1 files changed, 41 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 135d6637afe5..a86e7b445800 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7097,6 +7097,41 @@ int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
 }
 
 /**
+ * mem_cgroup_hugetlb_try_charge - try to charge the memcg for a hugetlb folio
+ * @memcg: memcg to charge.
+ * @gfp: reclaim mode.
+ * @nr_pages: number of pages to charge.
+ *
+ * This function is called when allocating a huge page folio to determine if
+ * the memcg has the capacity for it. It does not commit the charge yet,
+ * as the hugetlb folio itself has not been obtained from the hugetlb pool.
+ *
+ * Once we have obtained the hugetlb folio, we can call
+ * mem_cgroup_commit_charge() to commit the charge. If we fail to obtain the
+ * folio, we should instead call mem_cgroup_cancel_charge() to undo the effect
+ * of try_charge().
+ *
+ * Returns 0 on success. Otherwise, an error code is returned.
+ */
+int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,
+			long nr_pages)
+{
+	/*
+	 * If hugetlb memcg charging is not enabled, do not fail hugetlb allocation,
+	 * 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))
+		return -EOPNOTSUPP;
+
+	if (try_charge(memcg, gfp, nr_pages))
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
  * mem_cgroup_swapin_charge_folio - Charge a newly allocated folio for swapin.
  * @folio: folio to charge.
  * @mm: mm context of the victim
@@ -7365,7 +7400,12 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
 		return;
 
 	memcg = folio_memcg(old);
-	VM_WARN_ON_ONCE_FOLIO(!memcg, old);
+	/*
+	 * Note that it is normal to see !memcg for a hugetlb folio.
+	 * For e.g, itt could have been allocated when memory_hugetlb_accounting
+	 * was not selected.
+	 */
+	VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(old) && !memcg, old);
 	if (!memcg)
 		return;