From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Circular locking dependency with delalloc
Date: Thu, 22 May 2008 15:20:11 +0530
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=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.26-rc2 #56
-------------------------------------------------------
umount/2662 is trying to acquire lock:
(jbd2_handle){--..}, at: [<c01fa63b>] jbd2_journal_start+0xce/0xf0

but task is already holding lock:
(&type->s_lock_key#7){--..}, at: [<c0169685>] lock_super+0x1b/0x1d

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->s_lock_key#7){--..}:
[<c013cd50>] __lock_acquire+0x97f/0xb32
[<c013cf6f>] lock_acquire+0x6c/0x89
[<c043ac8a>] mutex_lock_nested+0xc9/0x248
[<c0169685>] lock_super+0x1b/0x1d
[<c01db851>] ext4_orphan_add+0x1b/0x12e
[<c01e5143>] ext4_ext_truncate+0x99/0x166
[<c01d7664>] ext4_truncate+0x84/0x40d
[<c01d88b0>] ext4_delete_inode+0x74/0xc0
[<c01790f4>] generic_delete_inode+0x61/0xcb
[<c0179170>] generic_drop_inode+0x12/0x137
[<c01787e3>] iput+0x4b/0x4e
[<c0170c4f>] do_unlinkat+0xd3/0x145
[<c0170cd1>] sys_unlink+0x10/0x12
[<c0103931>] sysenter_past_esp+0x6a/0xb1
[<ffffffff>] 0xffffffff

-> #1 (&ei->i_data_sem){----}:
[<c013cd50>] __lock_acquire+0x97f/0xb32
[<c013cf6f>] lock_acquire+0x6c/0x89
[<c043b1d0>] down_read+0x2b/0x65
[<c01d6afe>] ext4_get_blocks_wrap+0x2b/0xfc
[<c01d6ca5>] ext4_getblk+0x49/0x18a
[<c01da947>] ext4_find_entry+0x331/0x58b
[<c01dc7c3>] ext4_unlink+0x6e/0x18e
[<c016f236>] vfs_unlink+0x4d/0xa5
[<c0170c23>] do_unlinkat+0xa7/0x145
[<c0170cd1>] sys_unlink+0x10/0x12
[<c0103931>] sysenter_past_esp+0x6a/0xb1
[<ffffffff>] 0xffffffff

-> #0 (jbd2_handle){--..}:
[<c013cc77>] __lock_acquire+0x8a6/0xb32
[<c013cf6f>] lock_acquire+0x6c/0x89
[<c01fa650>] jbd2_journal_start+0xe3/0xf0
[<c01ddb4b>] ext4_journal_start_sb+0x40/0x42
[<c01d8c0c>] ext4_da_writepages+0x45/0xbb
[<c0150176>] do_writepages+0x23/0x34
[<c0180fe6>] __writeback_single_inode+0x12a/0x260
[<c01811bc>] write_inode_now+0x72/0xbc
[<c01791ef>] generic_drop_inode+0x91/0x137
[<c01787e3>] iput+0x4b/0x4e
[<c01ff465>] jbd2_journal_destroy+0x19f/0x1c9
[<c01de66c>] ext4_put_super+0x35/0x18d
[<c0169e19>] generic_shutdown_super+0x52/0xd3
[<c0169ea9>] kill_block_super+0xf/0x20
[<c0169f4a>] deactivate_super+0x3f/0x51
[<c017b4b3>] mntput_no_expire+0xba/0xdd
[<c017b955>] sys_umount+0x259/0x29b
[<c0103931>] sysenter_past_esp+0x6a/0xb1
[<ffffffff>] 0xffffffff

other info that might help us debug this:

2 locks held by umount/2662:
#0:  (&type->s_umount_key#17){----}, at: [<c0169f45>] deactivate_super+0x3a/0x51
#1:  (&type->s_lock_key#7){--..}, at: [<c0169685>] lock_super+0x1b/0x1d

stack backtrace:
Pid: 2662, comm: umount Not tainted 2.6.26-rc2 #56
[<c013af32>] print_circular_bug_tail+0x5b/0x66
[<c013cc77>] __lock_acquire+0x8a6/0xb32
[<c043c44d>] ? _spin_unlock+0x27/0x3c
[<c013cf6f>] lock_acquire+0x6c/0x89
[<c01fa63b>] ? jbd2_journal_start+0xce/0xf0
[<c01fa650>] jbd2_journal_start+0xe3/0xf0
[<c01fa63b>] ? jbd2_journal_start+0xce/0xf0
[<c01ddb4b>] ext4_journal_start_sb+0x40/0x42
[<c01d8c0c>] ext4_da_writepages+0x45/0xbb
[<c01d8bc7>] ? ext4_da_writepages+0x0/0xbb
[<c0150176>] do_writepages+0x23/0x34
[<c0180fe6>] __writeback_single_inode+0x12a/0x260
[<c01811bc>] write_inode_now+0x72/0xbc
[<c01791ef>] generic_drop_inode+0x91/0x137
[<c01787e3>] iput+0x4b/0x4e
[<c01ff465>] jbd2_journal_destroy+0x19f/0x1c9
[<c0132571>] ? autoremove_wake_function+0x0/0x33
[<c01de66c>] ext4_put_super+0x35/0x18d
[<c0169e19>] generic_shutdown_super+0x52/0xd3
[<c0169ea9>] kill_block_super+0xf/0x20
[<c0169f4a>] deactivate_super+0x3f/0x51
[<c017b4b3>] mntput_no_expire+0xba/0xdd
[<c017b955>] sys_umount+0x259/0x29b
[<c016b482>] ? vfs_stat+0x11/0x13
[<c010396c>] ? sysenter_past_esp+0xa5/0xb1
[<c0103931>] sysenter_past_esp+0x6a/0xb1
=======================
[ OK ]