I see this too on my AMD64 running intrepid.

When it happens I notice it because my keyboard doesn't react to any key presses anymore (using the mouse still works).
After some time everything is back to normal.

[14384.920039] INFO: task postgres:5413 blocked for more than 120 seconds.
[14384.920054] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14384.920059] postgres      D ffff88002800fb98     0  5413   5004
[14384.920074]  ffff88011ccfda58 0000000000000086 ffff88011ccfd9e8 ffffffff8039184d
[14384.920096]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14384.920116]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14384.920133] Call Trace:
[14384.920157]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14384.920172]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14384.920182]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14384.920190]  [<ffffffff80519c4a>] __wait_on_bit_lock+0x5a/0x90
[14384.920197]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14384.920205]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14384.920212]  [<ffffffff80519cf9>] out_of_line_wait_on_bit_lock+0x79/0x90
[14384.920222]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14384.920231]  [<ffffffff803152b6>] __lock_buffer+0x36/0x40
[14384.920270]  [<ffffffffa023f079>] lock_buffer+0x29/0x30 [jbd]
[14384.920286]  [<ffffffffa02408cb>] journal_invalidatepage+0x8b/0xf0 [jbd]
[14384.920313]  [<ffffffffa02559f1>] ext3_invalidatepage+0x41/0x50 [ext3]
[14384.920323]  [<ffffffff802b8e65>] do_invalidatepage+0x25/0x30
[14384.920330]  [<ffffffff802b906a>] truncate_complete_page+0x6a/0x80
[14384.920339]  [<ffffffff802b921e>] truncate_inode_pages_range+0x16e/0x400
[14384.920362]  [<ffffffffa02627c4>] ? __ext3_journal_stop+0x34/0x60 [ext3]
[14384.920372]  [<ffffffff80300241>] ? switch_names+0xc1/0xd0
[14384.920381]  [<ffffffff802b94c5>] truncate_inode_pages+0x15/0x20
[14384.920401]  [<ffffffffa025973d>] ext3_delete_inode+0x1d/0x110 [ext3]
[14384.920419]  [<ffffffffa0259720>] ? ext3_delete_inode+0x0/0x110 [ext3]
[14384.920429]  [<ffffffff80303749>] generic_delete_inode+0xb9/0x180
[14384.920438]  [<ffffffff80303835>] generic_drop_inode+0x25/0x30
[14384.920447]  [<ffffffff803024e2>] iput+0x62/0x70
[14384.920455]  [<ffffffff802ff1f0>] dentry_iput+0x90/0xe0
[14384.920463]  [<ffffffff802ff304>] d_kill+0x44/0x70
[14384.920471]  [<ffffffff80301475>] dput+0x95/0x190
[14384.920478]  [<ffffffff802f750b>] sys_renameat+0x20b/0x240
[14384.920489]  [<ffffffff802cedde>] ? free_pages_and_swap_cache+0x8e/0xb0
[14384.920499]  [<ffffffff803a9358>] ? __up_write+0x68/0x140
[14384.920508]  [<ffffffff802f755b>] sys_rename+0x1b/0x20
[14384.920519]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14384.920525] 
[14384.920556] INFO: task firefox:13261 blocked for more than 120 seconds.
[14384.920562] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14384.920568] firefox       D ffff88002800e068     0 13261      1
[14384.920581]  ffff8800df40fd58 0000000000000082 ffff8800df40fdc8 ffff880000001000
[14384.920600]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14384.920620]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14384.920636] Call Trace:
[14384.920646]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14384.920655]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14384.920664]  [<ffffffff802adbed>] sync_page+0x3d/0x70
[14384.920671]  [<ffffffff80519d72>] __wait_on_bit+0x62/0x90
[14384.920678]  [<ffffffff802adbb0>] ? sync_page+0x0/0x70
[14384.920687]  [<ffffffff802ade84>] wait_on_page_bit+0x74/0x80
[14384.920695]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14384.920702]  [<ffffffff802b7fc7>] ? pagevec_lookup_tag+0x27/0x40
[14384.920711]  [<ffffffff802ae014>] wait_on_page_writeback_range+0x164/0x1a0
[14384.920720]  [<ffffffff802b6c84>] ? generic_writepages+0x24/0x30
[14384.920727]  [<ffffffff802b6cd5>] ? do_writepages+0x45/0x50
[14384.920735]  [<ffffffff802adb25>] ? __filemap_fdatawrite_range+0x55/0x70
[14384.920744]  [<ffffffff802ae07f>] filemap_fdatawait+0x2f/0x40
[14384.920751]  [<ffffffff80313ed8>] do_fsync+0xc8/0xf0
[14384.920759]  [<ffffffff80313f36>] __do_fsync+0x36/0x50
[14384.920766]  [<ffffffff80313f63>] sys_fdatasync+0x13/0x20
[14384.920775]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14384.920781] 
[14418.208035] INFO: task kjournald:2404 blocked for more than 120 seconds.
[14418.208052] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14418.208057] kjournald     D ffff88002800cad8     0  2404      2
[14418.208065]  ffff88011a5e7ce0 0000000000000046 ffff88011a5e7c70 ffffffff8039184d
[14418.208073]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208081]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208087] Call Trace:
[14418.208098]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14418.208108]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14418.208115]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14418.208120]  [<ffffffff80519d72>] __wait_on_bit+0x62/0x90
[14418.208126]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14418.208131]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14418.208135]  [<ffffffff80519e19>] out_of_line_wait_on_bit+0x79/0x90
[14418.208142]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14418.208148]  [<ffffffff803155b6>] __wait_on_buffer+0x26/0x30
[14418.208181]  [<ffffffffa0242188>] journal_commit_transaction+0x728/0xd00 [jbd]
[14418.208189]  [<ffffffff8025a42b>] ? lock_timer_base+0x3b/0x70
[14418.208194]  [<ffffffff8025a4bf>] ? try_to_del_timer_sync+0x5f/0x70
[14418.208207]  [<ffffffffa0245d69>] kjournald+0xe9/0x250 [jbd]
[14418.208213]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14418.208225]  [<ffffffffa0245c80>] ? kjournald+0x0/0x250 [jbd]
[14418.208231]  [<ffffffff8026674e>] kthread+0x4e/0x90
[14418.208237]  [<ffffffff80213cc9>] child_rip+0xa/0x11
[14418.208242]  [<ffffffff80266700>] ? kthread+0x0/0x90
[14418.208246]  [<ffffffff80213cbf>] ? child_rip+0x0/0x11
[14418.208249] 
[14418.208254] INFO: task kjournald:4186 blocked for more than 120 seconds.
[14418.208260] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14418.208267] kjournald     D ffff880028012af0     0  4186      2
[14418.208280]  ffff88011c531ce0 0000000000000046 ffff88011c531c70 ffffffff8039184d
[14418.208299]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208317]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208333] Call Trace:
[14418.208340]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14418.208348]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14418.208355]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14418.208362]  [<ffffffff80519d72>] __wait_on_bit+0x62/0x90
[14418.208369]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14418.208376]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14418.208383]  [<ffffffff80519e19>] out_of_line_wait_on_bit+0x79/0x90
[14418.208391]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14418.208398]  [<ffffffff803155b6>] __wait_on_buffer+0x26/0x30
[14418.208413]  [<ffffffffa0242188>] journal_commit_transaction+0x728/0xd00 [jbd]
[14418.208421]  [<ffffffff8025a42b>] ? lock_timer_base+0x3b/0x70
[14418.208428]  [<ffffffff8025a4bf>] ? try_to_del_timer_sync+0x5f/0x70
[14418.208442]  [<ffffffffa0245d69>] kjournald+0xe9/0x250 [jbd]
[14418.208450]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14418.208464]  [<ffffffffa0245c80>] ? kjournald+0x0/0x250 [jbd]
[14418.208471]  [<ffffffff8026674e>] kthread+0x4e/0x90
[14418.208478]  [<ffffffff80213cc9>] child_rip+0xa/0x11
[14418.208485]  [<ffffffff80266700>] ? kthread+0x0/0x90
[14418.208492]  [<ffffffff80213cbf>] ? child_rip+0x0/0x11
[14418.208496] 
[14418.208535] INFO: task exim:12992 blocked for more than 120 seconds.
[14418.208541] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14418.208547] exim          D ffff88011a54e824     0 12992  12991
[14418.208560]  ffff88005b0d7cd8 0000000000000086 0000000000000286 ffff88011a54e8d8
[14418.208578]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208596]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14418.208611] Call Trace:
[14418.208627]  [<ffffffffa0245215>] log_wait_commit+0xc5/0x140 [jbd]
[14418.208635]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14418.208643]  [<ffffffff8023dc4e>] ? __wake_up+0x4e/0x70
[14418.208658]  [<ffffffffa023f1f5>] journal_stop+0x175/0x210 [jbd]
[14418.208672]  [<ffffffffa023faf9>] journal_force_commit+0x29/0x30 [jbd]
[14418.208700]  [<ffffffffa02607d7>] ext3_force_commit+0x37/0x40 [ext3]
[14418.208718]  [<ffffffffa02553d4>] ext3_write_inode+0x44/0x60 [ext3]
[14418.208728]  [<ffffffff8030fec5>] __sync_single_inode+0x215/0x2f0
[14418.208737]  [<ffffffff8030fff8>] __writeback_single_inode+0x58/0x1b0
[14418.208745]  [<ffffffff80310186>] sync_inode+0x36/0x60
[14418.208762]  [<ffffffffa0253dec>] ext3_sync_file+0xbc/0xe0 [ext3]
[14418.208769]  [<ffffffff80313e81>] do_fsync+0x71/0xf0
[14418.208776]  [<ffffffff80313f36>] __do_fsync+0x36/0x50
[14418.208783]  [<ffffffff80313f80>] sys_fsync+0x10/0x20
[14418.208793]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14418.208798] 
[14451.492032] INFO: task md1_raid1:2339 blocked for more than 120 seconds.
[14451.492048] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14451.492053] md1_raid1     D ffff88011a09dc88     0  2339      2
[14451.492061]  ffff88011a09dc20 0000000000000046 ffff88011b170ed0 0000000000000001
[14451.492069]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14451.492077]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14451.492083] Call Trace:
[14451.492098]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14451.492107]  [<ffffffff80393ab8>] get_request_wait+0xc8/0x1d0
[14451.492114]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14451.492123]  [<ffffffff8038f7be>] ? elv_merge+0x19e/0x1c0
[14451.492128]  [<ffffffff80393c3e>] __make_request+0x7e/0x420
[14451.492135]  [<ffffffff8023e2f6>] ? __dequeue_entity+0x36/0x90
[14451.492141]  [<ffffffff80392c69>] generic_make_request+0x369/0x490
[14451.492148]  [<ffffffff8024405b>] ? finish_task_switch+0x2b/0xf0
[14451.492154]  [<ffffffff805193a4>] ? thread_return+0x37/0x3c3
[14451.492160]  [<ffffffff8025a564>] ? del_timer+0x64/0x70
[14451.492195]  [<ffffffffa00b2806>] flush_pending_writes+0x86/0xc0 [raid1]
[14451.492204]  [<ffffffffa00b5c09>] raid1d+0x49/0x430 [raid1]
[14451.492227]  [<ffffffffa008aedc>] md_thread+0x5c/0x140 [md_mod]
[14451.492236]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14451.492253]  [<ffffffffa008ae80>] ? md_thread+0x0/0x140 [md_mod]
[14451.492261]  [<ffffffff8026674e>] kthread+0x4e/0x90
[14451.492269]  [<ffffffff80213cc9>] child_rip+0xa/0x11
[14451.492276]  [<ffffffff80266700>] ? kthread+0x0/0x90
[14451.492283]  [<ffffffff80213cbf>] ? child_rip+0x0/0x11
[14451.492288] 
[14451.492328] INFO: task postgres:12994 blocked for more than 120 seconds.
[14451.492334] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14451.492340] postgres      D ffff880028019c90     0 12994   5004
[14451.492353]  ffff8800750f7998 0000000000000082 ffff8800750f7928 ffffffff8039184d
[14451.492372]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14451.492391]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14451.492406] Call Trace:
[14451.492414]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14451.492423]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14451.492432]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14451.492438]  [<ffffffff80519c4a>] __wait_on_bit_lock+0x5a/0x90
[14451.492445]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14451.492452]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14451.492460]  [<ffffffff80519cf9>] out_of_line_wait_on_bit_lock+0x79/0x90
[14451.492467]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14451.492474]  [<ffffffff803152b6>] __lock_buffer+0x36/0x40
[14451.492493]  [<ffffffffa0240e7e>] do_get_write_access+0x8e/0x500 [jbd]
[14451.492501]  [<ffffffff80316d46>] ? __getblk+0x36/0x70
[14451.492521]  [<ffffffffa0241481>] journal_get_write_access+0x31/0x50 [jbd]
[14451.492549]  [<ffffffffa0264fe4>] __ext3_journal_get_write_access+0x34/0x70 [ext3]
[14451.492569]  [<ffffffffa0257463>] ext3_reserve_inode_write+0x93/0xb0 [ext3]
[14451.492587]  [<ffffffffa02574b6>] ext3_mark_inode_dirty+0x36/0x60 [ext3]
[14451.492606]  [<ffffffffa0257651>] ext3_dirty_inode+0x61/0xa0 [ext3]
[14451.492614]  [<ffffffff80310aba>] __mark_inode_dirty+0x3a/0x1d0
[14451.492623]  [<ffffffff802ad18b>] ? file_read_actor+0x4b/0x160
[14451.492632]  [<ffffffff80302418>] touch_atime+0xd8/0x140
[14451.492641]  [<ffffffff802af6f5>] do_generic_file_read+0x445/0x4a0
[14451.492648]  [<ffffffff802ad140>] ? file_read_actor+0x0/0x160
[14451.492656]  [<ffffffff802af821>] generic_file_aio_read+0xd1/0x1b0
[14451.492664]  [<ffffffff802eac79>] do_sync_read+0xf9/0x140
[14451.492672]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14451.492681]  [<ffffffff80387ee8>] ? apparmor_file_permission+0x28/0x30
[14451.492690]  [<ffffffff80362aa6>] ? security_file_permission+0x16/0x20
[14451.492698]  [<ffffffff802eb458>] vfs_read+0xc8/0x130
[14451.492705]  [<ffffffff802eb5c5>] sys_read+0x55/0x90
[14451.492715]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14451.492720] 
[14484.780068] INFO: task exim:12999 blocked for more than 120 seconds.
[14484.780085] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14484.780090] exim          D ffff88011a54e824     0 12999  12998
[14484.780098]  ffff880065913cd8 0000000000000082 ffff88003d22eb40 0000000000001000
[14484.780106]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14484.780114]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14484.780120] Call Trace:
[14484.780158]  [<ffffffffa0245215>] log_wait_commit+0xc5/0x140 [jbd]
[14484.780169]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14484.780183]  [<ffffffffa023f1f5>] journal_stop+0x175/0x210 [jbd]
[14484.780195]  [<ffffffffa023faf9>] journal_force_commit+0x29/0x30 [jbd]
[14484.780220]  [<ffffffffa02607d7>] ext3_force_commit+0x37/0x40 [ext3]
[14484.780236]  [<ffffffffa02553d4>] ext3_write_inode+0x44/0x60 [ext3]
[14484.780245]  [<ffffffff8030fec5>] __sync_single_inode+0x215/0x2f0
[14484.780252]  [<ffffffff8030fff8>] __writeback_single_inode+0x58/0x1b0
[14484.780259]  [<ffffffff80310186>] sync_inode+0x36/0x60
[14484.780274]  [<ffffffffa0253dec>] ext3_sync_file+0xbc/0xe0 [ext3]
[14484.780280]  [<ffffffff80313e81>] do_fsync+0x71/0xf0
[14484.780284]  [<ffffffff80313f36>] __do_fsync+0x36/0x50
[14484.780289]  [<ffffffff80313f80>] sys_fsync+0x10/0x20
[14484.780297]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14484.780300] 
[14518.064040] INFO: task postgres:5406 blocked for more than 120 seconds.
[14518.064055] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14518.064061] postgres      D ffff880028006aa8     0  5406   5004
[14518.064069]  ffff88011a177978 0000000000000086 ffff88011a177908 ffffffff8039184d
[14518.064077]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064085]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064091] Call Trace:
[14518.064103]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14518.064114]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14518.064121]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14518.064126]  [<ffffffff80519c4a>] __wait_on_bit_lock+0x5a/0x90
[14518.064131]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14518.064137]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14518.064142]  [<ffffffff80519cf9>] out_of_line_wait_on_bit_lock+0x79/0x90
[14518.064149]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14518.064155]  [<ffffffff803152b6>] __lock_buffer+0x36/0x40
[14518.064188]  [<ffffffffa0240e7e>] do_get_write_access+0x8e/0x500 [jbd]
[14518.064195]  [<ffffffff80316d46>] ? __getblk+0x36/0x70
[14518.064221]  [<ffffffffa0241481>] journal_get_write_access+0x31/0x50 [jbd]
[14518.064248]  [<ffffffffa0264fe4>] __ext3_journal_get_write_access+0x34/0x70 [ext3]
[14518.064266]  [<ffffffffa0257463>] ext3_reserve_inode_write+0x93/0xb0 [ext3]
[14518.064283]  [<ffffffffa02574b6>] ext3_mark_inode_dirty+0x36/0x60 [ext3]
[14518.064299]  [<ffffffffa0257651>] ext3_dirty_inode+0x61/0xa0 [ext3]
[14518.064305]  [<ffffffff80310aba>] __mark_inode_dirty+0x3a/0x1d0
[14518.064313]  [<ffffffff80302314>] file_update_time+0x114/0x140
[14518.064321]  [<ffffffff802afe0a>] __generic_file_aio_write_nolock+0x22a/0x470
[14518.064328]  [<ffffffff802b015c>] generic_file_aio_write+0x6c/0xd0
[14518.064347]  [<ffffffffa0253c8b>] ext3_file_write+0x2b/0xd0 [ext3]
[14518.064355]  [<ffffffff802eab39>] do_sync_write+0xf9/0x140
[14518.064365]  [<ffffffff8026a94f>] ? hrtimer_start+0xdf/0x1b0
[14518.064373]  [<ffffffff80266b80>] ? autoremove_wake_function+0x0/0x40
[14518.064382]  [<ffffffff80387ee8>] ? apparmor_file_permission+0x28/0x30
[14518.064392]  [<ffffffff80362aa6>] ? security_file_permission+0x16/0x20
[14518.064400]  [<ffffffff802eb1fb>] vfs_write+0xcb/0x130
[14518.064407]  [<ffffffff802eb355>] sys_write+0x55/0x90
[14518.064418]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14518.064423] 
[14518.064430] INFO: task postgres:5413 blocked for more than 120 seconds.
[14518.064435] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14518.064441] postgres      D ffff88002800fb98     0  5413   5004
[14518.064455]  ffff88011ccfda58 0000000000000086 ffff88011ccfd9e8 ffffffff8039184d
[14518.064474]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064493]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064508] Call Trace:
[14518.064515]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14518.064525]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14518.064532]  [<ffffffff803151d5>] sync_buffer+0x45/0x50
[14518.064539]  [<ffffffff80519c4a>] __wait_on_bit_lock+0x5a/0x90
[14518.064546]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14518.064554]  [<ffffffff80315190>] ? sync_buffer+0x0/0x50
[14518.064561]  [<ffffffff80519cf9>] out_of_line_wait_on_bit_lock+0x79/0x90
[14518.064569]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14518.064577]  [<ffffffff803152b6>] __lock_buffer+0x36/0x40
[14518.064592]  [<ffffffffa023f079>] lock_buffer+0x29/0x30 [jbd]
[14518.064607]  [<ffffffffa02408cb>] journal_invalidatepage+0x8b/0xf0 [jbd]
[14518.064625]  [<ffffffffa02559f1>] ext3_invalidatepage+0x41/0x50 [ext3]
[14518.064634]  [<ffffffff802b8e65>] do_invalidatepage+0x25/0x30
[14518.064641]  [<ffffffff802b906a>] truncate_complete_page+0x6a/0x80
[14518.064649]  [<ffffffff802b921e>] truncate_inode_pages_range+0x16e/0x400
[14518.064669]  [<ffffffffa02627c4>] ? __ext3_journal_stop+0x34/0x60 [ext3]
[14518.064678]  [<ffffffff80300241>] ? switch_names+0xc1/0xd0
[14518.064685]  [<ffffffff802b94c5>] truncate_inode_pages+0x15/0x20
[14518.064705]  [<ffffffffa025973d>] ext3_delete_inode+0x1d/0x110 [ext3]
[14518.064724]  [<ffffffffa0259720>] ? ext3_delete_inode+0x0/0x110 [ext3]
[14518.064733]  [<ffffffff80303749>] generic_delete_inode+0xb9/0x180
[14518.064741]  [<ffffffff80303835>] generic_drop_inode+0x25/0x30
[14518.064750]  [<ffffffff803024e2>] iput+0x62/0x70
[14518.064758]  [<ffffffff802ff1f0>] dentry_iput+0x90/0xe0
[14518.064765]  [<ffffffff802ff304>] d_kill+0x44/0x70
[14518.064773]  [<ffffffff80301475>] dput+0x95/0x190
[14518.064781]  [<ffffffff802f750b>] sys_renameat+0x20b/0x240
[14518.064790]  [<ffffffff802cedde>] ? free_pages_and_swap_cache+0x8e/0xb0
[14518.064798]  [<ffffffff803a9358>] ? __up_write+0x68/0x140
[14518.064805]  [<ffffffff802f755b>] sys_rename+0x1b/0x20
[14518.064814]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
[14518.064820] 
[14518.064850] INFO: task firefox:13261 blocked for more than 120 seconds.
[14518.064855] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[14518.064861] firefox       D ffff88002800e068     0 13261      1
[14518.064874]  ffff8800df40fd58 0000000000000082 ffff8800df40fdc8 ffff880000001000
[14518.064893]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064911]  ffffffff807c4400 ffffffff807c4400 ffffffff807c4400 ffffffff807c4400
[14518.064927] Call Trace:
[14518.064934]  [<ffffffff8039184d>] ? blk_unplug+0x3d/0x70
[14518.064943]  [<ffffffff80519767>] io_schedule+0x37/0x50
[14518.064952]  [<ffffffff802adbed>] sync_page+0x3d/0x70
[14518.064959]  [<ffffffff80519d72>] __wait_on_bit+0x62/0x90
[14518.064966]  [<ffffffff802adbb0>] ? sync_page+0x0/0x70
[14518.064974]  [<ffffffff802ade84>] wait_on_page_bit+0x74/0x80
[14518.064982]  [<ffffffff80266bc0>] ? wake_bit_function+0x0/0x50
[14518.064989]  [<ffffffff802b7fc7>] ? pagevec_lookup_tag+0x27/0x40
[14518.064997]  [<ffffffff802ae014>] wait_on_page_writeback_range+0x164/0x1a0
[14518.065004]  [<ffffffff802b6c84>] ? generic_writepages+0x24/0x30
[14518.065009]  [<ffffffff802b6cd5>] ? do_writepages+0x45/0x50
[14518.065018]  [<ffffffff802adb25>] ? __filemap_fdatawrite_range+0x55/0x70
[14518.065025]  [<ffffffff802ae07f>] filemap_fdatawait+0x2f/0x40
[14518.065033]  [<ffffffff80313ed8>] do_fsync+0xc8/0xf0
[14518.065040]  [<ffffffff80313f36>] __do_fsync+0x36/0x50
[14518.065047]  [<ffffffff80313f63>] sys_fdatasync+0x13/0x20
[14518.065055]  [<ffffffff8021288a>] system_call_fastpath+0x16/0x1b
(it continues for some more processes)