Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933967AbZDIM7V (ORCPT ); Thu, 9 Apr 2009 08:59:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758974AbZDIM7A (ORCPT ); Thu, 9 Apr 2009 08:59:00 -0400 Received: from mail-fx0-f158.google.com ([209.85.220.158]:36542 "EHLO mail-fx0-f158.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933813AbZDIM64 (ORCPT ); Thu, 9 Apr 2009 08:58:56 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; b=nJYM971LY1AzCFjx92SANTL+5g/O1gnzn9ZJfO8SVXbXXMXg2k25wgfwZSBKojRi04 Y3LVhzqYVp46Z9gHesU7XKxD/Sem2r7A4xDyNtZ8kFQWi8P32dq738pDICXmPotINHD0 x1gVHe/kjv9utKaaRZEwzHrNJmWHRa63Py1J8= Date: Thu, 9 Apr 2009 14:58:51 +0200 From: Andrea Righi To: Eric Miao Cc: LKML , Geert Uytterhoeven , Krzysztof Helt , Andrew Morton , "Rafael J. Wysocki" , Andrey Borzenkov , "Antonino A. Daplas" , linux-fbdev-devel@lists.sourceforge.net, linux-pm@lists.linux-foundation.org, Dave Jones , Harvey Harrison , Johannes Weiner , Stefan Richter Subject: Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and mm->mmap_sem ...} causes Xfbdev not working Message-ID: <20090409125850.GA2727@linux> Mail-Followup-To: Eric Miao , LKML , Geert Uytterhoeven , Krzysztof Helt , Andrew Morton , "Rafael J. Wysocki" , Andrey Borzenkov , "Antonino A. Daplas" , linux-fbdev-devel@lists.sourceforge.net, linux-pm@lists.linux-foundation.org, Dave Jones , Harvey Harrison , Johannes Weiner , Stefan Richter References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1173 Lines: 33 On Thu, Apr 09, 2009 at 07:36:24PM +0800, Eric Miao wrote: > This happens on my Marvell PXA310-based Littleton platform with > Angstrom Distribution. The offending paths are many: > > FBIOPUT_VSCREENINFO: > lock_fb_info() > --> fb_set_var() > --> fb_notifier_call_chain() [FBINFO_MISC_USEREVENT] > --> fbcon_event_notifier() [FB_EVENT_MODE_CHANGE] > --> lock_fb_info() > > OK, now hang. I'd suggest a clean fix to the original assumption of > circular locking > issue and revert this commit first. > > -- > Cheers > - eric I can agree to revert 66c1ca019078220dc1bf968f2bb18421100ef147, since I don't have a clean fix for this. Pushing down fb_info->lock in fb_set_var() excluding to call fb_notifier_call_chain with fb_info->lock held doesn't seem to be so trivial... However, reverting this will re-introduce the circular locking dependency fb_info->lock => mm->mmap_sem => fb_info->lock. -Andrea -- 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/