selftests/damon/sysfs.py: stop kdamonds before failing

When an assertion is failed, sysfs.py DAMON selftest immediately exits the
test program leaving the DAMON running behind.  Many of the following
tests need to start DAMON on their own.  But because DAMON that was
started by sysfs.py is still running, those start attempts fail, and the
tests are failed or skipped.  Update sysfs.py to stop DAMON before exiting
the test program due to the assertion failure.

Link: https://lore.kernel.org/20260522154026.80546-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/damon/sysfs.py b/tools/testing/selftests/damon/sysfs.py
index cd4d82c852113cde464c2b2eba058b00bf5b5dda..aa03a1187489f936e403f71ad5185b8c9d66adf5 100755 (executable)
--- a/tools/testing/selftests/damon/sysfs.py
+++ b/tools/testing/selftests/damon/sysfs.py
@@ -24,9 +24,12 @@ def dump_damon_status_dict(pid):
     except Exception as e:
         return None, 'json.load fail (%s)' % e
 
+kdamonds = None
 def fail(expectation, status):
     print('unexpected %s' % expectation)
     print(json.dumps(status, indent=4))
+    if kdamonds is not None:
+        kdamonds.stop()
     exit(1)
 
 def assert_true(condition, expectation, status):
@@ -248,6 +251,7 @@ def assert_ctxs_committed(kdamonds):
                 ctx.pause = False
 
 def main():
+    global kdamonds
     kdamonds = _damon_sysfs.Kdamonds(
             [_damon_sysfs.Kdamond(
                 contexts=[_damon_sysfs.DamonCtx(