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=-3.3 required=3.0 tests=BAYES_00, BUG6152_INVALID_DATE_TZ_ABSURD,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS,INVALID_DATE_TZ_ABSURD,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6FBE3C4727E for ; Fri, 25 Sep 2020 22:59:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A7AC21775 for ; Fri, 25 Sep 2020 22:59:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dv0bGpe7"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="JEWQHJ0T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729275AbgIYW7z (ORCPT ); Fri, 25 Sep 2020 18:59:55 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:59064 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729154AbgIYW7y (ORCPT ); Fri, 25 Sep 2020 18:59:54 -0400 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1601074792; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vssvkRTPmBq0TEWs5UmZrYu34ljdxxWXgeuqetaowvw=; b=dv0bGpe72nBqrLZBVZUXyuWUFzl3iVXi7i/kdZv4pQg1uhbRkVzmCv54Ih1Z9gY6paxKdN UqxmYSL9F9Yi7I8eR1ejXah+aB2vLKI6fx3JqYT5G6kEdXTTJJY/ObtoVfGuAR94+o58eG NkhXIhV5W6YfR9B7qH4zezqn/E+Q4xzD2KkKqbAmuJDnA4V2iLCHc27V6eWx436RelbnAE IqzBz5T6MrrXqsiqdflwo8Dj3otVvs+xtEW/U67WND9m1b44Ltjn0Ns1o7k6e+OpPwxZaY rekN3Lvu/Sys2HgF5vSL5HjZqbbrKr0v6iwiPDryMSYbXl7FF1bJaVidDUalzA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1601074792; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vssvkRTPmBq0TEWs5UmZrYu34ljdxxWXgeuqetaowvw=; b=JEWQHJ0TvJlZgOIuoOQKq4um3UCNFED4AyrbLZxFU7TBLRapPLfOx+9jbHSJrXHr5zMCrR biui1xAyKh0aNUBg== To: Marek Szyprowski , Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , Peter Zijlstra , Andrea Parri , Paul McKenney , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH printk v5 6/6] printk: reimplement log_cont using record extension In-Reply-To: References: <20200914123354.832-1-john.ogness@linutronix.de> <20200914123354.832-7-john.ogness@linutronix.de> Date: Sat, 26 Sep 2020 01:05:51 +0206 Message-ID: <87v9g1bgyg.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-09-25, Marek Szyprowski wrote: > This patch landed recently in linux-next as commit f5f022e53b87=20 > ("printk: reimplement log_cont using record extension"). I've noticed=20 > that it causes a regression on my test system (ARM 32bit Samsung Exynos=20 > 4412-based Trats2 board). The messages are printed correctly on the=20 > serial console during boot, but then when I run 'dmesg' command, the log= =20 > is truncated. > > Here is are the last lines of the dmesg log after this patch: > > [=C2=A0=C2=A0=C2=A0 6.649018] Waiting 2 sec before mounting root device... > [=C2=A0=C2=A0=C2=A0 6.766423] dwc2 12480000.hsotg: new device is high-spe= ed > [=C2=A0=C2=A0=C2=A0 6.845290] dwc2 12480000.hsotg: new device is high-spe= ed > [=C2=A0=C2=A0=C2=A0 6.914217] dwc2 12480000.hsotg: new address 51 > [=C2=A0=C2=A0=C2=A0 8.710351] RAMDISK: squashfs filesystem found at block= 0 > > The corresponding dmesg lines before applying this patch: > > [=C2=A0=C2=A0=C2=A0 8.864320] RAMDISK: squashfs filesystem found at block= 0 > [=C2=A0=C2=A0=C2=A0 8.868410] RAMDISK: Loading 37692KiB [1 disk] into ram= disk... / > [=C2=A0=C2=A0=C2=A0 9.071670] / > [=C2=A0=C2=A0=C2=A0 9.262498] / > [=C2=A0=C2=A0=C2=A0 9.540711] / > [=C2=A0=C2=A0=C2=A0 9.818031] done. Ah. One of the more creative printk users... init/do_mounts_rd.c:rd_load_image(). This is a set of LOG_CONT messages that try to display a rotating line, complete with '\b' control characters. The code is totally broken, but that is no excuse for printk to break. It should be easy to reproduce on any architecture. I will investigate it further. Thanks for reporting. John Ogness