mm: memcg/slab: introduce __memcg_kmem_uncharge_memcg()

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.

Link: http://lkml.kernel.org/r/20190611231813.3148843-5-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 22141eb..6840284 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1278,6 +1278,8 @@ 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;
@@ -1319,6 +1321,14 @@ 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 6de79ec..25e35a8 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2807,6 +2807,22 @@ 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
@@ -2821,14 +2837,7 @@ 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 */