[SRU][E][PATCH v2 0/1] bcache: fix hung task timeout in bch_bucket_alloc()

[Andrea Righi]

On Thu, Aug 08, 2019 at 10:30:08AM -0500, Seth Forshee wrote:
> On Wed, Aug 07, 2019 at 02:58:46PM +0200, Andrea Righi wrote:
> > BugLink: https://bugs.launchpad.net/bugs/1784665
> > 
> > [Impact]
> > 
> > bcache_allocator can call the following:
> > 
> >  bch_allocator_thread()
> >   -> bch_prio_write()
> >      -> bch_bucket_alloc()
> >         -> wait on &ca->set->bucket_wait
> > 
> > But the wake up event on bucket_wait is supposed to come from
> > bch_allocator_thread() itself causing a deadlock.
> > 
> > [Test Case]
> > 
> > This is a simple script that can easily trigger the deadlock condition:
> > https://launchpadlibrarian.net/381282009/bcache-basic-repro.sh
> > 
> > A better test case has been also provided in LP: #1796292:
> > https://bugs.launchpad.net/curtin/+bug/1796292/+attachment/5280353/+files/curtin-nvme.sh
> 
> Since I don't see it stated anywhere, I take this to mean that the patch
> has been tested against this script. Was any other regression testing
> done?

Correct, sorry I wasn't clear, curtin-nvme.sh was used to replicate the
bug and verify that the bug was fixed.

-Andrea