Re: possible circular locking in reiserfs_removexattr

[Jeff Mahoney <jeffm@suse.com>]

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Laurent Riffard wrote:
> Hello,
> 
> I've got this while running beagle. /home is mounted with the following
> options:

Thanks for the report. I have a patch queue I'm hoping to send to -mm
next week that cleans up the xattr code a lot and makes the locking
quite a bit saner. It's been in openSUSE for a few generations, so
hopefully there won't be a long incubation before it hits mainline.

- -Jeff

> /dev/mapper/vglinux1-lvhome /home reiserfs
> rw,noatime,nodiratime,user_xattr 0 0
> 
> This still happens with latest kernel (next-20080222), I can't tell when
> it first appears.
> 
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.25-rc1 #15
> -------------------------------------------------------
> beagled/3781 is trying to acquire lock:
> (&REISERFS_I(inode)->xattr_sem){----}, at: [<e1ac02fa>]
> reiserfs_removexattr+0x42/0xbf [reiserfs]
> 
> but task is already holding lock:
> (&sb->s_type->i_mutex_key#8){--..}, at: [<c016f006>]
> vfs_removexattr+0x59/0xc2
> 
> which lock already depends on the new lock.
> 
> 
> the existing dependency chain (in reverse order) is:
> 
> -> #2 (&sb->s_type->i_mutex_key#8){--..}:
>       [<c01311f5>] __lock_acquire+0x8d9/0xa83
>       [<e1aacd0e>] reiserfs_file_release+0x171/0x3b2 [reiserfs]
>       [<c01316f2>] lock_acquire+0x4c/0x63
>       [<e1aacd0e>] reiserfs_file_release+0x171/0x3b2 [reiserfs]
>       [<c0290e57>] mutex_lock_nested+0xa9/0x219
>       [<e1aacd0e>] reiserfs_file_release+0x171/0x3b2 [reiserfs]
>       [<e1aacd0e>] reiserfs_file_release+0x171/0x3b2 [reiserfs]
>       [<c015a01b>] __fput+0x90/0x155
>       [<e1ac0ebd>] reiserfs_xattr_set+0x2a2/0x2c5 [reiserfs]
>       [<e1ac0858>] reiserfs_setxattr+0x7a/0xe3 [reiserfs]
>       [<e1ac07de>] reiserfs_setxattr+0x0/0xe3 [reiserfs]
>       [<c016f3de>] vfs_setxattr+0x74/0xe4
>       [<c016f4fb>] setxattr+0xad/0xc7
>       [<c0292243>] _spin_unlock+0x25/0x3a
>       [<c01bfb26>] _atomic_dec_and_lock+0x22/0x2c
>       [<c016aeee>] mntput_no_expire+0x11/0x5b
>       [<c0160fc2>] link_path_walk+0xa5/0xaf
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c01122d0>] do_page_fault+0x0/0x484
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c0155b72>] kmem_cache_free+0x53/0x5a
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c01619e7>] __user_walk_fd+0x37/0x3f
>       [<c016f58a>] sys_lsetxattr+0x37/0x4a
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c01122d0>] do_page_fault+0x0/0x484
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c0104842>] sysenter_past_esp+0x5f/0xa5
>       [<ffffffff>] 0xffffffff
> 
> -> #1 (&REISERFS_SB(s)->xattr_dir_sem){----}:
>       [<c01311f5>] __lock_acquire+0x8d9/0xa83
>       [<e1ac0846>] reiserfs_setxattr+0x68/0xe3 [reiserfs]
>       [<c01316f2>] lock_acquire+0x4c/0x63
>       [<e1ac0846>] reiserfs_setxattr+0x68/0xe3 [reiserfs]
>       [<c0291367>] down_write+0x17/0x2f
>       [<e1ac0846>] reiserfs_setxattr+0x68/0xe3 [reiserfs]
>       [<e1ac0846>] reiserfs_setxattr+0x68/0xe3 [reiserfs]
>       [<e1ac07de>] reiserfs_setxattr+0x0/0xe3 [reiserfs]
>       [<c016f3de>] vfs_setxattr+0x74/0xe4
>       [<c016f4fb>] setxattr+0xad/0xc7
>       [<c0292243>] _spin_unlock+0x25/0x3a
>       [<c01bfb26>] _atomic_dec_and_lock+0x22/0x2c
>       [<c016aeee>] mntput_no_expire+0x11/0x5b
>       [<c0160fc2>] link_path_walk+0xa5/0xaf
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c01122d0>] do_page_fault+0x0/0x484
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c0155b72>] kmem_cache_free+0x53/0x5a
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c01619e7>] __user_walk_fd+0x37/0x3f
>       [<c016f58a>] sys_lsetxattr+0x37/0x4a
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c01122d0>] do_page_fault+0x0/0x484
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c010492b>] restore_nocheck+0x12/0x15
>       [<c0104842>] sysenter_past_esp+0x5f/0xa5
>       [<ffffffff>] 0xffffffff
> 
> -> #0 (&REISERFS_I(inode)->xattr_sem){----}:
>       [<c0131115>] __lock_acquire+0x7f9/0xa83
>       [<c01316f2>] lock_acquire+0x4c/0x63
>       [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
>       [<c0291367>] down_write+0x17/0x2f
>       [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
>       [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
>       [<c016f014>] vfs_removexattr+0x67/0xc2
>       [<c016f0ac>] removexattr+0x3d/0x4a
>       [<c0292243>] _spin_unlock+0x25/0x3a
>       [<c01bfb26>] _atomic_dec_and_lock+0x22/0x2c
>       [<c016aeee>] mntput_no_expire+0x11/0x5b
>       [<c0160fc2>] link_path_walk+0xa5/0xaf
>       [<c010487d>] sysenter_past_esp+0x9a/0xa5
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c0155b72>] kmem_cache_free+0x53/0x5a
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c01619e7>] __user_walk_fd+0x37/0x3f
>       [<c016f114>] sys_lremovexattr+0x2b/0x3c
>       [<c010487d>] sysenter_past_esp+0x9a/0xa5
>       [<c0130556>] trace_hardirqs_on+0xdd/0xfd
>       [<c010487d>] sysenter_past_esp+0x9a/0xa5
>       [<c0104842>] sysenter_past_esp+0x5f/0xa5
>       [<ffffffff>] 0xffffffff
> 
> other info that might help us debug this:
> 
> 1 lock held by beagled/3781:
> #0:  (&sb->s_type->i_mutex_key#8){--..}, at: [<c016f006>]
> vfs_removexattr+0x59/0xc2
> 
> stack backtrace:
> Pid: 3781, comm: beagled Not tainted 2.6.25-rc1 #15
> [<c012fafa>] print_circular_bug_tail+0x56/0x60
> [<c0131115>] __lock_acquire+0x7f9/0xa83
> [<c01316f2>] lock_acquire+0x4c/0x63
> [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
> [<c0291367>] down_write+0x17/0x2f
> [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
> [<e1ac02fa>] reiserfs_removexattr+0x42/0xbf [reiserfs]
> [<c016f014>] vfs_removexattr+0x67/0xc2
> [<c016f0ac>] removexattr+0x3d/0x4a
> [<c0292243>] _spin_unlock+0x25/0x3a
> [<c01bfb26>] _atomic_dec_and_lock+0x22/0x2c
> [<c016aeee>] mntput_no_expire+0x11/0x5b
> [<c0160fc2>] link_path_walk+0xa5/0xaf
> [<c010487d>] sysenter_past_esp+0x9a/0xa5
> [<c0130556>] trace_hardirqs_on+0xdd/0xfd
> [<c0155b72>] kmem_cache_free+0x53/0x5a
> [<c0130556>] trace_hardirqs_on+0xdd/0xfd
> [<c01619e7>] __user_walk_fd+0x37/0x3f
> [<c016f114>] sys_lremovexattr+0x2b/0x3c
> [<c010487d>] sysenter_past_esp+0x9a/0xa5
> [<c0130556>] trace_hardirqs_on+0xdd/0xfd
> [<c010487d>] sysenter_past_esp+0x9a/0xa5
> [<c0104842>] sysenter_past_esp+0x5f/0xa5
> =======================
> 
> step to reproduce:
> - mount /home as reiserfs with user_xattr option.
> - run "beagled --fg --debug --indexing-delay 5", and wait 10 seconds.
> 
> 
> ~~
> laurent
> -
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- --
Jeff Mahoney
SUSE Labs
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