=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.37-rc6+ #12
-------------------------------------------------------
grep/10562 is trying to acquire lock:
 (slub_lock){+++++.}, at: [<ffffffff8114baec>] show_slab_objects+0xfc/0x390

but task is already holding lock:
 (s_active#182){++++.+}, at: [<ffffffff811c4b16>] sysfs_read_file+0x96/0x1c0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (s_active#182){++++.+}:
       [<ffffffff81096b00>] lock_acquire+0xa0/0x150
       [<ffffffff811c5b77>] sysfs_deactivate+0x157/0x1c0
       [<ffffffff811c6273>] sysfs_addrm_finish+0x43/0x70
       [<ffffffff811c637e>] sysfs_remove_dir+0x7e/0xa0
       [<ffffffff812c3616>] kobject_del+0x16/0x40
       [<ffffffff8114c132>] kmem_cache_destroy+0x2f2/0x380
       [<ffffffffa01b4bd1>] 0xffffffffa01b4bd1
       [<ffffffff810a1682>] sys_delete_module+0x1a2/0x280
       [<ffffffff81003042>] system_call_fastpath+0x16/0x1b

-> #0 (slub_lock){+++++.}:
       [<ffffffff810968c0>] __lock_acquire+0x1370/0x1510
       [<ffffffff81096b00>] lock_acquire+0xa0/0x150
       [<ffffffff81548f41>] down_read+0x51/0xa0
       [<ffffffff8114baec>] show_slab_objects+0xfc/0x390
       [<ffffffff8114be33>] objects_show+0x13/0x20
       [<ffffffff81145e92>] slab_attr_show+0x22/0x30
       [<ffffffff811c4b59>] sysfs_read_file+0xd9/0x1c0
       [<ffffffff81158f8d>] vfs_read+0xcd/0x1a0
       [<ffffffff81159854>] sys_read+0x54/0x90
       [<ffffffff81003042>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

2 locks held by grep/10562:
 #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff811c4ac6>] sysfs_read_file+0x46/0x1c0
 #1:  (s_active#182){++++.+}, at: [<ffffffff811c4b16>] sysfs_read_file+0x96/0x1c0

stack backtrace:
Pid: 10562, comm: grep Tainted: G        W   2.6.37-rc6+ #12
Call Trace:
 [<ffffffff81094379>] print_circular_bug+0xf9/0x100
 [<ffffffff810968c0>] __lock_acquire+0x1370/0x1510
 [<ffffffff8100a3d9>] ? sched_clock+0x9/0x10
 [<ffffffff81148a5c>] ? check_object+0xac/0x250
 [<ffffffff81096b00>] lock_acquire+0xa0/0x150
 [<ffffffff8114baec>] ? show_slab_objects+0xfc/0x390
 [<ffffffff8109522d>] ? trace_hardirqs_on_caller+0x14d/0x190
 [<ffffffff81548f41>] down_read+0x51/0xa0
 [<ffffffff8114baec>] ? show_slab_objects+0xfc/0x390
 [<ffffffff8114baec>] show_slab_objects+0xfc/0x390
 [<ffffffff8114be33>] objects_show+0x13/0x20
 [<ffffffff81145e92>] slab_attr_show+0x22/0x30
 [<ffffffff811c4b59>] sysfs_read_file+0xd9/0x1c0
 [<ffffffff81158f8d>] vfs_read+0xcd/0x1a0
 [<ffffffff81159854>] sys_read+0x54/0x90
 [<ffffffff81003042>] system_call_fastpath+0x16/0x1b