From: Peter Zijlstra <peterz@infradead.org>
To: Michael Wu <flamingice@sourmilk.net>
Cc: "Luis R. Rodriguez" <mcgrof@gmail.com>,
linux-wireless <linux-wireless@vger.kernel.org>,
"John W. Linville" <linville@tuxdriver.com>,
Ingo Molnar <mingo@redhat.com>,
Johannes Berg <johannes@sipsolutions.net>,
linux-kernel@vger.kernel.org
Subject: Re: RFC: Reproducible oops with lockdep on count_matching_names()
Date: Fri, 02 Nov 2007 11:58:40 +0100 [thread overview]
Message-ID: <1194001120.27652.353.camel@twins> (raw)
In-Reply-To: <200711011926.07641.flamingice@sourmilk.net>
On Thu, 2007-11-01 at 19:26 -0400, Michael Wu wrote:
> On Thursday 01 November 2007 15:17:16 Luis R. Rodriguez wrote:
> > mcgrof@pogo:~/devel/wireless-2.6$ git-describe
> > v2.6.24-rc1-146-g2280253
> >
> > So I hit segfault with lockdep on count_matching_names() on the
> > strcmp() multiple times now. This is reproducible and with different
> > wireless drivers.
> >
> I've found the problem. It appears to be in lockdep. struct lock_class has a
> const char *name field which points to a statically allocated string that
> comes from the code which uses the lock. If that code/string is in a module
> and gets unloaded, the pointer in |name| is no longer valid. Next time this
> field is dereferenced (count_matching_names, in this case), we crash.
>
> The following patch fixes the issue but there's probably a better way.
Thanks, and indeed. From my understanding lockdep_free_key_range()
should destroy all classes of a module on module unload.
So I'm not quite sure what has gone wrong here..
next prev parent reply other threads:[~2007-11-02 10:58 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-01 19:17 RFC: Reproducible oops with lockdep on count_matching_names() Luis R. Rodriguez
2007-11-01 19:49 ` John W. Linville
2007-11-01 21:29 ` Luis R. Rodriguez
2007-11-01 23:26 ` Michael Wu
2007-11-02 10:58 ` Peter Zijlstra [this message]
2007-11-03 19:58 ` Luis R. Rodriguez
2007-11-03 20:06 ` Michael Buesch
2007-11-05 12:00 ` Peter Zijlstra
2007-11-05 12:23 ` Pekka Enberg
2007-11-05 13:03 ` Michael Buesch
2007-11-05 13:56 ` Pekka Enberg
2007-11-05 14:26 ` Michael Buesch
2007-11-05 18:47 ` Christoph Lameter
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