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=-2.3 required=3.0 tests=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 F11A2C433FF for ; Sun, 11 Aug 2019 12:58:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C59B82085B for ; Sun, 11 Aug 2019 12:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726484AbfHKM6g (ORCPT ); Sun, 11 Aug 2019 08:58:36 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:58704 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726070AbfHKM6f (ORCPT ); Sun, 11 Aug 2019 08:58:35 -0400 Received: from p200300ddd71876477e7a91fffec98e25.dip0.t-ipconnect.de ([2003:dd:d718:7647:7e7a:91ff:fec9:8e25]) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hwnQS-0000xO-SI; Sun, 11 Aug 2019 14:58:21 +0200 Date: Sun, 11 Aug 2019 14:58:15 +0200 (CEST) From: Thomas Gleixner To: Salvatore Bonaccorso cc: Paul Menzel , Jacob Pan , Len Brown , x86@kernel.org, LKML , linux-pm@vger.kernel.org, Steven Rostedt , Matthew Garrett Subject: Re: [Linux 5.2.x] /sys/kernel/debug/tracing/events/power/cpu_idle/id: BUG: kernel NULL pointer dereference, address: 0000000000000000 In-Reply-To: <20190811094630.GA18925@eldamar.local> Message-ID: References: <4b54ff1e-f18b-3c58-7caa-945a0775c24c@molgen.mpg.de> <01c7bc6b-dc6d-5eca-401a-8869e02f7c2a@molgen.mpg.de> <20190811094630.GA18925@eldamar.local> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 Salvatore, On Sun, 11 Aug 2019, Salvatore Bonaccorso wrote: > On Sun, Aug 11, 2019 at 08:22:35AM +0200, Thomas Gleixner wrote: > > On Sat, 10 Aug 2019, Paul Menzel wrote: > > > For the record. It is also reproducible with Linux 5.2.6, and trying to print > > > the file contents with cat already fails. > > > > > > ``` > > > $ sudo ls -l /sys/kernel/debug/tracing/events/power/cpu_idle/id > > > -r--r--r-- 1 root root 0 Aug 10 23:05 > > > /sys/kernel/debug/tracing/events/power/cpu_idle/id > > > $ sudo cat /sys/kernel/debug/tracing/events/power/cpu_idle/id > > > Killed > > > ``` > > This seems to be related to https://bugs.debian.org/934304 (in > particular https://bugs.debian.org/934304#29). The mentioned patch > features/all/lockdown/0031-tracefs-Restrict-tracefs-when-the-kernel-is-locked-d.patch > is a backport of https://patchwork.kernel.org/patch/11069661/ with > only change that it is converted back to the non-LSM lockdown API. So that's a debian kernel specific issue? Thanks, tglx