From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759667AbZELMcs (ORCPT ); Tue, 12 May 2009 08:32:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757701AbZELMck (ORCPT ); Tue, 12 May 2009 08:32:40 -0400 Received: from tac.ki.iif.hu ([193.6.222.43]:48294 "EHLO tac.ki.iif.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757173AbZELMcj (ORCPT ); Tue, 12 May 2009 08:32:39 -0400 From: Ferenc Wagner To: linux-kernel@vger.kernel.org Subject: mmap vs mtime in 2.6.26 and up References: <874ovws94s.fsf@tac.ki.iif.hu> Date: Tue, 12 May 2009 14:32:38 +0200 In-Reply-To: <874ovws94s.fsf@tac.ki.iif.hu> (Ferenc Wagner's message of "Fri, 08 May 2009 02:58:43 +0200") Message-ID: <87ljp2v6vt.fsf@tac.ki.iif.hu> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've noticed that the last modification times of our RRD files got stuck after upgrading from 2.6.24 to 2.6.26 (Debian Etch -> Lenny; I also tested with 2.6.30-rc5, they are still stuck). It has some literature, most notably kernel bug #2645, but that's closed long ago and the resulting patch http://lkml.org/lkml/2008/1/22/370 is present in my kernels. Still, the test program (version 3 from the bug report) gives failures: $ ./mmap_test junk Modifying junk... Flushing data using sync()... Failure: time not changed. Not modifying junk... Flushing data using msync()... Success: time not changed. Not modifying junk... Flushing data using fsync()... Success: time not changed. Modifying junk... Flushing data using msync()... Failure: time not changed. Modifying junk... Flushing data using fsync()... Failure: time not changed. Is this as expected? I reckon the bug wasn't solved fully, but it seems to be worse that that. I don't know if it's related or not, but another anomaly appeared after the upgrade: minutes-long remount times. The machine always was under a fair load (10), but mount /usr -oremount,rw never took noticeable time. The IO load pushes two other filesystems. Now strace -tt shows: [...] 01:24:08.463813 stat64("/sbin/mount.xfs", 0xbfa40eb0) = -1 ENOENT (No such file or directory) 01:24:08.463904 mount("/dev/mapper/noc7-usr", "/usr", 0x894a2c8, MS_MGC_VAL|MS_NODEV|MS_REMOUNT, NULL) = 0 01:26:58.705387 readlink("/dev", 0xbfa3ef3b, 4096) = -1 EINVAL (Invalid argument) [...] After this, remount ro and rw again are quick for some time. (I couldn't test this part with 2.6.30-rc5, but again, this may be totally unrelated.) This bug is quite serious in our environment, as it thwarts the backup software. The file system is xfs; rw,nosuid,nodev,nobarrier,noquota. -- Regards, Feri.