Re: system hang on start-up (mlx5?)

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, May 31 2023 at 18:52, Chuck Lever III wrote:
>> On May 31, 2023, at 1:11 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> This addresses the problem for me with both is_managed = 1
> and is_managed = false:
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> index db5687d9fec9..bcf5df316c8f 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
> @@ -570,11 +570,11 @@ int mlx5_irqs_request_vectors(struct mlx5_core_dev *dev, u16 *cpus, int nirqs,
>         af_desc.is_managed = false;
>         for (i = 0; i < nirqs; i++) {
> +               cpumask_clear(&af_desc.mask);
>                 cpumask_set_cpu(cpus[i], &af_desc.mask);
>                 irq = mlx5_irq_request(dev, i + 1, &af_desc, rmap);
>                 if (IS_ERR(irq))
>                         break;
> -               cpumask_clear(&af_desc.mask);
>                 irqs[i] = irq;
>         }
>
> If you agree this looks reasonable, I can package it with a
> proper patch description and send it to Eli and Saeed.

It does. I clearly missed that function when going through the possible
callchains. Yes, that's definitely broken and the fix is correct.

bbac70c74183 ("net/mlx5: Use newer affinity descriptor") is the culprit.

Feel free to add:

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>