From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 19 Apr 2007 01:01:42 -0700 From: Andrew Morton Subject: Re: dio_get_page() lockdep complaints Message-Id: <20070419010142.5b7b00cd.akpm@linux-foundation.org> In-Reply-To: <20070419073828.GB20928@kernel.dk> References: <20070419073828.GB20928@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Jens Axboe Cc: linux-kernel@vger.kernel.org, linux-aio@kvack.org, reiserfs-dev@namesys.com, "Vladimir V. Saveliev" , linux-mm@kvack.org List-ID: 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 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org