From: Guilherme Piccoli <gpiccoli@canonical.com>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>, Marc Zyngier <maz@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
afzal mohammed <afzal.mohd.ma@gmail.com>,
Lina Iyer <ilina@codeaurora.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Maulik Shah <mkshah@codeaurora.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Jonathan Corbet <corbet@lwn.net>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Oliver Neukum <oneukum@suse.com>,
linux-doc@vger.kernel.org,
Kexec Mailing List <kexec@lists.infradead.org>
Subject: Re: [PATCH 0/3] warn and suppress irqflood
Date: Mon, 26 Oct 2020 12:06:17 -0300 [thread overview]
Message-ID: <CAHD1Q_x99XW1zDr5HpVR27F_ksHLkaxc2W83e-N6F_xLYKyGbQ@mail.gmail.com> (raw)
In-Reply-To: <CAFgQCTvFwvvtPE0Eow4cebCEe5OD5OhgAQarckpbFc38Bphaag@mail.gmail.com>
On Sun, Oct 25, 2020 at 8:12 AM Pingfan Liu <kernelfans@gmail.com> wrote:
>
> On Thu, Oct 22, 2020 at 4:37 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > On Thu, Oct 22 2020 at 13:56, Pingfan Liu wrote:
> > > I hit a irqflood bug on powerpc platform, and two years ago, on a x86 platform.
> > > When the bug happens, the kernel is totally occupies by irq. Currently, there
> > > may be nothing or just soft lockup warning showed in console. It is better
> > > to warn users with irq flood info.
> > >
> > > In the kdump case, the kernel can move on by suppressing the irq flood.
> >
> > You're curing the symptom not the cause and the cure is just magic and
> > can't work reliably.
> Yeah, it is magic. But at least, it is better to printk something and
> alarm users about what happens. With current code, it may show nothing
> when system hangs.
Thanks Pingfan and Thomas for the points - I'd like to have a
mechanism in the kernel to warn users when an IRQ flood is potentially
happening.
Some time ago (2 years) we faced a similar issue in x86-64, a hard to
debug problem in kdump, that eventually was narrowed to a buggy NIC FW
flooding IRQs in kdump kernel, and no messages showed (although kernel
changed a lot since that time, today we might have better IRQ
handling/warning). We tried an early-boot fix, by disabling MSIs (as
per PCI spec) early in x86 boot, but it wasn't accepted - Bjorn asked
pertinent questions that I couldn't respond (I lost the reproducer)
[0].
Cheers,
Guilherme
[0] lore.kernel.org/linux-pci/20181018183721.27467-1-gpiccoli@canonical.com
next prev parent reply other threads:[~2020-10-26 15:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 5:56 [PATCH 0/3] warn and suppress irqflood Pingfan Liu
2020-10-22 5:56 ` [PATCH 1/3] kernel/watchdog: show irq percentage if irq floods Pingfan Liu
2020-10-22 5:56 ` [PATCH 2/3] kernel/watchdog: suppress max irq when " Pingfan Liu
2020-10-22 5:56 ` [PATCH 3/3] Documentation: introduce a param "irqflood_suppress" Pingfan Liu
2020-10-22 8:37 ` [PATCH 0/3] warn and suppress irqflood Thomas Gleixner
2020-10-25 11:12 ` Pingfan Liu
2020-10-25 12:21 ` [Skiboot] " Oliver O'Halloran
2020-10-25 13:11 ` Pingfan Liu
2020-10-25 13:51 ` Oliver O'Halloran
2020-10-26 15:06 ` Guilherme Piccoli [this message]
2020-10-26 19:59 ` Thomas Gleixner
2020-10-26 20:28 ` Guilherme Piccoli
2020-10-26 21:21 ` Thomas Gleixner
2020-10-27 12:28 ` Guilherme Piccoli
2020-10-28 6:02 ` Pingfan Liu
2020-10-28 11:58 ` Thomas Gleixner
2020-10-29 6:26 ` Pingfan Liu
2020-11-06 5:53 ` Pingfan Liu
2020-11-18 3:36 ` [PATCH 0/3] use soft lockup to detect irq flood Pingfan Liu
2020-11-18 3:36 ` [PATCH 1/3] x86/irq: account the unused irq Pingfan Liu
2020-11-18 3:36 ` [PATCH 2/3] kernel/watchdog: make watchdog_touch_ts more accurate by using nanosecond Pingfan Liu
2020-11-18 3:36 ` [PATCH 3/3] kernel/watchdog: use soft lockup to detect irq flood Pingfan Liu
2021-03-02 7:45 ` [PATCH 0/3] warn and suppress irqflood Sai Prakash Ranjan
2021-06-05 2:32 ` Sai Prakash Ranjan
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