Commit 3d3539018d2c ("mm: create the new vm_fault_t type") in mainline
5.1-rc1 changed the definition of vm_fault_t type to unsigned to catch
vm_operations_struct::fault handlers which still have int as return value.
LinuxDriverFault() in vmmon module is one of those.
As handler return type was changed by commit 1c8f422059ae ("mm: change
return type to vm_fault_t") in 4.17-rc1, make LinuxDriverFault() always
return vm_fault_t and define vm_fault_t as int when building against
a pre-4.17 kernel.
Michal Kubecek
4fdf7a77bb