mm/damon: introduce DAMOS filter type hugepage_size

Patch series "mm/damon: add support for hugepage_size DAMOS filter", v5.

hugepage_size DAMOS filter can be used to gather statistics to check if
memory regions of specific access tempratures are backed by hugepages of a
size in a specific range.  This filter can help to observe and prove the
effectivenes of different schemes for shrinking/collapsing hugepages.


This patch (of 4):

This is to gather statistics to check if memory regions of specific access
tempratures are backed by pages of a size in a specific range.  This
filter can help to observe and prove the effectivenes of different schemes
for shrinking/collapsing hugepages.

[sj@kernel.org: add kernel-doc comment for damos_filter->sz_range]
  Link: https://lkml.kernel.org/r/20250218223058.52459-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250211124437.278873-1-usamaarif642@gmail.com
Link: https://lkml.kernel.org/r/20250211124437.278873-2-usamaarif642@gmail.com
Signed-off-by: Usama Arif <usamaarif642@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Usama Arif <usamaarif642@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

4 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/damon.h b/include/linux/damon.h
index b4d37d9b9221..5e7ae7bca5dc 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -36,6 +36,16 @@ struct damon_addr_range {
 };
 
 /**
+ * struct damon_size_range - Represents size for filter to operate on [@min, @max].
+ * @min:	Min size (inclusive).
+ * @max:	Max size (inclusive).
+ */
+struct damon_size_range {
+	unsigned long min;
+	unsigned long max;
+};
+
+/**
  * struct damon_region - Represents a monitoring target region.
  * @ar:			The address range of the region.
  * @sampling_addr:	Address of the sample for the next access check.
@@ -326,6 +336,7 @@ struct damos_stat {
  * @DAMOS_FILTER_TYPE_ANON:	Anonymous pages.
  * @DAMOS_FILTER_TYPE_MEMCG:	Specific memcg's pages.
  * @DAMOS_FILTER_TYPE_YOUNG:	Recently accessed pages.
+ * @DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:	Page is part of a hugepage.
  * @DAMOS_FILTER_TYPE_ADDR:	Address range.
  * @DAMOS_FILTER_TYPE_TARGET:	Data Access Monitoring target.
  * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
@@ -345,6 +356,7 @@ enum damos_filter_type {
 	DAMOS_FILTER_TYPE_ANON,
 	DAMOS_FILTER_TYPE_MEMCG,
 	DAMOS_FILTER_TYPE_YOUNG,
+	DAMOS_FILTER_TYPE_HUGEPAGE_SIZE,
 	DAMOS_FILTER_TYPE_ADDR,
 	DAMOS_FILTER_TYPE_TARGET,
 	NR_DAMOS_FILTER_TYPES,
@@ -360,6 +372,7 @@ enum damos_filter_type {
  * @target_idx:	Index of the &struct damon_target of
  *		&damon_ctx->adaptive_targets if @type is
  *		DAMOS_FILTER_TYPE_TARGET.
+ * @sz_range:	Size range if @type is DAMOS_FILTER_TYPE_HUGEPAGE_SIZE.
  * @list:	List head for siblings.
  *
  * Before applying the &damos->action to a memory region, DAMOS checks if each
@@ -376,6 +389,7 @@ struct damos_filter {
 		unsigned short memcg_id;
 		struct damon_addr_range addr_range;
 		int target_idx;
+		struct damon_size_range sz_range;
 	};
 	struct list_head list;
 };
diff --git a/mm/damon/core.c b/mm/damon/core.c
index f663c8e99dfa..b1ce072b56f2 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -777,6 +777,9 @@ static void damos_commit_filter_arg(
 	case DAMOS_FILTER_TYPE_TARGET:
 		dst->target_idx = src->target_idx;
 		break;
+	case DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:
+		dst->sz_range = src->sz_range;
+		break;
 	default:
 		break;
 	}
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index eb10a723b0a7..1a5974640b93 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -211,6 +211,7 @@ static bool damos_pa_filter_match(struct damos_filter *filter,
 {
 	bool matched = false;
 	struct mem_cgroup *memcg;
+	size_t folio_sz;
 
 	switch (filter->type) {
 	case DAMOS_FILTER_TYPE_ANON:
@@ -230,6 +231,11 @@ static bool damos_pa_filter_match(struct damos_filter *filter,
 		if (matched)
 			damon_folio_mkold(folio);
 		break;
+	case DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:
+		folio_sz = folio_size(folio);
+		matched = filter->sz_range.min <= folio_sz &&
+			  folio_sz <= filter->sz_range.max;
+		break;
 	default:
 		break;
 	}
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 98f93ae9f59e..9020bc9befac 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -329,6 +329,7 @@ static const char * const damon_sysfs_scheme_filter_type_strs[] = {
 	"anon",
 	"memcg",
 	"young",
+	"hugepage_size",
 	"addr",
 	"target",
 };