From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: David Miller <davem@davemloft.net>
Cc: shemminger@vyatta.com, mroos@linux.ee,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: suspicious RCU usage warnings in 3.3.0
Date: Wed, 11 Apr 2012 18:53:41 -0700 [thread overview]
Message-ID: <20120412015341.GA2497@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120411.210319.370705937753558953.davem@davemloft.net>
On Wed, Apr 11, 2012 at 09:03:19PM -0400, David Miller wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> Date: Wed, 11 Apr 2012 17:45:07 -0700
>
> > On Wed, Apr 11, 2012 at 08:18:54PM -0400, David Miller wrote:
> >> From: Stephen Hemminger <shemminger@vyatta.com>
> >> Date: Wed, 11 Apr 2012 17:10:04 -0700
> >>
> >> > On Wed, 11 Apr 2012 16:08:37 -0700
> >> > "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> >> >
> >> >> Hmmm... What CPU family is this running on? From the look of the
> >> >> stack, it is sneaking out of idle into softirq without telling RCU.
> >> >> This would cause RCU to complain bitterly about being invoked from
> >> >> the idle loop -- and RCU ignores CPUs in the idle loop.
> >> >>
> >> >> Thanx, Paul
> >> >
> >> > Sun4... Ping David.
> >>
> >> So is there anything specific I need to do in the sparc64
> >> idle loop?
> >
> > Hmmm... I must confess that I don't immediately see how control
> > is passing from cpu_idle() in arch/sparc/kernel/process_64.c to
> > __handle_softirq().
> >
> > But it looks like a simple function call in the call trace:
>
> It's coming from the trap return code path at the end of hardware
> interrupt processing, on the IRQ stack.
Ah! I should have guessed something like that was happening given
that __handle_softirq() is written in assembly.
Thanx, Paul
next prev parent reply other threads:[~2012-04-12 1:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-28 8:45 suspicious RCU usage warnings in 3.3.0 Meelis Roos
2012-03-28 21:45 ` David Miller
2012-04-11 15:08 ` Meelis Roos
2012-04-11 23:08 ` Paul E. McKenney
2012-04-12 0:10 ` Stephen Hemminger
2012-04-12 0:18 ` David Miller
2012-04-12 0:45 ` Paul E. McKenney
2012-04-12 1:03 ` David Miller
2012-04-12 1:53 ` Paul E. McKenney [this message]
2012-04-12 1:08 ` David Miller
2012-04-12 4:54 ` Paul E. McKenney
2012-04-13 11:55 ` mroos
2012-04-13 13:35 ` Paul E. McKenney
2012-04-13 14:55 ` David Miller
2012-04-13 16:30 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120412015341.GA2497@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=davem@davemloft.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mroos@linux.ee \
--cc=netdev@vger.kernel.org \
--cc=shemminger@vyatta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).