Linux kernel (drivers/pci/hotplug): Unplugging the root of a nested PCIe bridge hierarchy leaks the IRQ resources the

Impact

Unplugging the root of a nested PCIe bridge hierarchy leaks the IRQ resources the child bridges were using for hotplug notification, and the stale MSI state then trips a warning and a panic in the device teardown path. The node goes down on a device removal, taking every tenant on it.

Who can reach it

Reached by removing a bridge that has child bridges below it - either an administrative slot power-off through sysfs or a physical removal, so both an operator action and a device-driven event qualify. PowerNV only (the pnv_php driver on OpenPOWER POWER9/POWER10); inert on x86 and ARM GPU nodes. No tenant privilege involved on the affected platforms.

What to do

Update to a kernel carrying the fix (no fixed_in published; stable commits below). Interim on PowerNV: drain the node before removing any bridge that has child bridges behind it.

References