Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751543AbVJLUMV (ORCPT ); Wed, 12 Oct 2005 16:12:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751545AbVJLUMV (ORCPT ); Wed, 12 Oct 2005 16:12:21 -0400 Received: from artax.karlin.mff.cuni.cz ([195.113.31.125]:31463 "EHLO artax.karlin.mff.cuni.cz") by vger.kernel.org with ESMTP id S1751542AbVJLUMU (ORCPT ); Wed, 12 Oct 2005 16:12:20 -0400 Date: Wed, 12 Oct 2005 22:12:18 +0200 (CEST) From: Mikulas Patocka To: Jeff Mahoney Cc: Anton Altaparmakov , Glauber de Oliveira Costa , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, ext2-devel@lists.sourceforge.net, hirofumi@mail.parknet.co.jp, linux-ntfs-dev@lists.sourceforge.net, aia21@cantab.net, hch@infradead.org, viro@zeniv.linux.org.uk, akpm@osdl.org Subject: Re: [PATCH] Use of getblk differs between locations In-Reply-To: <434D6CFA.4080802@suse.com> Message-ID: References: <20051010204517.GA30867@br.ibm.com> <20051010214605.GA11427@br.ibm.com> <1129017155.12336.4.camel@imp.csi.cam.ac.uk> <434D6932.1040703@suse.com> <434D6CFA.4080802@suse.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1263 Lines: 28 >> Is memory management ready for this? Can't deadlock like this happen? >> - displaying dialog window needs memory, so it waits until memory will >> be available >> - system decides to write some write-back cached data in order to free >> memory >> - the write of these data waits until the dialog window is displayed, >> user inserts the device and clicks 'OK' > > No, it's not, and deadlock is definitely possible. However, if we're at > the point where memory is tight enough that it's an issue, the timer can > expire and all the pending i/o is dropped just as it would be without > the multipath code enabled. > > I'm not saying it's a solution ready for production, just a good > starting point. But discarding data sometimes on USB unplug is even worse than discarding data always --- users will by experimenting learn that linux doesn't discard write-cached data and reminds them to replug the device --- and one day, randomly, they lose their data because of some memory management condition... Mikulas - 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/