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Message-ID: <CAFgQCTsbW3sBGgUj+8LJagpf_AMNPrB+PDvcZ+pLgeoFtNWv=w@mail.gmail.com>
Date: Fri, 6 Nov 2020 13:53:59 +0800
From: Pingfan Liu <kernelfans@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Guilherme Piccoli <gpiccoli@...onical.com>,
LKML <linux-kernel@...r.kernel.org>,
Peter Zijlstra <peterz@...radead.org>,
Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Petr Mladek <pmladek@...e.com>, Marc Zyngier <maz@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
afzal mohammed <afzal.mohd.ma@...il.com>,
Lina Iyer <ilina@...eaurora.org>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
Maulik Shah <mkshah@...eaurora.org>,
Al Viro <viro@...iv.linux.org.uk>,
Jonathan Corbet <corbet@....net>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Oliver Neukum <oneukum@...e.com>, linux-doc@...r.kernel.org,
Kexec Mailing List <kexec@...ts.infradead.org>,
Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH 0/3] warn and suppress irqflood
On Wed, Oct 28, 2020 at 7:58 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
[...]
> ---
> include/linux/irqdesc.h | 4 ++
> kernel/irq/manage.c | 3 +
> kernel/irq/spurious.c | 74 +++++++++++++++++++++++++++++++++++-------------
> 3 files changed, 61 insertions(+), 20 deletions(-)
>
> --- a/include/linux/irqdesc.h
> +++ b/include/linux/irqdesc.h
> @@ -30,6 +30,8 @@ struct pt_regs;
> * @tot_count: stats field for non-percpu irqs
> * @irq_count: stats field to detect stalled irqs
> * @last_unhandled: aging timer for unhandled count
> + * @storm_count: Counter for irq storm detection
> + * @storm_checked: Timestamp for irq storm detection
> * @irqs_unhandled: stats field for spurious unhandled interrupts
> * @threads_handled: stats field for deferred spurious detection of threaded handlers
> * @threads_handled_last: comparator field for deferred spurious detection of theraded handlers
> @@ -65,6 +67,8 @@ struct irq_desc {
> unsigned int tot_count;
> unsigned int irq_count; /* For detecting broken IRQs */
> unsigned long last_unhandled; /* Aging timer for unhandled count */
> + unsigned long storm_count;
> + unsigned long storm_checked;
> unsigned int irqs_unhandled;
> atomic_t threads_handled;
> int threads_handled_last;
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -1581,6 +1581,9 @@ static int
> if (!shared) {
> init_waitqueue_head(&desc->wait_for_threads);
>
> + /* Take a timestamp for interrupt storm detection */
> + desc->storm_checked = jiffies;
> +
> /* Setup the type (level, edge polarity) if configured: */
> if (new->flags & IRQF_TRIGGER_MASK) {
> ret = __irq_set_trigger(desc,
> --- a/kernel/irq/spurious.c
> +++ b/kernel/irq/spurious.c
> @@ -21,6 +21,7 @@ static void poll_spurious_irqs(struct ti
> static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
> static int irq_poll_cpu;
> static atomic_t irq_poll_active;
> +static unsigned long irqstorm_limit __ro_after_init;
>
> /*
> * We wait here for a poller to finish.
> @@ -189,18 +190,21 @@ static inline int bad_action_ret(irqretu
> * (The other 100-of-100,000 interrupts may have been a correctly
> * functioning device sharing an IRQ with the failing one)
> */
> -static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
> +static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret,
> + bool storm)
> {
> unsigned int irq = irq_desc_get_irq(desc);
> struct irqaction *action;
> unsigned long flags;
>
> - if (bad_action_ret(action_ret)) {
> - printk(KERN_ERR "irq event %d: bogus return value %x\n",
> - irq, action_ret);
> - } else {
> - printk(KERN_ERR "irq %d: nobody cared (try booting with "
> + if (!storm) {
> + if (bad_action_ret(action_ret)) {
> + pr_err("irq event %d: bogus return value %x\n",
> + irq, action_ret);
> + } else {
> + pr_err("irq %d: nobody cared (try booting with "
> "the \"irqpoll\" option)\n", irq);
> + }
> }
> dump_stack();
> printk(KERN_ERR "handlers:\n");
> @@ -228,7 +232,7 @@ static void report_bad_irq(struct irq_de
>
> if (count > 0) {
> count--;
> - __report_bad_irq(desc, action_ret);
> + __report_bad_irq(desc, action_ret, false);
> }
> }
>
> @@ -267,6 +271,33 @@ try_misrouted_irq(unsigned int irq, stru
> return action && (action->flags & IRQF_IRQPOLL);
> }
>
> +static void disable_stuck_irq(struct irq_desc *desc, irqreturn_t action_ret,
> + const char *reason, bool storm)
> +{
> + __report_bad_irq(desc, action_ret, storm);
> + pr_emerg("Disabling %s IRQ #%d\n", reason, irq_desc_get_irq(desc));
> + desc->istate |= IRQS_SPURIOUS_DISABLED;
> + desc->depth++;
> + irq_disable(desc);
> +}
> +
> +/* Interrupt storm detector for runaway interrupts (handled or not). */
> +static bool irqstorm_detected(struct irq_desc *desc)
> +{
> + unsigned long now = jiffies;
> +
> + if (++desc->storm_count < irqstorm_limit) {
> + if (time_after(now, desc->storm_checked + HZ)) {
> + desc->storm_count = 0;
> + desc->storm_checked = now;
> + }
> + return false;
> + }
> +
> + disable_stuck_irq(desc, IRQ_NONE, "runaway", true);
> + return true;
> +}
> +
> #define SPURIOUS_DEFERRED 0x80000000
>
> void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
> @@ -403,24 +434,16 @@ void note_interrupt(struct irq_desc *des
> desc->irqs_unhandled -= ok;
> }
>
> + if (unlikely(irqstorm_limit && irqstorm_detected(desc)))
> + return;
> +
> desc->irq_count++;
> if (likely(desc->irq_count < 100000))
> return;
>
> desc->irq_count = 0;
> if (unlikely(desc->irqs_unhandled > 99900)) {
> - /*
> - * The interrupt is stuck
> - */
> - __report_bad_irq(desc, action_ret);
> - /*
> - * Now kill the IRQ
> - */
> - printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
> - desc->istate |= IRQS_SPURIOUS_DISABLED;
> - desc->depth++;
> - irq_disable(desc);
> -
> + disable_stuck_irq(desc, action_ret, "unhandled", false);
> mod_timer(&poll_spurious_irq_timer,
> jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
> }
> @@ -462,5 +485,16 @@ static int __init irqpoll_setup(char *st
> "performance\n");
> return 1;
> }
> -
> __setup("irqpoll", irqpoll_setup);
> +
> +static int __init irqstorm_setup(char *arg)
> +{
> + int res = kstrtoul(arg, 0, &irqstorm_limit);
> +
> + if (!res) {
> + pr_info("Interrupt storm detector enabled. Limit=%lu / s\n",
> + irqstorm_limit);
> + }
> + return !!res;
> +}
> +__setup("irqstorm_limit", irqstorm_setup);
It should be
__setup("irqstorm_limit=", irqstorm_setup);
And I have tested this patch on the P9 machine, where I set the limit
to 70000. It works for kdump kernel.
Thanks,
Pingfan
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