slub: make ->inuse unsigned int

->inuse is "the number of bytes in actual use by the object",
can't be negative.

Link: http://lkml.kernel.org/r/20180305200730.15812-14-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/slub_def.h

@@ -98,7 +98,7 @@ struct kmem_cache {
 	gfp_t allocflags;	/* gfp flags to use on each alloc */
 	int refcount;		/* Refcount for slab cache destroy */
 	void (*ctor)(void *);
-	int inuse;		/* Offset to metadata */
+	unsigned int inuse;		/* Offset to metadata */
 	unsigned int align;		/* Alignment */
 	unsigned int reserved;		/* Reserved bytes at the end of slabs */
 	unsigned int red_left_pad;	/* Left redzone padding size */

mm/slub.c

@@ -4256,12 +4256,11 @@ __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
 		 * the complete object on kzalloc.
 		 */
 		s->object_size = max(s->object_size, (int)size);
-		s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
+		s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
 
 		for_each_memcg_cache(c, s) {
 			c->object_size = s->object_size;
-			c->inuse = max_t(int, c->inuse,
-					 ALIGN(size, sizeof(void *)));
+			c->inuse = max(c->inuse, ALIGN(size, sizeof(void *)));
 		}
 
 		if (sysfs_slab_alias(s, name)) {