[PATCH] damon: update outdated comment about DAMOS filter handling

[PATCH] damon: update outdated comment about DAMOS filter handling

[Song Hu]

The kernel-doc comment above enum damos_filter_type states that only the
anon and memcg type filters are handled by damon_operations (and therefore
accounted as 'tried'), and that DAMON_OPS_VADDR and DAMON_OPS_FVADDR do
not support those two filter types.

Neither is accurate anymore.  damos_filter_for_ops() routes every filter
type except ADDR and TARGET to the operations layer, and the VADDR and
FVADDR operations (the latter being a copy of the former) handle all of
those types through damos_folio_filter_match() / damos_va_filter_out().
Update the comment to match the code.

Signed-off-by: Song Hu <husong@kylinos.cn>
---
 include/linux/damon.h | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index f69442a9d431..d1bb3490792a 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -392,16 +392,15 @@ struct damos_stat {
  * @DAMOS_FILTER_TYPE_TARGET:	Data Access Monitoring target.
  * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
  *
- * The anon pages type and memcg type filters are handled by underlying
- * &struct damon_operations as a part of scheme action trying, and therefore
- * accounted as 'tried'.  In contrast, other types are handled by core layer
- * before trying of the action and therefore not accounted as 'tried'.
+ * All types except &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET
+ * are handled by the underlying &struct damon_operations as a part of scheme
+ * action trying, and therefore accounted as 'tried'.  In contrast,
+ * &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET filters are handled
+ * by the core layer before trying of the action, and therefore not accounted
+ * as 'tried'.
  *
- * The support of the filters that handled by &struct damon_operations depend
- * on the running &struct damon_operations.
- * &enum DAMON_OPS_PADDR supports both anon pages type and memcg type filters,
- * while &enum DAMON_OPS_VADDR and &enum DAMON_OPS_FVADDR don't support any of
- * the two types.
+ * Support for the operations-handled filters depends on the running
+ * &struct damon_operations.
  */
 enum damos_filter_type {
 	DAMOS_FILTER_TYPE_ANON,
-- 
2.43.0

Re: [PATCH] damon: update outdated comment about DAMOS filter handling

[SJ Park]

On Wed, 15 Jul 2026 17:26:34 +0800 Song Hu <husong@kylinos.cn> wrote:

> The kernel-doc comment above enum damos_filter_type states that only the
> anon and memcg type filters are handled by damon_operations (and therefore
> accounted as 'tried'), and that DAMON_OPS_VADDR and DAMON_OPS_FVADDR do
> not support those two filter types.
> 
> Neither is accurate anymore.  damos_filter_for_ops() routes every filter
> type except ADDR and TARGET to the operations layer, and the VADDR and
> FVADDR operations (the latter being a copy of the former) handle all of
> those types through damos_folio_filter_match() / damos_va_filter_out().
> Update the comment to match the code.

Thank you for updating this!
> 
> Signed-off-by: Song Hu <husong@kylinos.cn>

Reviewed-by: SJ Park <sj@kernel.org>

This patch is applied to damon/next [1] tree.  If this patch is not added to
mm.git in short term (~1 week?), I will ask mm.git maintainer (Andrew Morton)
to pick this.  So, no action from your side is needed for now.  If it seems I
also forgot doing that or you cannot wait for my action, please feel free to
directly ask that to Andrew.

[1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees


Thanks,
SJ

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