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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 55A57C388F7 for ; Thu, 22 Oct 2020 16:44:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EDADC22267 for ; Thu, 22 Oct 2020 16:44:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="V8JTAEYA"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="QLClwpsj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2897836AbgJVQoQ (ORCPT ); Thu, 22 Oct 2020 12:44:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2897775AbgJVQoQ (ORCPT ); Thu, 22 Oct 2020 12:44:16 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60E1FC0613CE; Thu, 22 Oct 2020 09:44:16 -0700 (PDT) Date: Thu, 22 Oct 2020 18:44:13 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1603385054; 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: in-reply-to:in-reply-to:references:references; bh=gAgp/FPQnzgtmkmILpnWcclVKTl0LshiSeRck3Sg+gg=; b=V8JTAEYAFi6C3CQZ86xwkcAn6RgwrBWPIO7128dxKoxZjawSt4CXvy994PtZc5a8fEFuCr Jg8WJA7r6c9N4zhz8PnynoUfmwrkWkIZ/q/AIEOMcaTrnSaPoXPLMB+IXBh00OHO2qJ4/C pRRAzIkpchkPTl8bonW3odEEmZ9mMu9zLl7TUFTprX2Mk+GobWDnSXl5oZovVlGHoybBXR YCc230QrQPMQGIOSz4YyKiX4fdD8fAGeye8W5PsfcvdJazaVTJ7yLYeGmhSugPZ8seF0CO xT7LJShfMnIiamHUwJMjUrRYUkj+BSeLzn2b0Z4iwdlWolQ7M0YLjfTszxsa1g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1603385054; 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: in-reply-to:in-reply-to:references:references; bh=gAgp/FPQnzgtmkmILpnWcclVKTl0LshiSeRck3Sg+gg=; b=QLClwpsjmIysJI/PUJReFABUGgGaLaRkiWdEPhKXAMsUGywP6mEI808fYh37LcxzDWBrIN r9Ig50GM9zdok5BQ== From: Sebastian Andrzej Siewior To: Mike Galbraith Cc: Thomas Gleixner , LKML , linux-rt-users , Steven Rostedt Subject: Re: ltp or kvm triggerable lockdep alloc_pid() deadlock gripe Message-ID: <20201022164413.tnchtyqbotvbnp2e@linutronix.de> References: <20201021125324.ualpvrxvzyie6d7d@linutronix.de> <1236de05e704f0a0b28dc0ad75f9ad4d81b7a057.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1236de05e704f0a0b28dc0ad75f9ad4d81b7a057.camel@gmx.de> Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On 2020-10-22 07:21:13 [+0200], Mike Galbraith wrote: > Greetings, Hi, > The gripe below is repeatable in two ways here, boot with nomodeset so > nouveau doesn't steal the lockdep show when I then fire up one of my > (oink) full distro VM's, or from an ltp directory ./runltp -f cpuset > with the attached subset of controllers file placed in ./runtest dir. > > Method2 may lead to a real deal deadlock, I've got a crashdump of one, > stack traces of uninterruptible sleepers attached. Just added commit 267580db047ef ("seqlock: Unbreak lockdep") and it is gone. Sebastian