From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162166AbdAIQuY (ORCPT ); Mon, 9 Jan 2017 11:50:24 -0500 Received: from mga06.intel.com ([134.134.136.31]:2764 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752570AbdAIQuX (ORCPT ); Mon, 9 Jan 2017 11:50:23 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,340,1477983600"; d="scan'208";a="920540645" Subject: Re: [Intel-gfx] 4.10-rc2 oops in DRM connector code To: Daniel Vetter References: <7fd16549-1349-a9e5-ceff-9aa6f748caae@intel.com> <20170109101516.y3acaev5ujbjugwl@phenom.ffwll.local> <16a1e734-667c-5d9a-c418-555b1f13e446@intel.com> Cc: Daniel Vetter , Jani Nikula , David Airlie , intel-gfx , dri-devel , Linux Kernel Mailing List From: Dave Hansen Message-ID: Date: Mon, 9 Jan 2017 08:50:22 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/2017 08:41 AM, Daniel Vetter wrote: > On Mon, Jan 9, 2017 at 2:40 PM, Dave Hansen wrote: >> Well, now I found where the -2 comes from. >> intel_dp_register_mst_connector() calls drm_connector_register(), which >> fails to add the kobject (warning below). But, it does zero error >> checking on the drm_connector_register() call and leaves the >> partially-constructed connector in place. >> >> The next time some poor, hapless code goes and tries to do anything with >> that kdev, they oops. I'm perplexed by this, though. The >> drm_dp_mst_topology_cbs->register_connector just returns void. It seems >> a bit goofy that it can't even _return_ failure. >> >> Is there some stable code to go back to here? Or, is there something >> about my configuration that's unique? I really wonder why nobody else >> is running into this. >> >> There's probably some other race going on here. This warning doesn't >> happen on every boot. > This smells more like the root-cause: Something goes wrong on boot > that prevents connectors from properly registering, then we fall over > later on. And the register callback is intentionally void, assuming > that any prep work has been done earlier and that therefore the > register step can't fail. Can you pls check whether the oops later on > only happens together with this warning at boot, or whether they're > not correlated? Looking through my logs, I can't find any instance of the oops without the warning at boot. So I do think the later oops is entirely caused by the issue warned about in early boot. My distro kernel (4.4.0-57-generic) is also unstable, but I haven't managed to capture a good oops there. It's hitting this, which I assume is unrelated: WARNING: CPU: 0 PID: 41 at /build/linux-lts-xenial-FdAdUy/linux- lts-xenial-4.4.0/ubuntu/i915/intel_pm.c:3675 skl_update_other_pipe_wm+0x191/0x1a0 [i915_bpo]()