[RFC PATCH 5/5] selftests/damon: add a test for update_schemes_tried_regions hang bug

[SeongJae Park <sj@kernel.org>]

The update_schemees_tried_{regions,bytes} command was able to be
indefinitely hang in some corner cases.  It has fixed by introducing a
timeout for the command[1].  Add a test for the corner case to not
introduce the problem again.

[1] https://lore.kernel.org/damon/20231124213840.39157-1-sj@kernel.org/

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/Makefile        |  1 +
 ...sysfs_update_schemes_tried_regions_hang.py | 33 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100755 tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py

diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile
index 1363987709c6..d90bdba28ff4 100644
--- a/tools/testing/selftests/damon/Makefile
+++ b/tools/testing/selftests/damon/Makefile
@@ -12,6 +12,7 @@ TEST_PROGS += debugfs_empty_targets.sh debugfs_huge_count_read_write.sh
 TEST_PROGS += debugfs_duplicate_context_creation.sh
 TEST_PROGS += debugfs_rm_non_contexts.sh
 TEST_PROGS += sysfs.sh sysfs_update_removed_scheme_dir.sh
+TEST_PROGS += sysfs_update_schemes_tried_regions_hang.py
 TEST_PROGS += sysfs_update_schemes_tried_regions_wss_estimation.py
 TEST_PROGS += reclaim.sh lru_sort.sh
 TEST_PROGS += dbgfs_target_ids_read_before_terminate_race.sh
diff --git a/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py
new file mode 100755
index 000000000000..14187be3b004
--- /dev/null
+++ b/tools/testing/selftests/damon/sysfs_update_schemes_tried_regions_hang.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import subprocess
+import time
+
+import _damon
+
+def main():
+    proc = subprocess.Popen(['sleep', '2'])
+    kdamonds = _damon.Kdamonds([_damon.Kdamond(
+            contexts=[_damon.DamonCtx(
+                ops='vaddr',
+                targets=[_damon.DamonTarget(pid=proc.pid)],
+                schemes=[_damon.Damos(
+                    access_pattern=_damon.DamosAccessPattern(
+                        nr_accesses=[200, 200]))] # schemes
+                )] # contexts
+            )]) # kdamonds
+
+    err = kdamonds.start()
+    if err != None:
+        print('kdmaond start failed: %s' % err)
+        exit(1)
+
+    while proc.poll() == None:
+        err = kdamonds.kdamonds[0].update_schemes_tried_bytes()
+        if err != None:
+            print('tried bytes update failed: %s' % err)
+            exit(1)
+
+if __name__ == '__main__':
+    main()
-- 
2.34.1