On Thu, May 07, 2020 at 04:52:36PM +0800, Ming Lei wrote: > for (i = 1; i < ptbl->len; i++) { > part = rcu_dereference(ptbl->part[i]); > > if (part && sector_in_part(part, sector)) { > + if (!hd_struct_try_get(part)) > + goto exit; I think this needs the comment that was in blk_account_io_start to explain the logic. Also no need for the goto, this can just be a break. > - rcu_assign_pointer(ptbl->last_lookup, NULL); > kobject_put(part->holder_dir); > device_del(part_to_dev(part)); > > @@ -393,6 +402,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, > p->nr_sects = len; > p->partno = partno; > p->policy = get_disk_ro(disk); > + p->disk = disk; Do we really need this pointer? Can't we use part_to_disk in the free path for some reason?