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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 46476C4707F for ; Tue, 25 May 2021 13:46:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1DC116141B for ; Tue, 25 May 2021 13:46:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233373AbhEYNrz (ORCPT ); Tue, 25 May 2021 09:47:55 -0400 Received: from elvis.franken.de ([193.175.24.41]:48737 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233184AbhEYNry (ORCPT ); Tue, 25 May 2021 09:47:54 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1llXO3-00079x-00; Tue, 25 May 2021 15:46:23 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 1B01DC10E2; Tue, 25 May 2021 15:38:58 +0200 (CEST) Date: Tue, 25 May 2021 15:38:58 +0200 From: Thomas Bogendoerfer To: Tiezhu Yang Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Xuefeng Li , Steven Rostedt Subject: Re: [PATCH 2/2] MIPS: Fix kernel hang under FUNCTION_GRAPH_TRACER and PREEMPT_TRACER Message-ID: <20210525133858.GA11166@alpha.franken.de> References: <1621076521-22412-1-git-send-email-yangtiezhu@loongson.cn> <1621076521-22412-3-git-send-email-yangtiezhu@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621076521-22412-3-git-send-email-yangtiezhu@loongson.cn> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 15, 2021 at 07:02:01PM +0800, Tiezhu Yang wrote: > When update the latest mainline kernel with the following three configs, > the kernel hangs during startup: > > (1) CONFIG_FUNCTION_GRAPH_TRACER=y > (2) CONFIG_PREEMPT_TRACER=y > (3) CONFIG_FTRACE_STARTUP_TEST=y > > When update the latest mainline kernel with the above two configs (1) > and (2), the kernel starts normally, but it still hangs when execute > the following command: > > echo "function_graph" > /sys/kernel/debug/tracing/current_tracer > > Without CONFIG_PREEMPT_TRACER=y, the above two kinds of kernel hangs > disappeared, so it seems that CONFIG_PREEMPT_TRACER has some influences > with function_graph tracer at the first glance. > > I use ejtag to find out the epc address is related with preempt_enable() > in the file arch/mips/lib/mips-atomic.c, because function tracing can > trace the preempt_{enable,disable} calls that are traced, replace them > with preempt_{enable,disable}_notrace to prevent function tracing from > going into an infinite loop, and then it can fix the kernel hang issue. > > By the way, it seems that this commit is a complement and improvement of > commit f93a1a00f2bd ("MIPS: Fix crash that occurs when function tracing > is enabled"). > > Signed-off-by: Tiezhu Yang > Cc: Steven Rostedt > --- > arch/mips/lib/mips-atomic.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) applied to mips-fixes. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]