From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758572AbXI3Pxv (ORCPT ); Sun, 30 Sep 2007 11:53:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757050AbXI3Pxo (ORCPT ); Sun, 30 Sep 2007 11:53:44 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:51844 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757363AbXI3Pxn (ORCPT ); Sun, 30 Sep 2007 11:53:43 -0400 Date: Sun, 30 Sep 2007 17:53:30 +0200 From: Ingo Molnar To: Jan Luebbe Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH] fix console change race exposed by CFS Message-ID: <20070930155328.GE24077@elte.hu> References: <1191084471.24185.11.camel@polaris> <20070930072056.GA18108@elte.hu> <1191141065.10375.9.camel@polaris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1191141065.10375.9.camel@polaris> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7-deb -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0015] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Jan Luebbe wrote: > I'm currenly porting the OpenMoko patchset to 2.6.23-rc8. We are using > psplash and kdrive. When booting, I got an error from psplash about > being unable to switch consoles. Strangely, it was possible to start > kdrive manually. So i set up qemu for kernel debugging, set some > interesting breakpoints and then saw that it was scheduling away > directly after the kill_pid. Then it was quite obvious. > > It was triggering every time, on the device and in qemu identically. > Most people testing the RCs probably don't run psplash (or any other > program which sets vt_mode.mode to VT_PROCESS), so it wasn't noticed > earlier. thx for the description. I did some searching on google.com/codesearch, and here are some other console apps that make active use of VT_PROCESS: 1diskxwin-2.0.0/X11/programs/Xserver/hw/kdrive/linux/linux.c usr/include/dev/wscons/wsdisplay_compat_usl.c busybox-1.01/loginutils/vlock.c allegro-4.2.2/src/linux/vtswitch.c tvision/classes/linux/linuxkey.cc xc/programs/Xserver/hw/xfree86/os-support/pmax/pmax_init.c aalib-1.4.0/src/aalinuxkbd.c qt-embedded-opensource-4.0.0-b2/src/gui/embedded/qkbdtty_qws.cpp mc-4.5.55/src/cons.handler.c psplash-0.1/psplash-console.c quakeforge-0.5.5/libs/video/targets/vid_fbdev.c just in case someone has a regression with any of them, on an older kernel. To me it appears X should have triggered this too. Perhaps people dont switch between VGA and X all that frequently anymore ... Ingo