Re: [PATCH V5 0/2] ublk: add io_uring based userspace block driver

[Jens Axboe]

On 7/13/22 8:54 PM, Jens Axboe wrote:
> On 7/13/22 6:19 PM, Ming Lei wrote:
>> On Wed, Jul 13, 2022 at 02:25:25PM -0600, Jens Axboe wrote:
>>> On 7/13/22 8:07 AM, Ming Lei wrote:
>>>> Hello Guys,
>>>>
>>>> ublk driver is one kernel driver for implementing generic userspace block
>>>> device/driver, which delivers io request from ublk block device(/dev/ublkbN) into
>>>> ublk server[1] which is the userspace part of ublk for communicating
>>>> with ublk driver and handling specific io logic by its target module.
>>>
>>> Ming, is this ready to get merged in an experimental state?
>>
>> Hi Jens,
>>
>> Yeah, I think so.
>>
>> IO path can survive in xfstests(-g auto), and control path works
>> well in ublksrv builtin hotplug & 'kill -9' daemon test.
>>
>> The UAPI data size should be good, but definition may change per
>> future requirement change, so I think it is ready to go as
>> experimental.
> 
> OK let's give it a go then. I tried it out and it seems to work for me,
> even if the shutdown-while-busy is something I'd to look into a bit
> more.
> 
> BTW, did notice a typo on the github page:
> 
> 2) dependency
> - liburing with IORING_SETUP_SQE128 support
> 
> - linux kernel 5.9(IORING_SETUP_SQE128 support)
> 
> that should be 5.19, typo.

I tried this:

axboe@m1pro-kvm ~/g/ubdsrv (master)> sudo ./ublk add -t loop /dev/nvme0n1
axboe@m1pro-kvm ~/g/ubdsrv (master) [255]> 

and got this dump:

[   34.041647] WARNING: CPU: 3 PID: 60 at block/blk-mq.c:3880 blk_mq_release+0xa4/0xf0
[   34.043858] Modules linked in:
[   34.044911] CPU: 3 PID: 60 Comm: kworker/3:1 Not tainted 5.19.0-rc6-00320-g5c37a506da31 #1608
[   34.047689] Hardware name: linux,dummy-virt (DT)
[   34.049207] Workqueue: events blkg_free_workfn
[   34.050731] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   34.053026] pc : blk_mq_release+0xa4/0xf0
[   34.054360] lr : blk_mq_release+0x44/0xf0
[   34.055694] sp : ffff80000b16bcb0
[   34.056804] x29: ffff80000b16bcb0 x28: 0000000000000000 x27: 0000000000000000
[   34.059135] x26: 0000000000000000 x25: ffff00001fe9bb05 x24: 0000000000000000
[   34.061454] x23: ffff000005062eb8 x22: ffff000004608998 x21: 0000000000000000
[   34.063775] x20: ffff000004608a50 x19: ffff000004608950 x18: ffff80000b7b3c88
[   34.066085] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[   34.068410] x14: 0000000000000002 x13: 0000000000013638 x12: 0000000000000000
[   34.070715] x11: ffff80000945b7e8 x10: 0000000000006f2e x9 : 00000000ffffffff
[   34.073037] x8 : ffff800008fb5000 x7 : ffff80000860cf28 x6 : 0000000000000000
[   34.075334] x5 : 0000000000000000 x4 : 0000000000000028 x3 : ffff80000b16bc14
[   34.077650] x2 : ffff0000086d66a8 x1 : ffff0000086d66a8 x0 : ffff0000086d6400
[   34.079966] Call trace:
[   34.080789]  blk_mq_release+0xa4/0xf0
[   34.081811]  blk_release_queue+0x58/0xa0
[   34.082758]  kobject_put+0x84/0xe0
[   34.083590]  blk_put_queue+0x10/0x18
[   34.084468]  blkg_free_workfn+0x58/0x84
[   34.085511]  process_one_work+0x2ac/0x438
[   34.086449]  worker_thread+0x1cc/0x264
[   34.087322]  kthread+0xd0/0xe0
[   34.088053]  ret_from_fork+0x10/0x20


-- 
Jens Axboe