Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751493AbbGMF4O (ORCPT ); Mon, 13 Jul 2015 01:56:14 -0400 Received: from mga11.intel.com ([192.55.52.93]:18413 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751123AbbGMF4M (ORCPT ); Mon, 13 Jul 2015 01:56:12 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,459,1432623600"; d="scan'208";a="745930045" Message-ID: <55A352FA.1000300@linux.intel.com> Date: Mon, 13 Jul 2015 07:56:10 +0200 From: Maarten Lankhorst User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Linus Torvalds , =?UTF-8?B?SsO2cmcgT3R0?= =?UTF-8?B?ZQ==?= , Daniel Vetter CC: David Airlie , DRI , Linux Kernel Mailing List Subject: Re: [4.2.0-rc1-00201-g59c3cb5] Regression: kernel NULL pointer dereference References:

In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1915 Lines: 50 Op 12-07-15 om 18:52 schreef Linus Torvalds: > On Sun, Jul 12, 2015 at 1:03 AM, Jörg Otte wrote: >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000009 >> IP: [] 0xffffffffbd3447bb > Ugh. Please enable KALLSYMS to get sane symbols. > > But yes, "crtc_state->base.active" is at offset 9 from "crtc_state", > so it's pretty clearly just that change frm > > - if (intel_crtc->active) { > + if (crtc_state->base.active) { > > and "crtc_state" is NULL. > > And the code very much knows that crtc_state can be NULL, since it's > initialized with > > crtc_state = state->base.state ? > intel_atomic_get_crtc_state(state->base.state, > intel_crtc) : NULL; > > Tssk. Daniel? Should I just revert that commit dec4f799d0a4 > ("drm/i915: Use crtc_state->active in primary check_plane func") for > now, or is there a better fix? Like just checking crtc_state for NULL? > > Linus More symbols would be nice. With the transitional helpers when crtc_state == NULL you don't want to update the scalers or funny things happen. Fix is probably something like this: diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index ba9321998a41..830e07b23a15 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -13276,7 +13276,7 @@ intel_check_primary_plane(struct drm_plane *plane, if (ret) return ret; - if (crtc_state->base.active) { + if (crtc_state ? crtc_state->base.active || crtc->state->active) { struct intel_plane_state *old_state = to_intel_plane_state(plane->state); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/