slab: mark slab->obj_exts allocation failures unconditionally

alloc_slab_obj_exts() should mark failed obj_exts vector allocations
independent on whether the vector is being allocated for a new or an
existing slab. Current implementation skips doing this for existing
slabs. Fix this by marking failed allocations unconditionally.

Fixes: 09c4656 ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations")
Reported-by: Shakeel Butt <shakeel.butt@linux.dev>
Closes: https://lore.kernel.org/all/avhakjldsgczmq356gkwmvfilyvf7o6temvcmtt5lqd4fhp5rk@47gp2ropyixg/
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org # v6.10+
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Author: surenbaghdasaryan

mm/slub.c

@@ -2039,8 +2039,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 			   slab_nid(slab));
 	if (!vec) {
 		/* Mark vectors which failed to allocate */
-		if (new_slab)
-			mark_failed_objexts_alloc(slab);
+		mark_failed_objexts_alloc(slab);
 
 		return -ENOMEM;
 	}