[PATCH 1/2] 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-of-by: Joshua Hahn <joshua.hahnjy@gmail.com>

---
 include/linux/memcontrol.h |  2 ++
 mm/memcontrol.c            | 12 ++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 34d2da05f2f1..25761d55799e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -694,6 +694,8 @@ static inline int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm,
 	return __mem_cgroup_charge(folio, mm, gfp);
 }
 
+bool memcg_accounts_hugetlb(void);
+
 int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,
 		long nr_pages);
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5444d0e7bb64..59dea0122579 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4497,6 +4497,15 @@ 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.
@@ -4522,8 +4531,7 @@ 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