Re: [2.6.20] BUG: workqueue leaked lock

Folkert van Heusden
2007-03-15T19:17:55Z

> > On Tue, 13 Mar 2007 17:50:14 +0100 Folkert van Heusden <folkert@vanheusden.com> wrote:
> > ...
> > [ 1756.728209] BUG: workqueue leaked lock or atomic: nfsd4/0x00000000/3577
...
> > [ 1846.684023] [<c1003bdb>] kernel_thread_helper+0x7/0x10
> Oleg, that's a fairly incomprehensible message we have in there. Can you
> please explain what it means?

Haha ok :-)

Good, since I run 2.6.20 with these debugging switches switched on, I
get occasionally errors like these. I get ALWAYS the following error
when the system first boots when the TOR executable is started:

[ 137.324255] =======================================================
[ 137.324359] [ INFO: possible circular locking dependency detected ]
[ 137.324412] 2.6.20 #2
[ 137.324457] -------------------------------------------------------
[ 137.324510] tor/4857 is trying to acquire lock:
[ 137.324559] (tty_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[ 137.324765]
[ 137.324766] but task is already holding lock:
[ 137.324859] (&s->s_dquot.dqptr_sem){----}, at: [<c1099403>] dquot_alloc_space+0x50/0x189
[ 137.325067]
[ 137.325069] which lock already depends on the new lock.
[ 137.325071]
[ 137.325206]
[ 137.325208] the existing dependency chain (in reverse order) is:
[ 137.325300]
[ 137.325301] -> #4 (&s->s_dquot.dqptr_sem){----}:
[ 137.325501] [<c10354b8>] check_prev_add+0x154/0x206
[ 137.325852] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.326197] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.326538] [<c1037624>] lock_acquire+0x62/0x81
[ 137.326887] [<c1032b5f>] down_read+0x2b/0x3d
[ 137.327241] [<c1099403>] dquot_alloc_space+0x50/0x189
[ 137.327588] [<c10a98e6>] ext3_new_blocks+0x44b/0x5a2
[ 137.327935] [<c10abe78>] ext3_alloc_blocks+0x40/0xdf
[ 137.328280] [<c10abf67>] ext3_alloc_branch+0x50/0x21b
[ 137.328622] [<c10ac445>] ext3_get_blocks_handle+0x1b8/0x367
[ 137.328980] [<c10ac76e>] ext3_getblk+0x97/0x228
[ 137.329330] [<c10ac919>] ext3_bread+0x1a/0x78
[ 137.329672] [<c10b1bc2>] ext3_mkdir+0xf4/0x270
[ 137.330022] [<c1072a6a>] vfs_mkdir+0xb3/0x161
[ 137.330368] [<c1072ba4>] sys_mkdirat+0x8c/0xc4
[ 137.330714] [<c1072bfc>] sys_mkdir+0x20/0x22
[ 137.331063] [<c1002f78>] syscall_call+0x7/0xb
[ 137.331406] [<ffffffff>] 0xffffffff
[ 137.331771]
[ 137.331772] -> #3 (&ei->truncate_mutex){--..}:
[ 137.331979] [<c10354b8>] check_prev_add+0x154/0x206
[ 137.332332] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.332676] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.333025] [<c1037624>] lock_acquire+0x62/0x81
[ 137.333370] [<c1205c09>] __mutex_lock_slowpath+0x75/0x28c
[ 137.333930] [<c1205b88>] mutex_lock+0x8/0xa
[ 137.334271] [<c10ae14f>] ext3_truncate+0x170/0x468
[ 137.334613] [<c1058e72>] vmtruncate+0xa6/0x116
[ 137.334949] [<c107d587>] inode_setattr+0x145/0x16c
[ 137.335286] [<c10af071>] ext3_setattr+0x150/0x22f
[ 137.335627] [<c107d909>] notify_change+0x35b/0x392
[ 137.335968] [<c10679d2>] do_truncate+0x52/0x75
[ 137.336305] [<c1071f5e>] may_open+0x1ec/0x231
[ 137.336642] [<c107211c>] open_namei+0xda/0x59b
[ 137.336975] [<c106863a>] do_filp_open+0x2c/0x53
[ 137.337310] [<c106896f>] do_sys_open+0x52/0xd8
[ 137.337645] [<c1068a11>] sys_open+0x1c/0x1e
[ 137.337980] [<c1002f78>] syscall_call+0x7/0xb
[ 137.338315] [<ffffffff>] 0xffffffff
[ 137.338665]
[ 137.338666] -> #2 (&inode->i_alloc_sem){--..}:
[ 137.338864] [<c10354b8>] check_prev_add+0x154/0x206
[ 137.339200] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.339535] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.339200] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.339535] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.339874] [<c1037624>] lock_acquire+0x62/0x81
[ 137.340207] [<c1032bf5>] down_write+0x2b/0x45
[ 137.340545] [<c107d890>] notify_change+0x2e2/0x392
[ 137.340886] [<c10679d2>] do_truncate+0x52/0x75
[ 137.341222] [<c1071f5e>] may_open+0x1ec/0x231
[ 137.341557] [<c107211c>] open_namei+0xda/0x59b
[ 137.341898] [<c1068a11>] sys_open+0x1c/0x1e
[ 137.343109] [<c1002f78>] syscall_call+0x7/0xb
[ 137.343444] [<ffffffff>] 0xffffffff
[ 137.343792]
[ 137.343793] -> #1 (&sysfs_inode_imutex_key){--..}:
[ 137.343988] [<c10354b8>] check_prev_add+0x154/0x206
[ 137.344320] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.344655] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.344986] [<c1037624>] lock_acquire+0x62/0x81
[ 137.345321] [<c1205c09>] __mutex_lock_slowpath+0x75/0x28c
[ 137.345658] [<c1205b88>] mutex_lock+0x8/0xa
[ 137.345991] [<c10a5447>] sysfs_hash_and_remove+0x43/0x11c
[ 137.346328] [<c10a5ef7>] sysfs_remove_file+0xd/0x12
[ 137.346660] [<c114b00c>] device_remove_file+0x32/0x44
[ 137.346992] [<c114b6d9>] device_del+0x174/0x1d2
[ 137.347325] [<c114b742>] device_unregister+0xb/0x15
[ 137.347661] [<c114b93d>] device_destroy+0x8d/0x9a
[ 137.347994] [<c1137a38>] vcs_remove_sysfs+0x1c/0x38
[ 137.348328] [<c113e0d8>] con_close+0x5e/0x6b
[ 137.348661] [<c1130103>] release_dev+0x4c4/0x6ce
[ 137.348999] [<c113077b>] tty_release+0x12/0x1c
[ 137.349332] [<c10aa723>] ext3_file_write+0x2d/0xba
[ 137.358495] [<c1069441>] do_sync_write+0xc7/0x116
[ 137.358838] [<c1069612>] vfs_write+0x182/0x187
[ 137.359176] [<c10696b8>] sys_write+0x3d/0x64
[ 137.359513] [<c1002f78>] syscall_call+0x7/0xb
[ 137.359848] [<ffffffff>] 0xffffffff
[ 137.360200]
[ 137.360202] other info that might help us debug this:
[ 137.360204]
[ 137.360335] 3 locks held by tor/4857:
[ 137.360382] #0: (&inode->i_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[ 137.360625] #1: (&ei->truncate_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[ 137.361072] #2: (&s->s_dquot.dqptr_sem){----}, at: [<c1099403>] dquot_alloc_space+0x50/0x189
[ 137.361313]
[ 137.361314] stack backtrace:
[ 137.361401] [<c1003d57>] show_trace_log_lvl+0x1a/0x30
[ 137.361488] [<c1003d7f>] show_trace+0x12/0x14
[ 137.361571] [<c1003e79>] dump_stack+0x16/0x18
[ 137.361663] [<c1034d6d>] print_circular_bug_tail+0x6f/0x71
[ 137.361752] [<c1035398>] check_prev_add+0x34/0x206
[ 137.361838] [<c10355d4>] check_prevs_add+0x6a/0xd5
[ 137.362786] [<c1036dd2>] __lock_acquire+0x61c/0xa05
[ 137.362877] [<c1037624>] lock_acquire+0x62/0x81
[ 137.362960] [<c1205c09>] __mutex_lock_slowpath+0x75/0x28c
[ 137.363047] [<c1205b88>] mutex_lock+0x8/0xa
[ 137.363132] [<c1098d79>] print_warning+0x8c/0x15d
[ 137.363217] [<c1099537>] dquot_alloc_space+0x184/0x189
[ 137.363302] [<c10a98e6>] ext3_new_blocks+0x44b/0x5a2
[ 137.363391] [<c10abe78>] ext3_alloc_blocks+0x40/0xdf
[ 137.363476] [<c10abf67>] ext3_alloc_branch+0x50/0x21b
[ 137.363561] [<c10ac445>] ext3_get_blocks_handle+0x1b8/0x367
[ 137.363650] [<c10ac66c>] ext3_get_block+0x78/0xe3
[ 137.363735] [<c108a239>] __block_prepare_write+0x168/0x3fd
[ 137.363822] [<c108ad10>] block_prepare_write+0x28/0x3b
[ 137.363908] [<c10acbcd>] ext3_prepare_write+0x3f/0x18d
[ 137.363996] [<c104dbe5>] generic_file_buffered_write+0x197/0x5e6
[ 137.364084] [<c104e2e2>] __generic_file_aio_write_nolock+0x2ae/0x5ad
[ 137.364171] [<c104e6ea>] generic_file_aio_write+0x58/0xc4
[ 137.364254] [<c10aa723>] ext3_file_write+0x2d/0xba
[ 137.364340] [<c1069441>] do_sync_write+0xc7/0x116
[ 137.364425] [<c1069612>] vfs_write+0x182/0x187
[ 137.364511] [<c10696b8>] sys_write+0x3d/0x64
[ 137.364595] [<c1002f78>] syscall_call+0x7/0xb
[ 137.364682] =======================

Now apart from this reproducable problem, I suddenly also get these errors in dmesg:

[ 137.471738] BUG: workqueue leaked lock or atomic: nfsd4/0x00000000/3577
[ 137.471812] last function: laundromat_main+0x0/0x69 [nfsd]
[ 137.471923] 2 locks held by nfsd4/3577:
[ 137.471971] #0: (client_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[ 137.472209] #1: (&inode->i_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[ 137.472445] [<c1003d57>] show_trace_log_lvl+0x1a/0x30
[ 137.472528] [<c1003d7f>] show_trace+0x12/0x14
[ 137.472613] [<c1003e79>] dump_stack+0x16/0x18
[ 137.472695] [<c102c2e8>] run_workqueue+0x167/0x170
[ 137.472779] [<c102c437>] worker_thread+0x146/0x165
[ 137.472861] [<c102f797>] kthread+0x97/0xc4
[ 137.472943] [<c1003bdb>] kernel_thread_helper+0x7/0x10

These happen on 2 times per minute and then once in 2 minutes.

The last one (while writing this message) is:

[182932.590394] BUG: workqueue leaked lock or atomic: nfsd4/0x00000000/3577
[182932.590450] last function: laundromat_main+0x0/0x69 [nfsd]
[182932.590557] 2 locks held by nfsd4/3577:
[182932.590600] #0: (client_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[182932.590830] #1: (&inode->i_mutex){--..}, at: [<c1205b88>] mutex_lock+0x8/0xa
[182932.591061] [<c1003d57>] show_trace_log_lvl+0x1a/0x30
[182932.591145] [<c1003d7f>] show_trace+0x12/0x14
[182932.591234] [<c1003e79>] dump_stack+0x16/0x18
[182932.591316] [<c102c2e8>] run_workqueue+0x167/0x170
[182932.591399] [<c102c437>] worker_thread+0x146/0x165
[182932.591482] [<c102f797>] kthread+0x97/0xc4
[182932.591564] [<c1003bdb>] kernel_thread_helper+0x7/0x10

Config can be found here:
http://keetweej.vanheusden.com/~folkert/config-2.6.20.txt

System is a P4 @ 3.2GHz with 2GB of ram. IDE harddisks, 5 mounts mounted
on a server connected via a 1Gb lan. The other end (the server) runs
2.6.19.1.

On the problem-system this is the output of nfsstat:

Server rpc stats:
calls badcalls badauth badclnt xdrcall
1833 611 611 0 0

Server nfs v2:
null getattr setattr root lookup readlink
611 100% 0 0% 0 0% 0 0% 0 0% 0 0%
read wrcache write create remove rename
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
link symlink mkdir rmdir readdir fsstat
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%

Server nfs v3:
null getattr setattr lookup access readlink
611 100% 0 0% 0 0% 0 0% 0 0% 0 0%
read write create mkdir symlink mknod
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
remove rmdir rename link readdir readdirplus
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
fsstat fsinfo pathconf commit
0 0% 0 0% 0 0% 0 0%

Server nfs v4:
null compound
611 100% 0 0%

Server nfs v4 operations:
op0-unused op1-unused op2-future access close commit
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
create delegpurge delegreturn getattr getfh link
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
lock lockt locku lookup lookup_root nverify
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
open openattr open_conf open_dgrd putfh putpubfh
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
putrootfh read readdir readlink remove rename
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
renew restorefh savefh secinfo setattr setcltid
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
setcltidconf verify write rellockowner
0 0% 0 0% 0 0% 0 0%

Client rpc stats:
calls retrans authrefrsh
1404874 5502 0

Client nfs v2:
null getattr setattr root lookup readlink
0 0% 157240 11% 11360 0% 0 0% 707396 50% 20434 1%
read wrcache write create remove rename
18 0% 0 0% 471048 33% 2900 0% 323 0% 2888 0%
link symlink mkdir rmdir readdir fsstat
0 0% 2 0% 60 0% 32 0% 27463 1% 3709 0%

Client nfs v4:
null read write commit open open_conf
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
open_noat open_dgrd close setattr fsinfo renew
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
setclntid confirm lock lockt locku access
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
getattr lookup lookup_root remove rename link
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
symlink create pathconf statfs readlink readdir
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
server_caps delegreturn
0 0% 0 0%

Folkert van Heusden

--
www.biglumber.com <- site where one can exchange PGP key signatures
----------------------------------------------------------------------
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