Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932331AbWI2Mpt (ORCPT ); Fri, 29 Sep 2006 08:45:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932341AbWI2Mpt (ORCPT ); Fri, 29 Sep 2006 08:45:49 -0400 Received: from ns.suse.de ([195.135.220.2]:37341 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S932331AbWI2Mps (ORCPT ); Fri, 29 Sep 2006 08:45:48 -0400 Date: Fri, 29 Sep 2006 14:45:47 +0200 Message-ID: From: Takashi Iwai To: Karsten Wiese Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, alsa-devel@lists.sourceforge.net Subject: Re: [PATCH] Reset file->f_op in snd_card_file_remove(). Take 2 In-Reply-To: <200609291429.21183.annabellesgarden@yahoo.de> References: <200609282228.02611.annabellesgarden@yahoo.de> <200609291429.21183.annabellesgarden@yahoo.de> User-Agent: Wanderlust/2.12.0 (Your Wildest Dreams) SEMI/1.14.6 (Maruoka) FLIM/1.14.7 (=?ISO-8859-4?Q?Sanj=F2?=) APEL/10.6 MULE XEmacs/21.5 (beta25) (eggplant) (+CVS-20060326) (i386-suse-linux) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2296 Lines: 71 At Fri, 29 Sep 2006 14:29:20 +0200, Karsten Wiese wrote: > > Am Freitag, 29. September 2006 12:48 schrieb Takashi Iwai: > > At Thu, 28 Sep 2006 22:28:02 +0200, > > Karsten Wiese wrote: > > > > > > Hi > > > > > > It oopses with 2.6.18-rt4 + alsa-kernel-1.0.13rc3 now. > > > I wrote before, 2.6.18-rt3 + alsa-driver-1.0.13rc3 would be ok, > > > but its not. bug showed again reliably under memory-pressure. > > > > > > Karsten > > > > > > === > > > > > > Reset file->f_op in snd_card_file_remove(). Take 2 > > > > > > > > > i think what happens here is: > > > > > > us428control runs, kernel has allocated a struct file for /dev/hwC1D0. > > > > > > usb disconnect > > > > > > snd_usb_usx2y calls snd_card_disconnect, > > > tells us428control to exit. > > > > > > snd_card_disconnect replaces /dev/hwC1D0's file->f_op > > > with a kmalloc()ed version, that would only allow releases. > > > > > > us428control starts exiting > > > > > > __fput is called with struct file for /dev/hwC1D0. > > > > > > snd_card_file_remove() is called, alsa notices struct file > > > for /dev/hwC1D0 is about to be closed. > > > with patch below, file->f_op would be set NULL now. > > > > > > snd_usb_usx2y's free()s snd_card instance and /dev/hwC1D0's > > > file->f_ops, those that would only allow releases. > > > > > > for reason I would like to know, > > > __fput is called again with struct file for /dev/hwC1D0 > > > from us428control's do_exit(). > > > __fput see's file->f_op is still set. > > > Without patch and under memory pressure, file->f_op can > > > point to anything now. > > > > > > > > > Signed-off-by: Karsten Wiese > > > > I guess this bug is fixed by Florin's patch below, juding from your > > explanation. Could you check it? > > > Florin's patch fixes it. > > This one for immediate consumation by mainline, mm, rt, > and the stable teams, hmm? It'll be pushed to mainline soon together with other ALSA fixes. Then I'll forward to stable, too. Takashi - 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/