> Date: Sat, 03 Feb 2007 00:55:11 -0700
> From: Eric W. Biederman <ebiederm@xmission.com>
> To: Arjan van de Ven <arjan@infradead.org>
> Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org,
> "Lu, Yinghai" <yinghai.lu@amd.com>,
> Luigi Genoni <luigi.genoni@pirelli.com>, Ingo Molnar <mingo@elte.hu>,
> Natalie Protasevich <protasnb@gmail.com>, Andi Kleen <ak@suse.de>
> Subject: Re: [PATCH 2/2] x86_64 irq: Handle irqs pending in IRR during irq
> migration.
> Resent-Date: Sat, 03 Feb 2007 09:05:10 +0100
> Resent-From: <l.genoni@sns.it>
>
> Arjan van de Ven <arjan@infradead.org> writes:
>
>>>> Once the migration operation is complete we know we will receive
>>>> no more interrupts on this vector so the irq pending state for
>>>> this irq will no longer be updated. If the irq is not pending and
>>>> we are in the intermediate state we immediately free the vector,
>>>> otherwise in we free the vector in do_IRQ when the pending irq
>>>> arrives.
>>>
>>> So is this a for-2.6.20 thing? The bug was present in 2.6.19, so
>>> I assume it doesn't affect many people?
>>
>> I got a few reports of this; irqbalance may trigger this kernel bug it
>> seems... I would suggest to consider this for 2.6.20 since it's a
>> hard-hang case
>
>
> Yes. The bug I fixed will not happen if you don't migrate irqs.
>
> At the very least we want the patch below (already in -mm)
> that makes it not a hard hang case.
>
> Subject: [PATCH] x86_64: Survive having no irq mapping for a vector
>
> Occasionally the kernel has bugs that result in no irq being
> found for a given cpu vector. If we acknowledge the irq
> the system has a good chance of continuing even though we dropped
> an missed an irq message. If we continue to simply print a
> message and drop and not acknowledge the irq the system is
> likely to become non-responsive shortly there after.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
> ---
> arch/x86_64/kernel/irq.c | 11 ++++++++---
> 1 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
> index 0c06af6..648055a 100644
> --- a/arch/x86_64/kernel/irq.c
> +++ b/arch/x86_64/kernel/irq.c
> @@ -120,9 +120,14 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
>
> if (likely(irq < NR_IRQS))
> generic_handle_irq(irq);
> - else if (printk_ratelimit())
> - printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
> - __func__, smp_processor_id(), vector);
> + else {
> + if (!disable_apic)
> + ack_APIC_irq();
> +
> + if (printk_ratelimit())
> + printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
> + __func__, smp_processor_id(), vector);
> + }
>
> irq_exit();
>
> --
> 1.4.4.1.g278f
>
> -
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