mm/damon/core: implement target type damos filter

One DAMON context can have multiple monitoring targets, and DAMOS schemes
are applied to all targets.  In some cases, users need to apply different
scheme to different targets.  Retrieving monitoring results via DAMON
sysfs interface' 'tried_regions' directory could be one good example. 
Also, there could be cases that cgroup DAMOS filter is not enough.  All
such use cases can be worked around by having multiple DAMON contexts
having only single target, but it is inefficient in terms of resource
usage, thogh the overhead is not estimated to be huge.

Implement DAMON monitoring target based DAMOS filter for the case.  Like
address range target DAMOS filter, handle these filters in the DAMON core
layer, since it is more efficient than doing in operations set layer. 
This also means that regions that filtered out by monitoring target type
DAMOS filters are counted as not tried by the scheme.  Hence, target
granularity monitoring results retrieval via DAMON sysfs interface becomes
available.

Link: https://lkml.kernel.org/r/20230802214312.110532-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 476f37a883a4..ae2664d1d5f1 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -227,6 +227,7 @@ struct damos_stat {
  * @DAMOS_FILTER_TYPE_ANON:	Anonymous pages.
  * @DAMOS_FILTER_TYPE_MEMCG:	Specific memcg's pages.
  * @DAMOS_FILTER_TYPE_ADDR:	Address range.
+ * @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
@@ -244,6 +245,7 @@ enum damos_filter_type {
 	DAMOS_FILTER_TYPE_ANON,
 	DAMOS_FILTER_TYPE_MEMCG,
 	DAMOS_FILTER_TYPE_ADDR,
+	DAMOS_FILTER_TYPE_TARGET,
 	NR_DAMOS_FILTER_TYPES,
 };
 
@@ -253,6 +255,9 @@ enum damos_filter_type {
  * @matching:	If the matching page should filtered out or in.
  * @memcg_id:	Memcg id of the question if @type is DAMOS_FILTER_MEMCG.
  * @addr_range:	Address range if @type is DAMOS_FILTER_TYPE_ADDR.
+ * @target_idx:	Index of the &struct damon_target of
+ *		&damon_ctx->adaptive_targets if @type is
+ *		DAMOS_FILTER_TYPE_TARGET.
  * @list:	List head for siblings.
  *
  * Before applying the &damos->action to a memory region, DAMOS checks if each
@@ -266,6 +271,7 @@ struct damos_filter {
 	union {
 		unsigned short memcg_id;
 		struct damon_addr_range addr_range;
+		int target_idx;
 	};
 	struct list_head list;
 };