Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752533AbbHUImm (ORCPT ); Fri, 21 Aug 2015 04:42:42 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:47756 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751518AbbHUImj (ORCPT ); Fri, 21 Aug 2015 04:42:39 -0400 Message-ID: <55D6E466.5060706@ti.com> Date: Fri, 21 Aug 2015 11:42:14 +0300 From: Tomi Valkeinen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: =?UTF-8?B?UGFsaSBSb2jDoXI=?= , Jean-Christophe Plagniol-Villard , Jyri Sarha CC: , , , Pavel Machek , Sebastian Reichel , Aaro Koskinen , Tony Lindgren , Nishanth Menon Subject: Re: omapdss: Division by zero in kernel References: <201507241803.42891@pali> In-Reply-To: <201507241803.42891@pali> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="3fXiekjU5QQHo2X9se3IiX54UKFeu3Jig" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2245 Lines: 62 --3fXiekjU5QQHo2X9se3IiX54UKFeu3Jig Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 24/07/15 19:03, Pali Roh=C3=A1r wrote: > Hello, >=20 > when on N900 (real HW or qemu) I run this command >=20 > / # echo 0 > /sys/devices/platform/omapdss/overlay0/enabled && echo 0 >= /sys/class/graphics/fb0/size >=20 > then kernel crash with this error message >=20 > / # [ 29.904113] Division by zero in kernel. The problem is that fb console uses the kernel mmapped framebuffer, but omapfb is not aware of the fb console. So the above commands free the framebuffer, as omapfb thinks no one is using it, and then fb console tries to touch the fb. omapfb tracks mmaps from userspace, and refuses to free a fb it it's mmapped. I don't know how to fix it straight away. Maybe there's a way for omapfb to check if the fbcon uses the fb in question, and if so, refuses to release/resize the memory. Tomi --3fXiekjU5QQHo2X9se3IiX54UKFeu3Jig Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJV1uRmAAoJEPo9qoy8lh71FzYP/1nBOv9YOJ+f8yCeXQMr4qFU wZKpfElAmUeXP+9uWhKiXIsHENzaw0M1shR/UoTgE3oe7nreVke5/2X7zImGCnwd Qk+AZpLtZQ6I1dsIw7+ya24H/7MSyDi+JHrdfVmjJfDePKikEREjr0oWbjLE02fy fxN0ka2lVFvQKYPgKWq43OQhLeFIcFpcGkv0PfaYgdg93XZycdtgKiFs2NoGMyG7 tbhf4WvMx4ICwVtz1wqmrYJMh+x5sVAi5yNEZUTeZc5SO54OzyuVM2jo9ip3rgsz y26ZrszRLIsNbhJDD1X00QtdWqXYfsgimpkvFBJJBgnvX2+cysGe/7g1FyzXoFRN hqsR17T5AHe6kR99gVG9jftmFn7pEb3rRr2hUwvJ5nlJwiDTd9oYQS3GGt53SOQU RGkcMbu4vJrLcFSk3PylwGsUKmKQEkaTXk/HCytyWm0dfR5ftvH4MMvT5Vq3l2pE tP2sdEK5DtrBlyCWSSIDZVBaFNP4jxOAWV5K1rT41Grm9cJaMuYolpG2dzS7I69N EcMG8u0hltXE43vKvDiFVzQwKYTyLvMV7+08h/zNWS71WurkI6qbZZWOubf/18mg 8oNjboIj1X0Z2MW3fHv62Casx2n+2xnOy3rEodlv/sQi5vL67WdGUL3LwCYaEZVX 2ZAuOL5o+ThndqBL8I2c =HNet -----END PGP SIGNATURE----- --3fXiekjU5QQHo2X9se3IiX54UKFeu3Jig-- -- 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/