* Re: [Intel-wired-lan] ixgbe: NULL-pointer panic in ixgbe_check_mdd_event() when SR-IOV disabled (num_vfs=0)
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@ 2026-08-06 9:14 ` Przemek Kitszel
0 siblings, 0 replies; only message in thread
From: Przemek Kitszel @ 2026-08-06 9:14 UTC (permalink / raw)
To: Viacheslav Tyryshkin, intel-wired-lan, netdev
Cc: Jedrzej Jagielski, Piotr Kwapulinski
On 8/3/26 16:47, Viacheslav Tyryshkin wrote:
> Hello
> I'm hitting the bug daily with Intel X550.
> please be informed, i may provide kernel dumps on request.
>
> ## One-line
> On an Intel X550 with **no VFs configured** (`sriov_numvfs=0`), a
> spurious MDD interrupt reaches `ixgbe_check_mdd_event()`, which writes
> into `adapter->vfinfo[]` without guarding for `num_vfs==0` — and
> `vfinfo` is NULL when SR-IOV is off → kernel panic in interrupt context.
> Reproduces roughly once a day under normal operation.
by looking at the code this is weird
ixgbe_handle_mdd_x550() reads two registers into wqbr, and the combined
read must be not-zero to trigger what you are observing
A patch will be much welcomed, given all the work you did with hunting
it down.
(avoid html, target at current iwl-net tree)
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