From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754095Ab0EKHs0 (ORCPT ); Tue, 11 May 2010 03:48:26 -0400 Received: from casper.infradead.org ([85.118.1.10]:45429 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752782Ab0EKHsZ convert rfc822-to-8bit (ORCPT ); Tue, 11 May 2010 03:48:25 -0400 Subject: Re: [BUG] perf_event: crash in perf_output_begin From: Peter Zijlstra To: Stephane Eranian Cc: LKML , mingo@elte.hu, Paul Mackerras , "David S. Miller" , =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , perfmon2-devel@lists.sf.net In-Reply-To: References: <1273506739.5605.3407.camel@twins> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 11 May 2010 09:47:57 +0200 Message-ID: <1273564077.5605.3489.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2010-05-10 at 22:03 +0200, Stephane Eranian wrote: > On Mon, May 10, 2010 at 5:52 PM, Peter Zijlstra wrote: > > On Mon, 2010-05-10 at 17:33 +0200, Stephane Eranian wrote: > >> Hi, > >> > >> While testing 2.6.34-rc7 I ran into the following issue when > >> using BTS sampling on Intel Core. It seems like something > >> is not terminated properly. I am sampling BTS per-thread > >> on a test program, then hit CTRL-C, one second later my > >> machine crashes while running bash. Crash dump below: > >> > >> [ 750.249109] general protection fault: 0000 [#1] SMP > >> [ 750.249270] CPU 3 > >> [ 750.249270] Pid: 6132, comm: bash Not tainted 2.6.34-rc7-tip+ #46 > > > > Can you try and reverting 4fd38e4595e2f6c9d27732c042a0e16b2753049c, I > > spend most of the day chasing that, and I can't say I'm much wiser. > > > > It seems to avoid my problem. So that means with STATE_FREE, some code > path is exercised differently and there is leftover state that > generates spurious > interrupts, as if some event_sched_out() code was not executed. You're spot on. I'll send a full new patch Ingo wards as he already pushed out the revert. --- kernel/perf_event.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 180151f..91f277e 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1871,6 +1871,7 @@ int perf_event_release_kernel(struct perf_event *event) { struct perf_event_context *ctx = event->ctx; + perf_event_disable(event); event->state = PERF_EVENT_STATE_FREE; WARN_ON_ONCE(ctx->parent_ctx);