From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263551AbUCTVzd (ORCPT ); Sat, 20 Mar 2004 16:55:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263552AbUCTVzd (ORCPT ); Sat, 20 Mar 2004 16:55:33 -0500 Received: from fw.osdl.org ([65.172.181.6]:12504 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S263551AbUCTVz2 (ORCPT ); Sat, 20 Mar 2004 16:55:28 -0500 Date: Sat, 20 Mar 2004 13:55:30 -0800 From: Andrew Morton To: "Michael W. Shaffer" Cc: linux-kernel@vger.kernel.org Subject: Re: Kernel 2.6.4 Hang in utime() on swap file Message-Id: <20040320135530.7f06a7b8.akpm@osdl.org> In-Reply-To: <20040320181630.27185.qmail@web10401.mail.yahoo.com> References: <20040320181630.27185.qmail@web10401.mail.yahoo.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Michael W. Shaffer" wrote: > > I have a Debian Sarge system running a 2.6 kernel (tested with 2.6.2, 2.6.3, > 2.6.4 with the same behavior as described here), and am seeing un-killable > hanging processes with our particular backup product. > > When the backup disk agent process is running, one the the last files it > tries to back up is a swap file at the path /swapfile00. The read of the > file appears to work fine, but then it wants to call utime() to reset the > atime/mtime on the file, and at this point the process becomes infinitely > hung, doing nothing, no more output from strace, never terminating. > > This only occurs if the swapfile is actively in use when the backup runs. If > I run swapoff to deactivate the swapfile, then the utime() call apparently > completes and the process immediately finishes and exits normally. If the > swapfile is not in use at all, everything works fine. > ho hum. We do this to prevent anyone from ftruncate()ing the swapfile while it is in use. That can destroy filesystems. Let me think about it a bit.