Comment 9 for bug 1837788

Tested with disco-proposed + patch (problem does not happen)
---

# uname -rv
5.0.0-22-generic #23+test20190725b1 SMP Mon Jul 29 14:43:55 -03 2019

# ./setup-bcache-wb_percent-before-attach.sh >/dev/null 2>&1
[ 69.567775] bcache: register_bdev() registered backing device loop0/null 2>&1
[ 69.577141] bcache: run_cache_set() invalidating existing data
[ 69.591172] bcache: register_cache() registered cache device loop1
[ 69.591517] bcache: register_bcache() error /dev/loop0: device already registered (emitting change event)
[ 73.570620] bcache: bch_cached_dev_attach() Caching loop0 as bcache0 on set 0ed05289-ed85-40da-bcf4-3991f2e18e03
#

(no warning message)

# reboot
# # comment last line in script.

# ./setup-bcache-wb_percent-before-attach.sh >/dev/null 2>&1
#

[ 40.045968] bcache: register_bdev() registered backing device loop0ev/null 2>&
[ 40.050914] bcache: run_cache_set() invalidating existing data
[ 40.060793] bcache: register_cache() registered cache device loop1
[ 40.068735] bcache: register_bcache() error /dev/loop1: device already registered

(wait a few seconds)
(ok no oops anymore)