From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: David Miller <davem@davemloft.net>
Cc: mroos@linux.ee, linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org
Subject: Re: RCU detected CPU 0 stall after panic on sparc64
Date: Mon, 14 Dec 2009 12:25:56 -0800 [thread overview]
Message-ID: <20091214202556.GC6679@linux.vnet.ibm.com> (raw)
In-Reply-To: <20091212.014002.173528710.davem@davemloft.net>
On Sat, Dec 12, 2009 at 01:40:02AM -0800, David Miller wrote:
> From: Meelis Roos <mroos@linux.ee>
> Date: Sat, 12 Dec 2009 10:54:19 +0200 (EET)
>
> > I tried 2.6.32 git gaad3bf0 on a SMP sparc64 machine (Ultra Enterprise
> > 250). For some reason my disks were not found (not important in this
> > bugreport) and this resulted in panic (cannnot mount root). However, the
> > machine kept going and got the below messages (RCU detected CPU 0 stall
> > (t=1000 jiffies)) from timer interrupts.
> >
> > This seems to be like a bug in RCU vs panic.
>
> It's normal actually. A panic() just loops forever and the cpu never
> goes through an RCU grace period again as a result, and this triggers
> the debugging timer that detects this condition.
>
> Probably the panic() code should disable that assertion check.
Hmmm... At first glance, it looks like RCU should put a notifier onto
the panic_notifier_list to disable this check. Or is there some global
variable that I can check?
Thanx, Paul
next prev parent reply other threads:[~2009-12-14 20:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-12 8:54 RCU detected CPU 0 stall after panic on sparc64 Meelis Roos
2009-12-12 9:40 ` David Miller
2009-12-14 20:25 ` Paul E. McKenney [this message]
2009-12-14 21:02 ` David Miller
2009-12-14 23:15 ` Paul E. McKenney
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