[RFC PATCH 1/3] mm/damon: add DAMOS filter type YOUNG

[SeongJae Park <sj@kernel.org>]

Define yet another DAMOS filter type, YOUNG.  Like anon and memcg, the
type of filter will be applied to each page in the memory region, and
check if the page is accessed since the last check.

Note that this commit is only defining the type.  Implementation of it
should be made on DAMON operations sets.  A couple of commits for the
implementation on 'paddr' DAMON operations set will follow.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h    | 2 ++
 mm/damon/sysfs-schemes.c | 1 +
 2 files changed, 3 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 886d07294f4e..f7da65e1ac04 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -297,6 +297,7 @@ struct damos_stat {
  * enum damos_filter_type - Type of memory for &struct damos_filter
  * @DAMOS_FILTER_TYPE_ANON:	Anonymous pages.
  * @DAMOS_FILTER_TYPE_MEMCG:	Specific memcg's pages.
+ * @DAMOS_FILTER_TYPE_YOUNG:	Recently accessed pages.
  * @DAMOS_FILTER_TYPE_ADDR:	Address range.
  * @DAMOS_FILTER_TYPE_TARGET:	Data Access Monitoring target.
  * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
@@ -315,6 +316,7 @@ struct damos_stat {
 enum damos_filter_type {
 	DAMOS_FILTER_TYPE_ANON,
 	DAMOS_FILTER_TYPE_MEMCG,
+	DAMOS_FILTER_TYPE_YOUNG,
 	DAMOS_FILTER_TYPE_ADDR,
 	DAMOS_FILTER_TYPE_TARGET,
 	NR_DAMOS_FILTER_TYPES,
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 53a90ac678fb..bea5bc52846a 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -343,6 +343,7 @@ static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(void)
 static const char * const damon_sysfs_scheme_filter_type_strs[] = {
 	"anon",
 	"memcg",
+	"young",
 	"addr",
 	"target",
 };
-- 
2.39.2