From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752865AbaGGLoA (ORCPT ); Mon, 7 Jul 2014 07:44:00 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:59858 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752001AbaGGLn7 (ORCPT ); Mon, 7 Jul 2014 07:43:59 -0400 Date: Mon, 7 Jul 2014 13:43:46 +0200 From: Peter Zijlstra To: Jiri Olsa Cc: Jiri Olsa , linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Corey Ashford , Frederic Weisbecker , Ingo Molnar , Paul Mackerras Subject: Re: [PATCH 1/1] perf: Prevent race in PERF_SAMPLE_READ group format sample output Message-ID: <20140707114346.GD19379@twins.programming.kicks-ass.net> References: <1403721875-15669-1-git-send-email-jolsa@kernel.org> <1403721875-15669-2-git-send-email-jolsa@kernel.org> <20140707090428.GG6758@twins.programming.kicks-ass.net> <20140707102020.GA22764@krava.redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="VE1+SxTILTm8udN6" Content-Disposition: inline In-Reply-To: <20140707102020.GA22764@krava.redhat.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 --VE1+SxTILTm8udN6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 07, 2014 at 12:20:20PM +0200, Jiri Olsa wrote: > On Mon, Jul 07, 2014 at 11:04:28AM +0200, Peter Zijlstra wrote: > > On Wed, Jun 25, 2014 at 08:44:35PM +0200, Jiri Olsa wrote: > > > From: Jiri Olsa > > >=20 > > > While iterating siblings in perf_output_read_group we could > > > race with addition and removal of sibling in perf_group_attach > > > and perf_group_detach respective. > >=20 > > So why would anybody do this? >=20 > the test program from 0/1 email hangs up my server > but no standard reason AFAICS >=20 > I've got soft lockup, sometimes ended up with unkillable perf process > also few total server hangs OK, so that's useful information to have in a Changelog ;-) Not immediately obvious how that can happen though. I can see the output getting scrambled. --VE1+SxTILTm8udN6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTuofxAAoJEHZH4aRLwOS6qfQQAJxKVQWWxB0FUbrX4lkz+/WV ROLhq/OY2SfXHYdcDaq0UTaKfjUj5NyI/nO8oo9z8euTPPteixjXO4YTLW41DWOj eS8Sr754yPeLXRr6dv3yI495RhEQQhfDxLKdukHjWS+thb8kHl5N2ANAIJ/amW1z nXczRD26rtIZzyjfUQwooTdviUydsQn10fXtM1xOvAnWfNxRBAugxV9L2R/pRhUW M1vo2tTNKIcgbaHJYc6dS7O8YLo8dzrXbwbPSo9nMfZF05WCE3bXq0qll7Vh1sOR zbRDt2KfPW3XWgrESa03IDbvC3mYc8ePJTFCxUoEvI9cUfqeQm/mnIwLiEySE7r+ ff8kVzWNaXqEBbwfHDW5iVqxvUNcMvHSnO1ATdHGCrSJZGpJVRBQBwxm2O4VfiAO 1Fr0prSt2tXw8fsY8ZOpubfAdgRpbCQON6dJKm/j8AGivjvvK9COomvl2y2vwnfo 5Rgzo7FA0+ARMuhcSGdRaqHDl0SVyO6Lmx5pCrw8cSyKTtcsQarxXZv5cKbeE5yR qNHdxYiie/PGbJHGJv3kk8W1QZ/dyJmxzxCwgy24MnsUy8n+gZ57n+vpaj84/Ubz Opw6PkCJOGbgqn3k6xrGzzEn1cWuCSccCaY0STKLzcZ50nCzRtG/NPjZH5XtbtFf jiThf6FKg+RYofuGlYV7 =IG4k -----END PGP SIGNATURE----- --VE1+SxTILTm8udN6--