diff -rauN linux-2.6.14.orig/arch/ppc/kernel/signal.c linux-2.6.14/arch/ppc/kernel/signal.c
--- linux-2.6.14.orig/arch/ppc/kernel/signal.c	2005-10-28 04:02:08.000000000 +0400
+++ linux-2.6.14/arch/ppc/kernel/signal.c	2005-11-30 17:24:15.268137752 +0300
@@ -705,6 +705,14 @@
 	unsigned long frame, newsp;
 	int signr, ret;
 
+#ifdef CONFIG_PREEMPT_RT
+	/*
+	 * Fully-preemptible kernel does not need interrupts disabled:
+	 */
+	local_irq_enable();
+	preempt_check_resched();
+#endif
+
 	if (try_to_freeze()) {
 		signr = 0;
 		if (!signal_pending(current))