[PATCH 3/3] memcg: simplify and inline __mem_cgroup_from_kmem

[Vladimir Davydov]

Before the previous patch, __mem_cgroup_from_kmem had to handle two
types of kmem - slab pages and pages allocated with alloc_kmem_pages -
differently, because slab pages did not store information about owner
memcg in the page struct. Now we can unify it. Since after it, this
function becomes tiny we can fold it into mem_cgroup_from_kmem.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
 include/linux/memcontrol.h |  7 ++++---
 mm/memcontrol.c            | 18 ------------------
 2 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 8a9b7a798f14..0e2e039609d1 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -769,8 +769,6 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
 struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep);
 void __memcg_kmem_put_cache(struct kmem_cache *cachep);
 
-struct mem_cgroup *__mem_cgroup_from_kmem(void *ptr);
-
 static inline bool __memcg_kmem_bypass(gfp_t gfp)
 {
 	if (!memcg_kmem_enabled())
@@ -832,9 +830,12 @@ static __always_inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
 
 static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
 {
+	struct page *page;
+
 	if (!memcg_kmem_enabled())
 		return NULL;
-	return __mem_cgroup_from_kmem(ptr);
+	page = virt_to_head_page(ptr);
+	return page->mem_cgroup;
 }
 #else
 #define for_each_memcg_cache_index(_idx)	\
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1d6413e0dd29..6329e6182d89 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2430,24 +2430,6 @@ void __memcg_kmem_uncharge(struct page *page, int order)
 	page->mem_cgroup = NULL;
 	css_put_many(&memcg->css, nr_pages);
 }
-
-struct mem_cgroup *__mem_cgroup_from_kmem(void *ptr)
-{
-	struct mem_cgroup *memcg = NULL;
-	struct kmem_cache *cachep;
-	struct page *page;
-
-	page = virt_to_head_page(ptr);
-	if (PageSlab(page)) {
-		cachep = page->slab_cache;
-		if (!is_root_cache(cachep))
-			memcg = cachep->memcg_params.memcg;
-	} else
-		/* page allocated by alloc_kmem_pages */
-		memcg = page->mem_cgroup;
-
-	return memcg;
-}
 #endif /* CONFIG_MEMCG_KMEM */
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-- 
2.1.4

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