Re: Upcoming merge window

[Jens Axboe <axboe@kernel.dk>]

On 12/17/18 5:16 PM, Jens Axboe wrote:
> On 12/17/18 4:49 PM, Jens Axboe wrote:
>> On 12/17/18 4:27 PM, Jens Axboe wrote:
>>> On 12/17/18 4:16 PM, Bart Van Assche wrote:
>>>> On Mon, 2018-12-17 at 11:28 -0700, Jens Axboe wrote:
>>>>> As I'm sure you're all aware, the merge window is coming up. This time
>>>>> it happens to coincide with that is a holiday for most. My plan is to
>>>>> send in an EARLY pull request to Linus, Thursday at the latest. If you're
>>>>> sitting on anything that should go in with the initial merge, then I need
>>>>> to have it ASAP.
>>>>>
>>>>> I'll do a later pull about a week in with things that were missed, but
>>>>> I'm really hoping to make that fixes only. Any driver updates etc should
>>>>> go in now.
>>>>
>>>> Hi Jens,
>>>>
>>>> If I run blktests/srp/002 against Linus' master branch then that test passes,
>>>> no matter how many times I run that test. If I run that test against your
>>>> for-next branch however (commit 6a252f2772c0) then that test hangs. The output
>>>> of my list-pending-block-requests script is as follows when the hang occurs:
>>>
>>> Ugh, I'll try and run that here again, that test is unfortunately such a pain
>>> to run and requires me to manually install multipath libs (and remember to
>>> uninstall before rebooting, or udev fails?).
>>>
>>> I'll take a look!
>>
>> Looks like what Ming was talking about. CC'ing Ming and Mike. Lots of
>> kworkers are stuck like this:
>>
>> [  252.310187] kworker/2:19    D14072  8147      2 0x80000000
>> [  252.316803] Workqueue: dio/dm-2 dio_aio_complete_work
>> [  252.322925] Call Trace:
>> [  252.326137]  ? __schedule+0x231/0x5f0
>> [  252.330703]  schedule+0x2a/0x80
>> [  252.334689]  rwsem_down_write_failed+0x204/0x320
>> [  252.340330]  ? generic_make_request_checks+0x55/0x370
>> [  252.346542]  ? call_rwsem_down_write_failed+0x13/0x20
>> [  252.352669]  call_rwsem_down_write_failed+0x13/0x20
>> [  252.358601]  down_write+0x1b/0x30
>> [  252.362781]  __generic_file_fsync+0x3e/0xb0
>> [  252.367933]  ext4_sync_file+0xcc/0x2e0
>> [  252.372599]  dio_complete+0x1c4/0x210
>> [  252.377168]  process_one_work+0x1cb/0x350
>> [  252.382915]  worker_thread+0x28/0x3c0
>> [  252.387482]  ? process_one_work+0x350/0x350
>> [  252.392632]  kthread+0x107/0x120
>> [  252.396717]  ? kthread_park+0x80/0x80
>> [  252.401285]  ret_from_fork+0x1f/0x30
>>
>> Where did this regression come from? This was passing just fine
>> recently.
> 
> Looks like this is the offending commit:
> 
> commit c4576aed8d85d808cd6443bda58393d525207d01
> Author: Mike Snitzer <snitzer@redhat.com>
> Date:   Tue Dec 11 09:10:26 2018 -0500
> 
>     dm: fix request-based dm's use of dm_wait_for_completion

Yep confirmed, reverted that on top and it passes. dm-2 has plenty of
requests that are allocated and pending dispatch, so the md_in_flight()
will return true. Mike, should it be checking for allocated requests or
in-flight?

-- 
Jens Axboe