[PATCH 1/3] memcg/hugetlb: Introduce memcg_accounts_hugetlb

[Joshua Hahn <joshua.hahnjy@gmail.com>]

This patch isolates the check for whether memcg accounts hugetlb.
This condition can only be true if the memcg mount option
memory_hugetlb_accounting is on, which includes hugetlb usage
in memory.current.

Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>

---
 mm/memcontrol.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f3a9653cef0e..97f63ec9c9fb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1425,6 +1425,9 @@ unsigned long memcg_page_state_local_output(struct mem_cgroup *memcg, int item)
 		memcg_page_state_output_unit(item);
 }
 
+/* Forward declaration */
+bool memcg_accounts_hugetlb(void);
+
 static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
 {
 	int i;
@@ -1446,7 +1449,7 @@ static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
 
 #ifdef CONFIG_HUGETLB_PAGE
 		if (unlikely(memory_stats[i].idx == NR_HUGETLB) &&
-		    !(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING))
+			!memcg_accounts_hugetlb())
 			continue;
 #endif
 		size = memcg_page_state_output(memcg, memory_stats[i].idx);
@@ -4483,6 +4486,15 @@ int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
 	return ret;
 }
 
+bool memcg_accounts_hugetlb(void)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	return cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING;
+#else
+	return false;
+#endif
+}
+
 /**
  * mem_cgroup_hugetlb_try_charge - try to charge the memcg for a hugetlb folio
  * @memcg: memcg to charge.
@@ -4508,8 +4520,7 @@ int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,
 	 * but do not attempt to commit charge later (or cancel on error) either.
 	 */
 	if (mem_cgroup_disabled() || !memcg ||
-		!cgroup_subsys_on_dfl(memory_cgrp_subsys) ||
-		!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING))
+		!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !memcg_accounts_hugetlb())
 		return -EOPNOTSUPP;
 
 	if (try_charge(memcg, gfp, nr_pages))
-- 
2.43.5