[RFC PATCH 09/11] mm/damon/core: implement DAMOS_QUOTA_NODE_MEMCG_FREE_BP

[SeongJae Park <sj@kernel.org>]

Implement the core part of DAMOS_QUOTA_NODE_MEMCG_FREE_BP to get the
real value.  The value is implemented as the entire memory of the given
NUMA node, except the given cgroup's portion.  So strictly speaking, it
is not free memory but memory that not used by the cgroup.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 1481b43f2710..ee3d6d4b3c9b 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2028,7 +2028,7 @@ static unsigned long damos_get_node_memcg_used_bp(
 {
 	struct mem_cgroup *memcg;
 	struct lruvec *lruvec;
-	unsigned long used_pages;
+	unsigned long used_pages, numerator;
 	struct sysinfo i;
 
 	rcu_read_lock();
@@ -2042,7 +2042,11 @@ static unsigned long damos_get_node_memcg_used_bp(
 	rcu_read_unlock();
 
 	si_meminfo_node(&i, goal->nid);
-	return used_pages * PAGE_SIZE * 10000 / i.totalram;
+	if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP)
+		numerator = used_pages * PAGE_SIZE;
+	else	/* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */
+		numerator = i.totalram - used_pages * PAGE_SIZE;
+	return numerator * 10000 / i.totalram;
 }
 #else
 static __kernel_ulong_t damos_get_node_mem_bp(
@@ -2092,6 +2096,7 @@ static void damos_set_quota_goal_current_value(struct damos_quota_goal *goal)
 		goal->current_value = damos_get_node_mem_bp(goal);
 		break;
 	case DAMOS_QUOTA_NODE_MEMCG_USED_BP:
+	case DAMOS_QUOTA_NODE_MEMCG_FREE_BP:
 		goal->current_value = damos_get_node_memcg_used_bp(goal);
 		break;
 	case DAMOS_QUOTA_ACTIVE_MEM_BP:
-- 
2.39.5