On 02/21/2017 09:55 AM, Jan Kara wrote: > diff --git a/block/blk-core.c b/block/blk-core.c > index 47104f6a398b..9a901dcfdd5c 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -580,8 +580,6 @@ void blk_cleanup_queue(struct request_queue *q) > q->queue_lock = &q->__queue_lock; > spin_unlock_irq(lock); > > - bdi_unregister(q->backing_dev_info); > - > /* @q is and will stay empty, shutdown and put */ > blk_put_queue(q); > } > diff --git a/block/genhd.c b/block/genhd.c > index f6c4d4400759..68c613edb93a 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -660,6 +660,13 @@ void del_gendisk(struct gendisk *disk) > disk->flags &= ~GENHD_FL_UP; > > sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); > + /* > + * Unregister bdi before releasing device numbers (as they can get > + * reused and we'd get clashes in sysfs) but after bdev inodes are > + * unhashed and thus will be soon destroyed as bdev inode's reference > + * to wb_writeback can block bdi_unregister(). > + */ > + bdi_unregister(disk->queue->backing_dev_info); > blk_unregister_queue(disk); > blk_unregister_region(disk_devt(disk), disk->minors); This change looks suspicious to me. There are drivers that create a block layer queue but neither call device_add_disk() nor del_gendisk(), e.g. drivers/scsi/st.c. Although bdi_init() will be called for the queues created by these drivers, this patch will cause the bdi_unregister() call to be skipped for these drivers. Bart.
