Regression in RCU subsystem in latest mainline kernel

[Benjamin Herrenschmidt]

On Fri, 2013-06-14 at 17:06 -0400, Steven Rostedt wrote:
> I was pretty much able to reproduce this on my PA Semi PPC box. Funny
> thing is, when I type on the console, it makes progress. Anyway, it
> seems that powerpc has an issue with irq_work(). I'll try to get some
> time either tonight or next week to figure it out.

Does this help ?

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 5cbcf4d..ea185e0 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -162,7 +162,7 @@ notrace unsigned int __check_irq_replay(void)
 	 * in case we also had a rollover while hard disabled
 	 */
 	local_paca->irq_happened &= ~PACA_IRQ_DEC;
-	if (decrementer_check_overflow())
+	if ((happened & PACA_IRQ_DEC) || decrementer_check_overflow())
 		return 0x900;
 
 	/* Finally check if an external interrupt happened */

Cheers,
Ben.