mm: kmem: switch to nr_pages in (__)memcg_kmem_charge_memcg()

These functions are charging the given number of kernel pages to the given
memory cgroup.  The number doesn't have to be a power of two.  Let's make
them to take the unsigned int nr_pages as an argument instead of the page
order.

It makes them look consistent with the corresponding uncharge functions
and functions like: mem_cgroup_charge_skmem(memcg, nr_pages).

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Link: http://lkml.kernel.org/r/20200109202659.752357-5-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -1369,7 +1369,8 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep);
 #ifdef CONFIG_MEMCG_KMEM
 int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order);
 void __memcg_kmem_uncharge_page(struct page *page, int order);
-int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp, int order);
+int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp,
+			      unsigned int nr_pages);
 void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
 				 unsigned int nr_pages);
 
@@ -1408,18 +1409,18 @@ static inline void memcg_kmem_uncharge_page(struct page *page, int order)
 }
 
 static inline int memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp,
-					  int order)
+					  unsigned int nr_pages)
 {
 	if (memcg_kmem_enabled())
-		return __memcg_kmem_charge_memcg(memcg, gfp, order);
+		return __memcg_kmem_charge_memcg(memcg, gfp, nr_pages);
 	return 0;
 }
 
 static inline void memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
-					     int order)
+					     unsigned int nr_pages)
 {
 	if (memcg_kmem_enabled())
-		__memcg_kmem_uncharge_memcg(memcg, 1 << order);
+		__memcg_kmem_uncharge_memcg(memcg, nr_pages);
 }
 
 /*

mm/memcontrol.c

@@ -2884,13 +2884,13 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep)
  * __memcg_kmem_charge_memcg: charge a kmem page
  * @memcg: memory cgroup to charge
  * @gfp: reclaim mode
- * @order: allocation order
+ * @nr_pages: number of pages to charge
  *
  * Returns 0 on success, an error code on failure.
  */
-int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp, int order)
+int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp,
+			      unsigned int nr_pages)
 {
-	unsigned int nr_pages = 1 << order;
 	struct page_counter *counter;
 	int ret;
 
@@ -2934,7 +2934,7 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order)
 
 	memcg = get_mem_cgroup_from_current();
 	if (!mem_cgroup_is_root(memcg)) {
-		ret = __memcg_kmem_charge_memcg(memcg, gfp, order);
+		ret = __memcg_kmem_charge_memcg(memcg, gfp, 1 << order);
 		if (!ret) {
 			page->mem_cgroup = memcg;
 			__SetPageKmemcg(page);

mm/slab.h

@@ -365,7 +365,7 @@ static __always_inline int memcg_charge_slab(struct page *page,
 		return 0;
 	}
 
-	ret = memcg_kmem_charge_memcg(memcg, gfp, order);
+	ret = memcg_kmem_charge_memcg(memcg, gfp, 1 << order);
 	if (ret)
 		goto out;