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=-2.3 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 A4C12C3F2CD for ; Sat, 29 Feb 2020 23:47:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 845F82468E for ; Sat, 29 Feb 2020 23:47:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727606AbgB2XrZ (ORCPT ); Sat, 29 Feb 2020 18:47:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:59344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727170AbgB2XrY (ORCPT ); Sat, 29 Feb 2020 18:47:24 -0500 Received: from oasis.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 211C820828; Sat, 29 Feb 2020 23:47:23 +0000 (UTC) Date: Sat, 29 Feb 2020 18:47:19 -0500 From: Steven Rostedt To: Sergey Senozhatsky Cc: "Theodore Y. Ts'o" , Petr Mladek , Greg Kroah-Hartman , Lech Perczak , "linux-kernel@vger.kernel.org" , Arnd Bergmann , Krzysztof =?UTF-8?B?RHJvYmnFhHNraQ==?= , Pawel Lenkow , John Ogness , Tejun Heo , Peter Zijlstra Subject: Re: Regression in v4.19.106 breaking waking up of readers of /proc/kmsg and /dev/kmsg Message-ID: <20200229184719.714dee74@oasis.local.home> In-Reply-To: <20200229033253.GA212847@google.com> References: <20200227123633.GB962932@kroah.com> <42d3ce5c-5ffe-8e17-32a3-5127a6c7c7d8@camlintechnologies.com> <20200228031306.GO122464@google.com> <20200228100416.6bwathdtopwat5wy@pathway.suse.cz> <20200228105836.GA2913504@kroah.com> <20200228113214.kew4xi5tkbo7bpou@pathway.suse.cz> <20200228130217.rj6qge2en26bdp7b@pathway.suse.cz> <20200228205334.GF101220@mit.edu> <20200229033253.GA212847@google.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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 29 Feb 2020 12:32:53 +0900 Sergey Senozhatsky wrote: > > What do folks think? > > Well, my 5 cents, there is nothing that prevents "too-early" > printk_deferred() calls in the future. From that POV I'd probably > prefer to "forbid" printk_deffered() to touch per-CPU deferred > machinery until it's not "too early" anymore. Similar to what we > do in printk_safe::queue_flush_work(). I agree that printk_deferred() should handle being called too early. But the issue is with per_cpu variables correct? Not the irq_work? We could add a flag in init/main.c after setup_per_cpu_areas() and then just have printk_deferred() act like a normal printk(). At that point, there shouldn't be an issue in calling printk() directly, is there? -- Steve