arch/tile: don't enable irqs unconditionally in page fault handler

If we took a page fault while we had interrupts disabled, we
shouldn't enable them in the page fault handler.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/mm/fault.c

@@ -342,9 +342,12 @@ static int handle_page_fault(struct pt_regs *regs,
 	/*
 	 * If we're trying to touch user-space addresses, we must
 	 * be either at PL0, or else with interrupts enabled in the
-	 * kernel, so either way we can re-enable interrupts here.
+	 * kernel, so either way we can re-enable interrupts here
+	 * unless we are doing atomic access to user space with
+	 * interrupts disabled.
 	 */
-	local_irq_enable();
+	if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
+		local_irq_enable();
 
 	mm = tsk->mm;