Am Mittwoch, 18. Januar 2017, 09:48:30 CET schrieb Andre Noll:

On Wed, Jan 18, 04:35, Kai Krakow wrote

FWIW, I'm seeing this as well on different hardware, and with both
deadline and CFQ, so it's not a scheduler issue. The problem seems to
be the bcache writeback thread calling down_write(&dc->writeback_lock)
while already holding this lock.

Yes, the bug doesn't get triggered when the caching mechanism is set to 
writethrough.

Regards,
Jan