There was a memory leak bug in DAMOS sysfs memcg_path file. Add a
selftest to ensure the bug never comes back.
Link: https://lkml.kernel.org/r/20250619183608.6647-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>