From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga07.intel.com ([134.134.136.100]:12181 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbdBOJx3 (ORCPT ); Wed, 15 Feb 2017 04:53:29 -0500 From: Jani Nikula To: Daniel Vetter Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, stable@vger.kernel.org, Dhinakaran Pandiyan , Dave Airlie Subject: Re: [Intel-gfx] [PATCH RESEND] drm/dp/mst: fix kernel oops when turning off secondary monitor In-Reply-To: <87r32zri60.fsf@intel.com> References: <1487076561-2169-1-git-send-email-jani.nikula@intel.com> <20170214213843.GD11138@dvetter-linux.ger.corp.intel.com> <87r32zri60.fsf@intel.com> Date: Wed, 15 Feb 2017 11:53:26 +0200 Message-ID: <87fujfrd9l.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: stable-owner@vger.kernel.org List-ID: On Wed, 15 Feb 2017, Jani Nikula wrote: > On Tue, 14 Feb 2017, Daniel Vetter wrote: >> On Tue, Feb 14, 2017 at 02:49:21PM +0200, Jani Nikula wrote: >>> From: Pierre-Louis Bossart >>> >>> 100% reproducible issue found on SKL SkullCanyon NUC with two external >>> DP daisy-chained monitors in DP/MST mode. When turning off or changing >>> the input of the second monitor the machine stops with a kernel >>> oops. This issue happened with 4.8.8 as well as drm/drm-intel-nightly. >>> >>> This issue is traced to an inconsistent control flow in >>> drm_dp_update_payload_part1(): the 'port' pointer is set to NULL at the >>> same time as 'req_payload.num_slots' is set to zero, but the pointer is >>> dereferenced even when req_payload.num_slot is zero. >>> >>> The problematic dereference was introduced in commit dfda0df34 >>> ("drm/mst: rework payload table allocation to conform better") and may >>> impact all versions since v3.18 >>> >>> The fix suggested by Chris Wilson removes the kernel oops and was found to >>> work well after 10mn of monkey-testing with the second monitor power and >>> input buttons >>> >>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98990 >>> Fixes: dfda0df34264 ("drm/mst: rework payload table allocation to conform better.") >>> Cc: Dave Airlie >>> Cc: Chris Wilson >>> Cc: Nathan D Ciobanu >>> Cc: Dhinakaran Pandiyan >>> Cc: Sean Paul >>> Cc: # v3.18+ >>> Tested-by: Nathan D Ciobanu >>> Reviewed-by: Dhinakaran Pandiyan >>> Signed-off-by: Pierre-Louis Bossart >>> Signed-off-by: Jani Nikula >> >> You haz drm-misc commit rights, pls use them :-) > > Sure, I just wanted to have a fresh CI run on this. > >> Since it doesn't have deps, probably simplest to smash into drm-misc-fixes >> and then send a pull req to Dave right away. If you want, you can roll >> -fixes forward to -rc8 while at it. > > Will do. And pushed to drm-misc-fixes, thanks for the patch, review and testing. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center