[PATCH v2] mm/damon: document that a zero sample_interval is accepted

[Karthikeyan KS <karthiproffesional@gmail.com>]

damon_set_attrs() accepts sample_interval == 0.  This was reported as
a bug in v1 of this patch (rejecting it in damon_set_attrs()).  A
similar patch was already declined for the same reason: a zero
interval is intentionally supported [1].

Document the behavior instead of changing it.

[1] https://lore.kernel.org/all/20260722094304.3132750-1-dayou5941@163.com/

Signed-off-by: Karthikeyan KS <karthiproffesional@gmail.com>
---

Hi SJ,

> I'd prefer adding a comment saying zero sampling interval is
> accepted.  I think damon_attr kernel-doc comment is a good place
> for adding that.

Adding comments instead of code changes.  Let me know if you'd
rather the wording live somewhere else, or be phrased differently.

Changes from v1:
- Dropped the damon_set_attrs() rejection and the KUnit cases that
  tested it.
- Added a kernel-doc note on struct damon_attrs's @sample_interval
  instead.

Thanks,
Karthikeyan KS

 include/linux/damon.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 0c8b7ddef9ab..1a7ef416ec46 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -787,7 +787,8 @@ struct damon_probe {
 /**
  * struct damon_attrs - Monitoring attributes for accuracy/overhead control.
  *
- * @sample_interval:		The time between access samplings.
+ * @sample_interval:		The time between access samplings.  Zero is
+ *				accepted.
  * @aggr_interval:		The time between monitor results aggregations.
  * @ops_update_interval:	The time between monitoring operations updates.
  * @intervals_goal:		Intervals auto-tuning goal.
-- 
2.34.1