mm/slab: convert cache name allocations to kstrdup_const

slab frequently performs duplication of strings located in read-only
memory section.  Replacing kstrdup by kstrdup_const allows to avoid such
operations.

[akpm@linux-foundation.org: make the handling of kmem_cache.name const-correct]
Signed-off-by: NAndrzej Hajda <a.hajda@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/slab_common.c

@@ -295,8 +295,8 @@ unsigned long calculate_alignment(unsigned long flags,
 }
 
 static struct kmem_cache *
-do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
-		     unsigned long flags, void (*ctor)(void *),
+do_kmem_cache_create(const char *name, size_t object_size, size_t size,
+		     size_t align, unsigned long flags, void (*ctor)(void *),
 		     struct mem_cgroup *memcg, struct kmem_cache *root_cache)
 {
 	struct kmem_cache *s;
@@ -363,7 +363,7 @@ kmem_cache_create(const char *name, size_t size, size_t align,
 		  unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *s;
-	char *cache_name;
+	const char *cache_name;
 	int err;
 
 	get_online_cpus();
@@ -390,7 +390,7 @@ kmem_cache_create(const char *name, size_t size, size_t align,
 	if (s)
 		goto out_unlock;
 
-	cache_name = kstrdup(name, GFP_KERNEL);
+	cache_name = kstrdup_const(name, GFP_KERNEL);
 	if (!cache_name) {
 		err = -ENOMEM;
 		goto out_unlock;
@@ -401,7 +401,7 @@ kmem_cache_create(const char *name, size_t size, size_t align,
 				 flags, ctor, NULL, NULL);
 	if (IS_ERR(s)) {
 		err = PTR_ERR(s);
-		kfree(cache_name);
+		kfree_const(cache_name);
 	}
 
 out_unlock:
@@ -607,7 +607,7 @@ void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
 void slab_kmem_cache_release(struct kmem_cache *s)
 {
 	destroy_memcg_params(s);
-	kfree(s->name);
+	kfree_const(s->name);
 	kmem_cache_free(kmem_cache, s);
 }