[2.6.21] circular locking dependency found in QUOTA OFF

["Folkert van Heusden" <folkert@vanheusden.com>]

Hi,

When I cleanly reboot my pc running 2.6.21 on a P4 with HT and 2GB of ram
and system on an 1-filesystem IDE disk, I get the following circular
locking dependency error:

[330961.226405] =======================================================
[330961.226489] [ INFO: possible circular locking dependency detected ]
[330961.226531] 2.6.21 #5
[330961.226569] -------------------------------------------------------
[330961.226611] quotaoff/12249 is trying to acquire lock:
[330961.226652]  (&sb->s_type->i_mutex_key#4){--..}, at: [<c120e2a1>]
mutex_lock+0x8/0xa
[330961.226861]
[330961.226862] but task is already holding lock:
[330961.226938]  (&s->s_dquot.dqonoff_mutex){--..}, at: [<c120e2a1>]
mutex_lock+0x8/0xa
[330961.227111]
[330961.227111] which lock already depends on the new lock.
[330961.227112]
[330961.227225]
[330961.227225] the existing dependency chain (in reverse order) is:
[330961.227303]
[330961.227303] -> #1 (&s->s_dquot.dqonoff_mutex){--..}:
[330961.227473]        [<c1039b02>] check_prev_add+0x15b/0x281
[330961.227766]        [<c1039cb3>] check_prevs_add+0x8b/0xe8
[330961.228056]        [<c103b683>] __lock_acquire+0x692/0xb81
[330961.228353]        [<c103bfda>] lock_acquire+0x62/0x81
[330961.228643]        [<c120e322>] __mutex_lock_slowpath+0x75/0x28c
[330961.228934]        [<c120e2a1>] mutex_lock+0x8/0xa
[330961.229221]        [<c109fbbe>] vfs_quota_on_inode+0xc1/0x25f
[330961.229513]        [<c109fdd1>] vfs_quota_on+0x75/0x79
[330961.229803]        [<c10bc92d>] ext3_quota_on+0x95/0xb0
[330961.230093]        [<c10a1eb2>] do_quotactl+0xc9/0x2dd
[330961.230384]        [<c10a214a>] sys_quotactl+0x84/0xd6
[330961.230673]        [<c1003f74>] syscall_call+0x7/0xb
[330961.230963]        [<ffffffff>] 0xffffffff
[330961.231268]
[330961.231268] -> #0 (&sb->s_type->i_mutex_key#4){--..}:
[330961.231469]        [<c10399db>] check_prev_add+0x34/0x281
[330961.231759]        [<c1039cb3>] check_prevs_add+0x8b/0xe8
[330961.232049]        [<c103b683>] __lock_acquire+0x692/0xb81
[330961.232344]        [<c103bfda>] lock_acquire+0x62/0x81
[330961.232632]        [<c120e322>] __mutex_lock_slowpath+0x75/0x28c
[330961.232923]        [<c120e2a1>] mutex_lock+0x8/0xa
[330961.233211]        [<c109fa6c>] vfs_quota_off+0x1cf/0x260
[330961.233500]        [<c10a2088>] do_quotactl+0x29f/0x2dd
[330961.233792]        [<c10a214a>] sys_quotactl+0x84/0xd6
[330961.234081]        [<c1003f74>] syscall_call+0x7/0xb
[330961.234503]        [<ffffffff>] 0xffffffff
[330961.234795]
[330961.234795] other info that might help us debug this:
[330961.234796]
[330961.234908] 2 locks held by quotaoff/12249:
[330961.234947]  #0:  (&type->s_umount_key#15){----}, at: [<c1070b5d>]
get_super+0x53/0x94
[330961.235183]  #1:  (&s->s_dquot.dqonoff_mutex){--..}, at: [<c120e2a1>]
mutex_lock+0x8/0xa
[330961.235386]
[330961.235387] stack backtrace:
[330961.235462]  [<c1004d53>] show_trace_log_lvl+0x1a/0x30
[330961.235535]  [<c1004d7b>] show_trace+0x12/0x14
[330961.235606]  [<c1004e75>] dump_stack+0x16/0x18
[330961.235679]  [<c1039352>] print_circular_bug_tail+0x6f/0x71
[330961.235753]  [<c10399db>] check_prev_add+0x34/0x281
[330961.235825]  [<c1039cb3>] check_prevs_add+0x8b/0xe8
[330961.235897]  [<c103b683>] __lock_acquire+0x692/0xb81
[330961.235969]  [<c103bfda>] lock_acquire+0x62/0x81
[330961.236041]  [<c120e322>] __mutex_lock_slowpath+0x75/0x28c
[330961.236113]  [<c120e2a1>] mutex_lock+0x8/0xa
[330961.236185]  [<c109fa6c>] vfs_quota_off+0x1cf/0x260
[330961.236257]  [<c10a2088>] do_quotactl+0x29f/0x2dd
[330961.236330]  [<c10a214a>] sys_quotactl+0x84/0xd6
[330961.236402]  [<c1003f74>] syscall_call+0x7/0xb
[330961.236473]  =======================

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