Regression: Connect-X5 doesn't connect with NVME-of

Regression: Connect-X5 doesn't connect with NVME-of

[Logan Gunthorpe]

Hello,

We've experienced a regression with using nvme-of and two Connect-X5s. 
With v4.15 and v4.14.16 we see the following dmesgs when trying to 
connect to the target:

> [   43.732539] nvme nvme2: creating 16 I/O queues.
> [   44.072427] nvmet: adding queue 1 to ctrl 1.
> [   44.072553] nvmet: adding queue 2 to ctrl 1.
> [   44.072597] nvme nvme2: Connect command failed, error wo/DNR bit: -16402
> [   44.072609] nvme nvme2: failed to connect queue: 3 ret=-18
> [   44.075421] nvmet_rdma: freeing queue 2
> [   44.075792] nvmet_rdma: freeing queue 1
> [   44.264293] nvmet_rdma: freeing queue 3
> *snip*

(on v4.15 there is additional error panics likely do to some other 
nvme-of error handling bugs)

And nvme connect returns:

> Failed to write to /dev/nvme-fabrics: Invalid cross-device link

The two adapters are the same with the latest available firmware:

> 	transport:			InfiniBand (0)
> 	fw_ver:				16.21.2010
> 	vendor_id:			0x02c9
> 	vendor_part_id:			4119
> 	hw_ver:				0x0
> 	board_id:			MT_0000000010

We bisected to find the commit that broke our setup is:

05e0cc84e00c net/mlx5: Fix get vector affinity helper function

Thanks,

Logan
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Saeed Mahameed]

On 02/01/2018 09:56 AM, Logan Gunthorpe wrote:
> Hello,
> 
> We've experienced a regression with using nvme-of and two Connect-X5s. With v4.15 and v4.14.16 we see the following dmesgs when trying to connect to the target:
> 
>> [   43.732539] nvme nvme2: creating 16 I/O queues.
>> [   44.072427] nvmet: adding queue 1 to ctrl 1.
>> [   44.072553] nvmet: adding queue 2 to ctrl 1.
>> [   44.072597] nvme nvme2: Connect command failed, error wo/DNR bit: -16402
>> [   44.072609] nvme nvme2: failed to connect queue: 3 ret=-18
>> [   44.075421] nvmet_rdma: freeing queue 2
>> [   44.075792] nvmet_rdma: freeing queue 1
>> [   44.264293] nvmet_rdma: freeing queue 3
>> *snip*
> 
> (on v4.15 there is additional error panics likely do to some other nvme-of error handling bugs)
> 
> And nvme connect returns:
> 
>> Failed to write to /dev/nvme-fabrics: Invalid cross-device link
> 
> The two adapters are the same with the latest available firmware:
> 
>>     transport:            InfiniBand (0)
>>     fw_ver:                16.21.2010
>>     vendor_id:            0x02c9
>>     vendor_part_id:            4119
>>     hw_ver:                0x0
>>     board_id:            MT_0000000010
> 
> We bisected to find the commit that broke our setup is:
> 
> 05e0cc84e00c net/mlx5: Fix get vector affinity helper function

I doubt that the issue is within this fix itself, but with this fix the Automatic affinity settings
for nvme over rdma is enabled, Maybe a bug was hiding there and we just stepped on it.

Added Sagi, maybe he can help us spot the issue here.

Thanks,
saeed.
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Max Gurtovoy]

Hi Logan,

On 2/3/2018 6:53 AM, Saeed Mahameed wrote:
> 
> 
> On 02/01/2018 09:56 AM, Logan Gunthorpe wrote:
>> Hello,
>>
>> We've experienced a regression with using nvme-of and two Connect-X5s. With v4.15 and v4.14.16 we see the following dmesgs when trying to connect to the target:

I would like to repro it in our labs so please describe the environment 
and the topology you run (B2B/switch/loopback ?)

>>
>>> [   43.732539] nvme nvme2: creating 16 I/O queues.
>>> [   44.072427] nvmet: adding queue 1 to ctrl 1.
>>> [   44.072553] nvmet: adding queue 2 to ctrl 1.
>>> [   44.072597] nvme nvme2: Connect command failed, error wo/DNR bit: -16402
>>> [   44.072609] nvme nvme2: failed to connect queue: 3 ret=-18
>>> [   44.075421] nvmet_rdma: freeing queue 2
>>> [   44.075792] nvmet_rdma: freeing queue 1
>>> [   44.264293] nvmet_rdma: freeing queue 3
>>> *snip*
>>
>> (on v4.15 there is additional error panics likely do to some other nvme-of error handling bugs)

I fixed the panic during connect error flow by fixing the state machine 
in the NVME core.
It should be pushed to 4.16-rc and I hope to 4.15.x soon.

>>
>> And nvme connect returns:
>>
>>> Failed to write to /dev/nvme-fabrics: Invalid cross-device link
>>
>> The two adapters are the same with the latest available firmware:
>>
>>>      transport:            InfiniBand (0)
>>>      fw_ver:                16.21.2010
>>>      vendor_id:            0x02c9
>>>      vendor_part_id:            4119
>>>      hw_ver:                0x0
>>>      board_id:            MT_0000000010
>>
>> We bisected to find the commit that broke our setup is:
>>
>> 05e0cc84e00c net/mlx5: Fix get vector affinity helper function
> 
> I doubt that the issue is within this fix itself, but with this fix the Automatic affinity settings
> for nvme over rdma is enabled, Maybe a bug was hiding there and we just stepped on it.
> 
> Added Sagi, maybe he can help us spot the issue here.
> 
> Thanks,
> saeed.
> 
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Sagi Grimberg]

>> Hello,

Hi Logan, thanks for reporting.

>> We've experienced a regression with using nvme-of and two Connect-X5s. With v4.15 and v4.14.16 we see the following dmesgs when trying to connect to the target:
>>
>>> [   43.732539] nvme nvme2: creating 16 I/O queues.
>>> [   44.072427] nvmet: adding queue 1 to ctrl 1.
>>> [   44.072553] nvmet: adding queue 2 to ctrl 1.
>>> [   44.072597] nvme nvme2: Connect command failed, error wo/DNR bit: -16402
>>> [   44.072609] nvme nvme2: failed to connect queue: 3 ret=-18
>>> [   44.075421] nvmet_rdma: freeing queue 2
>>> [   44.075792] nvmet_rdma: freeing queue 1
>>> [   44.264293] nvmet_rdma: freeing queue 3
>>> *snip*
>>
>> (on v4.15 there is additional error panics likely do to some other nvme-of error handling bugs)
>>
>> And nvme connect returns:
>>
>>> Failed to write to /dev/nvme-fabrics: Invalid cross-device link
>>
>> The two adapters are the same with the latest available firmware:
>>
>>>      transport:            InfiniBand (0)
>>>      fw_ver:                16.21.2010
>>>      vendor_id:            0x02c9
>>>      vendor_part_id:            4119
>>>      hw_ver:                0x0
>>>      board_id:            MT_0000000010
>>
>> We bisected to find the commit that broke our setup is:
>>
>> 05e0cc84e00c net/mlx5: Fix get vector affinity helper function

I'm really bummed out about this... I seem to have missed it
in my review and apparently went in untested.

If we look at the patch, it clearly shows that the behavior changed
as mlx5_get_vector_affinity does not add the offset of
MLX5_EQ_VEC_COMP_BASE as before.

The API assumes that completion vector 0 means the first _completion_
vector which means ignoring the private/internal mlx5 vectors created
for stuff like port async events, fw commands and page requests...

What happens is that the consumer asked for affinity mask of
completion vector 0 and got the async event vector and the skew
continued leading to unmapped block queues.

So I think this should make the problem go away:
--
diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
index a0610427e168..b82c4ae92411 100644
--- a/include/linux/mlx5/driver.h
+++ b/include/linux/mlx5/driver.h
@@ -1238,7 +1238,7 @@ mlx5_get_vector_affinity(struct mlx5_core_dev 
*dev, int vector)
         int eqn;
         int err;

-       err = mlx5_vector2eqn(dev, vector, &eqn, &irq);
+       err = mlx5_vector2eqn(dev, MLX5_EQ_VEC_COMP_BASE + vector, &eqn, 
&irq);
         if (err)
                 return NULL;
--

Can you verify that this fixes your problem?

Regardless, it looks like we also have a second bug in here such that we 
still attempt to connect a queue which is unmapped and fail the
controller association when it fails. This was not an option before
because PCI_IRQ_AFFINITY guaranteed us that we will have the cpu spread
that we need to ignore this case, but thats changed now.

We should either settle with less queues, or fallback to the
default mq_map for the queues that are left unmapped, or we should
at least continue forward without these unmapped queues (I think
the former makes better sense).
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Max Gurtovoy]

Hi Sagi/Logan,

I've repro it with v4.14.1 (not happens on each connect).
Sagi's proposal below fix the issue of the "Failed to write to 
/dev/nvme-fabrics: Invalid cross-device link".

Sagi can you push (with my Tested-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 
and Reviewed-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>) it or I will ?

The crush after the connection failure is fixed in my patches for NVMe 
core state machine fixes that are under review in the list.


> 
> So I think this should make the problem go away:
> -- 
> diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
> index a0610427e168..b82c4ae92411 100644
> --- a/include/linux/mlx5/driver.h
> +++ b/include/linux/mlx5/driver.h
> @@ -1238,7 +1238,7 @@ mlx5_get_vector_affinity(struct mlx5_core_dev 
> *dev, int vector)
>          int eqn;
>          int err;
> 
> -       err = mlx5_vector2eqn(dev, vector, &eqn, &irq);
> +       err = mlx5_vector2eqn(dev, MLX5_EQ_VEC_COMP_BASE + vector, &eqn, 
> &irq);
>          if (err)
>                  return NULL;
> -- 
> 
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Sagi Grimberg]

> Hi Sagi/Logan,
> 
> I've repro it with v4.14.1 (not happens on each connect).
> Sagi's proposal below fix the issue of the "Failed to write to 
> /dev/nvme-fabrics: Invalid cross-device link".
> 
> Sagi can you push (with my Tested-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 
> and Reviewed-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>) it or I will ?

Thanks, I'll send it.
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Laurence Oberman]

On Mon, 2018-02-05 at 16:18 +0200, Sagi Grimberg wrote:
> > Hi Sagi/Logan,
> > 
> > I've repro it with v4.14.1 (not happens on each connect).
> > Sagi's proposal below fix the issue of the "Failed to write to 
> > /dev/nvme-fabrics: Invalid cross-device link".
> > 
> > Sagi can you push (with my Tested-by: Max Gurtovoy <maxg@mellanox.c
> > om> 
> > and Reviewed-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>) it or I will ?
> 
> Thanks, I'll send it.
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This missed me because all my NVME is still using CX3 (mlx4)
I will move the NVME devices into the setup with mlx5 so next time I
will catch this sort of issue with the testing.
Currently the mlx5 is only testing ISER and SRP.

Thanks
Laurence 
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Re: Regression: Connect-X5 doesn't connect with NVME-of

[Max Gurtovoy]

On 2/5/2018 5:44 PM, Laurence Oberman wrote:
> On Mon, 2018-02-05 at 16:18 +0200, Sagi Grimberg wrote:
>>> Hi Sagi/Logan,
>>>
>>> I've repro it with v4.14.1 (not happens on each connect).
>>> Sagi's proposal below fix the issue of the "Failed to write to
>>> /dev/nvme-fabrics: Invalid cross-device link".
>>>
>>> Sagi can you push (with my Tested-by: Max Gurtovoy <maxg@mellanox.c
>>> om>
>>> and Reviewed-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>) it or I will ?
>>
>> Thanks, I'll send it.
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>> in
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> 
> This missed me because all my NVME is still using CX3 (mlx4)
> I will move the NVME devices into the setup with mlx5 so next time I
> will catch this sort of issue with the testing.
> Currently the mlx5 is only testing ISER and SRP.

Thanks Laurence,
This is well appreciated :)

> 
> Thanks
> Laurence
> 

Cheers,
Max
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