While doing a filesystem balance, lockdep detecting a potential lock
ordering issue [1].
Thanks,
Daniel
--- [1]
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.38.1-341cd+ #10
-------------------------------------------------------
btrfs/1101 is trying to acquire lock:
(&sb->s_type->i_mutex_key#12){+.+.+.}, at: [<ffffffff812cddb9>]
prealloc_file_extent_cluster+0x59/0x180
but task is already holding lock:
(&fs_info->cleaner_mutex){+.+.+.}, at: [<ffffffff812cfcb7>]
btrfs_relocate_block_group+0x197/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&fs_info->cleaner_mutex){+.+.+.}:
[<ffffffff8109628a>] lock_acquire+0x5a/0x70
[<ffffffff816c9cde>] mutex_lock_nested+0x5e/0x390
[<ffffffff812828e1>] btrfs_commit_super+0x21/0xe0
[<ffffffff812857a2>] close_ctree+0x332/0x3a0
[<ffffffff8125fd08>] btrfs_put_super+0x18/0x30
[<ffffffff8113ae7d>] generic_shutdown_super+0x6d/0xf0
[<ffffffff8113af91>] kill_anon_super+0x11/0x60
[<ffffffff8113b6b5>] deactivate_locked_super+0x45/0x60
[<ffffffff8113c2b5>] deactivate_super+0x45/0x60
[<ffffffff81158729>] mntput_no_expire+0x99/0xf0
[<ffffffff8115996c>] sys_umount+0x7c/0x3c0
[<ffffffff81002dfb>] system_call_fastpath+0x16/0x1b
-> #1 (&type->s_umount_key#24){++++++}:
[<ffffffff8109628a>] lock_acquire+0x5a/0x70
[<ffffffff816ca372>] down_read+0x42/0x60
[<ffffffff8115e935>] writeback_inodes_sb_nr_if_idle+0x35/0x60
[<ffffffff812723ae>] shrink_delalloc+0xee/0x180
[<ffffffff81273253>] btrfs_delalloc_reserve_metadata+0x163/0x180
[<ffffffff812732ab>] btrfs_delalloc_reserve_space+0x3b/0x60
[<ffffffff8129563d>] btrfs_file_aio_write+0x61d/0x9c0
[<ffffffff81137f12>] do_sync_write+0xd2/0x110
[<ffffffff81138a88>] vfs_write+0xc8/0x190
[<ffffffff81138c3c>] sys_write+0x4c/0x90
[<ffffffff81002dfb>] system_call_fastpath+0x16/0x1b
-> #0 (&sb->s_type->i_mutex_key#12){+.+.+.}:
[<ffffffff810961a8>] __lock_acquire+0x1ba8/0x1c30
[<ffffffff8109628a>] lock_acquire+0x5a/0x70
[<ffffffff816c9cde>] mutex_lock_nested+0x5e/0x390
[<ffffffff812cddb9>] prealloc_file_extent_cluster+0x59/0x180
[<ffffffff812ce0a1>] relocate_file_extent_cluster+0x91/0x380
[<ffffffff812ce44b>] relocate_data_extent+0xbb/0xd0
[<ffffffff812cf843>] relocate_block_group+0x323/0x600
[<ffffffff812cfcc8>] btrfs_relocate_block_group+0x1a8/0x2d0
[<ffffffff812b09c3>] btrfs_relocate_chunk+0x83/0x600
[<ffffffff812b160d>] btrfs_balance+0x20d/0x280
[<ffffffff812b8b86>] btrfs_ioctl+0x1b6/0xa80
[<ffffffff8114a43d>] do_vfs_ioctl+0x9d/0x590
[<ffffffff8114a97a>] sys_ioctl+0x4a/0x80
[<ffffffff81002dfb>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
2 locks held by btrfs/1101:
#0: (&fs_info->volume_mutex){+.+.+.}, at: [<ffffffff812b148b>]
btrfs_balance+0x8b/0x280
#1: (&fs_info->cleaner_mutex){+.+.+.}, at: [<ffffffff812cfcb7>]
btrfs_relocate_block_group+0x197/0x2d0
stack backtrace:
Pid: 1101, comm: btrfs Tainted: G W 2.6.38.1-341cd+ #10
Call Trace:
[<ffffffff810937fb>] ? print_circular_bug+0xeb/0xf0
[<ffffffff810961a8>] ? __lock_acquire+0x1ba8/0x1c30
[<ffffffff812a5fd1>] ? map_private_extent_buffer+0xe1/0x210
[<ffffffff812cddb9>] ? prealloc_file_extent_cluster+0x59/0x180
[<ffffffff8109628a>] ? lock_acquire+0x5a/0x70
[<ffffffff812cddb9>] ? prealloc_file_extent_cluster+0x59/0x180
[<ffffffff810565f5>] ? add_preempt_count+0x75/0xd0
[<ffffffff816c9cde>] ? mutex_lock_nested+0x5e/0x390
[<ffffffff812cddb9>] ? prealloc_file_extent_cluster+0x59/0x180
[<ffffffff81125fa3>] ? init_object+0x43/0x80
[<ffffffff81051121>] ? get_parent_ip+0x11/0x50
[<ffffffff812cddb9>] ? prealloc_file_extent_cluster+0x59/0x180
[<ffffffff812ce0a1>] ? relocate_file_extent_cluster+0x91/0x380
[<ffffffff812ce44b>] ? relocate_data_extent+0xbb/0xd0
[<ffffffff812cf843>] ? relocate_block_group+0x323/0x600
[<ffffffff812cfcc8>] ? btrfs_relocate_block_group+0x1a8/0x2d0
[<ffffffff812b09c3>] ? btrfs_relocate_chunk+0x83/0x600
[<ffffffff812a62d2>] ? read_extent_buffer+0xf2/0x230
[<ffffffff8126c286>] ? btrfs_search_slot+0x886/0xa90
[<ffffffff8105654d>] ? sub_preempt_count+0x9d/0xd0
[<ffffffff812a62d2>] ? read_extent_buffer+0xf2/0x230
[<ffffffff812b160d>] ? btrfs_balance+0x20d/0x280
[<ffffffff812b8b86>] ? btrfs_ioctl+0x1b6/0xa80
[<ffffffff8103146c>] ? do_page_fault+0x1cc/0x440
[<ffffffff8114a43d>] ? do_vfs_ioctl+0x9d/0x590
[<ffffffff8113943f>] ? fget_light+0x1df/0x3c0
[<ffffffff8114a97a>] ? sys_ioctl+0x4a/0x80
[<ffffffff81002dfb>] ? system_call_fastpath+0x16/0x1b
--
Daniel J Blueman
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