selftests/damon/damos_quota_goal: handle minimum quota that cannot be further reduced

damos_quota_goal.py selftest see if DAMOS quota goals tuning feature
increases or reduces the effective size quota for given score as expected.
The tuning feature sets the minimum quota size as one byte, so if the
effective size quota is already one, we cannot expect it further be
reduced.  However the test is not aware of the edge case, and fails since
it shown no expected change of the effective quota.  Handle the case by
updating the failure logic for no change to see if it was the case, and
simply skips to next test input.

Link: https://lkml.kernel.org/r/20250217182304.45215-1-sj@kernel.org
Fixes: f1c07c0 ("selftests/damon: add a test for DAMOS quota goal")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202502171423.b28a918d-lkp@intel.com
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>	[6.10.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: sjp38

tools/testing/selftests/damon/damos_quota_goal.py

@@ -63,6 +63,9 @@ def main():
             if last_effective_bytes != 0 else -1.0))
 
         if last_effective_bytes == goal.effective_bytes:
+            # 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)
             exit(1)