Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965171AbXAGVhr (ORCPT ); Sun, 7 Jan 2007 16:37:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965201AbXAGVhr (ORCPT ); Sun, 7 Jan 2007 16:37:47 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:52074 "EHLO omx2.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965171AbXAGVhq (ORCPT ); Sun, 7 Jan 2007 16:37:46 -0500 Date: Mon, 8 Jan 2007 08:37:34 +1100 From: David Chinner To: linux-kernel Mailing List Cc: xfs@oss.sgi.com Subject: Re: xfs_file_ioctl / xfs_freeze: BUG: warning at kernel/mutex-debug.c:80/debug_mutex_unlock() Message-ID: <20070107213734.GS44411608@melbourne.sgi.com> References: <20070104001420.GA32440@m.safari.iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070104001420.GA32440@m.safari.iki.fi> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6330 Lines: 156 On Thu, Jan 04, 2007 at 02:14:21AM +0200, Sami Farin wrote: > just a simple test I did... > xfs_freeze -f /mnt/newtest > cp /etc/fstab /mnt/newtest > xfs_freeze -u /mnt/newtest > > 2007-01-04 01:44:30.341979500 <4>BUG: warning at kernel/mutex-debug.c:80/debug_mutex_unlock() > 2007-01-04 01:44:30.385771500 <4> [] dump_trace+0x215/0x21a > 2007-01-04 01:44:30.385774500 <4> [] show_trace_log_lvl+0x1a/0x30 > 2007-01-04 01:44:30.385775500 <4> [] show_trace+0x12/0x14 > 2007-01-04 01:44:30.385777500 <4> [] dump_stack+0x19/0x1b > 2007-01-04 01:44:30.385778500 <4> [] debug_mutex_unlock+0x69/0x120 > 2007-01-04 01:44:30.385779500 <4> [] __mutex_unlock_slowpath+0x44/0xf0 > 2007-01-04 01:44:30.385780500 <4> [] mutex_unlock+0x8/0xa > 2007-01-04 01:44:30.385782500 <4> [] thaw_bdev+0x57/0x6e > 2007-01-04 01:44:30.385791500 <4> [] xfs_ioctl+0x7ce/0x7d3 > 2007-01-04 01:44:30.385793500 <4> [] xfs_file_ioctl+0x33/0x54 > 2007-01-04 01:44:30.385794500 <4> [] do_ioctl+0x76/0x85 > 2007-01-04 01:44:30.385795500 <4> [] vfs_ioctl+0x59/0x1aa > 2007-01-04 01:44:30.385796500 <4> [] sys_ioctl+0x67/0x77 > 2007-01-04 01:44:30.385797500 <4> [] syscall_call+0x7/0xb > 2007-01-04 01:44:30.385799500 <4> [<001be410>] 0x1be410 > 2007-01-04 01:44:30.385800500 <4> ======================= > > fstab was there just fine after -u. Oh, that still hasn't been fixed? Generic bug, not XFS - the global semaphore->mutex cleanup converted the bd_mount_sem to a mutex, and mutexes complain loudly when a the process unlocking the mutex is not the process that locked it. Basically, the generic code is broken - the bd_mount_mutex needs to be reverted back to a semaphore because it is locked and unlocked by different processes. The following patch does this.... BTW, Sami, can you cc xfs@oss.sgi.com on XFS bug reports in future; you'll get more XFS savvy eyes there..... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group --- Revert bd_mount_mutex back to a semaphore so that xfs_freeze -f /mnt/newtest; xfs_freeze -u /mnt/newtest works safely and doesn't produce lockdep warnings. Signed-off-by: Dave Chinner --- fs/block_dev.c | 2 +- fs/buffer.c | 6 +++--- fs/gfs2/ops_fstype.c | 4 ++-- fs/super.c | 4 ++-- include/linux/fs.h | 2 +- 5 files changed, 9 insertions(+), 9 deletions(-) Index: 2.6.x-xfs-new/fs/block_dev.c =================================================================== --- 2.6.x-xfs-new.orig/fs/block_dev.c 2006-12-22 10:53:20.000000000 +1100 +++ 2.6.x-xfs-new/fs/block_dev.c 2007-01-08 08:26:15.843378600 +1100 @@ -263,7 +263,7 @@ static void init_once(void * foo, kmem_c { memset(bdev, 0, sizeof(*bdev)); mutex_init(&bdev->bd_mutex); - mutex_init(&bdev->bd_mount_mutex); + sema_init(&bdev->bd_mount_sem, 1); INIT_LIST_HEAD(&bdev->bd_inodes); INIT_LIST_HEAD(&bdev->bd_list); #ifdef CONFIG_SYSFS Index: 2.6.x-xfs-new/fs/buffer.c =================================================================== --- 2.6.x-xfs-new.orig/fs/buffer.c 2006-12-12 12:04:51.000000000 +1100 +++ 2.6.x-xfs-new/fs/buffer.c 2007-01-08 08:28:40.832542651 +1100 @@ -179,7 +179,7 @@ int fsync_bdev(struct block_device *bdev * freeze_bdev -- lock a filesystem and force it into a consistent state * @bdev: blockdevice to lock * - * This takes the block device bd_mount_mutex to make sure no new mounts + * This takes the block device bd_mount_sem to make sure no new mounts * happen on bdev until thaw_bdev() is called. * If a superblock is found on this device, we take the s_umount semaphore * on it to make sure nobody unmounts until the snapshot creation is done. @@ -188,7 +188,7 @@ struct super_block *freeze_bdev(struct b { struct super_block *sb; - mutex_lock(&bdev->bd_mount_mutex); + down(&bdev->bd_mount_sem); sb = get_super(bdev); if (sb && !(sb->s_flags & MS_RDONLY)) { sb->s_frozen = SB_FREEZE_WRITE; @@ -230,7 +230,7 @@ void thaw_bdev(struct block_device *bdev drop_super(sb); } - mutex_unlock(&bdev->bd_mount_mutex); + up(&bdev->bd_mount_sem); } EXPORT_SYMBOL(thaw_bdev); Index: 2.6.x-xfs-new/fs/gfs2/ops_fstype.c =================================================================== --- 2.6.x-xfs-new.orig/fs/gfs2/ops_fstype.c 2006-12-12 12:04:58.000000000 +1100 +++ 2.6.x-xfs-new/fs/gfs2/ops_fstype.c 2007-01-08 08:27:12.847973663 +1100 @@ -867,9 +867,9 @@ static int gfs2_get_sb_meta(struct file_ error = -EBUSY; goto error; } - mutex_lock(&sb->s_bdev->bd_mount_mutex); + down(&sb->s_bdev->bd_mount_sem); new = sget(fs_type, test_bdev_super, set_bdev_super, sb->s_bdev); - mutex_unlock(&sb->s_bdev->bd_mount_mutex); + up(&sb->s_bdev->bd_mount_sem); if (IS_ERR(new)) { error = PTR_ERR(new); goto error; Index: 2.6.x-xfs-new/fs/super.c =================================================================== --- 2.6.x-xfs-new.orig/fs/super.c 2006-12-22 11:45:59.000000000 +1100 +++ 2.6.x-xfs-new/fs/super.c 2007-01-08 08:24:20.718330640 +1100 @@ -736,9 +736,9 @@ int get_sb_bdev(struct file_system_type * will protect the lockfs code from trying to start a snapshot * while we are mounting */ - mutex_lock(&bdev->bd_mount_mutex); + down(&bdev->bd_mount_sem); s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); - mutex_unlock(&bdev->bd_mount_mutex); + up(&bdev->bd_mount_sem); if (IS_ERR(s)) goto error_s; Index: 2.6.x-xfs-new/include/linux/fs.h =================================================================== --- 2.6.x-xfs-new.orig/include/linux/fs.h 2006-12-12 12:06:31.000000000 +1100 +++ 2.6.x-xfs-new/include/linux/fs.h 2007-01-08 08:24:53.602060200 +1100 @@ -456,7 +456,7 @@ struct block_device { struct inode * bd_inode; /* will die */ int bd_openers; struct mutex bd_mutex; /* open/close mutex */ - struct mutex bd_mount_mutex; /* mount mutex */ + struct semaphore bd_mount_sem; struct list_head bd_inodes; void * bd_holder; int bd_holders; - 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/