From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752798AbcBOX1j (ORCPT ); Mon, 15 Feb 2016 18:27:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56304 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810AbcBOX1i (ORCPT ); Mon, 15 Feb 2016 18:27:38 -0500 Date: Mon, 15 Feb 2016 17:27:35 -0600 From: Josh Poimboeuf To: Jiri Kosina Cc: Rusty Russell , Jessica Yu , Seth Jennings , Vojtech Pavlik , Miroslav Benes , Petr Mladek , Steven Rostedt , Ingo Molnar , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/4] livepatch/module: remove livepatch module notifier Message-ID: <20160215232735.GC3018@treble.redhat.com> References: <1454993424-31031-1-git-send-email-jeyu@redhat.com> <1454993424-31031-5-git-send-email-jeyu@redhat.com> <87r3glzbzj.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 14, 2016 at 11:59:00PM +0100, Jiri Kosina wrote: > On Wed, 10 Feb 2016, Jiri Kosina wrote: > > > > > Remove the livepatch module notifier in favor of directly enabling and > > > > disabling patches to modules in the module loader. Hard-coding the > > > > function calls ensures that ftrace_module_enable() is run before > > > > klp_module_coming() during module load, and that klp_module_going() is > > > > run before ftrace_release_mod() during module unload. This way, ftrace > > > > and livepatch code is run in the correct order during the module > > > > load/unload sequence without dependence on the module notifier call chain. > > > > > > > > This fixes a notifier ordering issue in which the ftrace module notifier > > > > (and hence ftrace_module_enable()) for coming modules was being called > > > > after klp_module_notify(), which caused livepatch modules to initialize > > > > incorrectly. > > > > > > Without a Fixes: line, it's not absolutely clear whether this needs > > > CC:stable, needs to go to Linus now, or can wait for the next merge > > > window. > > > > > > I *think* you want all four merged this merge window, and 3 and 4 are > > > required to fix a regression introduced since 4.4... > > > > Your understanding is correct; #3 and #4 are needed to fix a 4.4 > > regression. It makes sense for the whole lot go to together, but for #1 > > and #2 I absolutely need your Ack before I take it to my tree, as I don't > > want to be merging this behind your back. > > > > Once you Ack #1 and #2, I plan to take this to Linus immediately so that > > we avoid doing these changes as very last minute. > > Rusty, friendly ping? :) > > I know that this is quite tight timing, but I'd like to have the 4.4 > regression fixed, and we are quite late in the -rc phase already. So I think the commit causing the regression is 5156dca34a3e, which occurred in the 4.5 cycle, *not* in 4.4. Also it's my understanding that only the third patch ("remove ftrace module notifier") is needed to fix the regression, and the other patches are just general improvements. So if needed I think we can just rebase that patch (which already has Rusty's ack I believe) and send it to Linus now. -- Josh