From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clark Williams Subject: Re: [RT] RCU splat on 2.6.33.4-rt20 Date: Thu, 20 May 2010 08:59:27 -0500 Message-ID: <20100520085927.480047d4@torg> References: <20100519211911.5450c1dd@torg> <20100520032246.GB2708@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/xDQV/D.S7bLxt2/RhB8/gcO"; protocol="application/pgp-signature" Cc: Thomas Gleixner , RT To: paulmck@linux.vnet.ibm.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:54376 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199Ab0ETN7l (ORCPT ); Thu, 20 May 2010 09:59:41 -0400 In-Reply-To: <20100520032246.GB2708@linux.vnet.ibm.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: --Sig_/xDQV/D.S7bLxt2/RhB8/gcO Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 19 May 2010 20:22:46 -0700 "Paul E. McKenney" wrote: > On Wed, May 19, 2010 at 09:19:11PM -0500, Clark Williams wrote: > > Thomas/Paul, > >=20 > > Resumed my laptop (T60, 64-bit kernel) and after about five > > minutes of doing nothing but surfing with firefox, got the following > > RCU stall notification from a 2.6.33.4-rt20 kernel: > >=20 > > INFO: RCU detected CPU 1 stall (t=3D0 jiffies) >=20 > Hmmm... "t=3D0 jiffies". I wonder if the hibernation/resumption confused > the stall-warning code. My first thought was that an RCU grace period > had spanned the hibernation, but that would not be consistent with it > waiting five minutes after resumption to splat. >=20 > I will look into this. >=20 Don't take that "five minutes" as anything approaching some degree of accuracy. It could have been quicker; I was distracted and not even touching the keyboard when a loud beep sounded and I had to poke around a bit to realize that an NMI backtrace had triggered. Depending on your timeout values, I think that it's quite reasonable to suspect that an RCU spanned the suspend/resume. Clark --Sig_/xDQV/D.S7bLxt2/RhB8/gcO Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (GNU/Linux) iEYEARECAAYFAkv1QEMACgkQHyuj/+TTEp1AegCglbEOLVUggBdlCZsGqJDGzqAq 2kEAn2IG/LXaxiKImNkb6ivkXR42kbyf =AoC0 -----END PGP SIGNATURE----- --Sig_/xDQV/D.S7bLxt2/RhB8/gcO--