Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756335Ab2HJKLG (ORCPT ); Fri, 10 Aug 2012 06:11:06 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:55610 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751236Ab2HJKLB (ORCPT ); Fri, 10 Aug 2012 06:11:01 -0400 MIME-Version: 1.0 X-Originating-IP: [178.83.130.250] In-Reply-To: <5021F00B.7000503@ionic.de> References: <5021F00B.7000503@ionic.de> Date: Fri, 10 Aug 2012 12:10:59 +0200 Message-ID: Subject: Re: null pointer dereference while loading i915 From: Daniel Vetter To: Mihai Moldovan Cc: LKML Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1884 Lines: 41 On Wed, Aug 8, 2012 at 6:50 AM, Mihai Moldovan wrote: > Hi Daniel, hi list > > ever since version 3.2.0 (maybe even earlier, but 3.0.2 is still working fine), > my box is crashing when loading the i915 driver (mode-setting enabled.) > > The current version I'm testing with is 3.5.0. > > I was able to get the BUG output (please forgive any errors/flips in the output, > I have had to transcribe the messages from the screen/images), however, I'm not > able to find out what's wrong. > > If I see it correctly, there's a null pointer dereference in a printk called > from inside gmbus_xfer. The only printk calls I can see in > drivers/gpu/drm/i915/intel_i2c.c gmbus_xfer() however are issued by the > DRM_DEBUG_KMS() and DRM_INFO() macros. > Neither call looks wrong to me, I even tried to swap adapter->name with > bus->adapter.name and make *sure* i < num is true, but haven't had any success. > > I'd really like to see this bug fixed, as it's preventing me from updating the > kernel for over a year now. > > Also, while 3.0.2 works, it *does* spew error/warning messages related to gmbus > and I've had corrupted VTs in the past (albeit after a long uptime with multiple > X restarting and DVI cable unplugging/reattaching events), so maybe there's a > lot more broken than "expected". Hm, this is rather strange. gmbus should not be enable on 3.2 nor 3.0, since exactly this issue might happen. We've re-enabled gmbus again on 3.5 after having fixed this bug. Are you sure that this is plain 3.2 you're running? Yours, Daniel -- Daniel Vetter daniel.vetter@ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- 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/