Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757099AbcJYIJi (ORCPT ); Tue, 25 Oct 2016 04:09:38 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34293 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752306AbcJYIJf (ORCPT ); Tue, 25 Oct 2016 04:09:35 -0400 Date: Tue, 25 Oct 2016 10:09:30 +0200 From: Daniel Vetter To: Takashi Iwai Cc: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Vetter , Noralf =?iso-8859-1?Q?Tr=F8nnes?= , David Airlie Subject: Re: [PATCH v2] drm/fb-helper: Don't call dirty callback for untouched clips Message-ID: <20161025080930.2wnshqm274mf4m5k@phenom.ffwll.local> Mail-Followup-To: Takashi Iwai , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Noralf =?iso-8859-1?Q?Tr=F8nnes?= , David Airlie References: <20161020150530.5787-1-tiwai@suse.de> <20161021125207.GH4329@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Operating-System: Linux phenom 4.6.0-1-amd64 User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2957 Lines: 81 On Tue, Oct 25, 2016 at 08:46:28AM +0200, Takashi Iwai wrote: > On Fri, 21 Oct 2016 14:52:07 +0200, > Ville Syrj?l? wrote: > > > > On Thu, Oct 20, 2016 at 05:05:30PM +0200, Takashi Iwai wrote: > > > Since 4.7 kernel, we've seen the error messages like > > > > > > kernel: [TTM] Buffer eviction failed > > > kernel: qxl 0000:00:02.0: object_init failed for (4026540032, 0x00000001) > > > kernel: [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO > > > > > > on QXL when switching and accessing on VT. The culprit was the > > > generic deferred_io code (qxl driver switched to it since 4.7). > > > There is a race between the dirty clip update and the call of > > > callback. > > > > > > In drm_fb_helper_dirty(), the dirty clip is updated in the spinlock, > > > while it kicks off the update worker outside the spinlock. Meanwhile > > > the update worker clears the dirty clip in the spinlock, too. Thus, > > > when drm_fb_helper_dirty() is called concurrently, schedule_work() is > > > called after the clip is cleared in the first worker call. > > > > > > This patch addresses it by validating the clip before calling the > > > dirty fb callback. > > > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98322 > > > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1003298 > > > Fixes: eaa434defaca ('drm/fb-helper: Add fb_deferred_io support') > > > Cc: > > > Signed-off-by: Takashi Iwai > > > > Reviewed-by: Ville Syrj?l? > > Daniel, could you pick this if it's OK as a quick fix? Currently > qxl driver is utterly broken, and we should recover it ASAP. On top > of this, we can put a more comprehensive fix covering both this and > dirtyfb ioctl code paths. I thought I've pinged Dave already to pick up, I'll poke him again. -Daniel > > > thanks, > > Takashi > > > > > > --- > > > v1->v2: simplified the code as suggested by Ville > > > > > > drivers/gpu/drm/drm_fb_helper.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > > > index 03414bde1f15..aae7df01864d 100644 > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > @@ -644,7 +644,9 @@ static void drm_fb_helper_dirty_work(struct work_struct *work) > > > clip->x2 = clip->y2 = 0; > > > spin_unlock_irqrestore(&helper->dirty_lock, flags); > > > > > > - helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1); > > > + /* call dirty callback only when it has been really touched */ > > > + if (clip_copy.x1 < clip_copy.x2 && clip_copy.y1 < clip_copy.y2) > > > + helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1); > > > } > > > > > > /** > > > -- > > > 2.10.1 > > > > -- > > Ville Syrj?l? > > Intel OTC > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch