Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751858AbaJTEmA (ORCPT ); Mon, 20 Oct 2014 00:42:00 -0400 Received: from mail-qa0-f43.google.com ([209.85.216.43]:47635 "EHLO mail-qa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220AbaJTEl4 (ORCPT ); Mon, 20 Oct 2014 00:41:56 -0400 From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Mon, 20 Oct 2014 00:48:43 -0400 (EDT) To: Vince Weaver cc: "linux-kernel@vger.kernel.org" , Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo Subject: Re: perf: 3.17 another perf_fuzzer lockup In-Reply-To: Message-ID: References: User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 17 Oct 2014, Vince Weaver wrote: > On Fri, 17 Oct 2014, Vince Weaver wrote: > > > Now to find out why this could happen. Probably something to do with > > crazy RCU magic :( > > it looks like there's an unbalanced get_ctx() / put_ctx() here, as the > software event context on the main process should not get decremented > to 0 unless that process is exiting, yet it happens. > > Maybe this is bisectable. Hmmm. nope. Wasted 3 days trying to bisect this. Something during the 3.17 merge window changed enough to make the perf_fuzzer results non-deterministic, and that makes it nearly impossibe to reproduce the issue properly. Ugh. I might be reduced to sprinkling printks around unless anyone chimes in with better advice. Vince -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/