From patchwork Mon Jul 13 05:56:10 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Maarten Lankhorst X-Patchwork-Id: 6774221 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6F3989F2E8 for ; Mon, 13 Jul 2015 05:56:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9235620678 for ; Mon, 13 Jul 2015 05:56:16 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id AAE17205F2 for ; Mon, 13 Jul 2015 05:56:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1E5CC6E0F4; Sun, 12 Jul 2015 22:56:14 -0700 (PDT) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTP id EECC86E0F4 for ; Sun, 12 Jul 2015 22:56:12 -0700 (PDT) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 12 Jul 2015 22:56:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,459,1432623600"; d="scan'208";a="745930045" Received: from cfinn-mobl.ger.corp.intel.com (HELO patser.lan) ([10.252.21.57]) by fmsmga001.fm.intel.com with ESMTP; 12 Jul 2015 22:56:10 -0700 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 Subject: Re: [4.2.0-rc1-00201-g59c3cb5] Regression: kernel NULL pointer dereference References: In-Reply-To: Cc: Linux Kernel Mailing List , DRI X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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);