should clean up !mmu

arch/um/kernel/process.c

@@ -142,9 +142,10 @@ static void fork_handler(void)
 	 *
 	 * This fork can only come from libc's vfork, which
 	 * does this:
-	 *	popq %%rdx;
-	 *	call *%rax; // zpoline => __kernel_vsyscall
-	 *	pushq %%rdx;
+	 *	pop %%rdx;
+	 *	mov $58,%eax
+	 *	syscall   ; // hook => __kernel_vsyscall
+	 *	push %%rdx;
 	 * %rcx stores the return address which is stored
 	 * at pt_regs[HOST_IP] at the moment.  As child returns
 	 * via userspace() with a jmp instruction (while parent