Re: [RFC PATCH 08/10] selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The selftest unconditionally fails because the kernel implementation for the 'hugepage_mem_bp' quota goal target metric is missing.
--

--- Patch [8]: [RFC PATCH 08/10] selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal ---
commit 033ea051e9d9dfb2787f833f5569853c4af61194
Author: SJ Park <sj@kernel.org>

selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal

DAMON sysfs quota goal target_metric file now accepts 'hugepage_mem_bp'
input. Test it is accepted in fundamental DAMON sysfs file operation
selftest.

> diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
> --- a/tools/testing/selftests/damon/sysfs.sh
> +++ b/tools/testing/selftests/damon/sysfs.sh
> @@ -210,6 +210,7 @@ test_goal()
>  	ensure_write_succ "$fpath" "active_mem_bp" "valid input"
>  	ensure_write_succ "$fpath" "inactive_mem_bp" "valid input"
>  	ensure_write_succ "$fpath" "node_eligible_mem_bp" "valid input"
> +	ensure_write_succ "$fpath" "hugepage_mem_bp" "valid input"

[Severity: Medium]
Will this selftest fail when executed?

Looking at target_metric_store() in mm/damon/sysfs-schemes.c, the kernel
validation loop returns -EINVAL because "hugepage_mem_bp" is not present in
the damos_sysfs_qgoal_metric_names array:

mm/damon/sysfs-schemes.c:target_metric_store() {
	...
	for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_metric_names); i++) {
		struct damos_sysfs_qgoal_metric_name *metric_name;

		metric_name = &damos_sysfs_qgoal_metric_names[i];
		if (sysfs_streq(buf, metric_name->name)) {
			goal->metric = metric_name->metric;
			return count;
		}
	}
	return -EINVAL;
}

Because the test assumes the write will succeed, the missing kernel
implementation for this quota goal target metric will cause the write to be
rejected and trigger a selftest failure.

>  	ensure_write_fail "$fpath" "foo" "invalid input"
>  	ensure_file "$goal_dir/nid" "exist" "600"
>  	ensure_file "$goal_dir/path" "exist" "600"

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260728052811.192712-1-sj@kernel.org?part=8