Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756153AbcC2HuH (ORCPT ); Tue, 29 Mar 2016 03:50:07 -0400 Received: from mail-oi0-f41.google.com ([209.85.218.41]:36247 "EHLO mail-oi0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753276AbcC2HuD (ORCPT ); Tue, 29 Mar 2016 03:50:03 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Andy Lutomirski Date: Tue, 29 Mar 2016 00:49:42 -0700 Message-ID: Subject: Re: i915 4.5 bugfix backport and release management issue? To: Daniel Vetter Cc: DRI , Dave Airlie , Matt Roper , Jani Nikula , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2236 Lines: 53 On Tue, Mar 29, 2016 at 12:43 AM, Daniel Vetter wrote: > On Tue, Mar 29, 2016 at 4:39 AM, Andy Lutomirski wrote: >> AFAICT something got rather screwed up in i915 land for 4.5. >> >> $ git log --oneline --grep='Pretend cursor is always on' v4.5 >> drivers/gpu/drm/i915/ >> e2e407dc093f drm/i915: Pretend cursor is always on for ILK-style WM >> calculations (v2) >> >> $ git log --oneline --grep='Pretend cursor is always on' v4.6-rc1 >> drivers/gpu/drm/i915/ >> e2e407dc093f drm/i915: Pretend cursor is always on for ILK-style WM >> calculations (v2) >> b2435692dbb7 drm/i915: Pretend cursor is always on for ILK-style WM >> calculations (v2) >> >> The two patches there are almost, but not quite, the same thing, which >> makes me wonder how they both ended up in Linus' tree without an >> obvious merge conflict. >> >> I have no idea what caused this. However, I think (on very little >> inspection, but it's consistent with problems I have with 4.5 on my >> laptop) that the first one is an *incorrect* fix for a regression in >> 4.5 and the second is a correct fix for the same regression. 4.6-rc1 >> seems okay. >> >> I reported the regression and everyone involved has known about it for >> weeks. Nonetheless, 4.5 final is busted. > > Quoting from e2e407dc093f > > "(cherry picked from commit b2435692dbb709d4c8ff3b2f2815c9b8423b72bb)" > > i.e. this is intentionally twice in the history. We started to soak > bugfixes in -next and then cherry pick them because we had too much > fun with things blowing up, and also too much fun with really messy > conflicts. It's not a botched patch in 4.5 or anything else nefarious > at all. Bah, sorry, I read it wrong. They have the same final state but they were on different bases. I somehow reversed this in my head and thought they had the same initial state and different final states. > > - We've genuinely failed to cherry-pick a bugfix over. It happens, > despite our best efforts (which of course includes running stuff on > Linus' tree). Please do a reverse bisect so we know which precise > commit fell through the cracks. If I find some time, I'll try. I've already failed miserably at bisecting this thing once. --Andy