[PATCH] mm/memcg: Relocate mod_objcg_mlstate(), get_obj_stock() and put_obj_stock()

[Waiman Long]

All the calls to mod_objcg_mlstate(), get_obj_stock() and put_obj_stock()
are done by functions defined within the same "#ifdef CONFIG_MEMCG_KMEM"
compilation block. When CONFIG_MEMCG_KMEM isn't defined, the following
compilation warnings will be issued [1] and [2].

  mm/memcontrol.c:785:20: warning: unused function 'mod_objcg_mlstate'
  mm/memcontrol.c:2113:33: warning: unused function 'get_obj_stock'

Fix these warning by moving those functions to under the same
CONFIG_MEMCG_KMEM compilation block. There is no functional change.

[1] https://lore.kernel.org/lkml/202111272014.WOYNLUV6-lkp@xxxxxxxxx/
[2] https://lore.kernel.org/lkml/202111280551.LXsWYt1T-lkp@xxxxxxxxx/

Fixes: 559271146efc ("mm/memcg: optimize user context object stock access")
Fixes: 68ac5b3c8db2 ("mm/memcg: cache vmstat data in percpu memcg_stock_pcp")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
 mm/memcontrol.c | 106 ++++++++++++++++++++++++------------------------
 1 file changed, 53 insertions(+), 53 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6863a834ed42..2ed5f2a0879d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -776,24 +776,6 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
 	rcu_read_unlock();
 }
 
-/*
- * mod_objcg_mlstate() may be called with irq enabled, so
- * mod_memcg_lruvec_state() should be used.
- */
-static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
-				     struct pglist_data *pgdat,
-				     enum node_stat_item idx, int nr)
-{
-	struct mem_cgroup *memcg;
-	struct lruvec *lruvec;
-
-	rcu_read_lock();
-	memcg = obj_cgroup_memcg(objcg);
-	lruvec = mem_cgroup_lruvec(memcg, pgdat);
-	mod_memcg_lruvec_state(lruvec, idx, nr);
-	rcu_read_unlock();
-}
-
 /**
  * __count_memcg_events - account VM events in a cgroup
  * @memcg: the memory cgroup
@@ -2137,41 +2119,6 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 }
 #endif
 
-/*
- * Most kmem_cache_alloc() calls are from user context. The irq disable/enable
- * sequence used in this case to access content from object stock is slow.
- * To optimize for user context access, there are now two object stocks for
- * task context and interrupt context access respectively.
- *
- * The task context object stock can be accessed by disabling preemption only
- * which is cheap in non-preempt kernel. The interrupt context object stock
- * can only be accessed after disabling interrupt. User context code can
- * access interrupt object stock, but not vice versa.
- */
-static inline struct obj_stock *get_obj_stock(unsigned long *pflags)
-{
-	struct memcg_stock_pcp *stock;
-
-	if (likely(in_task())) {
-		*pflags = 0UL;
-		preempt_disable();
-		stock = this_cpu_ptr(&memcg_stock);
-		return &stock->task_obj;
-	}
-
-	local_irq_save(*pflags);
-	stock = this_cpu_ptr(&memcg_stock);
-	return &stock->irq_obj;
-}
-
-static inline void put_obj_stock(unsigned long flags)
-{
-	if (likely(in_task()))
-		preempt_enable();
-	else
-		local_irq_restore(flags);
-}
-
 /**
  * consume_stock: Try to consume stocked charge on this cpu.
  * @memcg: memcg to consume from.
@@ -2816,6 +2763,59 @@ static struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg)
  */
 #define OBJCGS_CLEAR_MASK	(__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT)
 
+/*
+ * Most kmem_cache_alloc() calls are from user context. The irq disable/enable
+ * sequence used in this case to access content from object stock is slow.
+ * To optimize for user context access, there are now two object stocks for
+ * task context and interrupt context access respectively.
+ *
+ * The task context object stock can be accessed by disabling preemption only
+ * which is cheap in non-preempt kernel. The interrupt context object stock
+ * can only be accessed after disabling interrupt. User context code can
+ * access interrupt object stock, but not vice versa.
+ */
+static inline struct obj_stock *get_obj_stock(unsigned long *pflags)
+{
+	struct memcg_stock_pcp *stock;
+
+	if (likely(in_task())) {
+		*pflags = 0UL;
+		preempt_disable();
+		stock = this_cpu_ptr(&memcg_stock);
+		return &stock->task_obj;
+	}
+
+	local_irq_save(*pflags);
+	stock = this_cpu_ptr(&memcg_stock);
+	return &stock->irq_obj;
+}
+
+static inline void put_obj_stock(unsigned long flags)
+{
+	if (likely(in_task()))
+		preempt_enable();
+	else
+		local_irq_restore(flags);
+}
+
+/*
+ * mod_objcg_mlstate() may be called with irq enabled, so
+ * mod_memcg_lruvec_state() should be used.
+ */
+static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
+				     struct pglist_data *pgdat,
+				     enum node_stat_item idx, int nr)
+{
+	struct mem_cgroup *memcg;
+	struct lruvec *lruvec;
+
+	rcu_read_lock();
+	memcg = obj_cgroup_memcg(objcg);
+	lruvec = mem_cgroup_lruvec(memcg, pgdat);
+	mod_memcg_lruvec_state(lruvec, idx, nr);
+	rcu_read_unlock();
+}
+
 int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s,
 				 gfp_t gfp, bool new_page)
 {
-- 
2.27.0