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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 F216CC43143 for ; Mon, 1 Oct 2018 20:30:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A17722145D for ; Mon, 1 Oct 2018 20:30:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A17722145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726521AbeJBDJf (ORCPT ); Mon, 1 Oct 2018 23:09:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:53540 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726317AbeJBDJf (ORCPT ); Mon, 1 Oct 2018 23:09:35 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 3D1E6208AE; Mon, 1 Oct 2018 20:30:00 +0000 (UTC) Date: Mon, 1 Oct 2018 16:29:58 -0400 From: Steven Rostedt To: Pavel Machek Cc: Daniel Wang , stable@vger.kernel.org, pmladek@suse.com, Alexander.Levin@microsoft.com, akpm@linux-foundation.org, byungchul.park@lge.com, dave.hansen@intel.com, hannes@cmpxchg.org, jack@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mathieu.desnoyers@efficios.com, mgorman@suse.de, mhocko@kernel.org, penguin-kernel@I-love.SAKURA.ne.jp, peterz@infradead.org, tj@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, xiyou.wangcong@gmail.com, pfeiner@google.com Subject: Re: 4.14 backport request for dbdda842fe96f: "printk: Add console owner and waiter logic to load balance console writes" Message-ID: <20181001162958.3b8e4640@gandalf.local.home> In-Reply-To: <20181001201309.GA9835@amd> References: <20180927194601.207765-1-wonderfly@google.com> <20181001152324.72a20bea@gandalf.local.home> <20181001201309.GA9835@amd> X-Mailer: Claws Mail 3.16.0 (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 Mon, 1 Oct 2018 22:13:10 +0200 Pavel Machek wrote: > > > [1] https://lore.kernel.org/lkml/20180409081535.dq7p5bfnpvd3xk3t@pathway.suse.cz/T/#u > > > > > > Serial console logs leading up to the deadlock. As can be seen the stack trace > > > was incomplete because the printing path hit a timeout. > > > > I'm fine with having this backported. > > Dunno. Is the patch perhaps a bit too complex? This is not exactly > trivial bugfix. > > pavel@duo:/data/l/clean-cg$ git show dbdda842fe96f | diffstat > printk.c | 108 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > > I see that it is pretty critical to Daniel, but maybe kernel with > console locking redone should no longer be called 4.4? But it prevents a deadlock. I usually weigh backporting as benefit vs risk. And I believe the benefit outweighs the risk in this case. -- Steve