slab, slub, slob: add slab_flags_t

Add sparse-checked slab_flags_t for struct kmem_cache::flags (SLAB_POISON,
etc).

SLAB is bloated temporarily by switching to "unsigned long", but only
temporarily.

Link: http://lkml.kernel.org/r/20171021100225.GA22428@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
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>
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 8f7d2b1..072e46e 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -20,7 +20,7 @@ struct kmem_cache {
 	struct reciprocal_value reciprocal_buffer_size;
 /* 2) touched by every alloc & free from the backend */
 
-	unsigned int flags;		/* constant flags */
+	slab_flags_t flags;		/* constant flags */
 	unsigned int num;		/* # of objs per slab */
 
 /* 3) cache_grow/shrink */