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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C568C433EF for ; Wed, 16 Feb 2022 19:32:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232686AbiBPTcP (ORCPT ); Wed, 16 Feb 2022 14:32:15 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:43388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232083AbiBPTcL (ORCPT ); Wed, 16 Feb 2022 14:32:11 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D6067CDFC; Wed, 16 Feb 2022 11:31:59 -0800 (PST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 21GJHekl025850; Wed, 16 Feb 2022 19:31:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : references : date : in-reply-to : message-id : mime-version : content-type; s=pp1; bh=7eSi80sucexNTq5VTd+FJqwj5S44r/5XDWArAHdBcgE=; b=Lp9CbHCT2JEEKJS6guX1c8c+bem6OCUGFxBBdSwH5xDMSUkH97kqjEQeLHlIyqB+82nM mTgkfDMw6nOMVxfywDQRMudEstBdPujfJPM2h6UTb3WbKLiw9Y0m6MUNUzFFC5o8MI7u rzVC+LrK8NUOIvxhZIZfSE2d4m4dmgp8q8Lc+EkbSiPtPbyXKLZGSgRKM+91885HBOn7 zn4X8cd+SmaKiSPM0HXBFUkiQzr62Sx3GcDyMQoOZNHeLILcVJb9/5Q247dz7geGj2ur JrRU7Z4BNxF1OOG/jM5fgrRpgtUjcKv6Y/73VPolRELQgYZaLE1ikX7EynctvxC9zJyS yQ== Received: from ppma06fra.de.ibm.com (48.49.7a9f.ip4.static.sl-reverse.com [159.122.73.72]) by mx0a-001b2d01.pphosted.com with ESMTP id 3e950tuukv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 16 Feb 2022 19:31:43 +0000 Received: from pps.filterd (ppma06fra.de.ibm.com [127.0.0.1]) by ppma06fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 21GJS8FV029970; Wed, 16 Feb 2022 19:31:40 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma06fra.de.ibm.com with ESMTP id 3e645k2319-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 16 Feb 2022 19:31:40 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 21GJVcKN40763862 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 16 Feb 2022 19:31:38 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4D6FD11C052; Wed, 16 Feb 2022 19:31:38 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 291E311C05E; Wed, 16 Feb 2022 19:31:38 +0000 (GMT) Received: from tuxmaker.linux.ibm.com (unknown [9.152.85.9]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 16 Feb 2022 19:31:38 +0000 (GMT) From: Sven Schnelle To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: ftrace startup tests crashing due to missing rcu_synchronize() References: <20220216135419.01d96fe1@gandalf.local.home> <20220216135821.67a22c52@gandalf.local.home> Date: Wed, 16 Feb 2022 20:31:37 +0100 In-Reply-To: <20220216135821.67a22c52@gandalf.local.home> (Steven Rostedt's message of "Wed, 16 Feb 2022 13:58:21 -0500") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: VVYir-Eh-pwmDtOVaJejuq5TvIGaxO8Z X-Proofpoint-ORIG-GUID: VVYir-Eh-pwmDtOVaJejuq5TvIGaxO8Z X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-02-16_09,2022-02-16_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 suspectscore=0 spamscore=0 phishscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 clxscore=1015 mlxlogscore=615 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202160109 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Steven Rostedt writes: > On Wed, 16 Feb 2022 13:54:19 -0500 > Steven Rostedt wrote: > >> That is, shutdown is called, the item is removed from the list and freed, >> but something got preempted while on the ftrace trampoline, with a >> reference to the item, and then woke up and executed the item that was >> freed. >> >> I'll look into it. Thanks for the report. > > OK, I wonder if something changed with "is_kernel_core_date()"? > > Because on registering, we have: > > if (!is_kernel_core_data((unsigned long)ops)) > ops->flags |= FTRACE_OPS_FL_DYNAMIC; I checked, and the flag gets set here. I cannot say whether it is also set when the system crashes, but i would expect it.