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=-2.2 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 3D26EC54FCB for ; Fri, 24 Apr 2020 14:31:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A9752075A for ; Fri, 24 Apr 2020 14:31:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727031AbgDXObe (ORCPT ); Fri, 24 Apr 2020 10:31:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:34736 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726698AbgDXObd (ORCPT ); Fri, 24 Apr 2020 10:31:33 -0400 Received: from gandalf.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 053FD20736; Fri, 24 Apr 2020 14:31:32 +0000 (UTC) Date: Fri, 24 Apr 2020 10:31:31 -0400 From: Steven Rostedt To: Tetsuo Handa Cc: Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Dmitry Safonov , Michal Hocko , Yafang Shao Subject: Re: [PATCH] printk: Add loglevel for "do not print to consoles". Message-ID: <20200424103131.7987f890@gandalf.local.home> In-Reply-To: <579fbe97-9aae-2b67-03ff-01291b9cbb7d@i-love.sakura.ne.jp> References: <20200424024239.63607-1-penguin-kernel@I-love.SAKURA.ne.jp> <20200424092816.62a61b1d@gandalf.local.home> <579fbe97-9aae-2b67-03ff-01291b9cbb7d@i-love.sakura.ne.jp> 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 Fri, 24 Apr 2020 23:00:01 +0900 Tetsuo Handa wrote: > Since KERN_NO_CONSOLES is for -ENOMEM situations (GFP_KERNEL allocation which > can sleep needs to invoke the OOM killer, or GFP_ATOMIC allocation which cannot > sleep has failed), we can't create buffer on demand. For process context, it > would be possible to create buffer upon fork() time. But for atomic context, > it is so difficult to create buffer on demand. We could allocate shared buffer > like logbuf but it means that we have to replicate what printk() is doing (too > much code), for when atomic memory allocation happens resembles when printk() > is called. Borrowing printk()'s logbuf is simpler. I would have a buffer allocated for this at start up. What exactly would you be "replicating" in printk? The point of printk is to print to a console, not to be a generic ring buffer. This change is breaking printk's most useful feature. -- Steve