1401a2b>] mutex_lock_nested+0x5b/0x340
       [<c11432b9>] reiserfs_write_lock_once+0x29/0x50
       [<c1117012>] reiserfs_lookup+0x62/0x140
       [<c10bd85f>] __lookup_hash+0xef/0x110
       [<c10bf21d>] lookup_one_len+0x8d/0xc0
       [<c1141e2a>] open_xa_dir+0xea/0x1b0
       [<c1141fe5>] xattr_lookup+0x15/0x160
       [<c1142476>] reiserfs_xattr_get+0x56/0x2a0
       [<c1144042>] reiserfs_get_acl+0xa2/0x360
       [<c114461a>] reiserfs_cache_default_acl+0x3a/0x160
       [<c111789c>] reiserfs_mkdir+0x6c/0x2c0
       [<c10bea96>] vfs_mkdir+0xd6/0x180
       [<c10c0c10>] sys_mkdirat+0xc0/0xd0
       [<c10c0c40>] sys_mkdir+0x20/0x30
       [<c1002ec4>] sysenter_do_call+0x12/0x32

other info that might help us debug this:

2 locks held by cp/3204:
 #0:  (&sb->s_type->i_mutex_key#4/1){+.+.+.}, at: [<c10bd8d6>] lookup_create+0x26/0xa0
 #1:  (&sb->s_type->i_mutex_key#4/3){+.+.+.}, at: [<c1141e18>] open_xa_dir+0xd8/0x1b0

stack backtrace:
Pid: 3204, comm: cp Not tainted 2.6.32-atom #173
Call Trace:
 [<c13ff993>] ? printk+0x18/0x1a
 [<c105d33a>] print_circular_bug+0xca/0xd0
 [<c105f176>] __lock_acquire+0x18f6/0x19e0
 [<c105d3aa>] ? check_usage+0x6a/0x460
 [<c105f2c8>] lock_acquire+0x68/0x90
 [<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
 [<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
 [<c1401a2b>] mutex_lock_nested+0x5b/0x340
 [<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
 [<c11432b9>] reiserfs_write_lock_once+0x29/0x50
 [<c1117012>] reiserfs_lookup+0x62/0x140
 [<c105ccca>] ? debug_check_no_locks_freed+0x8a/0x140
 [<c105cbe4>] ? trace_hardirqs_on_caller+0x124/0x170
 [<c10bd85f>] __lookup_hash+0xef/0x110
 [<c10bf21d>] lookup_one_len+0x8d/0xc0
 [<c1141e2a>] open_xa_dir+0xea/0x1b0
 [<c1141fe5>] xattr_lookup+0x15/0x160
 [<c1142476>] reiserfs_xattr_get+0x56/0x2a0
 [<c1144042>] reiserfs_get_acl+0xa2/0x360
 [<c10ca2e7>] ? new_inode+0x27/0xa0
 [<c114461a>] reiserfs_cache_default_acl+0x3a/0x160
 [<c1402eb7>] ? _spin_unlock+0x27/0x40
 [<c111789c>] reiserfs_mkdir+0x6c/0x2c0
 [<c10c7cb8>] ? __d_lookup+0x108/0x190
 [<c105c932>] ? mark_held_locks+0x62/0x80
 [<c1401c8d>] ? mutex_lock_nested+0x2bd/0x340
 [<c10bd17a>] ? generic_permission+0x1a/0xa0
 [<c11788fe>] ? security_inode_permission+0x1e/0x20
 [<c10bea96>] vfs_mkdir+0xd6/0x180
 [<c10c0c10>] sys_mkdirat+0xc0/0xd0
 [<c10505c6>] ? up_read+0x16/0x30
 [<c1002fd8>] ? restore_all_notrace+0x0/0x18
 [<c10c0c40>] sys_mkdir+0x20/0x30
 [<c1002ec4>] sysenter_do_call+0x12/0x32

v2: Don't drop reiserfs_mutex_lock_nested_safe() as we'll still
    need it later

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
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