
 tools/testing/selftests/damon/drgn_dump_damon_status.py     | 2 +-
 tools/testing/selftests/damon/sysfs.py                      | 4 ++--
 tools/testing/selftests/damon/sysfs.sh                      | 6 +++---
 .../sysfs_update_schemes_tried_regions_wss_estimation.py    | 2 +-
 7 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/selftests/damon/_damon_sysfs.py
index 2f6f2699db25..f6127081dfb2 100644
--- a/tools/testing/selftests/damon/_damon_sysfs.py
+++ b/tools/testing/selftests/damon/_damon_sysfs.py
@@ -837,7 +837,7 @@ class Kdamond:
                 for goal in scheme.quota.goals:
                     err = goal.stage()
                     if err is not None:
-                        print('commit_schemes_quota_goals failed stagign: %s'%
+                        print('commit_schemes_quota_goals failed staging: %s'%
                               err)
                         exit(1)
         return write_file(os.path.join(self.sysfs_dir(), 'state'),
diff --git a/tools/testing/selftests/damon/damos_apply_interval.py b/tools/testing/selftests/damon/damos_apply_interval.py
index f04d43702481..0f2f36584e48 100755
--- a/tools/testing/selftests/damon/damos_apply_interval.py
+++ b/tools/testing/selftests/damon/damos_apply_interval.py
@@ -56,7 +56,7 @@ def main():
     # Because the second scheme was having the apply interval that is ten times
     # lower than that of the first scheme, the second scheme should be tried
     # about ten times more frequently than the first scheme.  For possible
-    # timing errors, check if it was at least nine times more freuqnetly tried.
+    # timing errors, check if it was at least nine times more frequently tried.
     ratio = nr_tried_stats[1] / nr_tried_stats[0]
     if ratio < 9:
         print('%d / %d = %f (< 9)' %
diff --git a/tools/testing/selftests/damon/damos_quota_goal.py b/tools/testing/selftests/damon/damos_quota_goal.py
index f76e0412b564..661e4ba4765a 100755
--- a/tools/testing/selftests/damon/damos_quota_goal.py
+++ b/tools/testing/selftests/damon/damos_quota_goal.py
@@ -66,7 +66,7 @@ def main():
             # effective quota was already minimum that cannot be more reduced
             if expect_increase is False and last_effective_bytes == 1:
                 continue
-            print('efective bytes not changed: %d' % goal.effective_bytes)
+            print('effective bytes not changed: %d' % goal.effective_bytes)
             exit(1)
 
         increased = last_effective_bytes < goal.effective_bytes
diff --git a/tools/testing/selftests/damon/drgn_dump_damon_status.py b/tools/testing/selftests/damon/drgn_dump_damon_status.py
index 972948e6215f..26b207e44268 100755
--- a/tools/testing/selftests/damon/drgn_dump_damon_status.py
+++ b/tools/testing/selftests/damon/drgn_dump_damon_status.py
@@ -163,7 +163,7 @@ def damos_filter_to_dict(damos_filter):
                                int(damos_filter.addr_range.end)]
     elif type_ == 'target':
         dict_['target_idx'] = int(damos_filter.target_idx)
-    elif type_ == 'hugeapge_size':
+    elif type_ == 'hugepage_size':
         dict_['sz_range'] = [int(damos_filter.sz_range.min),
                              int(damos_filter.sz_range.max)]
     return dict_
diff --git a/tools/testing/selftests/damon/sysfs.py b/tools/testing/selftests/damon/sysfs.py
index aa03a1187489..99412f0d31f3 100755
--- a/tools/testing/selftests/damon/sysfs.py
+++ b/tools/testing/selftests/damon/sysfs.py
@@ -119,7 +119,7 @@ def assert_access_pattern_committed(pattern, dump):
                 'max_nr_accesses', dump)
     assert_true(dump['min_age_region'] == pattern.age[0], 'min_age_region',
                 dump)
-    assert_true(dump['max_age_region'] == pattern.age[1], 'miaxage_region',
+    assert_true(dump['max_age_region'] == pattern.age[1], 'max_age_region',
                 dump)
 
 def assert_scheme_committed(scheme, dump):
@@ -129,7 +129,7 @@ def assert_scheme_committed(scheme, dump):
             'cold': 1,
             'pageout': 2,
             'hugepage': 3,
-            'nohugeapge': 4,
+            'nohugepage': 4,
             'collapse': 5,
             'lru_prio': 6,
             'lru_deprio': 7,
diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index 78f4badb5beb..2eaaa5ae3c5e 100755
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -3,7 +3,7 @@
 
 source _common.sh
 
-# Kselftest frmework requirement - SKIP code is 4.
+# Kselftest framework requirement - SKIP code is 4.
 ksft_skip=4
 
 ensure_write_succ()
@@ -28,7 +28,7 @@ ensure_write_fail()
 
 	if (echo "$content" > "$file") 2> /dev/null
 	then
-		echo "writing $content to $file succeed ($fail_reason)"
+		echo "writing $content to $file succeeded ($reason)"
 		echo "expected failure because $reason"
 		exit 1
 	fi
@@ -363,7 +363,7 @@ test_context()
 {
 	context_dir=$1
 	ensure_dir "$context_dir" "exist"
-	ensure_file "$context_dir/avail_operations" "exit" 400
+	ensure_file "$context_dir/avail_operations" "exist" 400
 	ensure_file "$context_dir/operations" "exist" 600
 	ensure_file "$context_dir/addr_unit" "exist" 600
 	ensure_file "$context_dir/pause" "exist" 600
diff --git a/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py
index 35c724a63f6c..16fdc6e7fc56 100755
--- a/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py
+++ b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_wss_estimation.py
@@ -7,7 +7,7 @@ import time
 import _damon_sysfs
 
 def pass_wss_estimation(sz_region):
-    # access two regions of given size, 2 seocnds per each region
+    # access two regions of given size, 2 seconds per each region
     proc = subprocess.Popen(
             ['./access_memory', '2', '%d' % sz_region, '2000', 'repeat'])
     kdamonds = _damon_sysfs.Kdamonds([_damon_sysfs.Kdamond(
-- 
2.43.0

Re: [PATCH v2 0/3] selftests/damon: misc fixes for test bugs

[SeongJae Park]

On Mon,  1 Jun 2026 11:23:11 +0800 Kunwu Chan <kunwu.chan@linux.dev> wrote:

> From: Kunwu Chan <chentao@kylinos.cn>
> 
> This series fixes several bugs in the DAMON selftests.  Most are
> trivial but cause tests to silently pass when they shouldn't, or
> fail prematurely on slow machines.

Nit.  Only patch 3 fixes a fake test pass for "avail_operations" file existence
test, and the series is not doing something for slow machines, right?  I think
the last sentence should be updated, for example:

'''
Most are trivial but makes test output wrong or even silently pass the one for
'avail_operation' file existence check.
'''

Other than that, all look good to me, and already have my Reviewed-by: tag.

Asssuming you are ok with the above change, I applied this series to damon/next
[1] tree with the above change.  If this series is not added to mm.git in short
term (~1 week?), I will ask mm.git maintainer (Andrew Morton) to pick this.
So, no action from your side is needed for now.  If it seems I also forgot
doing that or you cannot wait for my action, please feel free to directly ask
that to Andrew.

[1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees


Thanks,
SJ

[...]

Re: [PATCH v2 0/3] selftests/damon: misc fixes for test bugs

[SeongJae Park]

On Mon,  1 Jun 2026 11:23:11 +0800 Kunwu Chan <kunwu.chan@linux.dev> wrote:

> From: Kunwu Chan <chentao@kylinos.cn>
> 
> This series fixes several bugs in the DAMON selftests.  Most are
> trivial but cause tests to silently pass when they shouldn't, or
> fail prematurely on slow machines.
> 
> Patch 1 fixes mutable default arguments in DamonCtx.__init__()
> that cause state to leak between test instances.
> 
> Patch 2 fixes wrong operator precedence and join TypeError in
> damos_tried_regions.py.
> 
> Patch 3 fixes several wrong strings that produce dead elif
> branches, skipped file existence checks, and broken dict key
> lookups.
> 
> Based on next-20260529.
> base-commit: 7da7f07112610a520567421dd2ffcb51beaefbcc
> ---
> Changes in v2:
> - Fix From:/Signed-off-by mismatch.
> - Add Reviewed-by tags from SeongJae Park.
> - Drop the duplicate memcg_path fix.
> - Drop the empty aggregation-cycle retry fix pending root-cause
>   investigation.
> - No code change

From the next time, please add links to previous versions [1].  For other
readers, the v1 of this series is available on the mailing list [2].

[1] https://docs.kernel.org/process/submitting-patches.html#commentary
[2] https://lore.kernel.org/20260531085633.48626-1-kunwu.chan@linux.dev


Thanks,
SJ

[....]