mm: slub: remove dead and buggy code from sysfs_slab_add()

The function sysfs_slab_add() has two callers:

One is slab_sysfs_init(), which first initializes slab_kset, and only
when that succeeds sets slab_state to FULL, and then proceeds to call
sysfs_slab_add() for all previously created slabs.

The other is __kmem_cache_create(), but only after a

	if (slab_state <= UP)
		return 0;

check.

So in other words, sysfs_slab_add() is never called without
slab_kset (aka the return value of cache_kset()) being non-NULL.

And this is just as well, because if we ever did take this path and
called kobject_init(&s->kobj), and then later when called again from
slab_sysfs_init() would end up calling kobject_init_and_add(), we
would hit

	if (kobj->state_initialized) {
		/* do not error out as sometimes we can recover */
		pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.\n",
		dump_stack();
	}

in kobject.c.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

diff --git a/mm/slub.c b/mm/slub.c
index 157527d7101be0da54026376ff4f4095deb9ec2d..76f4d3c4151167bf77a5ff2d05c7d2fd0b2fb8ff 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5920,11 +5920,6 @@ static int sysfs_slab_add(struct kmem_cache *s)
        struct kset *kset = cache_kset(s);
        int unmergeable = slab_unmergeable(s);
 
-       if (!kset) {
-               kobject_init(&s->kobj, &slab_ktype);
-               return 0;
-       }
-
        if (!unmergeable && disable_higher_order_debug &&
                        (slub_debug & DEBUG_METADATA_FLAGS))
                unmergeable = 1;