From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id B6BBE6B0008 for ; Mon, 1 Oct 2018 16:30:03 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id h76-v6so12983986pfd.10 for ; Mon, 01 Oct 2018 13:30:03 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id y129-v6si12944700pgy.551.2018.10.01.13.30.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 01 Oct 2018 13:30:02 -0700 (PDT) Date: Mon, 1 Oct 2018 16:29:58 -0400 From: Steven Rostedt 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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: 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 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