[PATCH v4 3/7] mm: introduce __memcg_kmem_uncharge_memcg()

Roman Gushchin
2019-05-14T21:44:58Z

Let's separate the page counter modification code out of
__memcg_kmem_uncharge() in a way similar to what
__memcg_kmem_charge() and __memcg_kmem_charge_memcg() work.

This will allow to reuse this code later using a new
memcg_kmem_uncharge_memcg() wrapper, which calls
__memcg_kmem_uncharge_memcg() if memcg_kmem_enabled()
check is passed.

Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
include/linux/memcontrol.h | 10 ++++++++++
mm/memcontrol.c | 25 +++++++++++++++++--------
2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 36bdfe8e5965..deb209510902 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1298,6 +1298,8 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order);
void __memcg_kmem_uncharge(struct page *page, int order);
int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
struct mem_cgroup *memcg);
+void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
+ unsigned int nr_pages);

extern struct static_key_false memcg_kmem_enabled_key;
extern struct workqueue_struct *memcg_kmem_cache_wq;
@@ -1339,6 +1341,14 @@ static inline int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp,
return __memcg_kmem_charge_memcg(page, gfp, order, memcg);
return 0;
}
+
+static inline void memcg_kmem_uncharge_memcg(struct page *page, int order,
+ struct mem_cgroup *memcg)
+{
+ if (memcg_kmem_enabled())
+ __memcg_kmem_uncharge_memcg(memcg, 1 << order);
+}
+
/*
* helper for accessing a memcg's index. It will be used as an index in the
* child cache array in kmem_cache, and also to derive its name. This function
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 48a8f1c35176..b2c39f187cbb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2750,6 +2750,22 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
css_put(&memcg->css);
return ret;
}
+
+/**
+ * __memcg_kmem_uncharge_memcg: uncharge a kmem page
+ * @memcg: memcg to uncharge
+ * @nr_pages: number of pages to uncharge
+ */
+void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
+ unsigned int nr_pages)
+{
+ if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
+ page_counter_uncharge(&memcg->kmem, nr_pages);
+
+ page_counter_uncharge(&memcg->memory, nr_pages);
+ if (do_memsw_account())
+ page_counter_uncharge(&memcg->memsw, nr_pages);
+}
/**
* __memcg_kmem_uncharge: uncharge a kmem page
* @page: page to uncharge
@@ -2764,14 +2780,7 @@ void __memcg_kmem_uncharge(struct page *page, int order)
return;

VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
-
- if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
- page_counter_uncharge(&memcg->kmem, nr_pages);
-
- page_counter_uncharge(&memcg->memory, nr_pages);
- if (do_memsw_account())
- page_counter_uncharge(&memcg->memsw, nr_pages);
-
+ __memcg_kmem_uncharge_memcg(memcg, nr_pages);
page->mem_cgroup = NULL;

/* slab pages do not have PageKmemcg flag set */
--
2.20.1