[PATCH mm-stable] selftests/damon/sysfs.py: stop DAMON for dumping failures

[SeongJae Park <sj@kernel.org>]

Commit 4ece01897627 ("selftests/damon: add python and drgn-based DAMON
sysfs test") in mm-stable tree introduced sysfs.py that runs drgn for
dumping DAMON status.  When the DAMON status dumping fails for reasons
including drgn uninstalled environment, the test fails without stopping
DAMON.  Following DAMON selftests that assumes DAMON is not running when
they executed therefore fail.  Catch dumping failures and stop DAMON for
that case.

Fixes: 4ece01897627 ("selftests/damon: add python and drgn-based DAMON sysfs test") # mm-stable
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202507220707.9c5d6247-lkp@intel.com
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs.py b/tools/testing/selftests/damon/sysfs.py
index 4ff99db0d247..dbf6613529bd 100755
--- a/tools/testing/selftests/damon/sysfs.py
+++ b/tools/testing/selftests/damon/sysfs.py
@@ -8,6 +8,10 @@ import subprocess
 import _damon_sysfs
 
 def dump_damon_status_dict(pid):
+    try:
+        subprocess.check_output(['which', 'drgn'], stderr=subprocess.DEVNULL)
+    except:
+        return None, 'drgn not found'
     file_dir = os.path.dirname(os.path.abspath(__file__))
     dump_script = os.path.join(file_dir, 'drgn_dump_damon_status.py')
     rc = subprocess.call(['drgn', dump_script, pid, 'damon_dump_output'],
@@ -31,6 +35,7 @@ def main():
     status, err = dump_damon_status_dict(kdamonds.kdamonds[0].pid)
     if err is not None:
         print(err)
+        kdamonds.stop()
         exit(1)
 
     if len(status['contexts']) != 1:

base-commit: 49c3f600a9088332b3c1a6db2dc6f3516f273609
-- 
2.39.5