[PATCH v3 2/3] mm: page_counters: put page_counter_calculate_protection() under CONFIG_MEMCG

[Roman Gushchin <roman.gushchin@linux.dev>]

Put page_counter_calculate_protection() under CONFIG_MEMCG.

The protection functionality (min/low limits) is not supported by any
other cgroup subsystem, so page_counter_calculate_protection() and
related static effective_protection() can be compiled out if
CONFIG_MEMCG is not enabled.

Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
---
 include/linux/page_counter.h | 6 ++++++
 mm/page_counter.c            | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
index aadd42f5ab7b..cf837d0f8ed1 100644
--- a/include/linux/page_counter.h
+++ b/include/linux/page_counter.h
@@ -95,8 +95,14 @@ static inline void page_counter_reset_watermark(struct page_counter *counter)
 	counter->watermark = usage;
 }
 
+#ifdef CONFIG_MEMCG
 void page_counter_calculate_protection(struct page_counter *root,
 				       struct page_counter *counter,
 				       bool recursive_protection);
+#else
+static inline void page_counter_calculate_protection(struct page_counter *root,
+						     struct page_counter *counter,
+						     bool recursive_protection) {}
+#endif
 
 #endif /* _LINUX_PAGE_COUNTER_H */
diff --git a/mm/page_counter.c b/mm/page_counter.c
index a54382a58ace..b249d15af9dd 100644
--- a/mm/page_counter.c
+++ b/mm/page_counter.c
@@ -288,6 +288,7 @@ int page_counter_memparse(const char *buf, const char *max,
 }
 
 
+#ifdef CONFIG_MEMCG
 /*
  * This function calculates an individual page counter's effective
  * protection which is derived from its own memory.min/low, its
@@ -459,3 +460,4 @@ void page_counter_calculate_protection(struct page_counter *root,
 			atomic_long_read(&parent->children_low_usage),
 			recursive_protection));
 }
+#endif /* CONFIG_MEMCG */
-- 
2.46.0.rc1.232.g9752f9e123-goog