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From: Vladimir Oltean <olteanv@gmail.com>
To: Mike Galbraith <efault@gmx.de>
Cc: Heiner Kallweit <hkallweit1@gmail.com>,
	netdev <netdev@vger.kernel.org>,
	Realtek linux nic maintainers <nic_swsd@realtek.com>
Subject: Re: [patchlet] r8169: fix napi_schedule_irqoff() called with irqs enabled warning
Date: Fri, 16 Oct 2020 20:19:36 +0300	[thread overview]
Message-ID: <20201016171936.vidrappu4gdiv5cm@skbuf> (raw)
In-Reply-To: <42ff951039f3c92def8490d3842e3f7eaf6900ff.camel@gmx.de>

On Fri, Oct 16, 2020 at 07:11:22PM +0200, Mike Galbraith wrote:
> Yeah, it's a straight up correctness issue as it sits.

Yeah, tell me about it, you don't even want to know what it looks like
when the local_softirq_pending_ref percpu mask gets corrupted. The
symptom will be that random syscalls, like clock_nanosleep, will make
user processes hang in the kernel, because their timers will appear to
never expire. You'll also see negative expiry times in /proc/timer_list.
Eventually the entire system dies. All of that, reproducible with a
simple flood ping, given enough time.  Ask me how I come to know....
The 215602a8d212 ("enetc: use napi_schedule to be compatible with
PREEMPT_RT") commit is from before the lockdep warning came to be.

  reply	other threads:[~2020-10-16 17:19 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-16 11:26 [patchlet] r8169: fix napi_schedule_irqoff() called with irqs enabled warning Mike Galbraith
2020-10-16 11:34 ` Heiner Kallweit
2020-10-16 11:57   ` Mike Galbraith
2020-10-16 14:26   ` Vladimir Oltean
2020-10-16 14:41     ` Heiner Kallweit
2020-10-16 15:40       ` Vladimir Oltean
2020-10-16 17:11     ` Mike Galbraith
2020-10-16 17:19       ` Vladimir Oltean [this message]
2020-10-16 19:15       ` Heiner Kallweit
2020-10-17  2:26         ` Mike Galbraith

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