From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754130Ab3LTHKq (ORCPT ); Fri, 20 Dec 2013 02:10:46 -0500 Received: from home.keithp.com ([63.227.221.253]:35773 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752622Ab3LTHKp (ORCPT ); Fri, 20 Dec 2013 02:10:45 -0500 From: Keith Packard To: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org Subject: Re: [PATCH] fbcon: Clean up fbcon data in fb_info on FB_EVENT_FB_UNBIND with 0 fbs In-Reply-To: <1387498677-25653-1-git-send-email-keithp@keithp.com> References: <1387498677-25653-1-git-send-email-keithp@keithp.com> User-Agent: Notmuch/0.16 (http://notmuchmail.org) Emacs/23.4.1 (i486-pc-linux-gnu) Date: Thu, 19 Dec 2013 23:10:39 -0800 Message-ID: <86pposdmkw.fsf@miki.keithp.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable Keith Packard writes: > When FB_EVENT_FB_UNBIND is sent, fbcon has two paths, one path taken > when there is another frame buffer to switch any affected vcs to and > another path when there isn't. What I meant to attach to this bug report but clearly failed was that I thi= nk this case essentially *always* occurs if you have a generic frame buffer driver loaded before a 'real' driver is loaded. In my case, this is efifb. So, we have a reference to freed memory hanging out on a timer list. I'm really unsure why this hasn't caused more grief, but I can say that it was greatly aggravated by adding 'fbcon=3Dvc:2-6' to the kernel command line, which limits fbcon to supporting consoles only on vt 2-6. Definitely one of those 'how could this ever have worked, and why hasn't my machine been crashing every day' moments when I read through the code. As the patch indicates, I'm not sure this patch is actually what we want, but I'd love to know if I've isolated the root cause correctly and then figure out what patch we actually want. For my own part, I've got a happy customer with the patch, which is definitely a nice way to end the day. =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIVAwUBUrPtb9siGmkAAAARAQhQqRAAouoxEF1w4ZelQ8UWaVDOZwOF7chbOKHU 16zulH5ehkxVxZeYhv4XKLiXYbhvs+pFkwgQljdrY7/5nx1jtfNyBe3MSIQTVK6N cTa+tFnI8k/dX58KWTLj9csexM9QsK3+mkS6WqNLYvjmzI/IhlDBBL8Dt9cfA7wW rbyq6FEhDcyibmGFbGDX5DE7TOtBvX2hdWhHIyFtYtIccWDDETSZdw5jt/Zv664f qlauxuQM6Dz/bY/v3CH9d7uTjnHFZ5n9LGmRe7SLxHr2PGKefmmjzGhrNopdEdLH MMxg3SIQWJ/hxmLuqF7pVnv28nTs9b1eChOqFSp8Zt+fgLfvho06q6ud7DyGyN3J aI/Myin/J6faE1cMAcnzLdqRIedJoEaGfSzc5nNg2tm4eavMLGBzBEjpNSlal2Du +SDLr3WPzWrvsFPIT/ej0TgLiskHmBizOQ76WuhksaA9SR5uXLgnA169PPq8mB8g 3aXueaYfeiJd/sPS6EwG0n9IIQIkiOfzKpoLeNt1stZz7vVNksnmc0ydGPyOVpbS yVlgTsCS18bbrbCuntPxJ9Q/b2ICmki79f6Ah2Nk61UKoaV9R52f9a7wlmxtDfUR 2T2gtuj99cqEG85Z2gqQqmt9B2II/Tn3LqQCaCYroFIpQmmnBeAgpP0yyQxlcl1Q qAQVVxnCcIk= =pxpa -----END PGP SIGNATURE----- --=-=-=--