Hang when running LLVM+clang test suite

[David Zarzycki]

> On Jan 22, 2018, at 13:37, Keith Busch <keith.busch at intel.com> wrote:
> 
> On Sun, Jan 21, 2018 at 09:13:27AM -0500, David Zarzycki wrote:
>> To my surprise, I think I’ve narrowed down the bug to the block multi-queue layer. Can you please confirm that the following test is reasonable?
>> 
>> 1) Create a file in /tmp (tmpfs with plenty of RAM and 2x the size needed by the test suite)
>> 2) ‘losetup’ the file
>> 3) 'cat /sys/block/loop0/queue/scheduler' ("[mq-deadline] none” in this case)
>> 4) Create ext4 partition on /dev/loop0 and mount it
>> 5) Run stress test in the loopback filesystem
> 
> The test looks fair to run. Does your error only happen if using
> mq-deadline, or are there problems when using "none”?

Hi Keith,

Thanks and yes it does. FWIW, I’ve elimited a variable from the setup (nohz_full), and now it locks up hard. I’m going persuing this further on the linux-block at vger.kernel.org mailing list.

Dave