The show all regs sysrq uses the nmi function to do it. But this
function expects preemption to be off, or funny things happen.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Index: linux-2.6.21-rt9/drivers/char/sysrq.c
===================================================================

--- linux-2.6.21-rt9.orig/drivers/char/sysrq.c
+++ linux-2.6.21-rt9/drivers/char/sysrq.c

@@ -213,7 +213,9 @@ static struct sysrq_key_op sysrq_showreg
 
 static void sysrq_handle_showallregs(int key, struct tty_struct *tty)
 {
+        preempt_disable();
 	nmi_show_all_regs();
+        preempt_enable();
 }
 
 static struct sysrq_key_op sysrq_showallregs_op = {