From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751515AbaGGUGB (ORCPT ); Mon, 7 Jul 2014 16:06:01 -0400 Received: from casper.infradead.org ([85.118.1.10]:51570 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750981AbaGGUF7 (ORCPT ); Mon, 7 Jul 2014 16:05:59 -0400 Date: Mon, 7 Jul 2014 22:05:50 +0200 From: Peter Zijlstra To: Sasha Levin Cc: Ingo Molnar , LKML , Dave Jones Subject: Re: sched: spinlock recursion in sched_rr_get_interval Message-ID: <20140707200550.GA6758@twins.programming.kicks-ass.net> References: <53B98709.3090603@oracle.com> <20140707083016.GA19379@twins.programming.kicks-ass.net> <53BAA6DF.5060409@oracle.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="C2AE+UNCNp5RBAjn" Content-Disposition: inline In-Reply-To: <53BAA6DF.5060409@oracle.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --C2AE+UNCNp5RBAjn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 07, 2014 at 09:55:43AM -0400, Sasha Levin wrote: > I've also had this one, which looks similar: >=20 > [10375.005884] BUG: spinlock recursion on CPU#0, modprobe/10965 > [10375.006573] lock: 0xffff8803a0fd7740, .magic: dead4ead, .owner: modpr= obe/10965, .owner_cpu: 15 > [10375.007412] CPU: 0 PID: 10965 Comm: modprobe Tainted: G W = 3.16.0-rc3-next-20140704-sasha-00023-g26c0906-dirty #765 Something's fucked; so we have: debug_spin_lock_before() SPIN_BUG_ON(lock->owner =3D=3D current, "recursion"); Causing that, _HOWEVER_ look at .owner_cpu and the reporting cpu!! How can the lock owner, own the lock on cpu 15 and again contend with it on CPU 0. That's impossible. About when-ish did you start seeing things like this? Lemme go stare hard at recent changes. --C2AE+UNCNp5RBAjn Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTuv2eAAoJEHZH4aRLwOS6UJkQAKhk6ehFbBtjLp/RkkhsE05A RouX/ZdI1cC7l6n2U3CsWF0Vs7t5o3ls8baaJC/gjkJeoTZq67GElzTnbolX1HSH mlEuG1uihOlr6gRDYw3RkxXzJfz9WQHAaFS5GDzb/vPHBozjs0HuYC+KL1umPgAZ 65MTAY3eWx4m8p73XV+pAgpMlGWFCNBffhu3xdEyrm3osIofbqHDLKp24UJCfAHR cybHRr+EGFCnaQQOcq8aEnh9UBtgOIg63VLVToXmRp+AXCNpIy0I2esCU31v5ZeV yP/KmaCZM2hwZxu0ki1hp1fXJx+i+QeXqcJ/O67/TanyniUGIQCpBAPFLMOEGlJn VWgTmatTPKYZFvzd8xvCVU5MpXpLOCdZeY+VgdIqhM1pVilfK06ppxaCd7i4yTHn xwTg9HhRGeFi4qiGDlPZOHk47ewM5uN8Xnp5wHBpkNC5OsTz9LzE/vqQKvKPlGwZ eOEYAhIn7kRJh8ovYUpdIqRytT8sM+vQVplS1r8x4TzM9Fx0DSf5edlpSppvRQWx F/m8lclDjsOAF6t8ho9wHPQrNuR6wWOmEdapF/htPQLCmPdqfcY2bc+htzoehcp9 3lgJCkIWlfrUXf4f/U9hBrgrqujqWJ2XD21clUukejvz6OTmh1R+m/LyNKaZCtKu 1RdAOjzYwvJ6bjc9IrTq =IQnx -----END PGP SIGNATURE----- --C2AE+UNCNp5RBAjn--