s390/mm: Dump fault info in case of low address protection fault

In case of an unexpected low address protection fault in user mode dump
fault info to make debugging a bit easier. At least the teid is valid,
while dumping the page table is racy, since no lock is held.
But it might still give some hints.

Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/mm/fault.c

@@ -376,6 +376,7 @@ void do_protection_exception(struct pt_regs *regs)
 	if (unlikely(!teid.b61)) {
 		if (user_mode(regs)) {
 			/* Low-address protection in user mode: cannot happen */
+			dump_fault_info(regs);
 			die(regs, "Low-address protection");
 		}
 		/*