Re: 2.6.17-rc5-mm1

[Ingo Molnar <mingo@elte.hu>]

* Andrew Morton <akpm@osdl.org> wrote:

> > [   36.489028] Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: 
> > [   36.500245]  [<0000000000000000>] stext+0x7feff0e8/0xe8

> > [   37.103370] Call Trace:
> > [   37.140640]  <IRQ> [<ffffffff8010b711>] do_IRQ+0x4f/0x5e
> > [   37.167285]  [<ffffffff80107d21>] mwait_idle+0x0/0x53
> > [   37.193322]  [<ffffffff80109708>] ret_from_intr+0x0/0xa
> > [   37.219723]  <EOI>

Randy, do you have an MSI-X device perhaps? Could you try the patch 
below?

	Ingo

------------------------------------------------------
Subject: genirq MSI fixes
From: Ingo Molnar <mingo@elte.hu>


This is a fixed up and cleaned up replacement for genirq-msi-fixes.patch,
which should solve the i386 4KSTACKS problem.  I also added Ben's idea of
pushing the __do_IRQ() check into generic_handle_irq().

I booted this with MSI enabled, but i only have MSI devices, not MSI-X
devices.  I'd still expect MSI-X to work now.

irqchip migration helper: call __do_IRQ() if a descriptor is attached to an
irqtype-style controller.  This also fixes MSI-X IRQ handling on i386 and
x86_64.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/i386/kernel/irq.c |    5 +++++
 include/linux/irq.h    |   27 ++++++++++++++++-----------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff -puN arch/i386/kernel/irq.c~genirq-msi-fixes-2 arch/i386/kernel/irq.c
--- devel/arch/i386/kernel/irq.c~genirq-msi-fixes-2	2006-05-30 23:47:30.000000000 -0700
+++ devel-akpm/arch/i386/kernel/irq.c	2006-05-30 23:47:30.000000000 -0700
@@ -77,6 +77,10 @@ fastcall unsigned int do_IRQ(struct pt_r
 	}
 #endif
 
+	if (!irq_desc[irq].handle_irq) {
+		__do_IRQ(irq, regs);
+		goto out_exit;
+	}
 #ifdef CONFIG_4KSTACKS
 
 	curctx = (union irq_ctx *) current_thread_info();
@@ -109,6 +113,7 @@ fastcall unsigned int do_IRQ(struct pt_r
 #endif
 		desc->handle_irq(irq, desc, regs);
 
+out_exit:
 	irq_exit();
 
 	return 1;
diff -puN include/linux/irq.h~genirq-msi-fixes-2 include/linux/irq.h
--- devel/include/linux/irq.h~genirq-msi-fixes-2	2006-05-30 23:47:30.000000000 -0700
+++ devel-akpm/include/linux/irq.h	2006-05-30 23:47:30.000000000 -0700
@@ -176,17 +176,6 @@ typedef struct irq_desc		irq_desc_t;
  */
 #include <asm/hw_irq.h>
 
-/*
- * Architectures call this to let the generic IRQ layer
- * handle an interrupt:
- */
-static inline void generic_handle_irq(unsigned int irq, struct pt_regs *regs)
-{
-	struct irq_desc *desc = irq_desc + irq;
-
-	desc->handle_irq(irq, desc, regs);
-}
-
 extern int setup_irq(unsigned int irq, struct irqaction *new);
 
 #ifdef CONFIG_GENERIC_HARDIRQS
@@ -324,6 +313,22 @@ handle_irq_name(void fastcall (*handle)(
  */
 extern fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs);
 
+/*
+ * Architectures call this to let the generic IRQ layer
+ * handle an interrupt. If the descriptor is attached to an
+ * irqchip-style controller then we call the ->handle_irq() handler,
+ * and it calls __do_IRQ() if it's attached to an irqtype-style controller.
+ */
+static inline void generic_handle_irq(unsigned int irq, struct pt_regs *regs)
+{
+	struct irq_desc *desc = irq_desc + irq;
+
+	if (likely(desc->handle_irq))
+		desc->handle_irq(irq, desc, regs);
+	else
+		__do_IRQ(irq, regs);
+}
+
 /* Handling of unhandled and spurious interrupts: */
 extern void note_interrupt(unsigned int irq, struct irq_desc *desc,
 			   int action_ret, struct pt_regs *regs);
_