From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f49.google.com (mail-wg0-f49.google.com [74.125.82.49]) by kanga.kvack.org (Postfix) with ESMTP id 07F376B0037 for ; Thu, 26 Dec 2013 22:22:18 -0500 (EST) Received: by mail-wg0-f49.google.com with SMTP id x12so7676490wgg.4 for ; Thu, 26 Dec 2013 19:22:18 -0800 (PST) Received: from mail-wi0-x231.google.com (mail-wi0-x231.google.com [2a00:1450:400c:c05::231]) by mx.google.com with ESMTPS id 10si12298294wjp.35.2013.12.26.19.22.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 26 Dec 2013 19:22:18 -0800 (PST) Received: by mail-wi0-f177.google.com with SMTP id cc10so9189374wib.10 for ; Thu, 26 Dec 2013 19:22:18 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 27 Dec 2013 14:22:18 +1100 Message-ID: Subject: Re: [REGRESSION] [BISECTED] MM patch causes kernel lockup with 3.12 and acpi_backlight=vendor From: Bradley Baetz Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: platform-driver-x86@vger.kernel.org, linux-mm@kvack.org, hannes@cmpxchg.org Cc: hdegoede@redhat.com Resending in plain text mode.... Bradley On Fri, Dec 27, 2013 at 2:21 PM, Bradley Baetz wrote: > Hi, > > I have a Dell laptop (Vostro 3560). When I boot Fedora 20 with the > acpi_backlight=vendor option, the kernel locks up hard during the boot > proces, when systemd runs udevadm trigger. This is a hard lockup - > magic-sysrq doesn't work, and neither does caps lock/vt-change/etc. > > I've bisected this to: > > commit 81c0a2bb515fd4daae8cab64352877480792b515 > Author: Johannes Weiner > Date: Wed Sep 11 14:20:47 2013 -0700 > > mm: page_alloc: fair zone allocator policy > > which seemed really unrelated, but I've confirmed that: > > - the commit before this patch doesn't cause the problem, and the commit > afterwrads does > - reverting that patch from 3.12.0 fixes the problem > - reverting that patch (and the partial revert > fff4068cba484e6b0abe334ed6b15d5a215a3b25) from master also fixes the problem > - reverting that patch from the fedora 3.12.5-302.fc20 kernel fixes the > problem > - applying that patch to 3.11.0 causes the problem > > so I'm pretty sure that that is the patch that causes (or at least triggers) > this issue > > I'm using the acpi_backlight option to get the backlight working - without > this the backlight doesn't work at all. Removing 'acpi_backlight=vendor' (or > blacklisting the dell-laptop module, which is effectively the same thing) > fixes the issue. > > The lockup happens when systemd runs "udevadm trigger", not when the module > is loaded - I can reproduce the issue by booting into emergency mode, > remounting the filesystem as rw, starting up systemd-udevd and running > udevadm trigger manually. It dies a few seconds after loading the > dell-laptop module. > > This happens even if I don't boot into X (using > systemd.unit=multi-user.target) > > Triggering udev individually for each item doesn't trigger the issue ie: > > for i in `udevadm --debug trigger --type=devices --action=add --dry-run > --verbose`; do echo $i; udevadm --debug trigger --type=devices --action=add > --verbose --parent-match=$i; sleep 1; done > > works, so I haven't been able to work out what specific combination of > actions are causing this. > > With the acpi_backlight option, I can manually read/write to the sysfs > dell-laptop backlight file, and it works (and changes the backlight as > expected) > > This is 100% reproducible. I've also tested by powering off the laptop and > pulling the battery just in case one of the previous boots with the bisect > left the hardware in a strange state - no change. > > I did successfully boot a 3.12 kernel on F19 (before I upgraded to F20), so > there's presumably something that F20 is doing differently. It was only one > boot though. > > I reported this to fedora > (https://bugzilla.redhat.com/show_bug.cgi?id=1045807) but it looks like this > is an upstream issue so I was asked to report it here. > > This is an 8-core single i7 cpu (one numa node) - its a laptop, so nothing > fancy. DMI data is attached to the fedora bug. > > Bradley -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org