Re: [PATCH net v2] net/mlx5e: Use sender devcom for MPV master-up

[Tariq Toukan <tariqt@nvidia.com>]

On 08/07/2026 2:39, Manjunath Patil wrote:
> After PCIe DPC recovery, mlx5 reloads the affected functions and
> replays multiport affiliation events. In the reported failure, the
> first relevant device error was:
> 
>    pcieport 0000:10:01.1: DPC: containment event
>    pcieport 0000:10:01.1: PCIe Bus Error: severity=Uncorrected (Fatal)
>    pcieport 0000:10:01.1:    [ 5] SDES                   (First)
> 
> mlx5 recovered the PCI functions and resumed 0000:11:00.1. During
> that resume, RDMA multiport binding replayed
> MLX5_DRIVER_EVENT_AFFILIATION_DONE and mlx5e sent
> MPV_DEVCOM_MASTER_UP. The host then panicked with:
> 
>    BUG: kernel NULL pointer dereference, address: 0000000000000010
>    RIP: mlx5_devcom_comp_set_ready+0x5/0x40 [mlx5_core]
>    RDI: 0000000000000000
> 
> Call trace included:
> 
>    mlx5_devcom_comp_set_ready
>    mlx5e_devcom_event_mpv
>    mlx5_devcom_send_event
>    mlx5_ib_bind_slave_port
>    mlx5r_mp_probe
>    mlx5_pci_resume
> 
> MPV devcom registration publishes mlx5e private data to the component
> peer list before mlx5e_devcom_init_mpv() stores the returned component
> device in priv->devcom. A concurrent master-up event can therefore
> reach a peer whose private data is visible but whose priv->devcom
> backpointer is still NULL.
> 
> MPV_DEVCOM_MASTER_UP already carries the sender/master mlx5e private
> data as event_data. The ready bit is stored on the shared devcom
> component, not on an individual peer. Use the sender devcom when
> marking the MPV component ready.
> 
> This preserves the readiness transition while avoiding a NULL
> dereference of the peer devcom pointer during affiliation replay after
> PCI error recovery.
> 
> Fixes: bf11485f8419 ("net/mlx5: Register mlx5e priv to devcom in MPV mode")
> Assisted-by: Codex:gpt-5
> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
> Cc: stable@vger.kernel.org # 6.7+
> ---
> v2:
> - Drop defensive master_priv/master_priv->devcom check as suggested by Tariq.
> - Resend as an independent thread per netdev posting rules.
> 
>   drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index 8f2b3abe0092..9b27afeb9b12 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -211,11 +211,11 @@ static void mlx5e_disable_async_events(struct mlx5e_priv *priv)
>   
>   static int mlx5e_devcom_event_mpv(int event, void *my_data, void *event_data)
>   {
> -	struct mlx5e_priv *slave_priv = my_data;
> +	struct mlx5e_priv *master_priv = event_data;
>   
>   	switch (event) {
>   	case MPV_DEVCOM_MASTER_UP:
> -		mlx5_devcom_comp_set_ready(slave_priv->devcom, true);
> +		mlx5_devcom_comp_set_ready(master_priv->devcom, true);
>   		break;
>   	case MPV_DEVCOM_MASTER_DOWN:
>   		/* no need for comp set ready false since we unregister after
> 
> base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8

Reviewed-by: Tariq Toukan <tariqt@nvidia.com>

Thanks for your patch.