If the device underlying a zoned target is removed, its capacity is set to 0 and blkdev_report_zones() returns 0 without reporting any zones. The mapped device keeps its old capacity, so args->zone_idx and args->next_sector never advance and dm_blk_do_report_zones() loops forever. On non-preemptible kernels this causes soft lockups and RCU stalls. The following sequence of commands triggers the hang: modprobe scsi_debug zbc=managed dev_size_mb=1024 zone_size_mb=64 udevadm settle echo '0 2097152 linear /dev/sda 0' | dmsetup create lin echo 1 > /sys/block/sda/device/delete blkzone report -o 0 -c 1 /dev/mapper/lin Fix this by returning -EIO when a target reports no zones. The target always maps args->next_sector, so a zero return means the underlying device no longer covers that sector. Fixes: d41003513e61 ("block: rework zone reporting") Cc: stable@vger.kernel.org Signed-off-by: Mark Bundschuh --- drivers/md/dm-zone.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/md/dm-zone.c b/drivers/md/dm-zone.c index f29acf64429a..ce4f94685a78 100644 --- a/drivers/md/dm-zone.c +++ b/drivers/md/dm-zone.c @@ -33,6 +33,8 @@ static int dm_blk_do_report_zones(struct mapped_device *md, struct dm_table *t, nr_zones - args->zone_idx); if (ret < 0) return ret; + if (!ret) + return -EIO; } while (args->zone_idx < nr_zones && args->next_sector < get_capacity(md->disk)); -- 2.50.1