Re: Upcoming merge window

[Jens Axboe <axboe@kernel.dk>]

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

-- 
Jens Axboe