From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EF09C433E0 for ; Fri, 24 Jul 2020 14:50:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54F1E206D8 for ; Fri, 24 Jul 2020 14:50:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726863AbgGXOu6 (ORCPT ); Fri, 24 Jul 2020 10:50:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726317AbgGXOu5 (ORCPT ); Fri, 24 Jul 2020 10:50:57 -0400 Received: from theia.8bytes.org (8bytes.org [IPv6:2a01:238:4383:600:38bc:a715:4b6d:a889]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90481C0619D3 for ; Fri, 24 Jul 2020 07:50:57 -0700 (PDT) Received: by theia.8bytes.org (Postfix, from userid 1000) id D2C746FA; Fri, 24 Jul 2020 16:50:54 +0200 (CEST) Date: Fri, 24 Jul 2020 16:50:53 +0200 From: Joerg Roedel To: Ingo Molnar Cc: Thomas Gleixner , x86@kernel.org, Peter Zijlstra , Arnaldo Carvalho de Melo , Andy Lutomirski , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: Regression on todays tip/master (commit 16f70beccf43) Message-ID: <20200724145053.GV27672@8bytes.org> References: <20200723133743.GA30716@8bytes.org> <871rl2xpar.fsf@nanos.tec.linutronix.de> <20200723145219.GP27672@8bytes.org> <20200724132802.GA640628@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200724132802.GA640628@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 24, 2020 at 03:28:02PM +0200, Ingo Molnar wrote: > Given that you are perf stress-testing the box, some recent perf > commit would be the primary suspect - before doing a full bisect you > might want to try current perf/core (2ac5413e5edc) and its upstream > base: v5.8-rc3, to narrow it down. > > But in principle any other commit could be the cause as well, the > assert suggests memory corruption - I don't think we changed anything > in the signal code. I tried to bisec, but it didn't yield something useful yet. The outcome was commit commit 1abdfe706a579a702799fce465bceb9fb01d407c Author: Alex Belits Date: Thu Jun 25 18:34:41 2020 -0400 lib: Restrict cpumask_local_spread to houskeeping CPUs But it looks totally unrelated to the backtrace I am seeing, and reverting it didn't fix the problem. Next thing is, I can reliable reproduce it with yesterdays tip/master (commit 16f70beccf43), but did not see it with tip/master pulled today (commit c02699cd25e8) yet. To trigger it is sufficient to run the test_syscall_vdso_32 self-test in a loop, ideally multiple $times, where $times > `nproc`. It usually triggers withing the first 5 minutes in my test VMs. It turned out that a running perf is not needed to trigger it. Regards, Joerg