Am Donnerstag, 19. Januar 2017, 04:42:44 CET schrieb Kent Overstreet:

On Thu, Jan 19, 2017 at 01:22:47PM +0100, Jan Wiele wrote:

quoted

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

quoted

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.

Is there something else blocked that's holding writeback_lock?

I'm not seeing any other blocked tasks in the kernel log, if it is that what 
you mean. 

If you could provide me with some instructions to follow on a hang, I will try 
to reproduce it next weekend.