memcg, kmem: rename cache_from_memcg to cache_from_memcg_idx

We can't see the relationship with memcg from the parameters,
so the name with memcg_idx would be more reasonable.

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

diff --git a/mm/slab.c b/mm/slab.c
index 2580db0..0c8967b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3982,7 +3982,7 @@
 
 	VM_BUG_ON(!mutex_is_locked(&slab_mutex));
 	for_each_memcg_cache_index(i) {
-		c = cache_from_memcg(cachep, i);
+		c = cache_from_memcg_idx(cachep, i);
 		if (c)
 			/* return value determined by the parent cache only */
 			__do_tune_cpucache(c, limit, batchcount, shared, gfp);