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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 52A5FC433DF for ; Thu, 28 May 2020 20:19:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FBE7207D3 for ; Thu, 28 May 2020 20:19:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407123AbgE1UTN (ORCPT ); Thu, 28 May 2020 16:19:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406991AbgE1UTK (ORCPT ); Thu, 28 May 2020 16:19:10 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2138C08C5C7 for ; Thu, 28 May 2020 13:19:09 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jeOzY-0008GM-KY; Thu, 28 May 2020 22:19:04 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id A2E86100D01; Thu, 28 May 2020 22:19:02 +0200 (CEST) From: Thomas Gleixner To: paulmck@kernel.org Cc: syzbot , Paolo Bonzini , bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@kernel.org, syzkaller-bugs@googlegroups.com, x86@kernel.org Subject: Re: WARNING: suspicious RCU usage in idtentry_exit In-Reply-To: <20200528161143.GF2869@paulmck-ThinkPad-P72> References: <000000000000840d4d05a6850c73@google.com> <87wo4wnpzb.fsf@nanos.tec.linutronix.de> <20200528161143.GF2869@paulmck-ThinkPad-P72> Date: Thu, 28 May 2020 22:19:02 +0200 Message-ID: <878shbols9.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul, "Paul E. McKenney" writes: > On Thu, May 28, 2020 at 03:33:44PM +0200, Thomas Gleixner wrote: >> syzbot writes: >> Weird. I have no idea how that thing is an EQS here. > > No argument on the "Weird" part! ;-) > > Is this a NO_HZ_FULL=y kernel? No, it has only NO_HZ_IDLE. https://syzkaller.appspot.com/x/.config?x=47b0740d89299c10 > If so, one possibility is that the call > to rcu_user_exit() went missing somehow. If not, then RCU should have > been watching userspace execution. > > Again, the only thing I can think of (should this prove to be > reproducible) is the rcu_dyntick trace event. :) Thanks, tglx