Linux kernel (drivers/iommu/intel): The whole node hangs. VT-d keeps re-issuing an ATS device-TLB invalidation to a

Impact

The whole node hangs. VT-d keeps re-issuing an ATS device-TLB invalidation to a device that is already gone, retrying forever inside interrupt context after the invalidation-timeout fault. The NMI watchdog reports a hard lockup and the box stops serving every tenant on it.

Who can reach it

Needs a device behind a hotplug-capable PCIe port to vanish or its link to flap: an operator hot-unplugging a GPU or NIC, a flaky link, or a tenant-initiated device/bus reset on a passthrough function that ends in link-down. Conditional on Intel VT-d with ATS enabled, which is the normal state for passthrough-capable accelerators and SmartNICs. Not reachable from the network fabric; the trigger is a PCIe topology event, not a crafted request.

What to do

The record lists no fixed release; boot a kernel carrying the stable fix commits below. Interim controls: keep ATS-capable endpoints out of hotplug-capable slots, disable PCIe hotplug on slots holding passthrough devices, and do not let tenants initiate bus resets on assigned functions.

References