[PATCH 1/6] Revert "memcg: remove mem_cgroup_uncharge_list()"

Usama Arif
2024-07-30T12:54:11Z

mem_cgroup_uncharge_list will be needed in a later patch for an
optimization to free zapped tail pages when splitting isolated thp.

Signed-off-by: Usama Arif <usamaarif642@gmail.com>
---
include/linux/memcontrol.h | 12 ++++++++++++
mm/memcontrol.c | 19 +++++++++++++++++++
2 files changed, 31 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 07eadf7ecbba..cbaf0ea1b217 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -713,6 +713,14 @@ static inline void mem_cgroup_uncharge(struct folio *folio)
__mem_cgroup_uncharge(folio);
}

+void __mem_cgroup_uncharge_list(struct list_head *page_list);
+static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+ if (mem_cgroup_disabled())
+ return;
+ __mem_cgroup_uncharge_list(page_list);
+}
+
void __mem_cgroup_uncharge_folios(struct folio_batch *folios);
static inline void mem_cgroup_uncharge_folios(struct folio_batch *folios)
{
@@ -1203,6 +1211,10 @@ static inline void mem_cgroup_uncharge(struct folio *folio)
{
}

+static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+}
+
static inline void mem_cgroup_uncharge_folios(struct folio_batch *folios)
{
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9b3ef3a70833..f568b9594c2b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4717,6 +4717,25 @@ void __mem_cgroup_uncharge(struct folio *folio)
uncharge_batch(&ug);
}

+/**
+ * __mem_cgroup_uncharge_list - uncharge a list of page
+ * @page_list: list of pages to uncharge
+ *
+ * Uncharge a list of pages previously charged with
+ * __mem_cgroup_charge().
+ */
+void __mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+ struct uncharge_gather ug;
+ struct folio *folio;
+
+ uncharge_gather_clear(&ug);
+ list_for_each_entry(folio, page_list, lru)
+ uncharge_folio(folio, &ug);
+ if (ug.memcg)
+ uncharge_batch(&ug);
+}
+
void __mem_cgroup_uncharge_folios(struct folio_batch *folios)
{
struct uncharge_gather ug;
--
2.43.0