Re: [PATCH] mm: slub: remove dead and buggy code from sysfs_slab_add()

[David Rientjes <rientjes@google.com>]

On Fri, 30 Sep 2022, Rasmus Villemoes wrote:

> 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>

Acked-by: David Rientjes <rientjes@google.com>