Re: [REGRESSION] Commit 447cbe95ebb9 causes IOMMU DMA faults on macvlan/vlan with bnxt_en

[Stefan Fleischmann <sfle@kth.se>]

On Sun, 4 Oct 2026 13:46:08 +0200
Eric Dumazet <edumazet@kernel.org> wrote:


> 
> Notice that 0xfc499000 is on an exact 4KB page boundary. This points
> to a DMA read overrun where the Broadcom DMA engine reads past the
> end of a buffer mapped in page 0xfc498xxx into the adjacent unmapped
> page 0xfc499000.
> 
> Have you tried a recent net kernel ?

Hi Eric,

that might be a bit tricky. We use ZFS on this server and the version
we have installed only supports up to kernel 7.2.

> Could you please test whether disabling TSO or hardware VLAN offload 
> prevents the crash? (maybe adding one option at a time)
> 
>    # ethtool -K eno1np0 tso off
> 
>    # ethtool -K eno1np0 tx-vlan-offload off

I tested this now and none of these options made a difference. I've also
tested disabling other offloads, no difference.

Best,
Stefan

> Adding Joe to this thread, because some parts in
> tso_dma_map_init() or tso_start() might have bugs.
> 
> # Disable USO on the physical interface
> ethtool -K eno1np0 tx-udp-segmentation off
> 
> This reminds me on a prior attempt I made months ago to sanitize
> tso_start()
> 
> Note that my email address has changed to edumazet@kernel.org
> 
> Thanks.
>