kmemleak: Add the slab memory allocation/freeing hooks

This patch adds the callbacks to kmemleak_(alloc|free) functions from
the slab allocator. The patch also adds the SLAB_NOLEAKTRACE flag to
avoid recursive calls to kmemleak when it allocates its own data
structures.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/linux/slab.h

@@ -62,6 +62,8 @@
 # define SLAB_DEBUG_OBJECTS	0x00000000UL
 #endif
 
+#define SLAB_NOLEAKTRACE	0x00800000UL	/* Avoid kmemleak tracing */
+
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */