INFO: possible recursive locking detected

[Steven Haigh]

I've noticed that in the latest lot of kernels I get the following in dmesg:

=============================================
[ INFO: possible recursive locking detected ]
2.6.18-1.2679.fc6PAE #1
---------------------------------------------
init/1 is trying to acquire lock:
  (&md->io_lock){----}, at: [<f891148e>] dm_request+0x18/0xea [dm_mod]

but task is already holding lock:
  (&md->io_lock){----}, at: [<f891148e>] dm_request+0x18/0xea [dm_mod]

other info that might help us debug this:
1 lock held by init/1:
  #0:  (&md->io_lock){----}, at: [<f891148e>] dm_request+0x18/0xea [dm_mod]

stack backtrace:
  [<c04051e3>] show_trace_log_lvl+0x58/0x16a
  [<c04057f0>] show_trace+0xd/0x10
  [<c0405900>] dump_stack+0x19/0x1b
  [<c043ba51>] __lock_acquire+0x778/0x99c
  [<c043c1e6>] lock_acquire+0x4b/0x6d
  [<c04391f8>] down_read+0x2d/0x40
  [<f891148e>] dm_request+0x18/0xea [dm_mod]
  [<c04db963>] generic_make_request+0x28c/0x29c
  [<f891044c>] __map_bio+0xc1/0xef [dm_mod]
  [<f8910d27>] __split_bio+0x159/0x3a1 [dm_mod]
  [<f8911552>] dm_request+0xdc/0xea [dm_mod]
  [<c04db963>] generic_make_request+0x28c/0x29c
  [<c04dd7f7>] submit_bio+0xbf/0xc6
  [<c0472fd1>] submit_bh+0xfc/0x11b
  [<c04758d4>] block_read_full_page+0x2c3/0x2d3
  [<c04781fd>] blkdev_readpage+0xf/0x11
  [<c0459a0f>] __do_page_cache_readahead+0x15f/0x1af
  [<c0459aa9>] blockable_page_cache_readahead+0x4a/0x9f
  [<c0459ca3>] page_cache_readahead+0x112/0x174
  [<c04545e1>] do_generic_mapping_read+0x12b/0x451
  [<c0455111>] __generic_file_aio_read+0x187/0x1e8
  [<c0456087>] generic_file_read+0x87/0x9b
  [<c0471de0>] vfs_read+0xa9/0x155
  [<c0472270>] sys_read+0x3b/0x60
  [<c0403fb7>] syscall_call+0x7/0xb
DWARF2 unwinder stuck at syscall_call+0x7/0xb
Leftover inexact backtrace:
  [<c04057f0>] show_trace+0xd/0x10
  [<c0405900>] dump_stack+0x19/0x1b
  [<c043ba51>] __lock_acquire+0x778/0x99c
  [<c043c1e6>] lock_acquire+0x4b/0x6d
  [<c04391f8>] down_read+0x2d/0x40
  [<f891148e>] dm_request+0x18/0xea [dm_mod]
  [<c04db963>] generic_make_request+0x28c/0x29c
  [<f891044c>] __map_bio+0xc1/0xef [dm_mod]
  [<f8910d27>] __split_bio+0x159/0x3a1 [dm_mod]
  [<f8911552>] dm_request+0xdc/0xea [dm_mod]
  [<c04db963>] generic_make_request+0x28c/0x29c
  [<c04dd7f7>] submit_bio+0xbf/0xc6
  [<c0472fd1>] submit_bh+0xfc/0x11b
  [<c04758d4>] block_read_full_page+0x2c3/0x2d3
  [<c04781fd>] blkdev_readpage+0xf/0x11
  [<c0459a0f>] __do_page_cache_readahead+0x15f/0x1af
  [<c0459aa9>] blockable_page_cache_readahead+0x4a/0x9f
  [<c0459ca3>] page_cache_readahead+0x112/0x174
  [<c04545e1>] do_generic_mapping_read+0x12b/0x451
  [<c0455111>] __generic_file_aio_read+0x187/0x1e8
  [<c0456087>] generic_file_read+0x87/0x9b
  [<c0471de0>] vfs_read+0xa9/0x155
  [<c0472270>] sys_read+0x3b/0x60
  [<c0403fb7>] syscall_call+0x7/0xb

Anyone else see this?

-- 
Steven Haigh

Email: netwiz at crc.id.au
Web: http://www.crc.id.au
Phone: (03) 9017 0597 - 0412 935 897