Re: Blocked tasks on 3.15.1

[Chris Mason <clm@fb.com>]

On 06/30/2014 02:11 PM, Chris Mason wrote:
> On 06/29/2014 04:02 PM, Cody P Schafer wrote:
>> On Fri, Jun 27, 2014 at 7:22 PM, Chris Samuel <chris@csamuel.org> wrote:
>>> On Fri, 27 Jun 2014 05:20:41 PM Duncan wrote:
>>>
>>>> If I'm not mistaken the fix for the 3.16 series bug was:
>>>>
>>>> ea4ebde02e08558b020c4b61bb9a4c0fcf63028e
>>>>
>>>> Btrfs: fix deadlocks with trylock on tree nodes.
>>>
>>> That patch applies cleanly to 3.15.2 so if it is indeed the fix it should
>>> probably go to -stable for the next 3.15 release..
>>>
>>> Unfortunately my test system died a while ago (hardware problem) and I've not
>>> been able to resurrect it yet.
>>
>> I'm also seeing stuck tasks on btrfs (3.14.4, 3.15.1, 3.15.2).
>> I've also tried 3.15.2 with ea4ebde02e08558b020c4b61bb9a4c applied on
>> top with similar results.
>> I've been triggering the hang with 'rsync -hPaHAXx --del /mnt/home/a/
>> /home/a/' where /mnt/home and /home are 2 separate btrfs filesystems
>> on 2 separate disks.
>>
>> dmesg with w-trigger: http://bpaste.net/show/419555
>> --
> 
> These traces show us waiting for IO, but it doesn't show anyone doing
> the IO.  Either we're failing to kick off our work queues or they are
> stuck on something else.
> 
> Could you please send a sysrq-t and sysrq-l while you're stuck?  That
> will show us all the procs and all the CPUs.

Also, do you have any nodatacow files in here?  Please say yes.

-chris