Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757361AbcJXL1g (ORCPT ); Mon, 24 Oct 2016 07:27:36 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55560 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753962AbcJXL1d (ORCPT ); Mon, 24 Oct 2016 07:27:33 -0400 Date: Mon, 24 Oct 2016 13:27:32 +0200 From: Peter Zijlstra To: Oleg Nesterov Cc: "Ni, BaoleX" , "mingo@redhat.com" , "acme@kernel.org" , "linux-kernel@vger.kernel.org" , "alexander.shishkin@linux.intel.com" , "Liu, Chuansheng" , Jiri Olsa Subject: Re: hit a KASan bug related to Perf during stress test Message-ID: <20161024112732.GJ3102@twins.programming.kicks-ass.net> References: <318B87A793BE164187D8851D6CE09D64371C8811@shsmsx102.ccr.corp.intel.com> <20161024095341.GF3102@twins.programming.kicks-ass.net> <20161024111526.GA13509@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161024111526.GA13509@redhat.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 640 Lines: 21 On Mon, Oct 24, 2016 at 01:15:27PM +0200, Oleg Nesterov wrote: > How about the trivial fix below? > > Oleg. > > --- x/kernel/events/core.c > +++ x/kernel/events/core.c > @@ -1257,7 +1257,7 @@ static u32 perf_event_pid(struct perf_ev > if (event->parent) > event = event->parent; > > - return task_tgid_nr_ns(p, event->ns); > + return pid_alive(p) ? task_tgid_nr_ns(p, event->ns) : 0; > } Also, now we get a (few) sample(s) with a different pid:tid than prior samples and not matching the sched_switch() events. I can imagine that being somewhat confusing for people/tools. Acme/Jolsa, any idea if that will bugger perf-report?