From: Sasha Levin <levinsasha928@gmail.com>
To: paulmck@linux.vnet.ibm.com
Cc: Dave Jones <davej@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: rcu: BUG: spinlock recursion on CPU#3, trinity-child19/5970
Date: Sat, 30 Jun 2012 00:40:07 +0200 [thread overview]
Message-ID: <1341009607.27537.0.camel@lappy> (raw)
In-Reply-To: <20120629222744.GD2416@linux.vnet.ibm.com>
On Fri, 2012-06-29 at 15:27 -0700, Paul E. McKenney wrote:
> On Fri, Jun 29, 2012 at 11:40:40PM +0200, Sasha Levin wrote:
> > On Fri, 2012-06-29 at 10:23 -0700, Paul E. McKenney wrote:
> > > On Fri, Jun 29, 2012 at 12:09:44PM +0200, Sasha Levin wrote:
> > > > Hi Paul,
> > > >
> > > > I think I've stumbled on another bug that will increase your paranoia levels even further.
> > > >
> > > > I got the following lockup when fuzzing with trinity inside a KVM tools guest, using latest linux-next.
> > > >
> > > > It appears that it was caused by a03d6178 ("rcu: Move RCU grace-period cleanup into kthread"). This issue doesn't reproduce easily though, it took some fuzzing before hitting it.
> > >
> > > Hmmm... If the preemption at that point in __rcu_read_unlock() is
> > > required to make this happen, then it would be pretty hard to hit.
> > > I suspect that you can make it reproduce more quickly by putting
> > > a udelay(10) or similar right after the assignment of INT_MIN to
> > > t->rcu_read_lock_nesting in __rcu_read_unlock() in kernel/rcupdate.c.
> > > Can this be reproduced while running with lockdep enabled?
> >
> > The good news are that it is much easier to reproduce it by adding a udelay(10) at the point you've mentioned.
>
> How quickly does it reproduce?
10 seconds more or less.
next prev parent reply other threads:[~2012-06-29 22:39 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 10:09 rcu: BUG: spinlock recursion on CPU#3, trinity-child19/5970 Sasha Levin
2012-06-29 17:23 ` Paul E. McKenney
2012-06-29 21:40 ` Sasha Levin
2012-06-29 22:27 ` Paul E. McKenney
2012-06-29 22:40 ` Sasha Levin [this message]
2012-06-29 23:01 ` Paul E. McKenney
2012-07-02 10:32 ` Peter Zijlstra
2012-07-02 11:35 ` Paul E. McKenney
2012-07-02 11:59 ` Peter Zijlstra
2012-07-02 13:12 ` Sasha Levin
2012-07-02 13:33 ` Paul E. McKenney
2012-07-02 14:22 ` Paul E. McKenney
2012-07-02 14:36 ` Sasha Levin
2012-07-02 14:59 ` Paul E. McKenney
2012-07-04 14:54 ` Sasha Levin
2012-07-04 19:07 ` Paul E. McKenney
2012-06-30 11:36 ` Sasha Levin
2012-06-30 13:14 ` Paul E. McKenney
2012-06-30 13:28 ` Sasha Levin
2012-06-30 13:58 ` 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=1341009607.27537.0.camel@lappy \
--to=levinsasha928@gmail.com \
--cc=davej@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
/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).