From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993181AbXDSIS3 (ORCPT ); Thu, 19 Apr 2007 04:18:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2993187AbXDSISY (ORCPT ); Thu, 19 Apr 2007 04:18:24 -0400 Received: from brick.kernel.dk ([80.160.20.94]:17294 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993180AbXDSIEZ (ORCPT ); Thu, 19 Apr 2007 04:04:25 -0400 Date: Thu, 19 Apr 2007 10:01:57 +0200 From: Jens Axboe To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-aio@kvack.org, reiserfs-dev@namesys.com, "Vladimir V. Saveliev" , linux-mm@kvack.org Subject: Re: dio_get_page() lockdep complaints Message-ID: <20070419080157.GC20928@kernel.dk> References: <20070419073828.GB20928@kernel.dk> <20070419010142.5b7b00cd.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070419010142.5b7b00cd.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 19 2007, Andrew Morton wrote: > On Thu, 19 Apr 2007 09:38:30 +0200 Jens Axboe wrote: > > > Hi, > > > > Doing some testing on CFQ, I ran into this 100% reproducible report: > > > > ======================================================= > > [ INFO: possible circular locking dependency detected ] > > 2.6.21-rc7 #5 > > ------------------------------------------------------- > > fio/9741 is trying to acquire lock: > > (&mm->mmap_sem){----}, at: [] dio_get_page+0x54/0x161 > > > > but task is already holding lock: > > (&inode->i_mutex){--..}, at: [] mutex_lock+0x1c/0x1f > > > > which lock already depends on the new lock. > > > > This is the correct ranking: i_mutex outside mmap_sem. > > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (&inode->i_mutex){--..}: > > [] __lock_acquire+0xdee/0xf9c > > [] lock_acquire+0x57/0x70 > > [] __mutex_lock_slowpath+0x73/0x297 > > [] mutex_lock+0x1c/0x1f > > [] reiserfs_file_release+0x54/0x447 > > [] __fput+0x53/0x101 > > [] fput+0x19/0x1c > > [] remove_vma+0x3b/0x4d > > [] do_munmap+0x17f/0x1cf > > [] sys_munmap+0x32/0x42 > > [] sysenter_past_esp+0x5d/0x99 > > [] 0xffffffff > > > > -> #0 (&mm->mmap_sem){----}: > > [] __lock_acquire+0xc4c/0xf9c > > [] lock_acquire+0x57/0x70 > > [] down_read+0x3a/0x4c > > [] dio_get_page+0x54/0x161 > > [] __blockdev_direct_IO+0x514/0xe2a > > [] ext3_direct_IO+0x98/0x1e5 > > [] generic_file_direct_IO+0x63/0x133 > > [] generic_file_aio_read+0x16b/0x222 > > [] aio_rw_vect_retry+0x5a/0x116 > > [] aio_run_iocb+0x69/0x129 > > [] io_submit_one+0x194/0x2eb > > [] sys_io_submit+0x92/0xe7 > > [] syscall_call+0x7/0xb > > [] 0xffffffff > > But here reiserfs is taking i_mutex in its file_operations.release(), > which can be called under mmap_sem. > > Vladimir's recent de14569f94513279e3d44d9571a421e9da1759ae. > "resierfs: avoid tail packing if an inode was ever mmapped" comes real > close to this code, but afaict it did not cause this bug. > > I can't think of anything which we've done in the 2.6.21 cycle which > would have caused this to start happening. Odd. The bug may be holder, let me know if you want me to check 2.6.20 or earlier. > > The test run was fio, the job file used is: > > > > # fio job file snip below > > [global] > > bs=4k > > buffered=0 > > ioengine=libaio > > iodepth=4 > > thread > > > > [readers] > > numjobs=8 > > size=128m > > rw=read > > # fio job file snip above > > > > Filesystem was ext3, default mkfs and mount options. Kernel was > > 2.6.21-rc7 as of this morning, with some CFQ patches applied. > > > > It's interesting that lockdep learned the (wrong) ranking from a reiserfs > operation then later detected it being violated by ext3. It's a scratch test box, which for some reason has reiserfs as the rootfs. So reiser gets to run first :-) -- Jens Axboe