slab: Remove dead code in free_consistency_checks()

We already know that slab is a valid slab as that's checked by the
caller.  In the future, we won't be able to get to a slab pointer
from a non-slab page.

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Harry Yoo <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

Author: Matthew Wilcox (Oracle)

mm/slub.c

@@ -1684,10 +1684,7 @@ static inline int free_consistency_checks(struct kmem_cache *s,
 		return 0;
 
 	if (unlikely(s != slab->slab_cache)) {
-		if (!folio_test_slab(slab_folio(slab))) {
-			slab_err(s, slab, "Attempt to free object(0x%p) outside of slab",
-				 object);
-		} else if (!slab->slab_cache) {
+		if (!slab->slab_cache) {
 			slab_err(NULL, slab, "No slab cache for object 0x%p",
 				 object);
 		} else {