Linux kernel (drivers/pci/hotplug): A surprise device removal freezes the PCI host bridge's partitionable endpoint and

Impact

A surprise device removal freezes the PCI host bridge's partitionable endpoint and the driver never clears the freeze. MSI interrupts from the hotplug logic stop arriving, so every slot behind that PE goes deaf - no further plug or unplug events are processed on any of them, and new devices are not detected until the machine is rebooted. One tenant's device dropping off silently disables device management for the whole PE.

Who can reach it

Device-driven and needs no credentials: a card that drops off the link, an unplanned removal, or a device error that causes the upstream bridge to freeze the PE is enough. Applies only to PowerNV - OpenPOWER POWER9/POWER10 hosts running the pnv_php hotplug driver; it is inert on x86 and ARM GPU nodes. Worth tracking only if IBM POWER machines are part of the fleet.

What to do

Update to a kernel carrying the fix (no fixed_in published; stable commits below). Interim on PowerNV: monitor for PE freezes and treat a frozen PE as a drain-and-reboot condition rather than expecting hotplug to recover on its own.

References