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=-7.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 D44BEC43381 for ; Sat, 23 Feb 2019 10:38:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A4C6F206B6 for ; Sat, 23 Feb 2019 10:38:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="IJKs8/4E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727835AbfBWKiT (ORCPT ); Sat, 23 Feb 2019 05:38:19 -0500 Received: from mail.skyhub.de ([5.9.137.197]:47750 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726437AbfBWKiT (ORCPT ); Sat, 23 Feb 2019 05:38:19 -0500 Received: from zn.tnic (p200300EC2BDB49004460C94D34A9E8FA.dip0.t-ipconnect.de [IPv6:2003:ec:2bdb:4900:4460:c94d:34a9:e8fa]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id F23E81EC021C; Sat, 23 Feb 2019 11:38:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1550918297; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=ngwZVIDy2UDCyrbXqx92leOuZ9icNJOE6TgaEx/6uPE=; b=IJKs8/4EUqFbl1L5ADuLqxrwQgKZA/EIZZAF3KNntm7E7sz/fLJK51UJZS8Hux0oTTMVYK tFHGA1NcZBaD9Ae895ehwandvbpK4BY/Ca7srW7j+gRQkuqAq+dV/59Iqbd4NePNA4KNht ddemskTNT5+l2GUMcYzrXhaj82pCDIY= Date: Sat, 23 Feb 2019 11:38:09 +0100 From: Borislav Petkov To: Dmitry Vyukov Cc: syzbot , Dou Liyang , "H. Peter Anvin" , konrad.wilk@oracle.com, Len Brown , LKML , Ingo Molnar , puwen@hygon.cn, syzkaller-bugs , Thomas Gleixner , wang.yi59@zte.com.cn, the arch/x86 maintainers , Peter Zijlstra Subject: Re: WARNING in rcu_check_gp_start_stall Message-ID: <20190223103809.GB23376@zn.tnic> References: <0000000000007da94e05827ea99a@google.com> <20190222222036.GC30766@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Sat, Feb 23, 2019 at 11:33:33AM +0100, Dmitry Vyukov wrote: > On Fri, Feb 22, 2019 at 11:20 PM Borislav Petkov wrote: > > > > On Fri, Feb 22, 2019 at 09:10:04AM -0800, syzbot wrote: > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 8a61716ff2ab Merge tag 'ceph-for-5.0-rc8' of git://github... > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1531dd3f400000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=7132344728e7ec3f > > > dashboard link: https://syzkaller.appspot.com/bug?extid=111bc509cd9740d7e4aa > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d4966cc00000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10c492d0c00000 > > > > So I ran this for more than an hour in a guest here with the above > > .config but nothing happened. The compiler I used is 8.2, dunno of that > > makes the difference or I'm missing something else... > > I was able to reproduce this on the first run: > > # ./syz-execprog -procs=8 -repeat=0 hang Ok, this is what I'm missing: I ran the reproducer directly but you run a multithreaded thing with this syz-execprog. Where do I get that syz- thing? > There is a bunch of other bug reports about hangs where reproducers > mention perf_event_open and sched_setattr. This is a known issue, says peterz. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.