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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 D07DAC48BCF for ; Wed, 9 Jun 2021 18:12:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A734F61359 for ; Wed, 9 Jun 2021 18:12:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229734AbhFISOX (ORCPT ); Wed, 9 Jun 2021 14:14:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229472AbhFISOT (ORCPT ); Wed, 9 Jun 2021 14:14:19 -0400 Received: from mail-pg1-x52d.google.com (mail-pg1-x52d.google.com [IPv6:2607:f8b0:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EB42C061574 for ; Wed, 9 Jun 2021 11:12:24 -0700 (PDT) Received: by mail-pg1-x52d.google.com with SMTP id j12so20226329pgh.7 for ; Wed, 09 Jun 2021 11:12:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=gks6qbv9Lr+imHtC7AaeB4+/G8WI7NzfclheXnHYu0Y=; b=UdhbgzZUkddxIZ5rHW9r5JA7w1k60HSJek2eW6w9ZJzw/vlksEFnZgQ/MSRRILhjpU CPn+IdzCaDhGEx3viK0Uc7ioDMPVeCvbzlAGFDRk1d1hXyIMvW5HjV/CoTM+nXEbpc1A kescIHMYfbgdVwjWFpCwWbXDK+316/NOYRRc8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=gks6qbv9Lr+imHtC7AaeB4+/G8WI7NzfclheXnHYu0Y=; b=IcNtx7yQZUfyMwTExoX3N0vliRGGJUKSAwCSTI7va6RNhZQCUAH1K30Uha7/3xAl1j f0srlmLk47glEAvA5BzF4UYv+MI2sBLbscCMmHYTkxaqMG79ITZbjgyfSq3lkXOdSjJZ 3+1kZHL9CpSkcJEAZiZy137oZB45WhDlyoZ8mpyyUDoVbs238XJeOUU1l2IS6oFns2B/ 9JMMMgUaFzRa40wc0qY/NLGLz78Tl58scA5dZ1ftbBbqbhJVSSMrTgGMd5amdAQpsq8M gBLDwPe1VhNzZYvzYCiRJEs7VLvXuYXpOcMFo1dQGrusrtIpzA3OAHdzYlm4DKXP3P6S k/dA== X-Gm-Message-State: AOAM532aXxYSNEki/l6jk8Q3kleEegETY79KeKa1fIjI2GQ8B6hKyY26 E1aQiQSOqJgr9x9kmoJdU/91fKYs1nlW7A== X-Google-Smtp-Source: ABdhPJz2NS8YTClpY3QzVpJIjA5NuhRW9njVzmhpgF8VNv7ILKzJkp6maVlZgUrsgcXmluyEqRW9EA== X-Received: by 2002:a63:1d09:: with SMTP id d9mr941895pgd.302.1623262343701; Wed, 09 Jun 2021 11:12:23 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id d66sm246332pfa.32.2021.06.09.11.12.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Jun 2021 11:12:23 -0700 (PDT) Date: Wed, 9 Jun 2021 11:12:22 -0700 From: Kees Cook To: Joel Fernandes Cc: "Zhengyejian (Zetta)" , rostedt@goodmis.org, ccross@android.com, linux-kernel@vger.kernel.org, Zhangjinhao Subject: Re: [BUG] I found a bug when try to enable record_ftrace Message-ID: <202106091110.F13B8B6@keescook> References: <01472d0f-55c1-15ea-9beb-5d64b322bb44@huawei.com> <202106021042.8527F3AB30@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 08, 2021 at 03:16:44PM -0400, Joel Fernandes wrote: > On Wed, Jun 02, 2021 at 10:43:29AM -0700, Kees Cook wrote: > > > > On Wed, Jun 02, 2021 at 03:42:23PM +0800, Zhengyejian (Zetta) wrote: > > > Hello, > > > > > > There may be a deadlock caused by ftrace recursion when try to enable > > > record_ftrace. > > > > Hi, > > > > Thanks for the report. Joel, is this something you can take a look at? > > Kees, > > Sorry for late reply. Right now I am dealing with a production-stop bug and > would not likely get time. Plus I feel a bit less motivated, because the > ftrace in pstore the way it stands now is unusable due to perf issues anyway > (I wonder if anyone uses it at all now). I would rather someone who has time > to work on this try to revive: https://lkml.org/lkml/2020/9/2/1075 . Should > we just delete pstore function tracing till then? If no one is using it, then yes, let's rip it out. Zetta, are you using pstore ftrace? -Kees -- Kees Cook