[Devel] [PATCH RHEL COMMIT] mm/mecontrol: add memcg_[un]charge_kmem() API

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.vz9.1.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after ark-5.14
------>
commit 756d34aea77069e4612e4c9a352f7af04f60fcab
Author: Andrey Ryabinin <ryabinin.a.a at gmail.com>
Date:   Thu Sep 30 17:44:07 2021 +0300

    mm/mecontrol: add memcg_[un]charge_kmem() API
    
    This API will be used to charge kmem directly when using __GFP_ACCOUNT
    isn't possible.
    
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    (cherry-picked from vz8 commit c3432ecc2f0a ("mm/mecontrol:
    add memcg_[un]charge_kmem() API"))
    
    Signed-off-by: Nikita Yushchenko <nikita.yushchenko at virtuozzo.com>
---
 include/linux/memcontrol.h | 11 +++++++++++
 mm/memcontrol.c            | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a4e0e9830d29..1311eec888b1 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -911,6 +911,9 @@ static inline bool mem_cgroup_online(struct mem_cgroup *memcg)
  * For memory reclaim.
  */
 bool mem_cgroup_dcache_is_low(struct mem_cgroup *memcg, int vfs_cache_min_ratio);
+int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, unsigned long nr_pages);
+void memcg_uncharge_kmem(struct mem_cgroup *memcg, unsigned long nr_pages);
+
 bool mem_cgroup_cleancache_disabled(struct page *page);
 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
 struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
@@ -1395,6 +1398,14 @@ static inline bool mem_cgroup_dcache_is_low(struct mem_cgroup *memcg,
 	return false;
 }
 
+static inline int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp,
+				unsigned long nr_pages)
+{
+	return 0;
+}
+static inline void memcg_uncharge_kmem(struct mem_cgroup *memcg, unsigned long nr_pages)
+{ }
+
 static inline unsigned long mm_overdraft(struct mm_struct *mm)
 {
 	return 0;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1fc6a0c78c4e..41c3d5f25fba 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3378,6 +3378,26 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
 	refill_obj_stock(objcg, size, true);
 }
 
+int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp,
+			     unsigned long nr_pages)
+{
+	int ret = 0;
+
+	ret = try_charge(memcg, gfp, nr_pages);
+	if (!ret)
+		page_counter_charge(&memcg->kmem, nr_pages);
+
+	return ret;
+}
+
+void memcg_uncharge_kmem(struct mem_cgroup *memcg, unsigned long nr_pages)
+{
+	page_counter_uncharge(&memcg->kmem, nr_pages);
+	page_counter_uncharge(&memcg->memory, nr_pages);
+	if (!cgroup_memory_noswap)
+		page_counter_uncharge(&memcg->memsw, nr_pages);
+}
+
 #endif /* CONFIG_MEMCG_KMEM */
 
 /*