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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 0EE2EC54FCB for ; Fri, 24 Apr 2020 14:01:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7BF320776 for ; Fri, 24 Apr 2020 14:01:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727015AbgDXOBs (ORCPT ); Fri, 24 Apr 2020 10:01:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:52600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726753AbgDXOBs (ORCPT ); Fri, 24 Apr 2020 10:01:48 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BE74B2075A; Fri, 24 Apr 2020 14:01:47 +0000 (UTC) Date: Fri, 24 Apr 2020 10:01:46 -0400 From: Steven Rostedt To: Xiao Yang Cc: , , , Xiao Yang Subject: Re: preemptirq_delay_test module can trigger crash on arm64 vm Message-ID: <20200424100146.786bcd7f@gandalf.local.home> In-Reply-To: <5EA2B0C8.2080706@cn.fujitsu.com> References: <5EA2B0C8.2080706@cn.fujitsu.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Fri, 24 Apr 2020 17:26:32 +0800 Xiao Yang wrote: > Hi Steve, Joel > > Sorry to bother you. > > On my slow arm64 vm, inserting and removing preemptirq_delay_test module > in loops triggers kernel panic sometimes. > > Reproduce steps: > Do the following steps in loops(more than 10 times): > [root@CentOS81-aarch64 ]# modprobe preemptirq_delay_test > test_mode=preempt delay=500000; rmmod preemptirq_delay_test > > Joel, I never did really look at that module, but doing a quick scan, I see you never clean up the task you start. Which means, you can remove the module and the task still exists, and when it runs, it will execute code that has been freed. The module exit should still do a kthread_stop() on it. If anything, it will prevent the task existing after the module is removed. -- Steve