[4.8 hang] xfstests generic/361 hangs on dax enabled filesystems

[Dave Chinner]

On Wed, Aug 03, 2016 at 04:37:13PM -0600, Ross Zwisler wrote:
> On Wed, Aug 03, 2016 at 11:11:27AM -0600, Ross Zwisler wrote:
> > On Wed, Aug 03, 2016 at 10:33:54AM +1000, Dave Chinner wrote:
> > > Hi folks,
> > > 
> > > Just hit a reproducable hang in generic/361. Essentially this on
> > > a 8GB pmem device:
> > > 
> > > mkfs.xfs -f /dev/pmem1
> > > mount -o dax /dev/pmem1 /mnt/scratch
> > > xfs_io -f -c "truncate 1g" test.img
> > > losetup -f --show /mnt/scratch/test.img
> > > mkfs.xfs -f /dev/loop0
> > > 
> > > And the mkfs.xfs command hangs with a discard that never completes:
....
> > > This only reproduces when the underlying filesystem is mounted with
> > > -o dax, so there is a bad interaction with loop devices and DAX
> > > occurring somewhere. generic/361 is a recent test (committed june 14)
> > > so this probably hasn't actually been tested until now.
> > > 
> > > I haven't got time to look at this right now, hence the report.
> > 
> > Cool, thanks for the report.  I've reproduced this with linux/master, and the
> > test passes with v4.7.
> > 
> > Running a bisect...
> 
> This bisected to a commit to the block layer code.  I've sent a bug report to
> the author of the commit.

And the commit id is ...?

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com