mm: memcontrol: use generic mod_memcg_page_state for kmem pages

The kmem-specific functions do the same thing.  Switch and drop.

Link: http://lkml.kernel.org/r/20170530181724.27197-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/fork.c b/kernel/fork.c
index e53770d..aa01b81 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -326,8 +326,8 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
 		}
 
 		/* All stack pages belong to the same memcg. */
-		memcg_kmem_update_page_stat(vm->pages[0], MEMCG_KERNEL_STACK_KB,
-					    account * (THREAD_SIZE / 1024));
+		mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB,
+				     account * (THREAD_SIZE / 1024));
 	} else {
 		/*
 		 * All stack pages are in the same zone and belong to the
@@ -338,8 +338,8 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
 		mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
 				    THREAD_SIZE / 1024 * account);
 
-		memcg_kmem_update_page_stat(first_page, MEMCG_KERNEL_STACK_KB,
-					    account * (THREAD_SIZE / 1024));
+		mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
+				     account * (THREAD_SIZE / 1024));
 	}
 }