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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 4BB21C433E2 for ; Fri, 15 May 2020 10:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20CC720758 for ; Fri, 15 May 2020 10:33:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QQepBCDY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728456AbgEOKdU (ORCPT ); Fri, 15 May 2020 06:33:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728048AbgEOKdL (ORCPT ); Fri, 15 May 2020 06:33:11 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B397C061A0C for ; Fri, 15 May 2020 03:33:11 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id q9so765732pjm.2 for ; Fri, 15 May 2020 03:33:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=+XVj7Vn4q7UWK0rXA2mfb7XaH4le6Oj5JDX0rkTcjv8=; b=QQepBCDYSozWfCOr/eFEkoIrW01LVBw3ONlO+lac/N4lGJUp/URE0OM0R9XXbLQIJ3 YYf2/4K2rm8OLRPVubTJZFyO50CLzcAWr8nckIRaOLY+1f/vjSs2lR+Y5Y9bYDVQr+pO Fnas1I2V70MShXTLQFzApJ2ybjosMrusIzmosj5ERNkD0FNvl2r7xEpN3u7aiDcdK0tr JLoFrbFbEqVnmjAqh84lWcO60Bmd564ZmkSBEo0e8Y39SfjqK2Z8OgAUv8FeW0UIIq7Y 6HRB59wBCV00RZ4X9L92ig7LTwJGuZxKJZFNvgtQjZp6S88j5dMkuyDY9bSxQbZ/13/F /JTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=+XVj7Vn4q7UWK0rXA2mfb7XaH4le6Oj5JDX0rkTcjv8=; b=qpALtZVVHyhnxdR8erxrpZ/GB3XByRrj1qz/TVNuuDPs6wg2fqAHVC7qguqL8GYH0k 2wFUQdOy6fgdktEQMbOqu4LAp4PTxEOfZyOcFAtZrSANESzSzJNm3Y+oZiIj6cujpBtX HwmFWFwi12ZirvsZvgGgMg5dRXq1/ZegbpekdfcASEOLRkbHiW1X++P+1vpGVf5W6rKl nSMPw9Gr+doaZOsLTSKZC3D7rrBqlVKMdM5xhAoVDvIqqiMu191tChz/wLcpLhzpwrsl Qvn57TmuYHda4sRP0fjPIMFrnc+cZjadnB/4n1RCqDWdEIH51uMjEj4AjjAJo/bipWIe Vz9w== X-Gm-Message-State: AOAM5327nl+9CZHLOMlafkP8Ie3/WM4iJ6ioS4JfYaegLx/RRt4INMd/ iaQ+tP77urJ+U5xa0kbJ6/g= X-Google-Smtp-Source: ABdhPJweTKamypY9HN33QeOPRzMIehLxFsMWkxcut7xNXPUoTEgrKmllHE13oLf4hSc73mfTruAatA== X-Received: by 2002:a17:90a:1aa2:: with SMTP id p31mr2625068pjp.233.1589538791105; Fri, 15 May 2020 03:33:11 -0700 (PDT) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id j23sm1316378pjz.13.2020.05.15.03.33.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2020 03:33:10 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Fri, 15 May 2020 19:33:08 +0900 To: Petr Mladek Cc: Sumit Garg , Daniel Thompson , Jason Wessel , Douglas Anderson , kgdb-bugreport@lists.sourceforge.net, Linux Kernel Mailing List , Arnd Bergmann , Andrew Morton , Peter Zijlstra , Steven Rostedt , Sergey Senozhatsky , John Ogness Subject: Re: [PATCH] printk/kdb: Redirect printk messages into kdb in any context Message-ID: <20200515103308.GD42471@jagdpanzerIV.localdomain> References: <1589273314-12060-1-git-send-email-sumit.garg@linaro.org> <20200512142533.ta4uejwmq5gchtlx@holly.lan> <20200514084230.GO17734@linux-b0ei> <20200515085021.GS17734@linux-b0ei> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200515085021.GS17734@linux-b0ei> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/05/15 10:50), Petr Mladek wrote: > kdb is able to stop kernel even in NMI context where printk() is redirected > to the printk_safe() lockless variant. Move the check and redirect to kdb > even in this case. Can I please have some context what problem does this solve? I can see that vkdb_printf() calls into console drivers: for_each_console(c) { c->write(c, cp, retlen - (cp - kdb_buffer)); touch_nmi_watchdog(); } Is this guaranteed that we never execute this path from NMI? If so, can this please be added to the commit message? A more detailed commit message will help a lot. -ss