When I try to probe_write_common into a writable location (e.g a memory address on a usermode stack) which is not yet mapped or mapped as read only to the memory, the function sometimes return a EFAULT (bad address) error. This is happening since the pagefault handler was disabled and thus this memory location won't be mapped when the function tries to write into it, an error will be returned and no data will be written. Is that behavior intended? Did you want those functions to have as less side-effects are possible?